技术领域technical field
本发明属于MEMS技术领域，涉及一种温度检测装置，特别是一种基于CMUT的温度传感器及其制备方法与应用方法。The invention belongs to the technical field of MEMS, and relates to a temperature detection device, in particular to a CMUT-based temperature sensor, a preparation method and an application method thereof.
背景技术Background technique
温度传感器主要用于温度的测量，是一种应用广泛的传感器。温度是一个和人们生活环境密切相关的物理量，也是一个在生产、科研、生活中需要测量的重要物理量。因为材料的各种性能几乎都与温度有关，所以，温度的精确测量在相关领域的生产和科研中一直都是一项非常重要的任务。因此，对该类传感器的研究具有极其重要的价值。The temperature sensor is mainly used for temperature measurement and is a widely used sensor. Temperature is a physical quantity closely related to people's living environment, and it is also an important physical quantity that needs to be measured in production, scientific research, and life. Because various properties of materials are almost related to temperature, accurate measurement of temperature has always been a very important task in the production and scientific research of related fields. Therefore, the research on this kind of sensor has extremely important value.
目前出现的温度传感器主要包括热敏电阻、基于不同热膨胀系数的双金属片、热电偶、PN节、声表面波、石英晶体谐振式、MEMS温度传感器等。温度传感器的发展也从传统的分立式温度传感器到模拟集成温度传感器/控制器乃至智能温度传感器。随着工业自动化程度的提高和多传感器信息融合技术的发展，迫切的需要热惯性小，响应迅速，体积小，能耗低的温度传感器。The temperature sensors currently appearing mainly include thermistors, bimetallic strips based on different thermal expansion coefficients, thermocouples, PN junctions, surface acoustic waves, quartz crystal resonant types, MEMS temperature sensors, etc. The development of temperature sensors has also changed from traditional discrete temperature sensors to analog integrated temperature sensors/controllers and even intelligent temperature sensors. With the improvement of industrial automation and the development of multi-sensor information fusion technology, there is an urgent need for temperature sensors with small thermal inertia, fast response, small size and low energy consumption.
近年来，随着微电子技术和MEMS技术的发展，MEMS温度传感器的研究逐渐增多。MEMS温度传感器较传统的温度传感器而言，具有体积小，质量轻、固有热容小而且易于实现集成化的热点，相对传统温度传感器有很大的优势。In recent years, with the development of microelectronics technology and MEMS technology, research on MEMS temperature sensors has gradually increased. Compared with traditional temperature sensors, MEMS temperature sensors have hot spots of small size, light weight, small inherent heat capacity and easy integration, which have great advantages over traditional temperature sensors.
CMUT是基于MEMS技术的研究热点之一，具有尺寸小、重量轻、机电性能好、灵敏度高、带宽宽、噪声低、工作温度范围宽等优点。此外，CMUT可批量制造、形成高密度阵列，易与电子元件集成在同一硅片上。如今，CMUT已成功用于医学成像、无损探伤、物距检测和流速测量领域，并在市场上有成熟的商业产品。上述CMUT的诸多优点及其成功应用经验为基于CMUT的温度传感器的设计和制备供了有利条件。CMUT is one of the research hotspots based on MEMS technology. It has the advantages of small size, light weight, good electromechanical performance, high sensitivity, wide bandwidth, low noise, and wide operating temperature range. In addition, CMUTs can be mass-produced to form high-density arrays, and can be easily integrated with electronic components on the same silicon chip. Today, CMUT has been successfully used in the fields of medical imaging, non-destructive flaw detection, object distance detection and flow velocity measurement, and there are mature commercial products in the market. The above-mentioned advantages of CMUT and its successful application experience provide favorable conditions for the design and preparation of temperature sensors based on CMUT.
发明内容Contents of the invention
本发明的目的在于提出一种基于CMUT的温度传感器及其制备方法与应用方法，以实现低功耗、高灵敏度温度检测。The purpose of the present invention is to propose a temperature sensor based on CMUT and its preparation method and application method, so as to realize low power consumption and high sensitivity temperature detection.
