技术领域technical field
本发明涉及光栅掩模制作的微细加工技术领域，尤其涉及一种光栅掩模与硅片{111}晶面的对准方法。The invention relates to the technical field of microfabrication for making grating masks, in particular to a method for aligning the grating mask and the {111} crystal plane of a silicon wafer.
背景技术Background technique
高性能X射线透射光栅在激光惯性约束核聚变(ICF)和天文观测等重要领域有着刚性需求，其具有高线密度和高衍射效率的特点，要求光栅槽型保持高深宽比以及光滑的衍射面。各向异性湿法刻蚀是硅基透射光栅制备的重要技术，其中光栅掩模与硅片{111}晶面的对准精度决定了横向刻蚀的速率和侧壁的粗糙度。对准精度越高，侧壁越光滑，横向刻蚀速率越小，对于高深宽比的硅光栅，工艺宽容度也越高。High-performance X-ray transmission gratings have rigid requirements in important fields such as laser inertial confinement fusion (ICF) and astronomical observation. They have the characteristics of high linear density and high diffraction efficiency, and require the grating groove to maintain a high aspect ratio and a smooth diffraction surface. . Anisotropic wet etching is an important technology for the preparation of silicon-based transmission gratings, in which the alignment accuracy of the grating mask and the {111} crystal plane of the silicon wafer determines the lateral etching rate and the roughness of the sidewall. The higher the alignment accuracy, the smoother the sidewalls, the lower the lateral etch rate, and the higher the process latitude for silicon gratings with high aspect ratios.
目前，光栅掩模与硅片{111}晶面的对准方法通常采用扇形或圆形标志刻蚀出{111}晶面，再用相应的定位与表征方法与光栅掩模对准。At present, the method of aligning the grating mask and the {111} crystal plane of the silicon wafer usually uses a fan-shaped or circular mark to etch the {111} crystal plane, and then aligns with the grating mask using a corresponding positioning and characterization method.
MIT空间纳米技术实验室利用扇形标志湿法刻蚀方法结合电子显微镜在<110>硅片上定位横向刻蚀宽度最小的矩形条垂直{111}晶面，再通过位置敏感探测器，使干涉条纹与之对准，完成掩模制作。该对准方法，仅适用于复杂的扫描光束干涉系统，且由于靠近垂直{111}晶面的许多矩形条横向刻蚀宽度相近难以分辨，使垂直{111}晶面的定位误差在0.1°左右，占总误差的90％。另一种对准方法是利用扇形标志湿法刻蚀方法定位出<110>硅片的垂直{111}晶面，并在硅片上制作出与其平行的参考光栅，在光路中使参考光栅与干涉条纹对准。该方法得到了较高的对准精度，不针对特定系统，较为普适。但依然采用显微镜寻找横向刻蚀宽度最小的扇形条来定位{111}晶面，人工定位误差占总误差的75％；且用了两次光刻完成参考光栅的制作，耗时长，过程繁琐，对准标志占用单晶硅的面积大，工艺有待优化。The MIT Spatial Nanotechnology Laboratory uses the sector-shaped mark wet etching method combined with an electron microscope to locate the rectangular strip with the smallest lateral etching width on the <110> silicon wafer, which is vertical to the {111} crystal plane, and then passes through the position-sensitive detector to make interference fringes Align with it to complete the mask making. This alignment method is only suitable for complex scanning beam interference systems, and because many rectangular strips close to the vertical {111} crystal plane have similar lateral etching widths and are difficult to distinguish, the positioning error of the vertical {111} crystal plane is about 0.1° , accounting for 90% of the total error. Another alignment method is to locate the vertical {111} crystal plane of the <110> silicon wafer by using the sector mark wet etching method, and make a reference grating parallel to it on the silicon wafer, and make the reference grating and the Interference fringe alignment. This method obtains higher alignment accuracy, and is not specific to a specific system, and is more universal. However, a microscope is still used to locate the {111} crystal plane by finding the fan-shaped strip with the smallest lateral etching width, and the manual positioning error accounts for 75% of the total error; and it takes a long time and a cumbersome process to complete the production of the reference grating with two photolithography. Alignment marks occupy a large area of monocrystalline silicon, and the process needs to be optimized.
利用圆形标志湿法刻蚀出六边形定位{111}晶面的方法也被广泛应用于大周期的光栅掩模制作中，但受限于圆形标志的尺寸，该方法误差较大在0.2°左右，不适用于高线密度透射光栅的制作。The method of using circular marks to wet-etch the hexagonal {111} crystal planes is also widely used in the production of large-period grating masks, but limited by the size of the circular marks, the error of this method is relatively large. About 0.2°, not suitable for the production of high linear density transmission grating.
