技术领域technical field
本发明属于硅微机械传感器技术领域，特别是涉及一种热电堆式气体流量传感器及其制备方法。The invention belongs to the technical field of silicon micromechanical sensors, in particular to a thermopile gas flow sensor and a preparation method thereof.
背景技术Background technique
气体流量是工业生产过程、科学研究和各种经济核算的必要参数，气体流量的测量在工业生产中占有重要的地位。近些年来，由于过程工业、能量计量、城市公用事业对流量测量的需求急剧增长，其中热式流量传感器由于结构简单易于微型化而广泛应用。作为热式流量传感器的典型代表，热电堆式气体流量传感器主要有以下几点优势：温度输入即可作为它的能量输出，不需要电能来将热信号转为电信号；具有自产生效应，有温度差时才会有输出电压，所以输出电压无需补偿和零点漂移；此外，测试时只需电压表，操作便捷。因此，随着MEMS制造技术的不断进步，热电堆式气体流量传感器以其高性能、低成本、易于信号处理等优势在汽车电子、航空航天、生化医学等领域等到广泛应用。Gas flow rate is a necessary parameter for industrial production process, scientific research and various economic calculations. The measurement of gas flow rate plays an important role in industrial production. In recent years, due to the sharp increase in demand for flow measurement in process industries, energy metering, and urban utilities, thermal flow sensors are widely used due to their simple structure and easy miniaturization. As a typical representative of thermal flow sensors, thermopile gas flow sensors have the following advantages: temperature input can be used as its energy output, and no electric energy is needed to convert thermal signals into electrical signals; The output voltage will only be available when the temperature is different, so the output voltage does not need compensation and zero drift; in addition, only a voltmeter is needed for testing, and the operation is convenient. Therefore, with the continuous improvement of MEMS manufacturing technology, thermopile gas flow sensors are widely used in automotive electronics, aerospace, biochemical medicine and other fields due to their advantages of high performance, low cost, and easy signal processing.
热电堆式气体流量传感器的工作原理是基于塞贝克效应(Seebeck Effect)，测量因流体流动引起加热器两端温度非对称的变化量，从而确定流体流速。因此，提高热偶对塞贝克系数和减小器件尺寸是热电堆式气体流量传感器的发展趋势。The working principle of the thermopile gas flow sensor is based on the Seebeck Effect, which measures the asymmetric temperature change at both ends of the heater caused by the fluid flow, thereby determining the fluid flow rate. Therefore, it is the development trend of the thermopile gas flow sensor to improve the Seebeck coefficient of the thermocouple and reduce the device size.
目前受制作工艺限制，在非SOI硅片上多采用塞贝克系数低的多晶硅-金属组合，通过增加热偶对数量或增加热偶对臂长方式来提高传感器检测性能；此外，热电堆式流量传感器多在(100)硅片上以双面微机械加工为主，这样制作的器件检测灵敏度低，并且芯片尺寸较大，制作成本高，不利于批量化制造。Currently limited by the manufacturing process, polysilicon-metal combinations with low Seebeck coefficients are mostly used on non-SOI silicon wafers, and the detection performance of sensors can be improved by increasing the number of thermocouple pairs or increasing the length of thermocouple pairs; in addition, thermopile flow The sensors are mostly processed by double-sided micromachining on (100) silicon wafers. The detection sensitivity of the devices produced in this way is low, and the chip size is large, and the production cost is high, which is not conducive to mass production.
同时，为了降低芯片尺寸、提高检测灵敏度，科学工作者也做了大量研究，但难以兼顾高灵敏度和微型化。At the same time, in order to reduce the size of the chip and improve the detection sensitivity, scientists have also done a lot of research, but it is difficult to balance high sensitivity and miniaturization.
为了降低芯片尺寸，1999年G.Kaltsas等人用P型多晶硅-铝金属作为热偶材料，用多孔硅作为介质层采用单面微机械加工方式制造气体流量传感器[Kaltsas G,Nassiopoulou A.G.Novel C-MOS compatible monolithic silicon gas flow sensorwith porous silicon thermal isolation[J].Sensors and Actuators A:Physical,1999,76(1):133-138.]。这种热电堆式气体流量传感器虽然实现了单硅片单面制作，降低了芯片尺寸，但是这种工艺制备的热电堆式流量传感器具有以下几点不足：(1)无法实现单晶硅-金属热偶臂的制作，导致传感器检测灵敏度受到赛贝克系数限制；(2)多孔硅具有较大的内应力，在空气中长时间会出现不同程度的龟裂现象，会影响传感器的性能；(3)生成多孔硅的化学反应过程复杂，成型状况难以准确控制,这种缺陷会对传感器成品率带来不利影响；(4)这种多孔硅工艺的使用具有局限性，没有IC半导体代加工厂可以运行这样的特殊工艺；(5)多孔硅的热导率要远高于空气，导致所研制的传感器热耗散比较大。In order to reduce the chip size, in 1999, G.Kaltsas et al. used P-type polycrystalline silicon-aluminum metal as the thermocouple material, and used porous silicon as the dielectric layer to manufacture gas flow sensors by single-sided micromachining [Kaltsas G, Nassiopoulou A.G.Novel C- MOS compatible monolithic silicon gas flow sensor with porous silicon thermal isolation[J].Sensors and Actuators A:Physical,1999,76(1):133-138.]. Although this kind of thermopile gas flow sensor realizes single-sided fabrication of a single silicon chip and reduces the chip size, the thermopile flow sensor prepared by this process has the following disadvantages: (1) It is impossible to realize single crystal silicon-metal The production of the thermocouple arm leads to the limitation of the detection sensitivity of the sensor by the Seebeck coefficient; (2) Porous silicon has a large internal stress, and cracks of varying degrees will appear in the air for a long time, which will affect the performance of the sensor; (3) ) The chemical reaction process to generate porous silicon is complex, and the molding conditions are difficult to control accurately. This defect will have an adverse effect on the sensor yield; (4) The use of this porous silicon process has limitations, and no IC semiconductor foundry can Run such a special process; (5) The thermal conductivity of porous silicon is much higher than that of air, resulting in a relatively large heat dissipation of the developed sensor.
为了提高检测灵敏度，2002年IHTM-IMTM公司的D.Randjeloviü等人用塞贝克系数高的p型单晶硅-金作为热偶材料研制气体流量传感器[Randjelovic D,Kaltsas G,LazicZ,et al.Multipurpose thermal sensor based on Seebeck effect[C],Proc.23rdInternational Conference on Microelectronics(MIEL 2002),2002,1:261-264.]。首先在N型硅衬底上重掺杂硼形成30μm宽P型单晶硅热偶臂；然后与金热偶臂组成热偶对；最后通过硅片背面湿法腐蚀减薄单晶硅来形成薄层单晶硅+SiO2隔热介质膜。该器件虽然在一定程度上提高了气体流量传感器的灵敏度，但是仍存在以下几点不足：(1)传感器加热电阻所在的介质膜为薄层单晶硅+SiO2组合而成，由于单晶硅热导系数大，导致传感器热耗散高进而一定程度上降低传感器的检测灵敏度；(2)背面湿法腐蚀减薄硅片到薄层单晶硅+SiO2介质膜，腐蚀时间不易控制，如果腐蚀时间过长会导致热偶对被腐蚀；(3)由(100)硅片湿法腐蚀特性可知，介质膜面积与单晶硅背面掩膜开口区域面积比值很小，硅片厚度越大，芯片尺寸越大，成本越高。In order to improve the detection sensitivity, in 2002, D. Randjeloviü of IHTM-IMTM Company used p-type single crystal silicon-gold with high Seebeck coefficient as the thermocouple material to develop a gas flow sensor [Randjelovic D, Kaltsas G, LazicZ, et al. Multipurpose thermal sensor based on Seebeck effect [C], Proc. 23rd International Conference on Microelectronics (MIEL 2002), 2002, 1:261-264.]. Firstly, boron is heavily doped on the N-type silicon substrate to form a 30μm wide P-type single crystal silicon thermocouple arm; then it forms a thermocouple pair with the gold thermocouple arm; finally, it is formed by thinning the single crystal silicon by wet etching on the back of the silicon wafer Thin-layer monocrystalline silicon + SiO2 thermal insulation dielectric film. Although this device improves the sensitivity of the gas flow sensor to a certain extent, it still has the following disadvantages: (1) The dielectric film where the sensor heating resistor is located is composed of a thin layer of single crystal silicon + SiO2. The large conductivity leads to high heat dissipation of the sensor and reduces the detection sensitivity of the sensor to a certain extent; (2) The backside wet etching thins the silicon wafer to a thin layer of single crystal silicon + SiO2 dielectric film, and the etching time is not easy to control. If the etching time Too long will cause the thermocouple to be corroded; (3) According to the wet etching characteristics of (100) silicon wafers, the ratio of the area of the dielectric film to the area of the opening area of the single crystal silicon back mask is very small, and the larger the thickness of the silicon wafer, the larger the chip size. The bigger, the higher the cost.