为实现上述目的，本发明采用的技术方案如下：To achieve the above object, the technical scheme adopted in the present invention is as follows:
一种基于CMUT的温度传感器，其整体结构由温度敏感薄膜和基座两部分组成；其中温度敏感薄膜采用高热膨胀系数半导体材料制成，其中部经离子掺杂形成上电极；基座中部自上而下依次为C型空腔、二氧化硅隔绝层、T型下电极；且T型下电极下部外侧由内而外依次为应力缓解凹槽以及二氧化硅底板，二氧化硅底板上围绕C型空腔设置有二氧化硅支柱；所述T型下电极上部位于二氧化硅底板上侧，为下电极的主要部分；T型下电极下部在厚度方向上贯通二氧化硅底板，用于电连接。A temperature sensor based on CMUT. Its overall structure consists of two parts: a temperature-sensitive film and a base; the temperature-sensitive film is made of a semiconductor material with a high thermal expansion coefficient, and the upper electrode is formed by ion doping in the middle; the middle part of the base is from the top The lower part is a C-shaped cavity, a silicon dioxide insulating layer, and a T-shaped lower electrode; and the outer side of the lower part of the T-shaped lower electrode is a stress relief groove and a silicon dioxide bottom plate from the inside to the outside, and the silicon dioxide bottom plate is surrounded by C. A silicon dioxide pillar is provided in the cavity; the upper part of the T-shaped lower electrode is located on the upper side of the silicon dioxide base plate, which is the main part of the lower electrode; the lower part of the T-shaped lower electrode penetrates the silicon dioxide base plate in the thickness direction, and is used for electric connect.
所述应力缓解凹槽深度与T型下电极下部厚度相同，将T型下电极下部与二氧化硅底板在横向方向上隔开。The depth of the stress relief groove is the same as the thickness of the lower part of the T-shaped bottom electrode, and separates the lower part of the T-shaped bottom electrode from the silicon dioxide bottom plate in the lateral direction.
所述应力缓解凹槽表面覆盖有氮化硅层。The surface of the stress relief groove is covered with a silicon nitride layer.
一种基于CMUT的温度传感器的制备方法，包括以下步骤：A preparation method of a CMUT-based temperature sensor, comprising the following steps:
（1）取一<111>晶向单晶硅作为第一单晶硅，光刻、刻蚀其上表面形成第一凹槽，并采用局部离子掺杂技术，从第一单晶硅上、下两侧进行离子参杂，形成T型下电极；(1) Take a <111> oriented single crystal silicon as the first single crystal silicon, photolithographically etch its upper surface to form the first groove, and use local ion doping technology to form the first single crystal silicon, The lower two sides are doped with ions to form a T-shaped lower electrode;
（2）光刻第一单晶硅的第一凹槽表面，刻蚀第一凹槽内壁与T型下电极上部之间的未参杂单晶硅，刻蚀深度与T型下电极上部厚度相同，此时初步形成C型空腔形状；(2) Photoetching the surface of the first groove of the first monocrystalline silicon, etching the undoped monocrystalline silicon between the inner wall of the first groove and the upper part of the T-shaped lower electrode, the etching depth and the thickness of the upper part of the T-shaped lower electrode The same, at this time the C-shaped cavity shape is initially formed;
（3）光刻第一单晶硅下表面，从其下表面刻蚀与T型下电极下部相接的未掺杂单晶硅，形成第二凹槽，第二凹槽深度与下电极下部厚度相同；(3) Lithograph the lower surface of the first monocrystalline silicon, etch the undoped monocrystalline silicon connected with the lower part of the T-shaped lower electrode from the lower surface to form a second groove, the depth of the second groove is the same as that of the lower part of the lower electrode the same thickness;