现有的对准方法中，均是采用三步走的思路，即：第一步-定位晶向，利用圆形或扇形等标志刻蚀出{111}晶面，再用显微镜等手段寻找代表晶向的线条，并将其定位成垂直{111}晶面；第二步-表征晶向，利用该线条代表{111}晶面，制作与其平行的参考光栅或直接扫描跟踪，将{111}晶面表征；第三步-掩模对准，将表征{111}晶面的参考光栅或单根线条与代表着光栅掩模方向的干涉条纹等对准，从而完成光栅掩模与{111}晶面的对准。上述步骤中，定位晶向是误差的主要来源，占总误差的70％以上，可操作性差，需要利用显微镜反复寻找比较，费时费力，且精度很难提高。In the existing alignment methods, a three-step approach is adopted, that is, the first step is to locate the crystal direction, use a circle or fan-shaped mark to etch the {111} crystal plane, and then use a microscope to find the representative crystal plane. The line of crystal orientation, and position it as perpendicular to the {111} crystal plane; the second step - characterize the crystal orientation, use this line to represent the {111} crystal plane, make a reference grating parallel to it or directly scan and track it, and place {111} Crystal plane characterization; the third step-mask alignment, align the reference grating or single line representing the {111} crystal plane with the interference fringes representing the direction of the grating mask, so as to complete the grating mask and {111} Alignment of crystal planes. In the above steps, the orientation of crystal orientation is the main source of error, accounting for more than 70% of the total error, and the operability is poor. It is necessary to use a microscope to find and compare repeatedly, which is time-consuming and laborious, and it is difficult to improve the accuracy.
发明内容Contents of the invention
本发明解决的技术问题在于提供一种超高精度光栅掩模与硅片{111}晶面的对准方法。The technical problem solved by the invention is to provide a method for aligning an ultra-high-precision grating mask with a {111} crystal plane of a silicon wafer.
有鉴于此，本申请提供了一种光栅掩模与硅片{111}晶面的对准方法，包括以下步骤：In view of this, the present application provides a method for aligning a grating mask with a {111} crystal plane of a silicon wafer, comprising the following steps:
A)，在硅片上制作具有光栅衍射特性的多个对准标志图形，各对准标志图形具有与所述硅片的定位边平行的两长边；A), making a plurality of alignment mark patterns with grating diffraction characteristics on the silicon chip, each alignment mark pattern has two long sides parallel to the positioning side of the silicon chip;
B)，将步骤A)得到的硅片进行湿法刻蚀，使所述对准标志图形的长边沿着硅片的{111}晶面截止，得到具有多个第一对准标志图形的硅片；B), carrying out wet etching to the silicon wafer obtained in step A), so that the long side of the alignment mark pattern is cut off along the {111} crystal plane of the silicon wafer to obtain silicon with a plurality of first alignment mark patterns piece;
C)，定位表征光栅掩模的基准线，采用激光照射所述多个第一对准标志图形的长边，得到所述多个第一对准标志图形的长边的衍射斑，将所述基准线与所述衍射斑重合。C), positioning the reference line representing the grating mask, irradiating the long sides of the plurality of first alignment mark patterns with laser light, obtaining the diffraction spots of the long sides of the plurality of first alignment mark patterns, and irradiating the long sides of the plurality of first alignment mark patterns, The reference line coincides with the diffraction spot.
优选的，所述对准标志图形为矩形。Preferably, the alignment mark pattern is rectangular.
优选的，所述矩形的长边为50～1000μm，宽度为10～50μm。Preferably, the long side of the rectangle is 50-1000 μm, and the width is 10-50 μm.
优选的，所述对准标志图形的数量大于20，总面积小于1mm2。Preferably, the number of the alignment mark patterns is greater than 20, and the total area is less than 1 mm2 .
优选的，所述硅片为<110>硅片或<100>硅片。Preferably, the silicon wafer is a <110> silicon wafer or a <100> silicon wafer.
优选的，所述湿法刻蚀的时间小于4h。Preferably, the wet etching time is less than 4h.
优选的，所述湿法刻蚀的刻蚀液为各向异性刻蚀液。Preferably, the etchant used for wet etching is an anisotropic etchant.
本申请提供了一种光栅掩模与硅片{111}晶面对准的方法，其首先是在硅片上制作一块小面积的具有光栅衍射特性的对准标志图形，随着湿法刻蚀的进行，对准标志图形的两长边会严格沿着单晶硅的{111}晶面刻蚀截止，直至刻蚀完成，整个对准标志图形的两长边完全倾斜，并表现出新的光栅衍射特性，利用湿法刻蚀后对准标志图形的衍射特性，可以直接表征{111}晶面，将对准标志图形的衍射斑与表征掩模光栅掩模方向的定位标准线对准，从而完成{111}晶面与光栅掩模的高精度对准。该对准方法只需要制作一次对准标志图形，经过短时间的湿法刻蚀后，无需显微镜观察比较，便可零误差定位{111}晶面，并利用其衍射特性进行表征。试验结果表明，本申请提供的对准方法对准总误差≤±0.016°。This application provides a method for aligning a grating mask with the {111} crystal plane of a silicon wafer. First, a small-area alignment mark pattern with grating diffraction characteristics is fabricated on the silicon wafer. The two long sides of the alignment mark pattern will be etched strictly along the {111} crystal plane of single crystal silicon until the etching is completed, and the two long sides of the entire alignment mark pattern are completely inclined and show a new Grating diffraction characteristics, using the diffraction characteristics of the alignment mark pattern after wet etching, can directly characterize the {111} crystal plane, align the diffraction spot of the alignment mark pattern with the positioning standard line that characterizes the mask grating mask direction, Thus, the high-precision alignment between the {111} crystal plane and the grating mask is completed. This alignment method only needs to make an alignment mark pattern once, and after a short period of wet etching, the {111} crystal plane can be positioned with zero error without microscope observation and comparison, and its diffraction characteristics can be used for characterization. The test results show that the total alignment error of the alignment method provided by this application is ≤±0.016°.