综上，传统热电堆式气体流量传感器难以兼顾高灵敏度和微型化。2016年Piotto等人采用P型多晶硅-N型多晶硅作为热偶对研制出一款折中方案的热电堆式气体流量传感器[Massimo Piotto,Francesco Del Cesta,Paolo Bruschi,Integrated smart gas flowsensor with 2.6mW total power consumption and 80dB dynamic range[J].Microelectronic Engineering,2016,159:159-163]。该芯片采用单硅片单面制作，芯片尺寸大大减小。此外，P型多晶硅-N型多晶硅热偶对的赛贝克系数(赛贝克系数约200μV/K)相对于以单晶硅为热偶臂的赛贝克系数(赛贝克系数约450μV/K)虽然要差很多，但是相对于P型多晶硅-金属热偶对要提高不少。因此，相对于以往报道的热电堆式气体流量传感器，Piotto等人研制的传感器除了灵敏度还有待提升外在制作工艺上取得很大的进步。但是，Piotto等人依然没能解决采用普通单晶硅片通过单硅片单面工艺制作P型单晶硅-金属热偶对的技术难题。In summary, traditional thermopile gas flow sensors are difficult to balance high sensitivity and miniaturization. In 2016, Piotto et al. used P-type polysilicon-N-type polysilicon as a thermocouple pair to develop a compromised thermopile gas flow sensor [Massimo Piotto, Francesco Del Cesta, Paolo Bruschi, Integrated smart gas flowsensor with 2.6mW total power consumption and 80dB dynamic range[J].Microelectronic Engineering,2016,159:159-163]. The chip is made on one side of a single silicon chip, and the chip size is greatly reduced. In addition, the Seebeck coefficient of P-type polysilicon-N-type polysilicon thermocouple (Seebeck coefficient is about 200μV/K) is relatively higher than that of single crystal silicon as a thermocouple arm (Seebeck coefficient is about 450μV/K). It is much worse, but compared with the P-type polysilicon-metal thermocouple pair, it is much improved. Therefore, compared with the thermopile gas flow sensor reported in the past, the sensor developed by Piotto et al. has made great progress in the manufacturing process except that the sensitivity needs to be improved. However, Piotto et al. still failed to solve the technical problem of producing P-type monocrystalline silicon-metal thermocouple pairs through a single-sided process of a single silicon wafer using ordinary single crystal silicon wafers.
因此，设计一种可以解决现有技术中热耗散高、尺寸大、成本高、性能低等问题的热电堆式气体流量传感器实属必要。Therefore, it is necessary to design a thermopile gas flow sensor that can solve the problems of high heat dissipation, large size, high cost, and low performance in the prior art.
发明内容Contents of the invention
鉴于以上所述现有技术的缺点，本发明的目的在于提供一种热电堆式气体流量传感器及其制备方法，用于解决现有技术中热电堆式气体流量传感器热耗散高、尺寸大、成本高、性能低等问题。In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a thermopile gas flow sensor and its preparation method, which is used to solve the problem of high heat dissipation, large size, high cost and low performance.
为实现上述目的及其他相关目的，本发明提供一种热电堆式气体流量传感器，包括：To achieve the above purpose and other related purposes, the present invention provides a thermopile gas flow sensor, comprising:
衬底，具有一凹槽，所述凹槽开设于所述衬底的上表面；The substrate has a groove, and the groove is opened on the upper surface of the substrate;
第一介质膜，覆盖于所述凹槽上方，且与所述衬底相连接，所述第一介质膜与所述衬底共同围成一个隔热腔体；a first dielectric film covering the groove and connected to the substrate, the first dielectric film and the substrate jointly enclosing a heat-insulating cavity;
加热元件，位于所述第一介质膜表面；以及a heating element located on the surface of the first dielectric film; and
至少两个感测元件，位于所述第一介质膜上，且设置于所述加热元件的两侧，所述感测元件包括至少一组单晶硅-金属热偶对组，所述单晶硅-金属热偶对组包括若干个单晶硅-金属热偶对。At least two sensing elements are located on the first dielectric film and arranged on both sides of the heating element, the sensing elements include at least one single crystal silicon-metal thermocouple pair group, the single crystal The silicon-metal thermocouple pair group includes several monocrystalline silicon-metal thermocouple pairs.
作为本发明的一种优选方案，所述第一介质膜包括若干个贯穿其上下表面的槽型结构，所述槽型结构与所述单晶硅-金属热偶对组平行设置且交替间隔排布。As a preferred solution of the present invention, the first dielectric film includes several groove structures that run through its upper and lower surfaces, and the groove structures are arranged in parallel with the single crystal silicon-metal thermocouple pairs and alternately spaced apart. cloth.
作为本发明的一种优选方案，所述单晶硅-金属热偶对包括单晶硅热偶臂及金属热偶臂，所述单晶硅热偶臂位于所述第一介质膜靠近所述凹槽一侧的表面，所述金属热偶臂包括垂直部及水平部，所述垂直部贯穿所述第一介质膜与所述单晶硅热偶臂相连接，所述水平部与所述垂直部相连接且位于所述第一介质膜远离所述凹槽一侧的表面。As a preferred solution of the present invention, the single crystal silicon-metal thermocouple pair includes a single crystal silicon thermocouple arm and a metal thermocouple arm, and the single crystal silicon thermocouple arm is located near the first dielectric film On the surface of one side of the groove, the metal thermocouple arm includes a vertical part and a horizontal part, the vertical part passes through the first dielectric film and connects with the monocrystalline silicon thermocouple arm, and the horizontal part is connected to the single crystal silicon thermocouple arm. The vertical portion is connected to and located on a surface of the first dielectric film on a side away from the groove.
作为本发明的一种优选方案，所述加热元件位于所述第一介质膜靠近所述凹槽一侧的表面。As a preferred solution of the present invention, the heating element is located on the surface of the first dielectric film on a side close to the groove.
作为本发明的一种优选方案，所述衬底为(111)单晶硅。As a preferred solution of the present invention, the substrate is (111) single crystal silicon.
作为本发明的一种优选方案，所述第一介质膜包括自下而上依次叠置的TEOS钝化层及氮化硅层，所述第一介质膜与所述衬底之间还包括氧化层。As a preferred solution of the present invention, the first dielectric film includes a TEOS passivation layer and a silicon nitride layer stacked sequentially from bottom to top, and an oxide layer is also included between the first dielectric film and the substrate. Floor.
作为本发明的一种优选方案，所述加热元件沿<110>晶向排布，所述单晶硅-金属热偶对沿<211>晶向排布。As a preferred solution of the present invention, the heating elements are arranged along the <110> crystal direction, and the single crystal silicon-metal thermocouple pairs are arranged along the <211> crystal direction.
作为本发明的一种优选方案，还包括第二介质膜，所述第二介质膜覆盖于所述单晶硅-金属热偶对组及其周围的所述第一介质膜的上表面，用于保护所述单晶硅-金属热偶对。As a preferred solution of the present invention, it also includes a second dielectric film, the second dielectric film covers the upper surface of the single crystal silicon-metal thermocouple pair group and the surrounding first dielectric film, To protect the monocrystalline silicon-metal thermocouple pair.
作为本发明的一种优选方案，还包括若干个引线焊盘，位于所述衬底上，且设置于所述加热元件及每个所述感测元件的两端。As a preferred solution of the present invention, it also includes several lead pads located on the substrate and arranged at both ends of the heating element and each of the sensing elements.
作为本发明的一种优选方案，还包括环境电阻元件，设置于所述衬底上。As a preferred solution of the present invention, it also includes an environmental resistance element disposed on the substrate.
作为本发明的一种优选方案，所述环境电阻元件、所述加热元件以及所述单晶硅-金属热偶对中的单晶硅热偶臂均为硼掺杂的单晶硅。As a preferred solution of the present invention, the environmental resistance element, the heating element and the single crystal silicon thermocouple arm in the single crystal silicon-metal thermocouple pair are all boron-doped single crystal silicon.
本发明还提供一种热电堆式气体流量传感器的制备方法，所述制备方法为本发明所述提供的热电堆式气体流量传感器的制备方法，包括如下步骤：The present invention also provides a method for preparing a thermopile gas flow sensor, which is the method for preparing a thermopile gas flow sensor provided in the present invention, comprising the following steps:
1)提供一衬底，并于所述衬底上定义出加热元件区以及至少两个感测元件区，所述感测元件区位于所述加热元件区两侧，且包括至少一个单晶硅-金属热偶对组区，所述单晶硅-金属热偶对组区包括若干个单晶硅-金属热偶对区；1) Provide a substrate, and define a heating element area and at least two sensing element areas on the substrate, the sensing element areas are located on both sides of the heating element area and include at least one single crystal silicon - a metal thermocouple pair group area, the monocrystalline silicon-metal thermocouple pair group area includes several single crystal silicon-metal thermocouple pair areas;
2)刻蚀所述衬底以形成第一沟槽，用于定义出加热元件以及单晶硅-金属热偶对中的单晶硅热偶臂所在的位置及厚度；2) Etching the substrate to form a first groove, which is used to define the position and thickness of the heating element and the single crystal silicon thermocouple arm in the single crystal silicon-metal thermocouple pair;
3)于所述第一沟槽侧壁形成侧壁保护层，并于形成有所述侧壁保护层的所述第一沟槽内沉积牺牲层；3) forming a sidewall protection layer on the sidewall of the first trench, and depositing a sacrificial layer in the first trench on which the sidewall protection layer is formed;
4)于步骤3)所得到的结构表面沉积第一介质膜材料层，并刻蚀所述第一介质膜材料层至暴露出所述加热元件对应的衬底区域以形成加热元件连接孔，且暴露出所述单晶硅-金属热偶对中的单晶硅热偶臂对应的衬底区域以形成单晶硅热偶臂连接孔；4) depositing a first dielectric film material layer on the surface of the structure obtained in step 3), and etching the first dielectric film material layer to expose the substrate region corresponding to the heating element to form a heating element connection hole, and Exposing the substrate region corresponding to the single crystal silicon thermocouple arm in the single crystal silicon-metal thermocouple pair to form a single crystal silicon thermocouple arm connection hole;
5)于步骤4)所得到的结构的表面沉积金属层并对其图形化，以形成所述单晶硅-金属热偶对中的金属热偶臂，所述金属热偶臂包括垂直部及水平部，所述垂直部贯穿所述第一介质膜材料层，所述水平部与所述垂直部相连接且位于所述第一介质膜材料层表面；5) Depositing a metal layer on the surface of the structure obtained in step 4) and patterning it to form the metal thermocouple arm in the single crystal silicon-metal thermocouple pair, the metal thermocouple arm comprising a vertical portion and a horizontal part, the vertical part runs through the first dielectric film material layer, the horizontal part is connected to the vertical part and is located on the surface of the first dielectric film material layer;
6)刻蚀步骤5)得到的结构以形成第二沟槽，所述第二沟槽位于相邻所述单晶硅-金属热偶对组区之间和/或所述单晶硅-金属热偶对组区与所述衬底之间；6) Etching the structure obtained in step 5) to form a second groove, the second groove is located between adjacent regions of the monocrystalline silicon-metal thermocouple pairs and/or the monocrystalline silicon-metal Between the thermocouple pair group area and the substrate;
7)以所述第二沟槽为窗口腐蚀部分所述衬底形成隔热腔体，以释放所述第一介质膜、和所述单晶硅热偶臂，其中，所述第一介质膜与所述衬底相连接，并与所述衬底共同围成所述隔热腔体，所述单晶硅热偶臂与所述金属热偶臂构成所述单晶硅-金属热偶对，并形成感测元件。7) using the second trench as a window to etch part of the substrate to form a heat-insulating cavity to release the first dielectric film and the single crystal silicon thermocouple arm, wherein the first dielectric film It is connected with the substrate and together with the substrate to form the thermal insulation cavity, the monocrystalline silicon thermocouple arm and the metal thermocouple arm constitute the monocrystalline silicon-metal thermocouple pair , and form the sensing element.