（4）光刻第一单晶硅下表面，刻蚀第二凹槽外侧单晶硅，减薄第二凹槽外侧单晶硅厚度，以缩短后续氧化工艺时间；(4) Photoetching the lower surface of the first single crystal silicon, etching the single crystal silicon outside the second groove, and reducing the thickness of the single crystal silicon outside the second groove, so as to shorten the subsequent oxidation process time;
（5）在第一单晶硅上表面沉积氮化硅层，光刻、刻蚀除T型下电极上部表面以外的氮化硅层；同时在第一单晶硅下表面沉积氮化硅层，光刻、刻蚀第二凹槽外侧氮化硅层，余下的氮化硅层覆盖整个第二凹槽和T型下电极下部表面；(5) Deposit a silicon nitride layer on the upper surface of the first single crystal silicon, photolithography and etch the silicon nitride layer except the upper surface of the T-shaped lower electrode; at the same time, deposit a silicon nitride layer on the lower surface of the first single crystal silicon , photolithography and etching the silicon nitride layer outside the second groove, and the remaining silicon nitride layer covers the entire second groove and the lower surface of the T-shaped lower electrode;
（6）采用热氧化技术充分氧化第一单晶硅，使除被保护T型下电极部分外，其余部分单晶硅均被氧化成二氧化硅，此时形成二氧化硅支柱、应力缓解凹槽和二氧化硅底板；(6) Use thermal oxidation technology to fully oxidize the first single crystal silicon, so that except for the protected T-shaped lower electrode part, the rest of the single crystal silicon is oxidized into silicon dioxide. At this time, silicon dioxide pillars and stress relief recesses are formed. tank and silica floor;
（7）刻蚀掉覆盖在T型下电极上部表面的氮化硅层；(7) Etching away the silicon nitride layer covering the upper surface of the T-shaped lower electrode;
（8）采用干法热氧化技术，氧化T型下电极上部表面，形成一定厚度的二氧化硅隔绝层，最终C型空腔形状；同时，取另一单晶硅作为第二单晶硅，用作衬底，在其上表面沉积温度敏感薄膜层；(8) Use dry thermal oxidation technology to oxidize the upper surface of the T-shaped lower electrode to form a certain thickness of silicon dioxide insulating layer, and finally the shape of the C-shaped cavity; at the same time, take another single crystal silicon as the second single crystal silicon, Used as a substrate on which a temperature-sensitive thin film layer is deposited;
（9）采用化学机械抛光技术抛光第一单晶硅的上表面，即二氧化硅支柱表面；同时采用局部离子掺杂技术在第二单晶硅的温度敏感薄膜层上参杂硼离子形成上电极，并用化学机械抛光技术抛光其上表面；(9) Use chemical mechanical polishing technology to polish the upper surface of the first single crystal silicon, that is, the surface of the silicon dioxide pillar; at the same time, use local ion doping technology to dope boron ions on the temperature-sensitive thin film layer of the second single crystal silicon to form an upper surface. Electrode, and its upper surface is polished by chemical mechanical polishing technology;
（10）将第一单晶硅的支柱上表面与第二单晶硅上温度敏感薄膜上表面阳极键合，形成真空C型空腔；(10) Anodically bonding the upper surface of the pillar of the first single crystal silicon to the upper surface of the temperature-sensitive thin film on the second single crystal silicon to form a vacuum C-shaped cavity;
（11）刻蚀掉第二单晶硅，释放温度敏感薄膜，并化学机械抛光其表面；光刻第一单晶硅下表面氮化硅层，刻蚀掉覆盖在T型下电极下部表面的氮化硅层。(11) Etch away the second single crystal silicon, release the temperature-sensitive thin film, and chemically mechanically polish its surface; photolithographically etch the silicon nitride layer on the lower surface of the first single crystal silicon, etch away the silicon nitride layer covering the lower surface of the T-shaped lower electrode silicon nitride layer.
步骤（8）中在第二单晶硅表面沉积多晶硅或碳化硅层。In step (8), a polysilicon or silicon carbide layer is deposited on the surface of the second single crystal silicon.
