Study On The Surface Layer Damage Of Sawed Monocrystalline And Polycrystalline Silicon Wafers

Silicon wafers are the most widely used substrates in IC, semiconductor devices and photovoltaic solar cells manufacturing fields. The monocrystalline and polycrystalline silicon wafers are the main materials for the production of semiconductors and solar cells. While the polycrystalline silicon wafer is the raw material to produce monocrystalline silicon wafers. Both of them own semiconductor characteristics, they still show differences in physical characteristics and other aspects. In the use of solar power, monocrystalline and polycrystalline silicon wafers play a very important role. With the increasing of the silicon wafer diameter and the rapid improvement of photovoltaic industry, the requirements of the surface layer quality are increasingly higher. The quality of the wafer’s surface layer will directly affect the property, the rate of finished products and the lifetime of the device. Sawing is an important process in wafer manufacturing process. However, sawing would inevitably bring surface layer damage, and the damage will severely affect the processing time of the subsequent process and processing efficiency. Therefore, studying on the subsurface damage depth and crack characteristics generated in the sawing process has an important guiding significance on the subsequent processing.The detection method of sawed wafers’subsurface damage is studied in the article. We also detect the subsurface damage and crack types of different sawed wafers with the method of cross-section microscopy and angle polishing. Furthermore, a preliminary evaluation of Fixed Abrasive Sawed Monocrystalline Wafer (FASMW), Loose Abrasive Sawed Monocrystalline Wafer (LASMW) and Loose Abrasive Sawed Polycrystalline Wafer (LASPW) is shown in this paper, based on the comparation of the surface morphology, subsurface damage depth and subsurface damage micro-crack regularity of distribution between monocrystalline silicon wafers and polycrystalline silicon wafers. Experiments show that, under the same working condition, the maximum subsurface damage depth of FASMW is less than the maximum depth of subsurface damage in LASMW. While the subsurface damage depth of LASMW is almost the same of the LASPW depth of subsurface damage. Besides, there exists intensive corrosion pits and scratches in LASPW after the corrosion. Some of the polycrystalline silicon wafers will appear polysilicon film grain boundaries because of different slice locations, The FASMW, LASMW, LASPW micro-crack density and micro-crack length obey the exponential relationship, but FASMW micro-crack density and length distribution is uniform; the range of micro-crack density and length of LASMW and LASPW distribution is relatively large. Thesis study provides guidance to the choice of silicon cutting methods and process parameters.