作为本发明的一种优选方案，步骤1)与步骤2)之间，还包括对所述加热元件区以及所述感测元件区进行硼掺杂的步骤。As a preferred solution of the present invention, between step 1) and step 2), a step of boron doping the heating element region and the sensing element region is further included.
作为本发明的一种优选方案，进行所述硼掺杂工艺后，还包括对硼掺杂后的结构进行退火的步骤。As a preferred solution of the present invention, after performing the boron doping process, a step of annealing the boron-doped structure is also included.
作为本发明的一种优选方案，步骤3)中，于所述第一沟槽的侧壁形成侧壁保护层的具体步骤为：As a preferred solution of the present invention, in step 3), the specific steps of forming a sidewall protection layer on the sidewall of the first trench are:
3-1)于步骤2)得到的结构表面沉积侧壁保护材料层，所述侧壁材料保护层包括自下而上依次沉积的TEOS层和氮化硅层；3-1) Depositing a sidewall protection material layer on the surface of the structure obtained in step 2), the sidewall material protection layer comprising a TEOS layer and a silicon nitride layer deposited sequentially from bottom to top;
3-2)去除所述第一沟槽底部及其周围的所述衬底上的所述侧壁保护材料层，以形成位于所述第一沟槽侧壁的侧壁保护层。3-2) removing the sidewall protection material layer on the substrate at the bottom of the first trench and its surroundings, so as to form a sidewall protection layer on the sidewall of the first trench.
作为本发明的一种优选方案，步骤5)与步骤6)之间，还包括于步骤5)所得到的结构表面沉积第二介质膜材料层的步骤，所述第二介质膜材料层用于保护所述感测元件。As a preferred solution of the present invention, between step 5) and step 6), the step of depositing a second dielectric film material layer on the surface of the structure obtained in step 5) is also included, and the second dielectric film material layer is used for protect the sensing element.
作为本发明的一种优选方案，步骤6)中，形成所述第二沟槽的具体步骤包括：As a preferred solution of the present invention, in step 6), the specific steps of forming the second groove include:
6-1)刻蚀所述第二沟槽所在区域的第一介质膜材料层；6-1) etching the first dielectric film material layer in the region where the second trench is located;
6-2)沿所述第二沟槽所在区域继续刻蚀预定深度，以形成所述第二沟槽。6-2) Continue etching to a predetermined depth along the area where the second trench is located, so as to form the second trench.
作为本发明的一种优选方案，步骤1)中所述衬底为(111)单晶硅，步骤7)中所采用的腐蚀溶液为四甲基氢氧化氨溶液。As a preferred solution of the present invention, the substrate in step 1) is (111) single crystal silicon, and the etching solution used in step 7) is tetramethylammonium hydroxide solution.
作为本发明的一种优选方案，步骤7)中，释放的所述第一介质膜包括若干个槽型结构，其中，所述槽型结构由所述第二沟槽形成，所述槽型结构与所述单晶硅-金属热偶对组平行设置且交替间隔排布。As a preferred solution of the present invention, in step 7), the released first dielectric film includes several groove structures, wherein the groove structures are formed by the second grooves, and the groove structures It is arranged in parallel with the single crystal silicon-metal thermocouple pair group and arranged alternately and at intervals.
如上所述，本发明的热电堆式气体流量传感器及其制备方法，具有以下有益效果：As mentioned above, the thermopile gas flow sensor of the present invention and its preparation method have the following beneficial effects:
1)本发明通过巧妙的结构设计和创新的单芯片单面制作技术，在普通(111)单晶硅片上加工出赛贝克系数最高的P型单晶硅-金热偶对；1) The present invention processes a P-type single crystal silicon-gold thermocouple pair with the highest Seebeck coefficient on an ordinary (111) single crystal silicon wafer through ingenious structural design and innovative single-chip single-side manufacturing technology;
2)本发明的热电堆式气体流量传感器将热偶对以及加热元件通过位于其正下方的隔热腔体与衬底隔离，最大程度降低了加热电阻的热耗散，大大提高了传感器的检测灵敏度；2) The thermopile gas flow sensor of the present invention isolates the thermocouple pair and the heating element from the substrate through the heat insulation cavity directly below it, which minimizes the heat dissipation of the heating resistor and greatly improves the detection of the sensor. sensitivity;
3)本发明的整个流量传感器都是从单晶硅片的同一表面进行加工制作，因此芯片尺寸小，成本低，适于大批量生产。3) The entire flow sensor of the present invention is manufactured from the same surface of the monocrystalline silicon wafer, so the chip size is small, the cost is low, and it is suitable for mass production.
附图说明Description of drawings
图1显示为本发明提供的热电堆式气体流量传感器的全局结构示意图。Fig. 1 shows a schematic diagram of the overall structure of the thermopile gas flow sensor provided by the present invention.
图2显示为本发明提供的热电堆式气体流量传感器三维结构剖面示意图。Fig. 2 shows a schematic cross-sectional view of the three-dimensional structure of the thermopile gas flow sensor provided by the present invention.
图3至图14显示为本发明的热电堆式气体流量传感器的制备工艺各步骤的结构示意图：Fig. 3 to Fig. 14 are shown as the structural diagram of each step of the preparation process of the thermopile type gas flow sensor of the present invention:
图3显示为本发明的气体流量传感器制备过程中提供衬底的结构示意图；Fig. 3 shows the structural representation of the substrate provided during the preparation of the gas flow sensor of the present invention;
图4显示为本发明的气体流量传感器制备过程中定义加热元件及感测元件结构示意图；Fig. 4 shows the schematic diagram of the structure of the heating element and the sensing element defined in the preparation process of the gas flow sensor of the present invention;
图5显示为本发明的气体流量传感器制备过程中形成第一沟槽的结构示意图；FIG. 5 shows a schematic structural view of the formation of the first groove during the preparation process of the gas flow sensor of the present invention;
图6显示为本发明的气体流量传感器制备过程中沉积侧壁保护材料层的结构示意图；Fig. 6 is a schematic structural diagram of depositing a sidewall protection material layer during the preparation process of the gas flow sensor of the present invention;
图7显示为本发明的气体流量传感器制备过程中形成侧壁保护层的结构示意图；FIG. 7 is a schematic structural view showing the formation of a sidewall protection layer during the preparation of the gas flow sensor of the present invention;
图8显示为本发明的气体流量传感器制备过程中形成多晶硅牺牲层的结构示意图；Fig. 8 is a schematic diagram showing the structure of a polysilicon sacrificial layer formed during the preparation of the gas flow sensor of the present invention;
图9显示为本发明的气体流量传感器制备过程中形成第一介质膜材料层的结构示意图；Fig. 9 is a schematic structural view showing the formation of the first dielectric film material layer during the preparation process of the gas flow sensor of the present invention;
图10显示为本发明的气体流量传感器制备过程中形成单晶硅连接孔的结构示意图；Fig. 10 is a schematic diagram showing the structure of a single crystal silicon connection hole formed during the preparation process of the gas flow sensor of the present invention;
图11显示为本发明的气体流量传感器制备过程中形成金属热偶臂的结构示意图；FIG. 11 shows a schematic structural view of forming a metal thermocouple arm during the preparation process of the gas flow sensor of the present invention;
图12显示为本发明的气体流量传感器制备过程中形成第二介质材料层的结构示意图；Fig. 12 is a schematic structural diagram of forming a second dielectric material layer during the preparation process of the gas flow sensor of the present invention;
图13显示为本发明的气体流量传感器制备过程中形成第二沟槽的结构示意图；Fig. 13 shows a schematic structural view of forming a second groove during the preparation process of the gas flow sensor of the present invention;
图14显示为本发明的气体流量传感器制备过程中腐蚀释放隔热腔体的结构示意图；Fig. 14 shows a schematic structural diagram of a corrosion-release heat-insulating cavity during the preparation process of the gas flow sensor of the present invention;
图15显示为本发明的热电堆式气体流量传感器制备过程中的各步骤工艺流程图。Fig. 15 shows a process flow chart of each step in the preparation process of the thermopile gas flow sensor of the present invention.
