Method for monitoring end point of small opening density structure by dry etching

Abstract

The invention discloses a method for monitoring an end point of a small opening density structure by dry etching, which comprises the following steps: (1) increasing the opening density by adding at least one monitoring structure in a non-device area; and (2) monitoring the end point by adopting a plasma etching method. The method adds an etching stop layer by adding the monitoring structure or afilm texture monitoring structure which is different from an etching material when the etching layer film texture and the bottom etching film texture are the same and simultaneously ensures that the opening density is increased to be more than 3 percent so as to use a method for detecting the end point by the plasma etching for monitoring the etching end point. The thicknesses of a CD and a residual film can be accurately controlled, and etching process windows are greatly added.

Description

technical field [0001] The invention relates to a method for monitoring an etching end point in an etching process, in particular to a method for monitoring an etching end point in an etching small opening density structure. Background technique [0002] In the dry etching process, there are often etching processes with small opening density structures (such as tunnel window Tunnel, emission window EW), the opening density is small (generally less than 3%), or when the etch layer film quality and etch When the film quality of the etch bottom layer is the same, it can only be controlled by time, and it is difficult to use plasma etching end point monitor (EDP, end point monitor), which makes it difficult to control the critical dimension (CD) and residual film thickness, thus affecting the dry etching process. Eclipse window. Figure 1 is a schematic diagram of the existing dry-etched small opening density structure, wherein the etched bottom layer 3 is epitaxial silicon (EPi...

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Problems solved by technology

[0002] In the dry etching process, there are often etching processes with small opening density structures (such as tunnel window Tunnel, emission window EW), the opening density is small (generally less than 3%), or when the etch layer film quality and etch When the film quality of the etch bottom layer is the same, it can only be controlled by time, and it is difficult to use plasma etching end point monitor (EDP, end point monitor), which makes it difficult to control the critical dimension (CD) and residual film thickness, thus affecting the dry etching process. Eclipse window

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