Browse Prior Art Database

Improved Polysilicon-Filled Trench Isolation

IP.com Disclosure Number: IPCOM000043271D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Jambotkar, CG: AUTHOR

Abstract

This article describes a technique for obtaining about 1-micrometer thick insulation layer(s) above the polysilicon in polysilicon-filled trenches in a self-aligned manner; for example, the thickness of the insulation layer(s) just outside the trench regions can be maintained relatively thin, typically 0.3 micrometer. This technique avoids using thermal growth of about 1-micrometer SiO2 as the method for realizing the insulation above the polysilicon and thus avoids consequent creation of stresses in silicon outside the trench regions. Also, the substrate topography remains substantially planar as a result of application of the technique being described in this article. The technique allows the thickness of the insulation above polysilicon in selected trench regions to be thin, for example 0.3 micrometer.

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Improved Polysilicon-Filled Trench Isolation

This article describes a technique for obtaining about 1-micrometer thick insulation layer(s) above the polysilicon in polysilicon-filled trenches in a self- aligned manner; for example, the thickness of the insulation layer(s) just outside the trench regions can be maintained relatively thin, typically 0.3 micrometer. This technique avoids using thermal growth of about 1-micrometer SiO2 as the method for realizing the insulation above the polysilicon and thus avoids consequent creation of stresses in silicon outside the trench regions. Also, the substrate topography remains substantially planar as a result of application of the technique being described in this article. The technique allows the thickness of the insulation above polysilicon in selected trench regions to be thin, for example
0.3 micrometer. These selected trench regions are typically where a metal contact would eventually be made to the buried substrate via the polysilicon in the trenches. The following is a broad outline of the process steps in the technique being described: 1. Form the basic structure of Fig. 1 using the methods of prior art. In Fig. 1, 2 is the substrate, 4 is the insulation layer(s) outside the polysilicon-filled trench regions 9, the insulation layer(s) 6 cover(s) the trench peripheries formed prior to filling the trenches with polysilicon 8. Through selective etching, the top surface of polysilicon 8 is deliberately realized to be...