元件标号说明Component designation description
1 衬底1 substrate
11 凹槽11 grooves
12 硼离子注入区12 Boron ion implantation area
13 氧化层13 oxide layer
14 第一沟槽14 First groove
141 侧壁保护层141 Sidewall protective layer
1411 TEOS层1411 TEOS layer
1412 氮化硅层1412 silicon nitride layer
142 多晶硅牺牲层142 polysilicon sacrificial layer
2 第一介质膜2 The first dielectric film
21 槽型结构21 groove structure
22 第一介质膜材料层22 The first dielectric film material layer
221 氮化硅层221 silicon nitride layer
222 TEOS钝化层222 TEOS passivation layer
23 单晶硅连接孔23 Single crystal silicon connection hole
3 加热元件3 heating elements
4 感测元件4 sensing element
41 单晶硅-金属热偶对组41 single crystal silicon - metal thermocouple pair
411 单晶硅-金属热偶对411 single crystal silicon - metal thermocouple pair
4111 金属热偶臂4111 Metal Thermocouple Arm
4112 单晶硅热偶臂4112 Monocrystalline Silicon Thermocouple Arm
5 环境电阻元件5 Environmental resistance element
6 引线焊盘6 lead pad
7 第二介质膜7 Second Dielectric Film
71 第二介质膜材料层71 The second dielectric film material layer
8 第二沟槽8 Second groove
S1～S7 步骤S1～S7 steps
具体实施方式Detailed ways
以下通过特定的具体实例说明本发明的实施方式，本领域技术人员可由本说明书所揭露的内容轻易地了解本发明的其他优点与功效。本发明还可以通过另外不同的具体实施方式加以实施或应用，本说明书中的各项细节也可以基于不同观点与应用，在没有背离本发明的精神下进行各种修饰或改变。Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.
请参阅图1至图15。需要说明的是，本实施例中所提供的图示仅以示意方式说明本发明的基本构想，虽图示中仅显示与本发明中有关的组件而非按照实际实施时的组件数目、形状及尺寸绘制，其实际实施时各组件的形态、数量及比例可为一种随意的改变，且其组件布局形态也可能更为复杂。See Figures 1 through 15. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic concept of the present invention, although only the components related to the present invention are shown in the diagrams rather than the number, shape and Dimensional drawing, the shape, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the layout of the components may also be more complicated.
如图1、图2及图14所示，本发明提供一种热电堆式气体流量传感器，包括：As shown in Figure 1, Figure 2 and Figure 14, the present invention provides a thermopile gas flow sensor, comprising:
衬底1，具有一凹槽11，所述凹槽11开设于所述衬底1的上表面；The substrate 1 has a groove 11, and the groove 11 is opened on the upper surface of the substrate 1;
第一介质膜2，覆盖于所述凹槽11上方，且与所述衬底1相连接，所述第一介质膜2与所述衬底1共同围成一个隔热腔体；The first dielectric film 2 covers the groove 11 and is connected to the substrate 1, and the first dielectric film 2 and the substrate 1 together form a heat-insulating cavity;
加热元件3，位于所述第一介质膜2表面；以及a heating element 3 located on the surface of the first dielectric film 2; and
至少两个感测元件4，位于所述第一介质膜2上，且设置于所述加热元件3的两侧，所述感测元件包括至少一组单晶硅-金属热偶对组41，所述单晶硅-金属热偶对组41包括若干个单晶硅-金属热偶对411。At least two sensing elements 4 are located on the first dielectric film 2 and arranged on both sides of the heating element 3, and the sensing elements include at least one single crystal silicon-metal thermocouple pair group 41, The single crystal silicon-metal thermocouple pair group 41 includes several single crystal silicon-metal thermocouple pairs 411 .
具体的，在本实施例中，所述加热元件3可以为加热电阻，所述感测元件4位于所述加热元件3的两侧，即上下游的位置，分别组成上、下游两个独立的热电堆检测电路。其中，所述单晶硅-金属热偶对组41可以为一组或者两组或多组，依实际需求而定，当单晶硅-金属热偶对组41为两组或多组时，所述单晶硅-金属热偶对组41首位连接，构成完整的检测线路。进一步，所述单晶硅-金属热偶对组41可以包含任意个单晶硅-金属热偶对411，如2～100个，依实际需求而定，在此不做具体限制，本实施例中选择为7个。Specifically, in this embodiment, the heating element 3 can be a heating resistor, and the sensing element 4 is located on both sides of the heating element 3, that is, the upstream and downstream positions, respectively forming two independent upstream and downstream Thermopile detection circuit. Wherein, the single crystal silicon-metal thermocouple pair group 41 can be one group or two or more groups, depending on actual needs, when the single crystal silicon-metal thermocouple pair group 41 is two or more groups, The single crystal silicon-metal thermocouple pair group 41 is first connected to form a complete detection circuit. Further, the single crystal silicon-metal thermocouple pair group 41 may include any number of single crystal silicon-metal thermocouple pairs 411, such as 2 to 100, depending on actual needs, and no specific limitation is made here. Choose from 7.
具体的，所述第一介质膜2的尺寸518μm×350μm×1.3μm，且所构成的隔热腔体的深度为40～60μm，优选为50μm，所述单晶硅-金属热偶对采用P型单晶硅-金金属材料组成，上、下游两个独立的热电堆均有21对热偶对组成，其中热偶对长度为100～180μm，优选为144μm，宽度为1～5μm，优选为3μm，厚度为0.1～0.8μm，优选为0.3μm，所述加热元件的总长度为300～380μm，优选为340μm，宽度为8～12μm，优选为10μm，其厚度为0.1～0.5μm，优选为0.3μm。Specifically, the size of the first dielectric film 2 is 518 μm × 350 μm × 1.3 μm, and the depth of the formed heat insulation cavity is 40-60 μm, preferably 50 μm, and the single crystal silicon-metal thermocouple adopts P Type monocrystalline silicon-gold metal material, the two independent thermopiles upstream and downstream are composed of 21 pairs of thermocouples, wherein the length of the thermocouples is 100-180 μm, preferably 144 μm, and the width is 1-5 μm, preferably 3 μm, the thickness is 0.1-0.8 μm, preferably 0.3 μm, the total length of the heating element is 300-380 μm, preferably 340 μm, the width is 8-12 μm, preferably 10 μm, and its thickness is 0.1-0.5 μm, preferably 0.3 μm.
另外，本申请的热电堆式气体流量传感器的隔热腔体的设置使所述加热元件以及所述感测元件完全悬空与所述衬底，减少了本申请的硅体散热，在本实施例中，所述加热元件为加热电阻，所述感测元件包括P型单晶硅-金金属热偶对。In addition, the thermal insulation cavity of the thermopile gas flow sensor of the present application is set so that the heating element and the sensing element are completely suspended from the substrate, which reduces the heat dissipation of the silicon body of the present application. In this embodiment Wherein, the heating element is a heating resistor, and the sensing element includes a P-type single crystal silicon-gold metal thermocouple pair.
作为示例，所述第一介质膜2包括若干个贯穿其上下表面的槽型结构21，所述槽型结构21与所述单晶硅-金属热偶对组41平行设置且交替间隔排布。As an example, the first dielectric film 2 includes several groove structures 21 running through its upper and lower surfaces, and the groove structures 21 are arranged in parallel with the single crystal silicon-metal thermocouple pairs 41 and alternately arranged at intervals.
具体的，所述槽型结构21使相邻所述单晶硅-金属热偶对组41之间以及所述单晶硅-金属热偶对组41与所述衬底1之间物理隔开，也就是说，各所述单晶硅-金属热偶对组41所对应的所述第一介质膜2是相互隔开的，并且设置所述单晶硅-金属热偶对组41的第一介质膜和不设置热偶对组的第一介质膜部分也是互相隔开的，也就实现了所述单晶硅-金属热偶对41与衬底的物理隔离，从而可以防止热量在介质膜之间传递，也就是说，使所述感测元件4的各单晶硅-热偶对组41之间完全通过空气相隔离，从而减少了本申请的硅体散热，提高了传感器的性能。另外，所述槽型结构21还可以设置于所述加热元件与所述感测元件之间的所述第一介质膜上，从而使二者通过空气相隔离，减少热损耗。Specifically, the groove structure 21 physically separates the adjacent single crystal silicon-metal thermocouple pairs 41 and between the single crystal silicon-metal thermocouple pairs 41 and the substrate 1 That is to say, the first dielectric film 2 corresponding to each single crystal silicon-metal thermocouple pair group 41 is separated from each other, and the first dielectric film 2 of the single crystal silicon-metal thermocouple pair group 41 is set A dielectric film and the part of the first dielectric film that is not provided with the thermocouple pair group are also separated from each other, which realizes the physical isolation of the single crystal silicon-metal thermocouple pair 41 from the substrate, thereby preventing heat from flowing in the medium Transfer between the films, that is to say, to completely isolate the single crystal silicon-thermocouple pair groups 41 of the sensing element 4 through air, thereby reducing the heat dissipation of the silicon body of the present application and improving the performance of the sensor . In addition, the trough structure 21 may also be disposed on the first dielectric film between the heating element and the sensing element, so that the two are separated by air to reduce heat loss.