附图说明Description of drawings
图1为本发明矩形对准标准的示意图；Fig. 1 is the schematic diagram of the rectangular alignment standard of the present invention;
图2为本发明矩形对准标志的湿法刻蚀结构演化示意图；Fig. 2 is a schematic diagram of the evolution of the wet etching structure of the rectangular alignment mark of the present invention;
图3为本发明矩形对准标志的制作流程图；Fig. 3 is a flow chart of making a rectangular alignment mark of the present invention;
图4为本发明矩形对准标志与光栅掩模对准的示意图。FIG. 4 is a schematic diagram of the alignment between the rectangular alignment mark and the grating mask of the present invention.
具体实施方式detailed description
为了进一步理解本发明，下面结合实施例对本发明优选实施方案进行描述，但是应当理解，这些描述只是为进一步说明本发明的特征和优点，而不是对本发明权利要求的限制。In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.
本发明实施例公开了一种光栅掩模与硅片{111}晶面的对准方法，包括以下步骤：The embodiment of the present invention discloses a method for aligning a grating mask and a {111} crystal plane of a silicon wafer, which includes the following steps:
A)，在硅片上制作具有光栅衍射特性的多个对准标志图形，各对准标志图形具有与所述硅片的定位边平行的两长边；A), making a plurality of alignment mark patterns with grating diffraction characteristics on the silicon chip, each alignment mark pattern has two long sides parallel to the positioning side of the silicon chip;
B)，将步骤A)得到的硅片进行湿法刻蚀，使所述对准标志图形的长边沿着硅片的{111}晶面截止，得到具有多个第一对准标志图形的硅片；B), carrying out wet etching to the silicon wafer obtained in step A), so that the long side of the alignment mark pattern is cut off along the {111} crystal plane of the silicon wafer to obtain silicon with a plurality of first alignment mark patterns piece;
C)，定位表征光栅掩模的基准线，采用激光照射所述多个第一对准标志图形的长边，得到所述多个第一对准标志图形的长边的衍射斑，将所述基准线与所述衍射斑重合。C), positioning the reference line representing the grating mask, irradiating the long sides of the plurality of first alignment mark patterns with laser light, obtaining the diffraction spots of the long sides of the plurality of first alignment mark patterns, and irradiating the long sides of the plurality of first alignment mark patterns, The reference line coincides with the diffraction spot.
本申请提供了一种光栅掩模与硅片{111}晶面对准的方法，其首先是在硅片上制作一块小面积的具有光栅衍射特性的对准标志图形，随着湿法刻蚀的进行，对准标志图形的两长边会严格沿着单晶硅的{111}晶面刻蚀截止，直至刻蚀完成，整个对准标志图形的两长边完全倾斜，并表现出新的光栅衍射特性，利用湿法刻蚀后对准标志图形的衍射特性，可以直接表征{111}晶面，将对准标志图形的衍射斑与表征掩模光栅掩模方向的定位标准线对准，从而完成{111}晶面与光栅掩模的高精度对准。该对准方法只需要制作一次对准标志图形，经过短时间的湿法刻蚀后，无需显微镜观察比较，便可零误差定位{111}晶面，并利用其衍射特性进行表征，将对准总误差降到最低。This application provides a method for aligning a grating mask with the {111} crystal plane of a silicon wafer. First, a small-area alignment mark pattern with grating diffraction characteristics is fabricated on the silicon wafer. The two long sides of the alignment mark pattern will be etched strictly along the {111} crystal plane of single crystal silicon until the etching is completed, and the two long sides of the entire alignment mark pattern are completely inclined and show a new Grating diffraction characteristics, using the diffraction characteristics of the alignment mark pattern after wet etching, can directly characterize the {111} crystal plane, align the diffraction spot of the alignment mark pattern with the positioning standard line that characterizes the mask grating mask direction, Thus, the high-precision alignment between the {111} crystal plane and the grating mask is completed. This alignment method only needs to make an alignment mark pattern once. After a short period of wet etching, the {111} crystal plane can be positioned with zero error without microscope observation and comparison, and its diffraction characteristics can be used to characterize the alignment. The total error is minimized.
本申请是通过表征{111}晶面来实现光栅掩模的制作。在光栅掩模与{111}晶面对准的过程中，本申请首先在硅片上制作了具有光栅掩模特性的多个对准标志图形，且单个对准标志图形的两长边与硅片的定位边平行；即本申请制作的对准标志图形类似于矩形，只是该申请中矩形的短边可以是直线，也可以是曲线，对此本申请没有限制。本申请所述对准标志图形优选为矩形。In this application, the preparation of the grating mask is realized by characterizing the {111} crystal plane. In the process of aligning the grating mask with the {111} crystal plane, the present application first fabricated a plurality of alignment mark patterns with grating mask characteristics on the silicon wafer, and the two long sides of a single alignment mark pattern were aligned with the silicon wafer. The positioning sides of the sheet are parallel; that is, the alignment mark pattern made by this application is similar to a rectangle, except that the short side of the rectangle in this application can be a straight line or a curve, and this application has no limitation. The alignment mark pattern described in this application is preferably a rectangle.
如图1所示，图1为本发明矩形对准标志的示意图，其中，1为硅片，2为湿法刻蚀前的矩形对准标志，3为湿法刻蚀完成后的矩形对准标志，4为实际中的{111}晶面。As shown in Figure 1, Figure 1 is a schematic diagram of a rectangular alignment mark of the present invention, wherein, 1 is a silicon wafer, 2 is a rectangular alignment mark before wet etching, and 3 is a rectangular alignment mark after wet etching is completed. 4 is the actual {111} crystal plane.
