单晶硅定晶向电火花线切割晶向精度及损伤层厚度研究

发布时间：2018-06-17 09:19

本文选题：电火花线切割 + 单晶硅　；参考：《南京航空航天大学》2016年硕士论文

【摘要】：随着现代科技的飞速发展,具有特定晶向的单晶硅衍射晶体在高科技领域已经得到了越来越广泛的应用,如中子散射谱仪、硬X射线标定装置等。在大尺寸定晶向单晶硅电火花线切割加工时,加工后的衍射晶体表面并不是理想平面,每点的晶向误差与理想平面上每个点的晶向误差都是不同的,需要对整块晶体的晶向精度进行测量,同时由于晶体尺寸较大而载物台尺寸较小,所以每次测量得到的只是晶体表面部分的晶向精度,测量难度大、耗时长、测量精度低;此外,电火花线切割单晶硅时会在表面形成损伤层,如何方便地测定出该损伤层厚度为后续抛磨工序提供加工余量的依据也是难点之一。本课题首先采用单点晶向误差与硅片表面截面轮廓相结合的方法测定表面各点的晶向误差;其次,采用单晶回摆曲线法测定电火花线切割后硅片表面损伤层深度。最后,为进一步提高单晶硅定晶向切割的精度并减少切割中产生的损伤层厚度,将金属材料电火花多次切割技术运用到单晶硅电火花线切割中。围绕上述研究内容,开展的主要工作有:(1)针对大尺寸定晶向单晶硅,加工后衍射晶体表面不是理想平面,每一个点的晶向不同的情况。提出了一种利用测量表面轮廓和单点晶向误差相结合的方法来估算大尺寸定晶向单晶硅表面各个点的晶向误差,实验结果与理论分析吻合度较高。(2)制备高完整性表面的单晶硅片是光学检测器件生产中的一个重要部分。针对电火花线切割在加工单晶硅片的过程中所产生的损伤层,提出了基于X射线回摆曲线法与腐蚀相结合测定加工后硅片表面损伤深度的方法,分别从测量原理,不同晶向以及不同切割能量等方面进行了理论分析与实验研究。研究表明,该方法不仅可以有效地测定电火花定晶向切割单晶硅片表面损伤层厚度,还可以反映放电切割加工后表面损伤情况。(3)研究了单晶硅电火花线切割在不同放电能量下损伤层厚度和放电间隙。根据分析找出多次切割中合理的修刀补偿值等参数,并通过实验进行了验证。实验表明采用电火花多次切割技术,能够有效地对定晶向单晶硅进行高效、高表面质量切割加工,在同等加工表面质量条件下,与以往的一次切割相比,大大缩短了加工时间,简化了后续处理工序。(4)研究了电火花多次切割技术对加工定晶向单晶硅晶向精度的影响。当切割大尺寸单晶硅时,电火花多次切割不仅提高了定晶向切割硅片的表面质量,同时也提高了硅片表面的晶向精度,使得切割表面晶向误差的波动明显减少。
[Abstract]:With the rapid development of modern science and technology, single crystal diffraction crystals with specific crystal orientation have been more and more widely used in high-tech fields, such as neutron scattering spectrometer, hard X-ray calibration device and so on. The surface of the diffraction crystal is not an ideal plane during the wire-cutting of large size single-crystal silicon EDM, and the orientation error of each point is different from that of each point on the ideal plane. It is necessary to measure the crystal orientation accuracy of the whole crystal, and because the crystal size is larger and the load table size is smaller, only the crystal direction accuracy of the crystal surface part is obtained every time, it is difficult to measure, the time consuming is long, and the measuring precision is low. In addition, EDM monocrystalline silicon will form a damage layer on the surface. How to conveniently determine the thickness of the damage layer to provide processing allowance for the subsequent polishing process is also one of the difficulties. In this paper, the single point orientation error and the cross-section profile of the wafer surface are measured by the method of combining the single point orientation error with the profile of the surface section of the wafer, and the depth of the damaged layer on the surface of the silicon wafer after WEDM is measured by the single crystal swing curve method. Finally, in order to further improve the precision of single crystal silicon orientation cutting and reduce the thickness of damage layer produced in the cutting, the metal material EDM technology is applied to single crystal silicon wire discharge cutting. According to the above research contents, the main work carried out is: (1) for large size directionally oriented monocrystalline silicon, the surface of the diffraction crystal is not an ideal plane after processing, and the crystal orientation of each point is different. In this paper, a method is proposed to estimate the crystal direction errors of large size single-crystal silicon surface by combining the measurement of the surface profile with the single-point crystal orientation error. The experimental results are in good agreement with the theoretical analysis. The fabrication of single crystal silicon wafers with high integrity is an important part in the fabrication of optical detection devices. In view of the damage layer caused by WEDM in the process of machining single crystal silicon wafer, a method of measuring the surface damage depth of fabricated silicon wafer based on the combination of X-ray swing curve method and corrosion is put forward. Theoretical analysis and experimental study on different crystal directions and cutting energy were carried out. The results show that the method can not only effectively measure the thickness of the surface damage layer of the single crystal silicon wafer cut by EDM, but also can be used to determine the thickness of the surface damage layer. The damage layer thickness and discharge gap of single crystal silicon WEDM under different discharge energy are also studied. According to the analysis, reasonable parameters such as the compensation value of the cutter are found out and verified by experiments. The experimental results show that the EDM technology can be used to efficiently and efficiently cut the crystal oriented monocrystalline silicon with high surface quality. Under the same surface quality condition, the processing time is greatly shortened compared with the previous cutting. The effect of EDM on the orientation accuracy of single crystal silicon is studied. When the large size monocrystalline silicon is cut, the surface quality of the wafer is improved not only by EDM, but also by the crystal direction precision of the wafer surface, and the fluctuation of the crystal direction error of the cutting surface is obviously reduced.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG484

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