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硅衬底的质量直接影响外延层质量和器件的性能.一般要求外延前的衬底具备:(1)无或极少量机械损伤;(2)小的弯曲度;(3)高度平整光洁的抛光表面,且抛光表面的损伤应力尽量小.这三者是相互制约的.众所周知,晶体经切割、研磨之后会引入大量的机械损伤.据报道,损伤层的厚度在50μ以上,其中多晶层为2～3μ,裂纹层20μ,弹性畸变层为30μ左右.其中弹性畸变是由应力引起的,较深.单用抛光方法去除50μ以上的损伤层,需要6小时,难以达到良好的平整度,也是不经济的.化学减薄既能除去衬底原有的表面损
The quality of the silicon substrate directly affects the quality of the epitaxial layer and the performance of the device.Generally, the substrate before epitaxy is required to have: (1) no or minimal mechanical damage; (2) a small degree of curvature; (3) Surface, and the polishing surface damage stress as small as possible.The three are mutually constrained.It is well known that the crystal after cutting, grinding will introduce a large number of mechanical damage.It is reported that the damage layer thickness of 50μ or more, in which the polycrystalline layer is 2 ~ 3μ, crack layer 20μ, elastic deformation layer is about 30μ. Among them, the elastic distortion is caused by stress, deep. Single polishing method to remove more than 50μ damage layer, it takes 6 hours, it is difficult to achieve good flatness, is also Not economical. Chemical thinning can remove the original surface damage to the substrate