按照本发明，矩形对准标志的尺寸是综合考虑湿法刻蚀时间、制作倾斜角度以及对准标志衍射效率优化设计的。设计原则为：(1)横向刻蚀宽度小于单个矩形的宽度；(2)矩形的长度以及数量保证衍射斑肉眼可见；(3)保证湿法刻蚀时间尽量短。以上原则互相制约，湿法刻蚀时间优选小于4h，单个矩形的长度优选为50～1000微米，宽度优选为10～50微米，矩形的总数量大于20；对准标志总面积小于1mm2，可以制作在硅片的任意位置，极大的提高了硅片的有效使用面积。According to the present invention, the size of the rectangular alignment mark is optimally designed by comprehensively considering the wet etching time, manufacturing inclination angle and diffraction efficiency of the alignment mark. The design principles are: (1) the lateral etching width is smaller than the width of a single rectangle; (2) the length and quantity of the rectangles ensure that the diffraction spots are visible to the naked eye; (3) the wet etching time is kept as short as possible. The above principles are mutually restricted, the wet etching time is preferably less than 4h, the length of a single rectangle is preferably 50-1000 microns, the width is preferably 10-50 microns, the total number of rectangles is greater than 20; the total area of the alignment mark is less than 1mm2 , it can Manufactured at any position of the silicon wafer, greatly improving the effective use area of the silicon wafer.
在对准标志图形制作完成后，本申请则将硅片进行湿法刻蚀，使所述对准标志图形的长边沿着硅片的{111}晶面截止，得到具有多个第一对准标志图形的硅片。本申请所述湿法刻蚀的刻蚀液优选为各向异性刻蚀液，更优选为50wt％的KOH溶液。本申请对准标志图形湿法刻蚀结构演化示意图如图2所示，图2中W0为矩形对准标志的宽度，L为矩形对准标志的长度，W为矩形对准标志的总宽度，θ为湿法刻蚀前后矩形条倾斜的角度，y1为近{111}晶面端的横向刻蚀宽度，y2为远{111}晶面端的横向刻蚀宽度，y1t1、y1t2分别为近{111}晶面端在时间t1、t2时的横向刻蚀宽度，y2t1、y2t2分别为远{111}晶面端在时间t1、t2时的横向刻蚀宽度。由图2可知，湿法刻蚀时，单个矩形掩模顶端(交界处)的左右刻蚀宽度会出现差异。具体的过程为：After the alignment mark pattern is made, the present application performs wet etching on the silicon wafer, so that the long side of the alignment mark pattern is cut off along the {111} crystal plane of the silicon wafer, and a plurality of first alignment marks are obtained. Wafer of logo graphics. The etchant for wet etching described in this application is preferably an anisotropic etchant, more preferably a 50 wt% KOH solution. The schematic diagram of the evolution of the wet etching structure of the alignment mark pattern of this application is shown in Figure 2. In Figure 2, W0 is the width of the rectangular alignment mark, L is the length of the rectangular alignment mark, and W is the total width of the rectangular alignment mark , θ is the inclination angle of the rectangular bar before and after wet etching, y1 is the lateral etching width near the {111} crystal plane end, y2 is the lateral etching width at the far {111} crystal plane end, y1t1 and y1t2 are respectively is the lateral etching width of the near {111} crystal plane at time t1 and t2 , and y2t1 and y2t2 are the lateral etching width of the far {111} crystal plane at time t1 and t2 respectively. It can be seen from FIG. 2 that during wet etching, there will be differences in the left and right etching widths of the top (junction) of a single rectangular mask. The specific process is:
由各向异性湿法刻蚀的机理可知，近垂直{111}晶面端的横向刻蚀宽度y1等于垂直{111}晶面的横向刻蚀宽度，表示为：From the mechanism of anisotropic wet etching, it can be seen that the lateral etching width y1 at the end near the vertical {111} crystal plane is equal to the lateral etching width vertical to the {111} crystal plane, expressed as:
y1＝v(111)t；y1 =v(111)t;
远垂直{111}晶面端的横向刻蚀宽度y2表示为：The lateral etch width y2 at the end of the far perpendicular{ 111} crystal plane is expressed as:
y2＝v(θ)t，y2 =v(θ)t,
其中，θ是矩形条边与垂直{111}晶面的偏差角度。实际制作中，矩形条2与实际的{111}晶面4的角度偏差θ难以避免，v(111)＜＜v(θ)，各向异性湿法刻蚀时，矩形条的边会严格沿着{111}晶面推进刻蚀，随着时间的增加，刻蚀出的{111}晶面不断增长，直至矩形条范围内{111}晶面完全刻蚀截止。此时，形成了一条与原矩形对准标志2呈θ角度倾斜的新的矩形对准标志3。相应的，矩形对准标志3表现出新的光栅衍射特性。Among them, θ is the deviation angle between the sides of the rectangle and the vertical {111} crystal plane. In actual production, the angular deviation θ between the rectangular strip 2 and the actual {111} crystal plane 4 is unavoidable, v(111)<<v(θ), during anisotropic wet etching, the sides of the rectangular strip will be strictly along the The etching proceeds along the {111} crystal plane, and with the increase of time, the etched {111} crystal plane continues to grow until the complete etching of the {111} crystal plane within the rectangular strip ends. At this time, a new rectangular alignment mark 3 inclined at an angle θ with the original rectangular alignment mark 2 is formed. Correspondingly, the rectangular alignment mark 3 exhibits new grating diffraction characteristics.