一种基于CMUT的温度传感器应用方法，测量CMUT的谐振频率，当温度改变时，因温度敏感薄膜与二氧化硅底板之间因热膨胀系数存在较大差异而致使温度敏感薄膜在温度变化时产生较大内应力变化，进而引起CMUT谐振频率发生变化，记录该频率变化，通过温度变化与频率变化之间的对应关系即可得到所测温度值。A CMUT-based temperature sensor application method, measuring the resonant frequency of the CMUT, when the temperature changes, due to the large difference in the thermal expansion coefficient between the temperature-sensitive film and the silicon dioxide base plate, the temperature-sensitive film will produce a large difference when the temperature changes. Large internal stress changes, and then cause the CMUT resonance frequency to change, record the frequency change, and obtain the measured temperature value through the corresponding relationship between the temperature change and the frequency change.
本发明一种基于CMUT的温度传感器，其基本工作机理为：温度敏感薄膜与二氧化硅底板之间因热膨胀系数存在较大差异而致使温度敏感薄膜在温度变化时产生较大内应力变化，进而引起CMUT谐振频率发生变化，通过温度变化与频率变化之间的对应关系即可得到所测温度值。A kind of temperature sensor based on CMUT of the present invention, its basic working mechanism is: there is big difference in coefficient of thermal expansion between temperature-sensitive film and silicon dioxide bottom plate, causes temperature-sensitive film to produce bigger internal stress change when temperature changes, and then The resonant frequency of the CMUT is caused to change, and the measured temperature value can be obtained through the corresponding relationship between the temperature change and the frequency change.
本发明一种基于CMUT的温度传感器至少具有以下优点：A kind of temperature sensor based on CMUT of the present invention has the following advantages at least:
1、CMUT上、下电极均位于空腔内，相对于用整个单晶硅基底作为下电极的情况，该结构两电极之间有效电极间距较小、寄生电容小，因而可实现低功耗、高灵敏度温度检测。1. Both the upper and lower electrodes of the CMUT are located in the cavity. Compared with the case where the entire monocrystalline silicon substrate is used as the lower electrode, the effective electrode distance between the two electrodes of this structure is small, and the parasitic capacitance is small, so it can achieve low power consumption, High sensitivity temperature detection.
2、由于通过CMUT谐振频率变化实现温度检测，数字化输出信号、便于传输、抗干扰能力强。2. Since the temperature detection is realized through the change of the resonance frequency of the CMUT, the digital output signal is convenient for transmission and has strong anti-interference ability.
3、基座结构设计充分考虑温度变化对结构内应力及其形状的影响，能有效确保该温度传感器在大温度范围内工作性能的稳定性。3. The design of the base structure fully considers the influence of temperature changes on the internal stress and shape of the structure, which can effectively ensure the stability of the temperature sensor's working performance in a large temperature range.
附图说明Description of drawings
图1为本发明的剖面结构示意图；Fig. 1 is the sectional structure schematic diagram of the present invention;
图2为本发明制备方法的流程图；Fig. 2 is the flowchart of preparation method of the present invention;
图中的标号如下表示：The labels in the figure are as follows:
具体实施方式Detailed ways
下面结合附图对本发明进行详细描述：The present invention is described in detail below in conjunction with accompanying drawing:
请参考图1，对其具体结构及相应功能特征进行说明：Please refer to Figure 1 to illustrate its specific structure and corresponding functional features:
本发明总体结构由温度敏感薄膜1和基座2组成，其中基座2中部自上而下依次为C型空腔7、二氧化硅隔绝层6、T型下电极5；T型下电极下部4外侧由内而外依次为应力缓解凹槽10、二氧化硅底板9。The overall structure of the present invention is composed of a temperature-sensitive film 1 and a base 2, wherein the middle part of the base 2 is a C-shaped cavity 7, a silicon dioxide insulating layer 6, and a T-shaped lower electrode 5 from top to bottom; the lower part of the T-shaped lower electrode 4 The outer side is the stress relief groove 10 and the silicon dioxide bottom plate 9 sequentially from the inside to the outside.