作为示例，所述单晶硅-金属热偶对411包括单晶硅热偶臂4112及金属热偶臂4111，所述单晶硅热偶臂4112位于所述第一介质膜2靠近所述凹槽11一侧的表面，所述金属热偶臂4111包括垂直部及水平部，所述垂直部贯穿所述第一介质膜2与所述单晶硅热偶臂4111相连接，所述水平部与所述垂直部相连接且位于所述第一介质膜2远离所述凹槽一侧的表面。As an example, the single crystal silicon-metal thermocouple pair 411 includes a single crystal silicon thermocouple arm 4112 and a metal thermocouple arm 4111, and the single crystal silicon thermocouple arm 4112 is located at the first dielectric film 2 close to the concave The surface on one side of the groove 11, the metal thermocouple arm 4111 includes a vertical part and a horizontal part, the vertical part penetrates the first dielectric film 2 and connects with the single crystal silicon thermocouple arm 4111, and the horizontal part The surface connected to the vertical portion and located on the side of the first dielectric film 2 away from the groove.
作为示例，所述加热元件3位于所述第一介质膜2靠近所述凹槽11一侧的表面。As an example, the heating element 3 is located on the surface of the first dielectric film 2 close to the groove 11 .
具体的，在本实施例中，所述加热元件3以及所述单晶硅-金属热偶对411中的所述单晶硅热偶臂4112位于所述第一介质膜2的同一侧，而所述金属热偶臂4111位于与二者相对的所述第一介质膜2的另一侧，所述加热元件3与所述单晶硅热偶臂4112位于所述第一介质膜2的同侧，且位于靠近所述凹槽11的一侧，有利于减少热损耗，进一步保证热电堆式气体流量传感器的灵敏度，提高器件性能。另外，本实施例中所述单晶硅热偶臂可以为不同类型掺杂的单晶硅，所述金属热偶臂也可以为Pt、Ni、Au、Al、Cu等各种金属材料，在此不做具体限制。Specifically, in this embodiment, the heating element 3 and the single crystal silicon thermocouple arm 4112 in the single crystal silicon-metal thermocouple pair 411 are located on the same side of the first dielectric film 2, and The metal thermocouple arm 4111 is located on the opposite side of the first dielectric film 2, and the heating element 3 and the single crystal silicon thermocouple arm 4112 are located on the same side of the first dielectric film 2. side, and located on the side close to the groove 11, which is beneficial to reduce heat loss, further ensure the sensitivity of the thermopile gas flow sensor, and improve device performance. In addition, the monocrystalline silicon thermocouple arms in this embodiment can be single crystal silicon doped with different types, and the metal thermocouple arms can also be various metal materials such as Pt, Ni, Au, Al, Cu, etc. There is no specific limitation here.
作为示例，所述衬底1为(111)单晶硅。As an example, the substrate 1 is (111) single crystal silicon.
具体的，所述衬底1可以为单晶硅、多晶硅、金属衬低、有机衬低、PCB衬低等各种衬低材料，在本实施例中，采用(111)单晶硅衬底，进一步可以为N型(或P型)的(111)晶面的单面(或双面)抛光的硅片，其可以改善传统的硅片(如(100)硅片)的诸多缺陷，如由(100)硅片湿法腐蚀特性可知，介质膜面积与单晶硅背面掩膜开口区域面积比值很小，硅片厚度越大，芯片尺寸越大，成本越高，并且所述加热元件和所述热敏元件所在的梁式结构需要沿(110)晶向偏斜一定的夹角才能实现梁结构湿法腐蚀释放，这就导致了传感器后续安装定位比较困难。Specifically, the substrate 1 can be a variety of substrate materials such as single crystal silicon, polycrystalline silicon, metal substrate, organic substrate, PCB substrate, etc. In this embodiment, a (111) single crystal silicon substrate is used, Further, it can be a single-sided (or double-sided) polished silicon wafer of N-type (or P-type) (111) crystal plane, which can improve many defects of traditional silicon wafers (such as (100) silicon wafers), such as by (100) Wet etching characteristics of silicon wafers shows that the ratio of the area of the dielectric film to the area of the opening area of the single crystal silicon back mask is very small, the larger the thickness of the silicon wafer, the larger the chip size, and the higher the cost, and the heating element and the The beam structure where the thermal sensor is located needs to be deflected at a certain angle along the (110) crystal direction to realize the wet corrosion release of the beam structure, which makes the subsequent installation and positioning of the sensor more difficult.
作为示例，所述加热元件3沿<110>晶向排布，所述单晶硅-金属热偶对411沿<211>晶向排布。As an example, the heating elements 3 are arranged along the <110> crystal direction, and the single crystal silicon-metal thermocouple pairs 411 are arranged along the <211> crystal direction.
具体的，本发明的所述第一介质膜单元的设计，使加热元件3沿着<110>晶向排布，使所述单晶硅-金属热偶对411沿<211>晶向排布，从而保证了本发明的器件结构可以适应尺寸的缩小，保证了传感器的性能。另外，本实施例中，优选所述感测元件4于所述加热元件3两侧均匀对称分布，保证了传感器在使用过程中的热场的均匀分布，进一步提高了气体流量传感器的检测性能。Specifically, in the design of the first dielectric film unit of the present invention, the heating elements 3 are arranged along the <110> crystal direction, and the single crystal silicon-metal thermocouple pairs 411 are arranged along the <211> crystal direction , thereby ensuring that the device structure of the present invention can adapt to size reduction and ensure the performance of the sensor. In addition, in this embodiment, preferably, the sensing elements 4 are evenly and symmetrically distributed on both sides of the heating element 3, which ensures the uniform distribution of the thermal field of the sensor during use and further improves the detection performance of the gas flow sensor.
作为示例，所述第一介质膜2包括自下而上依次叠置的TEOS钝化层222及氮化硅层221，所述第一介质膜与所述衬底之间还包括氧化层。As an example, the first dielectric film 2 includes a TEOS passivation layer 222 and a silicon nitride layer 221 sequentially stacked from bottom to top, and an oxide layer is further included between the first dielectric film and the substrate.
作为示例，还包括第二介质膜7，所述第二介质膜7覆盖于所述单晶硅-金属热偶对组41及其周围所述第一介质膜2的上表面，用于保护所述单晶硅-金属热偶对。As an example, a second dielectric film 7 is also included, and the second dielectric film 7 covers the upper surface of the single crystal silicon-metal thermocouple pair group 41 and the first dielectric film 2 around it, for protecting all The single crystal silicon-metal thermocouple pair.
具体的，所述第一介质膜包括低应力的TEOS钝化层222及低应力的氮化硅层221，其中，所述TEOS钝化层为低应力TEOS(正硅酸乙酯，Si(OC2H5)4)钝化层。另外，当对本申请的定义了加热元件以及感测元件区的衬底进行退火后，还包括形成在所述第一介质膜与所述衬底之间的氧化层13，在其他实施例中，所述氧化层的形成工艺并不局限为退火工艺，还可以为沉积等工艺。Specifically, the first dielectric film includes a low-stress TEOS passivation layer 222 and a low-stress silicon nitride layer 221, wherein the TEOS passivation layer is a low-stress TEOS (orthoethyl silicate, Si(OC2 H5 )4 ) Passivation layer. In addition, after annealing the substrate defining the heating element and the sensing element region of the present application, an oxide layer 13 formed between the first dielectric film and the substrate is also included. In other embodiments, The formation process of the oxide layer is not limited to an annealing process, and may also be a process such as deposition.
具体的，本实施例中，还包括设置在所述感测元件4外围的第二介质膜7，所述第二介质膜7可以是二氧化硅保护层，也可以是氮化硅膜、二氧化硅和氮化硅复合膜、有机薄膜等各种具有绝缘特性的薄膜材料，其目的是与第一介质膜共同将部分所述单晶硅-金属热偶对包覆，以保护所有金属电阻结构不受外界影响，以增加器件的长期稳定性和可靠性。Specifically, in this embodiment, a second dielectric film 7 disposed on the periphery of the sensing element 4 is also included, and the second dielectric film 7 may be a silicon dioxide protective layer, or a silicon nitride film, two Silicon oxide and silicon nitride composite film, organic film and other thin film materials with insulating properties, the purpose of which is to cover part of the single crystal silicon-metal thermocouple together with the first dielectric film to protect all metal resistance The structure is protected from external influences to increase the long-term stability and reliability of the device.
作为示例，还包括若干个引线焊盘6，位于所述衬底1上，且设置于所述加热元件3及每个所述感测元件4的两端。As an example, it also includes several lead pads 6 located on the substrate 1 and arranged at both ends of the heating element 3 and each of the sensing elements 4 .
作为示例，还包括环境电阻元件5，设置于所述衬底1上。As an example, an environmental resistance element 5 is also included, disposed on the substrate 1 .
作为示例，所述环境电阻元件5、所述加热元件3以及所述单晶硅-金属热偶对411中的单晶硅热偶臂4112均为硼掺杂的单晶硅。As an example, the environmental resistance element 5 , the heating element 3 and the single crystal silicon thermocouple arm 4112 in the single crystal silicon-metal thermocouple pair 411 are all boron-doped single crystal silicon.