图3为本发明矩形对准标志刻蚀前后的流程图，图中5为湿法刻蚀掩模，6为硅基，图3a为湿法刻蚀前矩形对准标志的侧视图，图3b为湿法刻蚀完成时矩形对准标志的侧视图和侧视局剖图，图3c为湿法刻蚀后除去掩模的矩形对准标志的侧视图。Fig. 3 is the flow chart before and after the etching of the rectangular alignment mark of the present invention, among the figure 5 is the wet etching mask, 6 is the silicon base, Fig. 3 a is the side view of the rectangular alignment mark before wet etching, Fig. 3 b FIG. 3c is a side view of the rectangular alignment mark with the mask removed after wet etching.
按照本发明，在得到新的具有光栅特性的对准标志图形后，本申请则进行对准标志图形表征的{111}晶面与光栅掩模的对准过程，即定位表征光栅掩模的基准线，采用激光照射所述多个第一对准标志图形的长边，得到所述多个第一对准标志图形的长边的衍射斑，将所述基准线与所述衍射斑重合。图4为本发明矩形对准标志与光栅掩模对准示意图，图中7为激光器，8为光栅掩模，9为接收屏，10为表征光栅掩模方向的定位基准线，11为矩形对准标志3的衍射光斑。According to the present invention, after obtaining the new alignment mark pattern with grating characteristics, the applicant then performs the alignment process of the {111} crystal plane represented by the alignment mark pattern and the grating mask, that is, the benchmark for positioning and representing the grating mask irradiating the long sides of the plurality of first alignment mark patterns with laser light to obtain diffraction spots on the long sides of the plurality of first alignment mark patterns, and overlapping the reference line with the diffraction spots. Fig. 4 is the alignment diagram of rectangular alignment mark and grating mask of the present invention, among the figure 7 is a laser, 8 is a grating mask, 9 is a receiving screen, 10 is a positioning reference line representing the direction of a grating mask, and 11 is a rectangular pair The diffraction spot of quasi-marker 3.
在上述过程中，首先定位表征光栅掩模的基准线，光栅掩模的方向即是干涉条纹的方向，首先利用全息光路中的基准元件(平面镜等)或紫外光刻中的掩模版图形定位出一条表征光栅掩模方向的基准线，具体操作为：采用一束激光以多个入射角打在全息光路中的平面镜上，在接收屏上画出一条由反射斑组成的直线，该直线即是表征光栅掩模方向的基准线；或者用一束激光打在紫外光刻中的掩模版图形上，在接收屏上画出一条由衍射斑组成的直线，该直线即是表征光栅掩模方向的基准线；然后将一束激光入射矩形对准标志使其出现衍射级次；调整包含矩形对准标志的硅片方位，使对准标志的衍射斑与表征光栅掩模方向的定位基准线完全重合，至此，即完成了光栅掩模与硅片{111}晶面的对准。In the above process, the reference line representing the grating mask is firstly positioned. The direction of the grating mask is the direction of the interference fringes. A reference line representing the direction of the grating mask. The specific operation is: use a beam of laser light to hit the plane mirror in the holographic optical path at multiple incident angles, and draw a straight line composed of reflection spots on the receiving screen. The straight line is The reference line representing the direction of the grating mask; or use a beam of laser to hit the mask pattern in ultraviolet lithography, and draw a straight line composed of diffraction spots on the receiving screen, which is the line representing the direction of the grating mask Datum line; then a beam of laser light is incident on the rectangular alignment mark to make it appear diffraction orders; adjust the orientation of the silicon wafer containing the rectangular alignment mark so that the diffraction spot of the alignment mark coincides completely with the positioning reference line representing the direction of the grating mask , so far, the alignment between the grating mask and the {111} crystal plane of the silicon wafer is completed.
在上述对准过程中，对准误差来自基准线的定位误差以及衍射斑与基准线的对准误差，其大小取决于光斑与基准线重合的分辨误差Δl，光斑到基准元件或硅片的距离D。考量实际实验，设Δl＝1mm，D≥5000mm，则矩形对准标志与光栅掩模的对准误差计算公式如下所示，经计算总对准误差小于等于±0.016°。In the above alignment process, the alignment error comes from the positioning error of the reference line and the alignment error between the diffraction spot and the reference line, and its size depends on the resolution error Δl of the coincidence of the spot and the reference line, and the distance from the spot to the reference element or silicon wafer d. Considering the actual experiment, set Δl=1mm, D≥5000mm, then the calculation formula of the alignment error between the rectangular alignment mark and the grating mask is as follows, and the calculated total alignment error is less than or equal to ±0.016°.
本申请所述光栅掩模与硅片{111}晶面的对准方法，用于<110>硅片，经过一次短时间的湿法刻蚀定位并表征垂直{111}晶面；也可用于<100>硅片，经过一次短时间的湿法刻蚀定位并表征倾斜{111}晶面；适用于全息光刻中表征光栅掩模方向的干涉条纹与硅片{111}晶面的对准，也适用于紫外光刻中，掩模板上光栅线条与{111}晶面的对准。The method for aligning the grating mask and the {111} crystal plane of the silicon wafer described in this application is used for <110> silicon wafers, after a short wet etching process to position and characterize the vertical {111} crystal plane; it can also be used for <100>Silicon wafer, after a short wet etching to position and characterize the inclined {111} crystal plane; suitable for the alignment of the interference fringes representing the direction of the grating mask in holographic lithography and the {111} crystal plane of the silicon wafer , is also applicable to the alignment of the grating lines on the mask and the {111} crystal plane in ultraviolet lithography.
