Study of the Distorted Layer Structure of Silicon Wafers by the Method of Plasma-chemical Etching after Mechanical Machining Processes

In this experimental work, by using the method of plasma-chemical etching, we have dealt with the causes of the creation of a distorted layer on the surface of silicon wafers during mechanical machining processes, in addition, the elucidation of connections between the structure of this layer and characteristic parameters of the mechanical strength of these wafers have been studied. Experimental results obtained at room temperature show that after cutting and grinding processes, the mean value of mechanical strength σ, which is apparently independent of the types of conductivity, is significantly lower than its theoretical value. Analysis of the dependence of mechanical parameters on the time of plasma-chemical etching indicates that the lower values obtained for the mechanical strength of silicon wafers is basically due to the existence of a distorted layer and corresponding internal stresses created on the surface of these wafers after mechanical machining. Plasma-chemical etching leads to an increase in σ value. Dependency of σ on the etching time is qualitatively described by the microstructure of the distorted layer and parameters of the micro relief surface of the wafers. Correlation between parameters σ, H, K and the microstructure of the distorted layer allows us to suggest the method of plasma chemical etching as a method of investigating the microstructure of the distorted layer after the mechanical machining processes.