具体的，本发明还包括环境电阻元件5，环境的温度可以直接利用所述环境电阻元件5直接测量和补偿，从而可以消除气体温度波动对测量结果的影响，从而提高流量检测的精度。优选地，所述环境电阻元件沿<110>晶向排布。另外，所述环境电阻元件5、所述加热元件3以及所述单晶硅-金属热偶对411中的单晶硅热偶臂4112优选为浓硼掺杂，以进一步提高器件性能。Specifically, the present invention also includes an environmental resistance element 5, and the temperature of the environment can be directly measured and compensated by the environmental resistance element 5, so that the influence of gas temperature fluctuations on the measurement results can be eliminated, thereby improving the accuracy of flow detection. Preferably, the environmental resistance elements are arranged along the <110> crystal direction. In addition, the environmental resistance element 5 , the heating element 3 and the single crystal silicon thermocouple arm 4112 in the single crystal silicon-metal thermocouple pair 411 are preferably doped with concentrated boron to further improve device performance.
如图1～15所示，本发明还提供一种热电堆式气体流量传感器的制备方法，所述制备方法为本发明所述提供的热电堆式气体流量传感器的制备方法，包括如下步骤：As shown in Figures 1 to 15, the present invention also provides a method for preparing a thermopile gas flow sensor, which is a method for preparing a thermopile gas flow sensor provided in the present invention, including the following steps:
如图3～4及图15中的S1所示，1)提供一衬底1，并于所述衬底1上定义出加热元件区以及至少两个感测元件区，所述感测元件区位于所述加热元件区两侧，且包括至少一个单晶硅-金属热偶对组区，所述单晶硅-金属热偶对组区包括若干个单晶硅-金属热偶对区；As shown in Figures 3-4 and S1 in Figure 15, 1) a substrate 1 is provided, and a heating element area and at least two sensing element areas are defined on the substrate 1, and the sensing element area Located on both sides of the heating element area, and including at least one single crystal silicon-metal thermocouple pair group area, the single crystal silicon-metal thermocouple pair group area includes several single crystal silicon-metal thermocouple pair areas;
具体的，所述加热元件区用于形成加热元件3，所述感测元件区用于形成感测元件4，所述感测元件4位于所述加热元件3的两侧，即上下游的位置，分别组成上、下游两个独立的热电堆检测电路。所述单晶硅-金属热偶对组41可以为一组或者两组或多组，依实际需求而定，当单晶硅-金属热偶对组41为两组或多组时，所述单晶硅-金属热偶对组41首位连接，构成完成的检测线路。进一步，所述单晶硅-金属热偶对组41可以包含任意个单晶硅-金属热偶对411，如2～100个，依实际需求而定，在此不做具体限制，本实施例中选择为7个。Specifically, the heating element area is used to form the heating element 3, and the sensing element area is used to form the sensing element 4, and the sensing element 4 is located on both sides of the heating element 3, that is, upstream and downstream. , respectively constitute the upstream and downstream two independent thermopile detection circuits. The single crystal silicon-metal thermocouple pair group 41 can be one group or two or more groups, depending on actual needs, when the single crystal silicon-metal thermocouple pair group 41 is two or more groups, the The single crystal silicon-metal thermocouple pair group 41 is first connected to form a completed detection circuit. Further, the single crystal silicon-metal thermocouple pair group 41 may include any number of single crystal silicon-metal thermocouple pairs 411, such as 2 to 100, depending on actual needs, and no specific limitation is made here. Choose from 7.
作为示例，所述衬底1为(111)单晶硅。As an example, the substrate 1 is (111) single crystal silicon.
具体的，所述衬底1的厚度可以为350～500μm，优选为430μm，其轴偏切为0±(0.01～0.5)°，优选为0±0.1°。所述衬底1可以为单晶硅、多晶硅、金属衬低、有机衬低、PCB衬低等各种衬低材料，在本实施例中，采用(111)单晶硅衬底，进一步可以为N型(或P型)的(111)晶面的单面(或双面)抛光的硅片，其可以改善传统的硅片(如(100)硅片)的诸多缺陷，如由(100)硅片湿法腐蚀特性可知，介质膜面积与单晶硅背面掩膜开口区域面积比值很小，硅片厚度越大，芯片尺寸越大，成本越高，并且所述加热元件和所述热敏元件所在的梁式结构需要沿(110)晶向偏斜一定的夹角才能实现梁结构湿法腐蚀释放，这就导致了传感器后续安装定位比较困难。Specifically, the thickness of the substrate 1 may be 350-500 μm, preferably 430 μm, and its axis offcut is 0±(0.01-0.5)°, preferably 0±0.1°. The substrate 1 can be a variety of lining materials such as single crystal silicon, polycrystalline silicon, metal lining, organic lining, PCB lining, etc. In this embodiment, a (111) single crystal silicon substrate is used, and it can further be N-type (or P-type) (111) crystal plane single-sided (or double-sided) polished silicon wafers, which can improve many defects of traditional silicon wafers (such as (100) silicon wafers), such as by (100) Wet etching characteristics of silicon wafers show that the ratio of the area of the dielectric film to the area of the opening area of the single crystal silicon back mask is very small, the larger the thickness of the silicon wafer, the larger the chip size, and the higher the cost, and the heating element and the thermal sensor The beam structure where the element is located needs to be deflected at a certain angle along the (110) crystal direction to realize the wet corrosion release of the beam structure, which makes the subsequent installation and positioning of the sensor more difficult.
作为示例，步骤1)之后，还包括对所述加热元件区以及所述感测元件区进行硼掺杂的步骤。As an example, after step 1), a step of boron doping the heating element region and the sensing element region is also included.
作为示例，进行所述硼掺杂工艺后，还包括对硼掺杂后的结构进行退火的步骤。As an example, after performing the boron doping process, a step of annealing the boron-doped structure is further included.
具体的，定义所述加热元件区以及所述感测元件区的方法为：于所述衬底1表面热氧一定厚度的氧化层并形成一层光刻胶层，于所述氧化层和光刻胶层上形成所要定义的区域的开口，通过所述开口进行离子注入，在本实施例中优选为浓硼掺杂，注入剂量为5e15cm2～15e15cm2，优选为9e15cm2，注入能量为20～70Kev，优选为50Kev，注入了硼离子的硼离子注入区域12即为后续要形成加热元件、单晶硅-金属热偶臂的区域，另外，还可以包括后续的环境电阻元件区域。Specifically, the method for defining the heating element region and the sensing element region is as follows: heat an oxide layer with a certain thickness on the surface of the substrate 1 and form a layer of photoresist layer, between the oxide layer and the photoresist layer. An opening of the region to be defined is formed on the resist layer, and ion implantation is performed through the opening, preferably concentrated boron doping in this embodiment, and the implantation dose is 5e15 cm2 to 15e15 cm2 , preferably 9e15 cm2. The implantation energy is 20-70Kev, preferably 50Kev. The boron ion implantation region 12 implanted with boron ions is the region where heating elements and monocrystalline silicon-metal thermocouple arms will be formed later. In addition, the subsequent environment may also be included. Resistive element area.
进一步，本实施例还包括对掺杂硼的结构进行退火的步骤，退火时间约为1.5～2.5h，优选为2h，退火后表面生长一层氧化层13，所述氧化层的厚度为4000～6000埃，本实施例中，所述氧化层的厚度为5000埃，进一步保证器件的稳定性，如图4所示。Further, this embodiment also includes the step of annealing the structure doped with boron. The annealing time is about 1.5-2.5 hours, preferably 2 hours. After the annealing, an oxide layer 13 grows on the surface, and the thickness of the oxide layer is 4000-2. 6000 angstroms. In this embodiment, the thickness of the oxide layer is 5000 angstroms to further ensure the stability of the device, as shown in FIG. 4 .
如图5及图15中的S2所示，进行步骤2)，刻蚀所述衬底以形成第一沟槽14，用于定义出加热元件3以及单晶硅-金属热偶对411的位置和高度；As shown in FIG. 5 and S2 in FIG. 15 , step 2) is performed to etch the substrate to form a first groove 14, which is used to define the positions of the heating element 3 and the single crystal silicon-metal thermocouple pair 411 and height;
具体的，所述第一沟槽14的作用是用于限定加热元件3以及单晶硅-金属热偶对411，以所述单晶硅-金属热偶对411为例，所述第一沟槽14设置于所述后续要形成的单晶硅-金属热偶对411的两侧，作为牺牲材料，在后续的腐蚀工艺中，所述第一沟槽内的填充物会被腐蚀掉，则保留了其两侧的部分，也即单晶硅-金属热偶对411的部分。进一步，其深度用于限制后续衬底腐蚀过程中的程度，进而限制了单晶硅-金属热偶对411的厚度。Specifically, the function of the first groove 14 is to define the heating element 3 and the single crystal silicon-metal thermocouple pair 411, taking the single crystal silicon-metal thermocouple pair 411 as an example, the first groove The groove 14 is arranged on both sides of the single crystal silicon-metal thermocouple pair 411 to be formed later, as a sacrificial material, in the subsequent etching process, the filling in the first groove will be etched away, then The parts on both sides thereof, that is, the part of the monocrystalline silicon-metal thermocouple pair 411 are reserved. Further, its depth is used to limit the extent of the subsequent substrate etching process, thereby limiting the thickness of the single crystal silicon-metal thermocouple pair 411 .