本发明是一种光栅掩模与硅片{111}晶面的超高精度对准方法，首先在硅片1上制作一块小面积的具有光栅衍射特性的矩形对准标志2，随着湿法刻蚀的进行，矩形的四边会严格沿着单晶硅的{111}晶面刻蚀截止，直至刻蚀完成，整个矩形的边完全倾斜，并表现出新的光栅衍射特性，利用矩形对准标志3的衍射特性，可以直接表征{111}晶面4；将矩形对准标志3的衍射斑11与表征光栅掩模8的定位基准线10对准，从而完成{111}晶面4与光栅掩模8的高精度对准。该对准方法，只需要制作一次矩形对准标志，经过短时间的湿法刻蚀后，无需显微镜观察比较，便可零误差定位{111}晶面，并利用其衍射特性进行表征。The present invention is an ultra-high-precision alignment method between a grating mask and a {111} crystal plane of a silicon wafer. First, a small-area rectangular alignment mark 2 with grating diffraction characteristics is fabricated on a silicon wafer 1. During the etching, the four sides of the rectangle will be etched strictly along the {111} crystal plane of the single crystal silicon until the etching is completed, the sides of the entire rectangle are completely inclined, and exhibit new grating diffraction characteristics. The diffraction characteristics of the mark 3 can directly represent the {111} crystal plane 4; the diffraction spot 11 of the rectangular alignment mark 3 is aligned with the positioning reference line 10 representing the grating mask 8, thereby completing the {111} crystal plane 4 and the grating High-precision alignment of the mask 8. This alignment method only needs to make a rectangular alignment mark once, and after a short period of wet etching, the {111} crystal plane can be positioned with zero error without microscope observation and comparison, and its diffraction characteristics can be used for characterization.
本申请光栅掩模与硅片{111}晶面的对准方法具体为：In this application, the alignment method between the grating mask and the {111} crystal plane of the silicon wafer is as follows:
(1)利用对准标志图形湿法刻蚀定位并表征{111}晶面；(1) Locate and characterize the {111} crystal plane by wet etching of the alignment mark pattern;
在硅片1边缘制作对准标志图形如矩形2，矩形的长边与硅片现有定位边尽量对齐，无精度要求；湿法刻蚀足够时间，直至矩形标志的长边完全严格沿{111}晶面截止；去除对准标志的湿法刻蚀掩模5，使硅基6里的矩形对准标志3完全暴露。该步骤，不需要显微镜寻找近似{111}晶面，实现了省时高效、可重复的零误差定位。Make an alignment mark pattern such as a rectangle 2 on the edge of the silicon wafer 1. The long side of the rectangle should be aligned with the existing positioning side of the silicon wafer as far as possible without precision requirements; wet etching for enough time until the long side of the rectangular mark is completely along {111 } Crystal plane stop; remove the wet etching mask 5 of the alignment mark, so that the rectangular alignment mark 3 in the silicon substrate 6 is completely exposed. In this step, a microscope is not needed to find the approximate {111} crystal plane, which realizes time-saving, high-efficiency, repeatable zero-error positioning.
(2)使光栅掩模与矩形对准标志对准(2) Align the grating mask with the rectangular alignment mark
光栅掩模8的方向即是干涉条纹的方向，首先利用全息光路中的基准元件(平面镜等)或紫外光刻中的掩模版图形定位出一条表征光栅掩模方向的基准线10；将一束激光8入射对准标志3使其出现衍射级次；调整包含矩形对准标志3的硅片1方位，使对准标志的衍射斑11与表征光栅掩模8方向的定位基准线10完全重合，至此，即完成了光栅掩模8与硅片{111}晶面4的对准。结果显示，本发明光栅掩模与硅片{111}晶面的总对准误差为±0.016°，为高线密度高深宽比光栅的研制提供了有力的技术支持。The direction of the grating mask 8 is the direction of the interference fringes. First, use the reference element (plane mirror, etc.) in the holographic optical path or the mask pattern in the ultraviolet lithography to locate a reference line 10 representing the direction of the grating mask; The laser light 8 is incident on the alignment mark 3 to cause diffraction orders to appear; the orientation of the silicon wafer 1 containing the rectangular alignment mark 3 is adjusted so that the diffraction spot 11 of the alignment mark completely coincides with the positioning reference line 10 representing the direction of the grating mask 8, So far, the alignment between the grating mask 8 and the {111} crystal plane 4 of the silicon wafer is completed. The results show that the total alignment error between the grating mask of the present invention and the {111} crystal plane of the silicon wafer is ±0.016°, which provides strong technical support for the development of high line density and high aspect ratio gratings.
