锗单晶切割片中缺陷的表面腐蚀研究

发布时间：2018-03-21 00:13

本文选题：锗片　切入点：腐蚀速率　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：锗单晶在红外以及太阳能航空航天都有广泛应用。对锗单晶表面的平整度要求也不断提高,对内部的位错数量也有要求。直拉单晶技术直接决定锗锭内部的位错密度,锗锭的切割加工过程决定锗片表面质量,锗片的品质又影响着性能。因此研究锗单晶片表面的损伤层,位错等缺陷对改进锗单晶的性能与加工有重要意义。现阶段主要通过HNO_3-HF体系的腐蚀液抛光锗单晶片,必须先腐蚀抛光,后用择优腐蚀显示位错,其存在着步骤多、反应自催化不可控、污染大的问题。本文主要研究内容为寻找一种新型的优良腐蚀剂来显示锗单晶片的位错,通过观察、计算位错密度来正确评价锗单晶片的表面质量,并通过截面腐蚀再用电镜观察来测量获得其损伤层信息。通过定性分析,在多种氧化剂中选择了高锰酸钾作为腐蚀液中的氧化剂,并分析了超声对于锗片腐蚀的影响,结果表明在长时间超声时锗片表面会受到损伤,不能很好的应用于该体系加快反应。通过定性分析,得出氢氟酸必须加入的结论。在后续实验中根据酸性腐蚀原理,提高氢氟酸的量,使腐蚀后锗片表面平整并能显示位错。后对腐蚀温度进行研究,配比相同时,在温度较低时,腐蚀后的锗片表面粗糙无光亮;温度升到一定量时,腐蚀速率开始提升,表面平整度也开始变好,但温度过高时,锗片表面平整度又会下降。对腐蚀液配比研究发现,腐蚀液配比对于锗片腐蚀也有很大影响。这和腐蚀时包含两个过程有关。通过对腐蚀时间的研究,研究表明在腐蚀120 min后锗片的粗糙度不再明显变化,形貌上也趋于稳定。最后得到V(KMnO_4):V(HF):V(H_2SO_4)为10:9:1,其中KMnO_4浓度为0.4 mol/L、氢氟酸分析纯、H_2SO_4浓度为4 mol/L时,腐蚀温度60°C,腐蚀时间120 min后能很好抛光并显示位错。最后利用研究的腐蚀液腐蚀锗片,计算位错。解离锗片腐蚀后通过电镜观察截面可以观察到锗片的损伤层,通过测量得出其损伤层厚度。综合锗片表面的位错密度和损伤层厚度,可以较为系统的了解锗片的表面质量,从而促进其生产、加工工艺的改进。
[Abstract]:Germanium single crystals are widely used in infrared and solar aerospace. The flatness of germanium single crystal surface and the number of internal dislocations are also increased. Czochralski single crystal technology directly determines the dislocation density in germanium ingot. The cutting process of germanium ingot determines the surface quality of germanium wafer, and the quality of germanium wafer affects the properties of germanium wafer. Dislocations and other defects are of great significance in improving the performance and processing of germanium single crystals. At this stage, it is necessary to corrode and polish germanium single crystals mainly through corrosion solution of HNO_3-HF system, and then display dislocations with preferential corrosion, which has many steps. The main content of this paper is to find a new kind of excellent etchant to display the dislocation of germanium monocrystalline wafer. By observing and calculating dislocation density, the surface quality of germanium single crystal wafer can be correctly evaluated. The damage layer information was measured by electron microscope. Through qualitative analysis, potassium permanganate was selected as the oxidant in the corrosion solution, and the effect of ultrasonic on the corrosion of germanium sheet was analyzed. The results show that the surface of germanium sheet will be damaged after a long time of ultrasonic, so it can not be applied to the system to accelerate the reaction. By qualitative analysis, it is concluded that hydrofluoric acid must be added. In the subsequent experiments, according to the principle of acid corrosion, By increasing the amount of hydrofluoric acid, the surface of the etched germanium sheet is flat and the dislocation can be displayed. Then the corrosion temperature is studied. When the ratio is the same, the surface of the etched germanium sheet is rough and has no brightness when the temperature is lower, and when the temperature rises to a certain amount, The corrosion rate began to increase and the surface smoothness began to improve, but when the temperature was too high, the surface smoothness of germanium wafer would decrease again. The ratio of corrosion solution also has a great influence on the corrosion of germanium sheet, which is related to the two processes involved in the corrosion. Through the study of corrosion time, it is shown that the roughness of germanium sheet does not change obviously after corrosion for 120 min. Finally, it was found that VKMnO _ 4: V _ 2O _ 4 / V _ S _ 2SO _ 4) was 10: 9: 1, in which the concentration of KMnO_4 was 0.4 mol / L, the concentration of hydrofluoric acid was 4 mol/L, the corrosion temperature was 60 掳C, the corrosion time was 120 min, and the dislocations could be displayed. The damage layer of germanium sheet can be observed by electron microscope after corrosion. The thickness of damage layer can be obtained by measuring the thickness of the damage layer. We can systematically understand the surface quality of germanium sheet, thus promoting the improvement of production and processing technology.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304.11

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