如图6～8及图15中的S3所示，进行步骤3)，于所述第一沟槽14侧壁形成侧壁保护层141，并于形成有所述侧壁保护层的所述第一沟槽14内沉积牺牲层142；As shown in Figures 6-8 and S3 in Figure 15, step 3) is performed to form a sidewall protection layer 141 on the sidewall of the first trench 14, and to form a sidewall protection layer 141 on the A sacrificial layer 142 is deposited in the trench 14;
作为示例，步骤3)中，于所述第一沟槽14的侧壁形成侧壁保护层141的具体步骤为：As an example, in step 3), the specific steps of forming the sidewall protection layer 141 on the sidewall of the first trench 14 are:
3-1)于步骤2)得到的结构表面沉积侧壁保护材料层，所述侧壁材料保护层包括自下而上依次沉积的TEOS层1411和氮化硅层1412；3-1) Depositing a sidewall protection material layer on the surface of the structure obtained in step 2), the sidewall material protection layer including a TEOS layer 1411 and a silicon nitride layer 1412 deposited sequentially from bottom to top;
3-2)去除所述第一沟槽14底部及其周围的所述衬底1上的所述侧壁保护材料层1411、1412，以形成位于所述第一沟槽14侧壁的侧壁保护层141。3-2) removing the sidewall protection material layers 1411 and 1412 on the substrate 1 at the bottom of the first trench 14 and its surroundings, so as to form sidewalls located on the sidewalls of the first trench 14 protective layer 141 .
具体的，所述牺牲层142包括但不限于多晶硅层，其沉积工艺可以包括但不限于氧化、低压化学气相沉积(LPCVD)、等离子增强化学气相沉积(PECVD)等，所述侧壁保护层141以及所述牺牲层142用于在后续衬底腐蚀的步骤中被腐蚀掉，其起到保护所述加热元件3以及单晶硅-金属热偶对411的作用，进一步，所述氮化硅层1411的厚度为1000～3000埃，所述TEOS层1411的厚度为1000～3000埃，本实施例中，所述氮化硅层1412的厚度为2000埃，所述TEOS层1411的厚度为2000埃。Specifically, the sacrificial layer 142 includes but is not limited to a polysilicon layer, and its deposition process may include but not limited to oxidation, low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), etc., the sidewall protection layer 141 And the sacrificial layer 142 is used to be etched away in the subsequent substrate etching step, which plays a role in protecting the heating element 3 and the single crystal silicon-metal thermocouple pair 411, further, the silicon nitride layer The thickness of 1411 is 1000-3000 angstroms, and the thickness of the TEOS layer 1411 is 1000-3000 angstroms. In this embodiment, the thickness of the silicon nitride layer 1412 is 2000 angstroms, and the thickness of the TEOS layer 1411 is 2000 angstroms. .
如图9～10及图15中的S4所示，进行步骤4)，于步骤3)所得到的结构表面沉积第一介质膜材料层22，并刻蚀所述第一介质膜材料层22至暴露出所述加热元件对应的衬底区域以形成加热元件连接孔，且暴露出所述单晶硅-金属热偶对中的单晶硅热偶臂对应的衬底区域以形成单晶硅热偶臂连接孔23；As shown in FIGS. 9-10 and S4 in FIG. 15 , step 4) is carried out, a first dielectric film material layer 22 is deposited on the surface of the structure obtained in step 3), and the first dielectric film material layer 22 is etched to Exposing the substrate area corresponding to the heating element to form a heating element connection hole, and exposing the substrate area corresponding to the single crystal silicon thermocouple arm in the single crystal silicon-metal thermocouple pair to form a single crystal silicon thermal coupler. Even arm connecting hole 23;
具体的，所述第一介质膜材料层22用于作为支撑膜，其包括自下而上依次沉积的TEOS层以及氮化硅层，其中，所述TEOS层的厚度为1000～3000埃，所述氮化硅层的厚度为7000～9000埃，在本实施例中，所述TEOS层的厚度为2000埃，所述氮化硅层的厚度为8000埃，另外，该步骤的目的还在于制备金属热偶臂的连接孔23，其中，所述金属热偶臂的连接孔23的深度为1.2～2.5μm，在本实施例中为1.7μm。另外，还包括形成加热元件连接孔以及环境电阻元件连接孔的步骤，用于将加热元件以及环境电阻元件引出以实现电连接。Specifically, the first dielectric film material layer 22 is used as a supporting film, which includes a TEOS layer and a silicon nitride layer deposited sequentially from bottom to top, wherein the thickness of the TEOS layer is 1000-3000 angstroms, the The thickness of the silicon nitride layer is 7000-9000 angstroms. In this embodiment, the thickness of the TEOS layer is 2000 angstroms, and the thickness of the silicon nitride layer is 8000 angstroms. In addition, the purpose of this step is to prepare The connection hole 23 of the metal thermocouple arm, wherein the depth of the connection hole 23 of the metal thermocouple arm is 1.2-2.5 μm, and in this embodiment is 1.7 μm. In addition, a step of forming a heating element connection hole and an environmental resistance element connection hole is also included for leading out the heating element and the environment resistance element to realize electrical connection.
另外，当对本申请的定义了加热元件以及感测元件区的衬底进行退火后，还包括形成在所述第一介质膜与所述衬底之间的氧化层13，所述氧化层的厚度为4000～6000埃，本实施例中，所述氧化层的厚度为5000埃。在其他实施例中，所述氧化层的形成工艺并不局限为退火工艺，还可以为沉积等工艺。In addition, after annealing the substrate defining the heating element and the sensing element region of the present application, it also includes an oxide layer 13 formed between the first dielectric film and the substrate, and the thickness of the oxide layer is The thickness of the oxide layer is 4000-6000 angstroms. In this embodiment, the thickness of the oxide layer is 5000 angstroms. In other embodiments, the formation process of the oxide layer is not limited to an annealing process, and may also be a process such as deposition.
如图11～12及图15中的S5所示，进行步骤5)，于步骤4)所得到的结构的表面沉积金属层并对其图形化，以形成所述单晶硅-金属热偶对中的金属热偶臂4111，所述金属热偶臂4111包括垂直部及水平部，所述垂直部贯穿所述第一介质膜材料层22，所述水平部与所述垂直部相连接且位于所述第一介质膜材料层22表面；As shown in Figures 11-12 and S5 in Figure 15, step 5) is performed, and a metal layer is deposited on the surface of the structure obtained in step 4) and patterned to form the single crystal silicon-metal thermocouple pair The metal thermocouple arm 4111, the metal thermocouple arm 4111 includes a vertical part and a horizontal part, the vertical part penetrates the first dielectric film material layer 22, the horizontal part is connected to the vertical part and is located The surface of the first dielectric film material layer 22;
具体的，沉积所述金属层包括首先沉积一层Cr层，再于所述Cr层上沉积一层金属材料(如Au)的步骤，其中，Cr层的厚度为100～500埃，Au层的厚度为3000～8000埃，优选为5000埃。另外，所述图形化工艺包括但不限于离子束(Ionbeam)干法刻蚀，所述金属层形成工艺包括但不限于溅射法。Specifically, depositing the metal layer includes first depositing a layer of Cr, and then depositing a layer of metal material (such as Au) on the Cr layer, wherein the thickness of the Cr layer is 100-500 angstroms, and the thickness of the Au layer is The thickness is 3000-8000 angstroms, preferably 5000 angstroms. In addition, the patterning process includes but not limited to ion beam (Ionbeam) dry etching, and the metal layer forming process includes but not limited to sputtering.
作为示例，步骤5)与步骤6)之间，还包括于步骤5)所得到的结构表面沉积第二介质膜材料层71的步骤，所述第二介质膜材料层71用于保护所述感测元件4。As an example, between step 5) and step 6), the step of depositing a second dielectric film material layer 71 on the surface of the structure obtained in step 5) is also included, and the second dielectric film material layer 71 is used to protect the sensor. Measuring element 4.
具体的，所述第二介质膜材料层71可以是二氧化硅保护层，也可以是氮化硅膜、二氧化硅和氮化硅复合膜、有机薄膜等各种具有绝缘特性的薄膜材料，其目的是与第一介质膜共同将部分所述单晶硅-金属热偶对包覆，以保护所有金属电阻结构不受外界影响，以增加器件的长期稳定性和可靠性，其厚度为1000～5000埃，优选为3000埃。另外，所述第一介质膜材料层22以及所述第二介质膜材料层71的形成工艺可以包括但不限于氧化、低压化学气相沉积(LPCVD)、等离子增强化学气相沉积(PECVD)、溶胶凝胶工艺、有机材料涂覆固化工艺等。Specifically, the second dielectric film material layer 71 can be a silicon dioxide protective layer, or can be a silicon nitride film, a silicon dioxide and silicon nitride composite film, an organic film and other thin film materials with insulating properties, Its purpose is to cover part of the single crystal silicon-metal thermocouple pair together with the first dielectric film to protect all metal resistance structures from external influences and increase the long-term stability and reliability of the device. Its thickness is 1000 ~5000 angstroms, preferably 3000 angstroms. In addition, the formation process of the first dielectric film material layer 22 and the second dielectric film material layer 71 may include but not limited to oxidation, low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), sol-gel Glue process, organic material coating and curing process, etc.
具体的，还包括在该步骤中形成所述引线焊盘6的步骤，在刻蚀所述金属热偶臂时一同刻蚀形成，进一步，在形成所述第二介质膜材料层后，还包括去除所述引线焊盘6上的材料层的步骤，如可以采用BOE(Buffered Oxide Etch，缓冲氧化物刻蚀液)溶液腐蚀掉引线焊盘区域上方的SiO2钝化层。Specifically, it also includes the step of forming the lead pad 6 in this step, which is formed by etching the metal thermocouple arm together, and further, after forming the second dielectric film material layer, further includes In the step of removing the material layer on the lead pad 6, for example, a BOE (Buffered Oxide Etch, buffered oxide etching solution) solution may be used to etch away the SiO2 passivation layer above the lead pad region.