本发明采用的对准方法，只需要制作一次矩形对准标志，经过短时间的湿法刻蚀后，无需显微镜观察比较，便可零误差定位{111}晶面，并利用其衍射特性进行表征，将对准总误差降到最低；本发明优选采用矩形对准标志，图形简单，面积可达1mm2之内，可制作在硅片的任意位置，极大的增加了硅片的有效使用面积；对制作在<110>硅片、<100>硅片上需要与{111}晶面高精度对准的光栅掩模均适用；对全息光刻或紫外光刻中，光栅掩模与硅片{111}晶面的对准均适用；则本申请提供的对准方法具有普适性。The alignment method adopted in the present invention only needs to make a rectangular alignment mark once, and after a short period of wet etching, the {111} crystal plane can be positioned with zero error without microscope observation and comparison, and its diffraction characteristics can be used for characterization , to minimize the total alignment error; the present invention preferably adopts a rectangular alignment mark with a simple pattern and an area of up to1mm2 , which can be made at any position of the silicon wafer, greatly increasing the effective use area of the silicon wafer ;Applicable to the grating masks that need to be aligned with the {111} crystal plane with high precision on <110> silicon wafers and <100> silicon wafers; for holographic lithography or ultraviolet lithography, the grating mask and silicon wafer The alignment of the {111} crystal plane is applicable; then the alignment method provided in this application has universal applicability.
为了进一步理解本发明，下面结合实施例对本发明提供的光栅掩模与硅片{111}晶面的对准方法进行详细说明，本发明的保护范围不受以下实施例的限制。In order to further understand the present invention, the method for aligning the grating mask and the {111} crystal plane of the silicon wafer provided by the present invention will be described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.
实施例1Example 1
以<110>硅片为例，矩形对准标志单个矩形宽度W0为10微米，长度L为100微米，矩形条数量为200，对准标志的总面积为0.4mm2，用于全息光刻中干涉条纹与硅片{111}晶面的对准。对准方法的具体步骤包括：Taking the <110> silicon wafer as an example, the single rectangular width W0 of the rectangular alignment mark is 10 microns, the length L is 100 microns, the number of rectangular strips is 200, and the total area of the alignment mark is 0.4mm2 , which is used for holographic lithography Alignment of medium interference fringes to the {111} crystal plane of a silicon wafer. The specific steps of the alignment method include:
①在硅片1上制作矩形对准标志2，并刻蚀进氮化硅或二氧化硅等耐湿法刻蚀掩模5中；① Making a rectangular alignment mark 2 on the silicon wafer 1, and etching it into a wet-resistant etching mask 5 such as silicon nitride or silicon dioxide;
②在60℃，50wt％KOH溶液中湿法刻蚀3小时，在硅基6中形成新的矩形对准标志3，用HF溶液或干法刻蚀局部去除掩模5，使矩形对准标志3完全暴露，至此，硅片{111}晶面4的零误差定位完成；②Wet etching in 50wt% KOH solution at 60°C for 3 hours to form a new rectangular alignment mark 3 in the silicon substrate 6, and partially remove the mask 5 with HF solution or dry etching to make the rectangular alignment mark 3 is fully exposed, so far, the zero-error positioning of the {111} crystal plane 4 of the silicon wafer is completed;
③在搭建完成的全息光路中，选定代表光栅掩模8方向的基准元件，采用一束激光7扫描反射，在接收屏9上记录一条基准线10；③In the completed holographic optical path, select the reference element representing the direction of the grating mask 8, use a laser beam 7 to scan and reflect, and record a reference line 10 on the receiving screen 9;
④将包含矩形对准标志3的硅片1放置在待曝光位置(暂时遮挡干涉区域，防止硅片被曝光)，用激光7入射矩形对准标志3，在接收屏9上会出现一系列衍射光斑11，调整硅片1，使衍射光斑11与基准线10对准；④ Place the silicon wafer 1 containing the rectangular alignment mark 3 at the position to be exposed (temporarily block the interference area to prevent the silicon wafer from being exposed), use the laser 7 to incident the rectangular alignment mark 3, and a series of diffractions will appear on the receiving screen 9 The light spot 11 is adjusted to the silicon wafer 1 so that the diffraction light spot 11 is aligned with the reference line 10;
至此，光栅掩模8与硅片{111}晶面4的对准完成。So far, the alignment between the grating mask 8 and the {111} crystal plane 4 of the silicon wafer is completed.
本申请的方法对准误差来源于步骤③和④中基准线10的记录和衍射光斑11与基准线10的对准，其取决于光斑与基准线重合的分辨误差Δl，光斑到基准元件或硅片的距离D；Δl一定程度上取决于人眼分辨能力，通过增大D可以提高对准精度，本实施例中，取Δl＝1mm，D＝5000mm，则矩形对准标志与光栅掩模的对准误差计算公式如下所示，经计算总对准误差为±0.016°。The alignment error of the method of this application comes from the recording of the reference line 10 in steps ③ and ④ and the alignment of the diffraction spot 11 and the reference line 10, which depends on the resolution error Δl of the coincidence of the light spot and the reference line, and whether the light spot is aligned with the reference element or silicon The distance D of the sheet; Δl depends to a certain extent on the resolution of the human eye, and the alignment accuracy can be improved by increasing D. In this embodiment, Δl=1mm, D=5000mm, then the distance between the rectangular alignment mark and the grating mask The formula for calculating the alignment error is shown below, and the calculated total alignment error is ±0.016°.
实施例2Example 2
以<110>硅片为例，矩形对准标志单个矩形宽度W0为20微米，长度L为200微米，矩形条数量为100，对准标志的总面积为0.8mm2，用于全息光刻中干涉条纹与硅片{111}晶面的对准。Taking <110> silicon wafer as an example, the single rectangular width W0 of the rectangular alignment mark is 20 microns, the length L is 200 microns, the number of rectangular strips is 100, and the total area of the alignment mark is 0.8mm2 , which is used for holographic lithography Alignment of medium interference fringes to the {111} crystal plane of a silicon wafer.
