The effect of aluminum masks on the plasma etch rates of polysilicon and silicon nitride

Abstract

Plasma etch rates of both aluminum and photoresist masked polysilicon and silicon nitride are reported. Both thermally grown and plasma deposited substrates of both films were studied. It is shown that all aluminum masked substrates except thermal nitride exhibit enhanced etch rates relative to photoresist masked samples. Aluminum masked thermal nitride etches more slowly than does photoresist masked. These results are shown to be consistent with a metal catalyzed surface reaction which generates additional fluorine radicals at the surface of the wafer.