METHOD FOR FORMING CONTACT HOLE OF SEMICONDUCTOR DEVICE INCLUDING DRY ETCH PROCESS WITH RESPECT TO SILICON OXYNITRIDE LAYER TO GUARANTEE SUFFICIENT OVER ETCH MARGIN

摘要

PURPOSE: A method for forming a contact hole of a semiconductor device is provided to guarantee a sufficient over-etch margin when a silicon oxide layer is etched until a silicon oxynitride layer is exposed by setting up an etch condition for etching the silicon oxide layer in which the silicon oxide layer has high etch selectivity with respect to a lower etch blocking layer and a deposition of polymer is minimized. CONSTITUTION: A semiconductor substrate is prepared. A conductive layer pattern having a step is formed on the substrate. The uppermost layer of the conductive layer pattern is composed of a silicide layer. The conductive layer pattern and the front surface of the substrate are covered with a silicon oxynitride layer. The front surface of the silicon oxynitride layer is covered with a silicon oxide layer. A photoresist pattern that respectively exposes the silicon oxide layer on a predetermined region of the substrate and the silicon oxide layer on the conductive layer pattern is formed on the silicon oxide layer. The silicon oxide layer is etched to expose the silicon oxynitride layer by using the photoresist pattern as an etch mask. The photoresist pattern and the polymer generated in the etch process are eliminated. The silicon oxynitride layer is etched by using a gas composition in which CHF3 gas and Ar gas are mixed in a ratio of 1:3-1:0.1 so that contact holes for exposing a predetermined region of the substrate and a conductive layer pattern are simultaneously formed.