进行硅片{111}晶面的表征，光栅掩模与对准标志的对准等步骤，中间过程与实施例一相同。The characterization of the {111} crystal plane of the silicon wafer, the alignment of the grating mask and the alignment mark, and other steps are carried out, and the intermediate process is the same as that of the first embodiment.
其余与实施例一相同。All the other are the same as the first embodiment.
实施例3Example 3
以<100>硅片为例，矩形对准标志单个矩形宽度W0为20微米，长度L为200微米，矩形条数量为100，对准标志的总面积为0.8mm2，用于紫外光刻中掩模版图形与硅片{111}晶面的对准。Taking the <100> silicon wafer as an example, the single rectangular width W0 of the rectangular alignment mark is 20 microns, the length L is 200 microns, the number of rectangular strips is 100, and the total area of the alignment mark is 0.8mm2 , which is used for ultraviolet lithography Alignment of the reticle pattern and the {111} crystal plane of the silicon wafer.
①在硅片1上制作矩形对准标志2，并刻蚀进氮化硅或二氧化硅等耐湿法刻蚀掩模5中；① Making a rectangular alignment mark 2 on the silicon wafer 1, and etching it into a wet-resistant etching mask 5 such as silicon nitride or silicon dioxide;
②在60℃，50wt％KOH溶液中进行湿法刻蚀约4小时，在硅基6中形成新的矩形对准标志3，用HF溶液或干法刻蚀局部去除掩模5，使矩形对准标志3完全暴露，至此，硅片{111}晶面4的零误差定位完成；② Perform wet etching at 60°C in 50wt% KOH solution for about 4 hours to form a new rectangular alignment mark 3 in the silicon substrate 6, and partially remove the mask 5 with HF solution or dry etching to make the rectangular alignment mark 3 The quasi-mark 3 is completely exposed, so far, the zero-error positioning of the {111} crystal plane 4 of the silicon wafer is completed;
③在紫外光刻中，用一束激光7打在掩模版上预制作的光栅掩模8，在接收屏9上记录其衍射光斑，作为基准线10；③In ultraviolet lithography, use a beam of laser 7 to hit the prefabricated grating mask 8 on the reticle, and record its diffraction spot on the receiving screen 9 as a reference line 10;
④将包含矩形对准标志3的硅片1放置在待曝光位置，用激光7入射矩形对准标志3，在接收屏9上会出现一系列衍射光斑11，利用紫外光刻机的微调机构，调整硅片1，使衍射光斑11与基准线10对准；④ Place the silicon wafer 1 containing the rectangular alignment mark 3 at the position to be exposed, and use the laser 7 to incident the rectangular alignment mark 3, a series of diffraction spots 11 will appear on the receiving screen 9, using the fine-tuning mechanism of the ultraviolet lithography machine, Adjust the silicon wafer 1 so that the diffraction spot 11 is aligned with the reference line 10;
至此，光栅掩模8与硅片{111}晶面4的对准完成。So far, the alignment between the grating mask 8 and the {111} crystal plane 4 of the silicon wafer is completed.
本实施对准误差来源于步骤③和④中基准线10的记录和衍射光斑11与基准线10的对准，其大小取决于光斑与基准线重合的分辨误差Δl，光斑到基准元件或硅片的距离D；Δl一定程度上取决于人眼分辨能力，通过增大D可以提高对准精度，该实施例中。取Δl＝1mm，D＝5000mm，则矩形对准标志与光栅掩模的对准误差计算公式如下所示，经计算总对准误差为±0.016°。The alignment error in this implementation comes from the recording of the reference line 10 in steps ③ and ④ and the alignment of the diffraction spot 11 and the reference line 10, and its size depends on the resolution error Δl of the coincidence of the spot and the reference line, and the spot is transferred to the reference element or silicon wafer. The distance D; Δl depends to a certain extent on the resolution ability of the human eye, and the alignment accuracy can be improved by increasing D, in this embodiment. Taking Δl=1mm and D=5000mm, the formula for calculating the alignment error between the rectangular alignment mark and the grating mask is as follows, and the calculated total alignment error is ±0.016°.
以上实施例的说明只是用于帮助理解本发明的方法及其核心思想。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干改进和修饰，这些改进和修饰也落入本发明权利要求的保护范围内。The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
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|---|---|---|---|
| CN201510793828.1ACN105428292B (en) | 2015-11-17 | 2015-11-17 | A kind of alignment methods of grating mask and silicon chip { 111 } crystal face |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510793828.1ACN105428292B (en) | 2015-11-17 | 2015-11-17 | A kind of alignment methods of grating mask and silicon chip { 111 } crystal face |
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| CN105428292Atrue CN105428292A (en) | 2016-03-23 |
| CN105428292B CN105428292B (en) | 2018-08-03 |
| Application Number | Title | Priority Date | Filing Date |
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| CN201510793828.1AActiveCN105428292B (en) | 2015-11-17 | 2015-11-17 | A kind of alignment methods of grating mask and silicon chip { 111 } crystal face |
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| TR01 | Transfer of patent right | Effective date of registration:20201214 Address after:230000 building 3, No.1, Kechuang Town, Changlinhe Town, Feidong County, Hefei City, Anhui Province Patentee after:Anhui Zhongke Grating Technology Co.,Ltd. Address before:230026 Jinzhai Road, Baohe District, Hefei, Anhui Province, No. 96 Patentee before:University of Science and Technology of China |