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Characterization of Thin Oxides by Etch Decoration

IP.com Disclosure Number: IPCOM000075165D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Anolick, ES: AUTHOR [+3]

Abstract

The thin oxide protecting the gate region in field-effect transistors is subject to imperfections. These imperfections may lead to yield loss and/or field failures under use conditions. In order to control the quality of thin oxide, a method of gauging the degree of imperfection is desirable. This, in turn, can lead to proper process control in order to improve thin-oxide quality.

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Characterization of Thin Oxides by Etch Decoration

The thin oxide protecting the gate region in field-effect transistors is subject to imperfections. These imperfections may lead to yield loss and/or field failures under use conditions. In order to control the quality of thin oxide, a method of gauging the degree of imperfection is desirable. This, in turn, can lead to proper process control in order to improve thin-oxide quality.

The basic technique consists of etching a control wafer in a solution which attacks silicon rapidly and silicon dioxide very slowly. If there is a defect in the thin oxide, the etch will penetrate and attack the silicon below. This attack can be observed and the wafer characterized in terms of the number of such defects per unit area for a given etch time.

The decoration is carried out with standard Si etchants which attack thermal oxide (SiO(2)) slowly or not at all. Two etchants are used generally: (1) Ethelene diamine pyrocatechol mixture run in a refluxing chamber with nitrogen bubble agitation between 100 degrees C and 110 degrees C, (2) Hydrazine at between 55 degrees C and 60 degrees C.

The control is a wafer with a grid of simulated or actual devices. This wafer is to be representative of the other materials in the run or lot. The wafer is subject to all processing steps up to, but not including deposition of a sputtered quartz protective layer. In addition, no contact holes are opened but a simulated contact hole etch is given...