Abstract
Silicon substrate slices in (111) or (001) surface orientation have been machined in two ways: precision ground by a diamond abrasive wheel to a surface roughness R a ≈ 11 nm, or turned on a highly stiff single-point diamond turning machine to R a,≈0·5 nm. Transmission electron microscopy of cross-sections of the machined surfaces has established the following.
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The mean depth of permanent damage in both cases lies in the range 100–400 nm.
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In the ground specimens the damage depth is very variable, and the damage consists of regions of well defined dislocation loops on several slip systems, other regions with a very high density of irregular dislocation arrays, and occasional microcracks up to 500nm deep which do not always intersect the surfaces. Patches of amorphous silicon are also observed.
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Beneath the turned surfaces the damage appears more homogeneous, consisting of dislocation loops predominantly on a single slip system in any given region of the specimen.
