The effect of release-etch processing on surface microstructure stiction

A passive polysilicon microstructure is described which has been used to evaluate the stiction or unwanted adhesion occurring after release etch, rinse and dry processing. The results are interpreted in terms of particle adhesion theory. A residue dissolved in the water and redeposited during drying is responsible for one form of adhesion, by solid bridging. A reaction at silicon surfaces immersed in water is suggested as the source of this residue. Formation of a chemical oxide layer to protect the silicon surfaces alleviates adhesion due to this mechanism. Use of a hydrophobic, low surface energy coating that is applied as part of the rinse process is also described.<>