所述温度敏感薄膜1中部区域经离子重掺杂后用作上电极，采用高热膨胀系数半导体材料，其厚度以保持良好的导电性和温度敏感性为宜。The central region of the temperature-sensitive thin film 1 is heavily ion-doped and used as an upper electrode, and a semiconductor material with a high thermal expansion coefficient is used, and its thickness should maintain good electrical conductivity and temperature sensitivity.
所述二氧化硅隔绝层6覆盖在T型下电极上部3表面，采用干法氧化技术形成，其热膨胀系数为0.55×10-6/℃小于单晶硅材料的2.33×10-6/℃，因而能有效抑制T型下电极上部3因温度变化引起的变形，确保CMUT工作参数的稳定性（塌陷电压、机电耦合系数等）；另外，二氧化硅隔绝层6还用于上、下电极之间的电绝缘。二氧化硅隔绝层6厚度应根据T型下电极上部3厚度以及所测温度范围确定。The silicon dioxide insulating layer 6 covers the surface of the upper part 3 of the T-shaped lower electrode, and is formed by dry oxidation technology, and its thermal expansion coefficient is 0.55×10-6/°C, which is lower than 2.33×10-6/°C of the single crystal silicon material, Therefore, it can effectively suppress the deformation of the upper part 3 of the T-shaped lower electrode due to temperature changes, and ensure the stability of the CMUT's operating parameters (collapse voltage, electromechanical coupling coefficient, etc.); Electrical insulation between. The thickness of the silicon dioxide insulating layer 6 should be determined according to the thickness of the upper part 3 of the T-shaped lower electrode and the measured temperature range.
所述T型下电极5由电极上部3和电极下部4组成，其中电极上部3位于空腔内部，平行于温度敏感薄膜1（上电极），与上电极形成平行板电容；电极上部3厚度应使其具有良好的导电性和较小内应力。电极下部4在厚度方向（纵向方向）上贯通二氧化硅底板9，用于与外部电源之间的电连接，其横向尺寸应保证其具有良好的导电性能。The T-shaped lower electrode 5 is composed of an upper electrode 3 and a lower electrode 4, wherein the upper electrode 3 is located inside the cavity, parallel to the temperature sensitive film 1 (upper electrode), and forms a parallel plate capacitance with the upper electrode; the thickness of the upper electrode 3 should be Make it have good electrical conductivity and less internal stress. The lower part 4 of the electrode penetrates through the silicon dioxide bottom plate 9 in the thickness direction (longitudinal direction) for electrical connection with an external power supply, and its lateral dimension should ensure that it has good electrical conductivity.
所述应力缓解凹槽10围绕T型下电极下部4，位于T型下电极下部4与二氧化硅底板9之间，应力缓解凹槽10表面覆盖有氮化硅层11、其在横向方向上将T型下电极下部4与二氧化硅底板9隔离开，避免了二者之间因温度引起的内应对基座2结构的影响，应力缓解凹槽10在基座2上的深度与T型下电极下部4的厚度相同，其宽度可根据基座2结构强度和加工工艺确定。The stress relief groove 10 surrounds the lower part 4 of the T-shaped lower electrode, and is located between the lower part 4 of the T-shaped lower electrode and the silicon dioxide base plate 9. The surface of the stress relief groove 10 is covered with a silicon nitride layer 11, which in the lateral direction The lower part 4 of the T-shaped lower electrode is isolated from the silicon dioxide base plate 9, which avoids the influence of the internal response to the structure of the base 2 caused by the temperature between the two, and the depth of the stress relief groove 10 on the base 2 is the same as that of the T-shaped bottom electrode. The thickness of the lower part 4 of the lower electrode is the same, and its width can be determined according to the structural strength of the base 2 and the processing technology.
