硅晶体定晶向电火花线切割加工损伤层检测研究

发布时间：2019-02-24 19:19

【摘要】：在今天这个科学技术飞速发展的时代,具有特定晶向的单晶硅材料,其自身特殊的理化性能极大的满足了国防军事、精密仪器、光学仪表制造等领域的需求。在这些领域的生产加工过程中,作为核心材料的定晶向单晶硅需具有平整光洁的表面和较高的表面质量、无任何损伤、晶向精度符合预定要求。但是目前最常用的加工定晶向单晶硅片的方式是采用电火花线切割,该种方法会在加工表面造成电蚀坑、裂纹、深孔等加工损伤,故加工表面会存在损伤层(变质层)。而定晶向硅材料的后期加工,首先需对其表面的损伤层进行去除。本文对电火花定晶向线切割后的单晶硅的损伤层进行了研究,包括定晶向硅片损伤层的厚度和相关检测技术,加工过程中不同的蚀除方式及它们对硅晶体造成的损伤、成因、结构特征及减小损伤深度的措施,明确了不同蚀除方式下加工损伤层的划分。并将损伤层检测成果应用到了定晶向单晶硅损伤层的去除研究中,搭建了定晶向单晶硅损伤层去除平台,采用喷射电解法对单晶硅的加工损伤进行去除研究,进行了去除过程中试验参数的选择与优化,完成的主要工作如下:(1)提出了基于X射线回摆曲线法的定晶向单晶硅变质层厚度检测技术,并通过试验证明了其可行性。组建了定晶向单晶硅变质层检测平台,研究了切割过程中脉宽对加工出的单晶硅其表面变质层厚度的影响,得出脉宽越大变质层厚度就越厚。发现了相同加工参数切割出的不同晶向硅片的变质层厚度不同,且变质层厚度随着相邻晶面间键密度的增大而减小。(2)采用了X射线回摆曲线法与显微观测相结合的方法,对单晶硅电火花线切割加工过程中不同的蚀除方式进行了研究,并提出了减小加工损伤深度的措施。(3)研究了电火花定晶向线切割加工过程中不同的蚀除方式对硅晶体造成的损伤、成因、结构特征,明确了所造成损伤的类型、微观形貌结构特征,并对正常蚀除(以熔化和气化的放电蚀除形式为主)与复合蚀除(在正常蚀除的基础上还发生了热剥落蚀除)两种情况下的加工损伤层进行划分。(4)将损伤层检测成果应用到了定晶向单晶硅损伤层的去除研究中。搭建了定晶向单晶硅损伤层去除平台,采用喷射电解法对单晶硅的加工损伤进行去除研究,完成了去除过程中基本试验参数的选择及优化。在保证损伤层完全去除的前提下使硅基体材料损耗减小,并使损伤层去除后的单晶硅其加工表面质量得到提升。
[Abstract]:In the era of rapid development of science and technology, the monocrystalline silicon material with specific crystal orientation, its own special physical and chemical properties greatly meet the national defense military, precision instruments, optical instrument manufacturing and other fields. In the process of production and processing in these fields, the crystal oriented monocrystalline silicon, which is the core material, must have a smooth and clean surface and high surface quality without any damage, and the orientation accuracy meets the predetermined requirements. However, the most commonly used way to process single crystal wafers is electrical discharge wire cutting (WEDM), which will cause electrical etching pits, cracks, deep holes and so on, so there will be damage layer (metamorphic layer) on the machined surface. However, the surface damage layer should be removed in the later processing of crystalline silicon. In this paper, the damage layer of monocrystalline silicon after EDM has been studied, including the thickness of the damage layer and the related detection technology, the different ways of etching during the process, the damage caused by them to silicon crystal, and the cause of formation. The structural characteristics and the measures to reduce the depth of damage are discussed, and the division of damage layers under different erosion modes is clarified. The results of damage layer detection are applied to the study of the damage layer removal of the single crystal silicon in the fixed crystal direction, and the removal platform of the damage layer is set up, and the machining damage of the single crystal silicon is studied by jet electrolysis. The main work is as follows: (1) based on the method of X-ray reverberation curve, the thickness detection technique of fixed crystal silicon metamorphic layer is put forward, and its feasibility is proved by experiment. In this paper, a detecting platform for the monocrystalline silicon metamorphic layer with fixed crystal orientation is set up, and the influence of pulse width on the thickness of the modified layer on the surface of the machined monocrystalline silicon is studied. It is concluded that the larger the pulse width is, the thicker the metamorphic layer is. It is found that the thickness of the metamorphic layer of the different crystal orientation silicon wafers cut with the same processing parameters is different, and the thickness of the metamorphic layer decreases with the increase of the bond density between adjacent crystal planes. (2) the method of combining X-ray backswing curve method with microscopic observation is used. In this paper, the different etching methods in the process of single crystal silicon wire discharge cutting (WEDM) are studied. The measures to reduce the depth of damage are put forward. (3) the damage, cause of formation, structural characteristics of silicon crystals caused by different etching methods in the process of EDM are studied, and the types of damage caused by EDM are determined. Microscopic morphology and structure, The process damage layers under the two conditions of normal erosion (mainly in the form of melting and gasification) and composite etching (thermal denudation on the basis of normal erosion) are divided. (4) damage is divided into two kinds of conditions. (4) damage is divided into two kinds of processes. (4) damage is divided into two types: (4) damage is caused by thermal denudation. The results of layer detection have been applied to the study of the removal of the damage layer of single crystal silicon. The removal platform of the damage layer of single crystal silicon with fixed crystal orientation was set up. The machining damage removal of single crystal silicon was studied by jet electrolysis, and the selection and optimization of the basic test parameters in the process of removing the damage layer were completed. On the premise of completely removing the damage layer, the loss of silicon substrate is reduced, and the surface quality of monocrystalline silicon after the removal of the damage layer is improved.
【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】：2017
【分类号】：O786

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