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Determining Trace Contaminants in an Inductively Coupled Plasma Etching System

IP.com Disclosure Number: IPCOM000088858D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Rozich, WR: AUTHOR [+2]

Abstract

Trace contaminants in plasma etching (reactive ion etching) systems can cause an etching of silicon dioxide when the tool is used in the resist-strip mode. This etching may cause pin holes in a thin oxide which degrade its use as a diffusion carrier or mask.

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Determining Trace Contaminants in an Inductively Coupled Plasma Etching System

Trace contaminants in plasma etching (reactive ion etching) systems can cause an etching of silicon dioxide when the tool is used in the resist-strip mode. This etching may cause pin holes in a thin oxide which degrade its use as a diffusion carrier or mask.

In a typical process, silicon nitride is used as a mask atop a layer of silicon dioxide. The nitride is etched down to the silicon dioxide using DE100, which is a commercially available gas from the LFE Corporation. The gas is a mixture of CF(4) and O(2). The photo-or E-beam-resist which has defined the nitride openings is then stripped in the same tool using an O(2) plasma.

After the etching of the silicon nitride, the underlay oxide over specified active regions in the semiconductor may be as low as about 600 Angstroms. If this oxide layer has been thinned during the aforementioned resist-strip cycle due to contamination of the O(2) plasma gas by the DE100, then the underlay oxide will be thinned to a level where its integrity as a diffusion mask is impacted. The contamination may be due to foreign material in the DE100 gas or a leaking solenoid.

The method employed for checking the integrity of the resist-strip system comprises the use of a silicon substrate coated with a positive resist, such as AZ11 or AZ1350 which are commercially available from the Shipley Corporation. A masking pattern is developed in the usual manner, afte...