所述氮化硅层11覆盖T型下电极下部4外侧表面，或者覆盖应力缓解凹槽10，在实际制作过程中由于目前加工工艺的限制，只能满足覆盖应力缓解凹槽10大部分表面，未覆盖10整个表面，这是由所设计的加工工艺决定的。氮化硅层11一方面用于电隔离、保护T型下电极下部4，另一方面可以抑制T型下电极下部4因温度引起的形变。The silicon nitride layer 11 covers the outer surface of the lower part 4 of the T-shaped lower electrode, or covers the stress relief groove 10. In the actual production process, due to the limitation of the current processing technology, it can only cover most of the surface of the stress relief groove 10. Does not cover 10 the entire surface, which is determined by the designed processing technology. On the one hand, the silicon nitride layer 11 is used for electrical isolation and protection of the lower part 4 of the T-shaped lower electrode, and on the other hand, it can suppress deformation of the lower part 4 of the T-shaped lower electrode due to temperature.
所述二氧化硅底板9用于支撑基座2的其他结构部分，如二氧化硅支柱8、T型下电极5等。The silicon dioxide bottom plate 9 is used to support other structural parts of the base 2, such as silicon dioxide pillars 8, T-shaped bottom electrodes 5, and the like.
所述温度敏感薄膜1热膨胀系数远大于基座2即二氧化硅支柱和二氧化硅底板的（主要是热氧化二氧化硅，下电极5对基座2的影响可忽略）热膨胀系数，因而当温度变化时，温度敏感薄膜1应力状态会发生较大的变化，从而改变CMUT的谐振频率，本发明即是基于这一机理实现温度的检测。The thermal expansion coefficient of the temperature-sensitive film 1 is much greater than that of the base 2, that is, the silicon dioxide pillar and the silicon dioxide bottom plate (mainly thermally oxidized silicon dioxide, and the influence of the lower electrode 5 on the base 2 is negligible), so when When the temperature changes, the stress state of the temperature-sensitive thin film 1 will change greatly, thereby changing the resonant frequency of the CMUT. The present invention realizes temperature detection based on this mechanism.
本发明基于CMUT的温度传感器，该CMUT结构在用于温度测量时，主要通过温度敏感薄膜与基座之间的热应力失配而引起的敏感薄膜谐振频率变化来实现温度检测。其具体应用方法为：设计后续谐振电路来追踪CMUT敏感探头的谐振频率变化，用频率计数器或其他器件来测量该频率。具体测量时，需校准某一参考温度（如0℃）对应的谐振频率，当温度改变时，敏感薄膜1内应力状态发生改变，进而引起CMUT谐振频率也会发生相应的变化，用频率计数器记录此频率变化，即可通过谐振频移与温度变化之间的关系获得被测温度值。The invention is based on a CMUT temperature sensor. When the CMUT structure is used for temperature measurement, the temperature detection is mainly realized through the change of the resonant frequency of the sensitive film caused by the thermal stress mismatch between the temperature sensitive film and the base. Its specific application method is: design a subsequent resonance circuit to track the change of the resonance frequency of the CMUT sensitive probe, and use a frequency counter or other devices to measure the frequency. For specific measurement, it is necessary to calibrate the resonant frequency corresponding to a certain reference temperature (such as 0°C). When the temperature changes, the internal stress state of the sensitive film 1 changes, which in turn causes the CMUT resonant frequency to change accordingly. Record it with a frequency counter With this frequency change, the measured temperature value can be obtained through the relationship between the resonance frequency shift and the temperature change.
请参考图2，对本发明的制备方法进行详细说明：Please refer to Fig. 2, the preparation method of the present invention is described in detail:
（1）取一<111>晶向单晶硅作为第一单晶硅，光刻、刻蚀其上表面形成第一凹槽，并采用局部离子掺杂技术，从第一单晶硅上、下两侧进行离子参杂，形成T型下电极5及未掺杂单晶硅11。(1) Take a <111> oriented single crystal silicon as the first single crystal silicon, photolithographically etch its upper surface to form the first groove, and use local ion doping technology to form the first single crystal silicon, The lower two sides are doped with ions to form a T-shaped lower electrode 5 and undoped single crystal silicon 11 .
