Method for adding contact hole etching process window by setting top etching barrier layer

TL;DR: In this article, a method for adding a contact hole etching process window by setting a top etching barrier layer is described, where an etching stop layer which is generally positioned at the bottom of a dielectric layer is moved to the top and can be selectively made of silicon nitride.

Abstract: The invention discloses a method for adding a contact hole etching process window by setting a top etching barrier layer. According to the method, an etching stop layer which is generally positioned at the bottom of a dielectric layer is moved to the top and can be selectively made of silicon nitride. The method adopts the following basic flows of: firstly, normally etching to reach the height of a silicon gate; secondly, additionally arranging a mask plate of which the area contains holes on a substrate; selectively etching the contact hole by using a top film as a hard barrier layer, wherein the general etching depth is about 800A, the etching stop layer can be stripped in the subsequent CMP (Chemical Mechanical Polishing) engineering or can be certainly retained and the etching stop layer has no influence on the subsequent engineering. Although one extra photoetching work procedure is additionally arranged, a process window of the flow can be greatly increased and the area of a chip is reduced.