Browse Prior Art Database

Modelling Three-Dimensional Multi-Layer Etching

IP.com Disclosure Number: IPCOM000035746D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Evans, RC: AUTHOR [+3]

Abstract

Disclosed is a method for simulating multilayer, unidirectional, rate- dependent etching in a three-dimensional polyhedral model of a semiconductor device. Because different layers will etch at different rates for the same etchant, variations in the etch-front appear locally across the device as the etch progresses in time.

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Modelling Three-Dimensional Multi-Layer Etching

Disclosed is a method for simulating multilayer, unidirectional, rate- dependent etching in a three-dimensional polyhedral model of a semiconductor device. Because different layers will etch at different rates for the same etchant, variations in the etch-front appear locally across the device as the etch progresses in time.

The generic method (described in terms of a downward etch) consists of the following steps: 1) Divide the model of the device into regions called chimneys (see

Fig. 1). 1a) project regions of upward faces of vulnerable device layers into the z=0 plane, obtaining a collection of

polygons. 1b) compute intersections of these polygons and their planar complements. Define a plane as each smallest

polygonal result and a chimney as all material regions

above the plane. 1c) for each such chimney layer record its material type and the plane equations of its top and bottom faces.

2a) Within each chimney perform a simulated etch: Definitions Downward etch rates, Rn, are available to the modeller for each of the N material layers of the device. Within a chimney, let Sn and En refer, respectively, to the planar surface equations of the top and bottom boundaries of the nth layer. W refers to a temporary planar equation across the chimney. It is assumed that these equations are explicit functions of x and y. T stands for the total duration of the etch. Define an initial etch front as W = S1 - R1 *T. DO for J = 1 to N. Case A: W is entirely above Ej. Reduce the jth layer to...