（2）光刻第一单晶硅的第一凹槽表面，刻蚀第一凹槽内壁与下电极上部之间的未参杂单晶硅，刻蚀深度与T型电极上部厚度相同，此时初步形成C型空腔形状，形成未掺杂单晶硅12。(2) Photoetching the surface of the first groove of the first single crystal silicon, etching the undoped single crystal silicon between the inner wall of the first groove and the upper part of the lower electrode, the etching depth is the same as the thickness of the upper part of the T-shaped electrode, and this At this time, a C-type cavity shape is preliminarily formed, and undoped single crystal silicon 12 is formed.
（3）光刻第一单晶硅下表面，从其下表面刻蚀与T型下电极下部（参杂单晶硅）相接的未掺杂单晶硅，形成第二凹槽13，第二凹槽深度与下电极5下部厚度相同。(3) Photoetching the lower surface of the first single crystal silicon, etching the undoped single crystal silicon connected with the lower part of the T-shaped lower electrode (doped single crystal silicon) from the lower surface to form the second groove 13, and the second groove 13 is formed. The depth of the second groove is the same as the thickness of the lower part of the lower electrode 5 .
（4）光刻第一单晶硅下表面，刻蚀第二凹槽13外侧单晶硅，以减薄第二凹槽外侧单晶硅厚度，缩短后续氧化工艺时间，此时未掺杂单晶硅12变为14。(4) Lithographically etches the lower surface of the first monocrystalline silicon, and etches the monocrystalline silicon outside the second groove 13 to reduce the thickness of the monocrystalline silicon outside the second groove and shorten the subsequent oxidation process time. At this time, no monocrystalline silicon is doped. Crystalline silicon 12 becomes 14.
（5）在第一单晶硅上表面沉积氮化硅层，光刻、刻蚀除T型下电极5上部表面以外的氮化硅层，余下的T型下电极5上部表面的氮化硅层15用于防止T型下电极5的上表面在后续氧化工艺中被氧化；同时在第一单晶硅下表面沉积氮化硅层，光刻、刻蚀第二凹槽13外侧氮化硅层，余下的氮化硅层16覆盖整个凹槽13和下电极5下部表面，用于防止下电极5下部表面在后续氧化工艺中被氧化。(5) Depositing a silicon nitride layer on the upper surface of the first single crystal silicon, photolithography and etching the silicon nitride layer except the upper surface of the T-shaped lower electrode 5, and the remaining silicon nitride on the upper surface of the T-shaped lower electrode 5 Layer 15 is used to prevent the upper surface of the T-shaped lower electrode 5 from being oxidized in the subsequent oxidation process; at the same time, a silicon nitride layer is deposited on the lower surface of the first single crystal silicon, and the silicon nitride layer outside the second groove 13 is photolithographically etched. layer, and the remaining silicon nitride layer 16 covers the entire groove 13 and the lower surface of the lower electrode 5 to prevent the lower surface of the lower electrode 5 from being oxidized in the subsequent oxidation process.
（6）采用热氧化技术充分氧化第一单晶硅，使除被保护T型下电极5外其余部分单晶硅14均被氧化成二氧化硅，此时形成二氧化硅支柱8、应力缓解凹槽10和二氧化硅底板9。(6) Using thermal oxidation technology to fully oxidize the first single crystal silicon, so that the rest of the single crystal silicon 14 except the protected T-shaped lower electrode 5 is oxidized into silicon dioxide, and at this time silicon dioxide pillars 8 are formed, stress relief Groove 10 and silica bottom plate 9.
（7）刻蚀掉覆盖在T型下电极5上部表面的氮化硅层15。(7) Etching away the silicon nitride layer 15 covering the upper surface of the T-shaped bottom electrode 5 .
（8）采用干法热氧化技术，氧化T型下电极5上部表面，形成一定厚度二氧化硅隔绝层6和最终C型空腔形状。同时，取另一单晶硅作为第二单晶硅，用作衬底，在其上表面沉积温度敏感薄膜层（如多晶硅、碳化硅）。(8) Dry thermal oxidation technology is used to oxidize the upper surface of the T-shaped bottom electrode 5 to form a silicon dioxide insulating layer 6 with a certain thickness and a final C-shaped cavity shape. At the same time, take another single crystal silicon as the second single crystal silicon as a substrate, and deposit a temperature-sensitive thin film layer (such as polysilicon, silicon carbide) on its upper surface.