如图13及图15中的S6所示，进行步骤6)，刻蚀步骤5)所得到的结构以形成具有预设深度的第二沟槽8，所述第二沟槽8位于相邻所述单晶硅-金属热偶对组区之间和/或所述单晶硅-金属热偶对组区与所述衬底之间；As shown in FIG. 13 and S6 in FIG. 15, step 6) is performed, and the structure obtained in step 5) is etched to form a second groove 8 with a preset depth, and the second groove 8 is located adjacent to the Between the single crystal silicon-metal thermocouple pair group area and/or between the single crystal silicon-metal thermocouple pair group area and the substrate;
作为示例，步骤7)中，释放的所述第一介质膜2包括若干个槽型结构21，所述槽型结构由所述第二沟槽8形成，所述槽型结构21与所述单晶硅-金属热偶对组平行设置且交替间隔排布。As an example, in step 7), the released first dielectric film 2 includes several groove structures 21, the groove structures are formed by the second grooves 8, and the groove structures 21 and the single The crystalline silicon-metal thermocouple pairs are arranged in parallel and alternately arranged at intervals.
具体的，所述第二沟槽8用作后续进行衬底腐蚀的窗口，并且也进一步定义了所述衬底1中的所述凹槽11的深度，也即所述隔热腔体的深度，同时，所述第二沟槽8也作为后续形成所述槽型结构21的沟槽，其具体位置为相邻所述单晶硅-金属热偶对组区之间、或者所述单晶硅-金属热偶对组区与所述衬底之间，即所述感测元件区的一侧，也可以同时位于以上几种位置，以实际需求而定，其横截面形状优选为为长宽比较大的方条形，其长边与所述单晶硅-金属热偶对同向。Specifically, the second groove 8 is used as a window for subsequent substrate etching, and also further defines the depth of the groove 11 in the substrate 1, that is, the depth of the thermal insulation cavity , at the same time, the second groove 8 is also used as the groove for subsequent formation of the groove structure 21, and its specific position is between the adjacent single crystal silicon-metal thermocouple pairs, or the single crystal Between the silicon-metal thermocouple pair group area and the substrate, that is, one side of the sensing element area, can also be located at the above positions at the same time, depending on actual needs, and its cross-sectional shape is preferably long A square strip with a large width ratio, the long side of which is in the same direction as the single crystal silicon-metal thermocouple pair.
作为示例，步骤6)中，形成所述第二沟槽8的具体步骤包括：As an example, in step 6), the specific steps of forming the second trench 8 include:
6-1)刻蚀所述第二沟槽8所在区域的所述第一介质膜材料层22；6-1) Etching the first dielectric film material layer 22 in the area where the second trench 8 is located;
6-2)沿所述第二沟槽所在区域继续刻蚀预定深度，以形成所述第二沟槽8。6-2) Continue etching to a predetermined depth along the region where the second trench is located to form the second trench 8 .
具体的，步骤6-1)中的刻蚀可以采用反应离子刻蚀(RIE)，其中，步骤6-1)并可以形成位于所述第一介质膜上的所述槽型结构21，步骤6-2)中的刻蚀可以采用深硅反应离子刻蚀(Deep-RIE)，当然，也可以采用其他刻蚀工艺，如电感耦合反应离子刻蚀(ICP)、离子束刻蚀(IonBeam)、湿法腐蚀、聚焦离子束刻蚀(FIB)、激光扫描刻蚀等各种刻蚀技术。在其他实施例中，所述具有预设深度的沟槽也可以一次刻蚀形成。其中，经过步骤6-2)的刻蚀便定义了衬底中的所述凹槽的深度，即所述第二深度，也即所述隔热腔体的深度，可以为40～60μm，在本实施例中，优选为50μm。这里，所述的“所述第二沟槽所在区域”是指最终形成所述第二沟槽时的所述第二沟槽的位置所对应的第一介质膜材料层以及衬底的区域。Specifically, the etching in step 6-1) can use reactive ion etching (RIE), wherein, step 6-1) can also form the groove structure 21 on the first dielectric film, step 6 -2) The etching in deep silicon reactive ion etching (Deep-RIE) can be used, of course, other etching processes can also be used, such as inductively coupled reactive ion etching (ICP), ion beam etching (IonBeam), Various etching techniques such as wet etching, focused ion beam etching (FIB), laser scanning etching, etc. In other embodiments, the groove with the preset depth can also be formed by one-time etching. Wherein, after the etching in step 6-2), the depth of the groove in the substrate is defined, that is, the second depth, that is, the depth of the heat-insulating cavity, which may be 40-60 μm. In this embodiment, it is preferably 50 μm. Here, the "area where the second trench is located" refers to the area of the first dielectric film material layer and the substrate corresponding to the position of the second trench when the second trench is finally formed.
另外，当于步骤5)所得到的结构表面沉积第二介质膜材料层71时，步骤4-1)的刻蚀刻蚀掉第一介质膜材料层的同时还刻蚀掉了第二介质膜材料层。In addition, when the second dielectric film material layer 71 is deposited on the surface of the structure obtained in step 5), the etching in step 4-1) will etch away the first dielectric film material layer while also etching away the second dielectric film material Floor.
如图14及图15中的S7所示，进行步骤7)，以所述第二沟槽8为窗口腐蚀部分所述衬底形成隔热腔体，以释放所述第一介质膜2和所述单晶硅热偶臂4112，其中，所述第一介质膜2与所述衬底1相连接，并与所述衬底1共同围成所述隔热腔体，所述单晶硅热偶臂4112与所述金属热偶臂4111构成所述单晶硅-金属热偶对411，并形成感测元件4。As shown in FIG. 14 and S7 in FIG. 15, step 7) is performed, using the second trench 8 as a window to etch part of the substrate to form a heat-insulating cavity, so as to release the first dielectric film 2 and the The single crystal silicon thermocouple arm 4112, wherein, the first dielectric film 2 is connected to the substrate 1, and together with the substrate 1 forms the thermal insulation cavity, the single crystal silicon thermal The thermocouple arm 4112 and the metal thermocouple arm 4111 form the single crystal silicon-metal thermocouple pair 411 and form the sensing element 4 .
作为示例，步骤1)中所述衬底为(111)单晶硅，步骤7)中所采用的腐蚀溶液为四甲基氢氧化氨溶液。As an example, the substrate in step 1) is (111) single crystal silicon, and the etching solution used in step 7) is tetramethylammonium hydroxide solution.
具体的，在其他实施例中，MEMS体硅腐蚀技术还可以是氢氧化钾(KOH)溶液腐蚀、氟化氙(XeF)等各种硅材料腐蚀技术。Specifically, in other embodiments, the MEMS bulk silicon etching technology may also be potassium hydroxide (KOH) solution etching, xenon fluoride (XeF) and other silicon material etching technologies.
另外，在上述步骤完成后，还包括激光划片，以获取所需的器件结构的步骤。In addition, after the above steps are completed, a step of laser scribing is also included to obtain the required device structure.
综上所述，本发明提供一种热电堆式气体流量传感器及其制备方法，包括：衬底，具有一凹槽，所述凹槽开设于所述衬底的上表面；第一介质膜，覆盖于所述凹槽上方，且与所述衬底相连接，所述第一介质膜与所述衬底共同围成一个隔热腔体；加热元件，位于所述第一介质膜表面；以及至少两个感测元件，位于所述第一介质膜上，且设置于所述加热元件的两侧，所述感测元件包括至少一组单晶硅-金属热偶对组，所述单晶硅-金属热偶对组包括若干个单晶硅-金属热偶对。通过上述方案，本发明通过巧妙的结构设计和创新的单芯片单面制作技术，在普通(111)单晶硅片上加工出赛贝克系数最高的P型单晶硅-金热偶对；本发明的热电堆式气体流量传感器将热偶对以及加热元件通过位于其正下方的隔热腔体与衬底隔离，最大程度降低了加热电阻的热耗散，大大提高了传感器的检测灵敏度；本发明的整个流量传感器都是从单晶硅片的同一表面进行加工制作，因此芯片尺寸小，成本低，适于大批量生产。所以，本发明有效克服了现有技术中的种种缺点而具高度产业利用价值。In summary, the present invention provides a thermopile gas flow sensor and a manufacturing method thereof, comprising: a substrate having a groove, the groove being provided on the upper surface of the substrate; a first dielectric film, Covering above the groove and connected to the substrate, the first dielectric film and the substrate together form a heat-insulating cavity; a heating element is located on the surface of the first dielectric film; and At least two sensing elements are located on the first dielectric film and arranged on both sides of the heating element, the sensing elements include at least one single crystal silicon-metal thermocouple pair group, the single crystal The silicon-metal thermocouple pair group includes several monocrystalline silicon-metal thermocouple pairs. Through the above scheme, the present invention processes P-type single crystal silicon-gold thermocouple pairs with the highest Seebeck coefficient on ordinary (111) single crystal silicon wafers through ingenious structural design and innovative single-chip single-sided manufacturing technology; The invented thermopile gas flow sensor isolates the thermocouple pair and the heating element from the substrate through the heat insulation cavity directly below it, which minimizes the heat dissipation of the heating resistor and greatly improves the detection sensitivity of the sensor; The entire flow sensor of the invention is processed from the same surface of the single crystal silicon wafer, so the chip size is small, the cost is low, and it is suitable for mass production. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.
上述实施例仅例示性说明本发明的原理及其功效，而非用于限制本发明。任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.
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| CN201710548160.3ACN107328449B (en) | 2017-07-06 | 2017-07-06 | A thermopile gas flow sensor and its preparation method |
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| CN201710548160.3ACN107328449B (en) | 2017-07-06 | 2017-07-06 | A thermopile gas flow sensor and its preparation method |
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