Lam Research Corporation
SILICON OXIDE SILICON NITRIDE STACK STAIR STEP ETCH

Abstract:

A method for forming a stair-step structure in a stack on a substrate is provided. The method comprises at least one stair step cycle. Each stair step cycle comprises trimming the mask and etching the stack. Etching the stack is provided in a plurality of cycles wherein each cycle comprises etching a SiO.sub.2 layer and etching a SiN layer. Etching a SiO.sub.2 layer comprises flowing a SiO.sub.2 etching gas into the plasma processing chamber, wherein the SiO.sub.2 etching gas comprises a hydrofluorocarbon, an inert bombardment gas, and at least one of SF.sub.6 and NF.sub.3, generating a plasma from the SiO.sub.2 etching gas, providing a bias, and stopping the SiO.sub.2 layer etch. The etching a SiN layer comprises flowing a SiN etching gas into the plasma processing chamber, comprising a hydrofluorocarbon and oxygen, generating a plasma from the SiN etching gas, providing a bias, and stopping the SiN layer etch.