（9）采用化学机械抛光技术抛光第一单晶硅的上表面，也即支柱8表面；同时采用局部离子掺杂技术在第二单晶硅的温度敏感薄膜层上参杂硼离子形成上电极（温度敏感薄膜）1，并用化学机械抛光技术抛光1上表面。(9) Use chemical mechanical polishing technology to polish the upper surface of the first single crystal silicon, that is, the surface of the pillar 8; at the same time, use local ion doping technology to dope boron ions on the temperature-sensitive thin film layer of the second single crystal silicon to form the upper electrode (temperature-sensitive film) 1, and polish the upper surface of 1 with chemical mechanical polishing technology.
（10）将第一单晶硅支柱8上表面与第二单晶硅上温度敏感薄膜1上表面阳极键合，形成真空C型空腔7。(10) The upper surface of the first monocrystalline silicon pillar 8 is anodically bonded to the upper surface of the temperature-sensitive thin film 1 on the second monocrystalline silicon to form a vacuum C-shaped cavity 7 .
（11）刻蚀掉第二单晶硅，释放温度敏感薄膜1，并化学机械抛光其表面，以期获得较好的力学性能；光刻第一单晶硅下表面氮化硅层16，刻蚀掉覆盖在下电极5下部表面的氮化硅，以便于实现下电极电连接，形成最终氮化硅层11。(11) Etch away the second single crystal silicon, release the temperature-sensitive film 1, and chemically mechanically polish its surface in order to obtain better mechanical properties; photolithographically etch the silicon nitride layer 16 on the lower surface of the first single crystal silicon, etch The silicon nitride covering the lower surface of the lower electrode 5 is removed to facilitate the electrical connection of the lower electrode to form the final silicon nitride layer 11 .
结合上述实施方式，本发明基于CMUT的温度传感器，其参考结构参数为：In combination with the above embodiments, the present invention is based on the CMUT temperature sensor, and its reference structural parameters are:
温度敏感薄膜有效直径：10~200μmEffective diameter of temperature sensitive film: 10~200μm
温度敏感薄膜厚度：0.1~10μmTemperature sensitive film thickness: 0.1~10μm
有效空腔高度：0.2~5μmEffective cavity height: 0.2~5μm
空腔直径：10~200μmCavity diameter: 10~200μm
本发明一种基于CMUT的温度传感器，其参考性能指标为：A kind of temperature sensor based on CMUT of the present invention, its reference performance index is:
温度灵敏度：量级kHz/℃Temperature sensitivity: order of magnitude kHz/℃
温度范围：0~120℃，具体温度范围由传感器的结构和材料参数进行确定。Temperature range: 0~120°C, the specific temperature range is determined by the structure and material parameters of the sensor.
以上所述仅为本发明的一种实施方式，不是全部或唯一的实施方式，本领域普通技术人员通过阅读本发明说明书而对本发明技术方案采取的任何等效的变换，均为本发明的权利要求所涵盖。The above is only one embodiment of the present invention, not all or the only embodiment. Any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the description of the present invention is the right of the present invention. covered by the requirements.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310084404.9ACN103196577B (en) | 2013-03-15 | 2013-03-15 | Temperature sensor based on CMUT and preparation method and application method thereof |
| Application Number | Priority Date | Filing Date | Title |
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| CN201310084404.9ACN103196577B (en) | 2013-03-15 | 2013-03-15 | Temperature sensor based on CMUT and preparation method and application method thereof |
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| CN103196577A CN103196577A (en) | 2013-07-10 |
| CN103196577Btrue CN103196577B (en) | 2015-04-29 |
| Application Number | Title | Priority Date | Filing Date |
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| CN201310084404.9AActiveCN103196577B (en) | 2013-03-15 | 2013-03-15 | Temperature sensor based on CMUT and preparation method and application method thereof |
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