Surfaces physical sputtering

Likewise, when Ar impinged on the surface, pure sputtering ( 2 A/min) was noted. However, when the beams were simultaneously directed at the silicon surface, a relatively large (--SS A/min.) etch rate was observed the measured rate was approximately an order of magnitude greater than the sum of the chemical and physical components. Obviously, synergistic effects due to ion bombardment are crucial to this chemical etch process. Unfortunately, the exact nature of these effects is at present undefined. 

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