Isotropic etching of Si sacrifice layer
Wet etching has been the mainstream method of etching the Si sacrificial layer during MEMS microfabrication, but stiction (tension) has been a major problem. This problem can be solved by dry etching using xenon fluoride (XeF₂) gas, which has an isotropic etching action on Si at room temperature with a very high selectivity ratio. In addition, since plasma is not used, there is no electrical damage, and etching is done intermittently with gas flow, so it is easy to control the etching speed.
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