Browse Prior Art Database

Method for Controlling Trench Sidewall Taper

IP.com Disclosure Number: IPCOM000041007D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dobuzinsky, DM: AUTHOR [+3]

Abstract

A method is described which allows trench sidewall taper con- trol in semiconductor device fabrication.

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This is the abbreviated version, containing approximately 78% of the total text.

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Method for Controlling Trench Sidewall Taper

A method is described which allows trench sidewall taper con- trol in semiconductor device fabrication.

Trench sidewall profile control is generally achieved by changing an appropriate combination of plasma process parameters; most commonly gas flow, pressure and power. A smooth variation from a vertical slope is difficult to achieve and usually re- quires the variation of a large matrix of conditions.

By altering the silicon loading in a chlorine-based reactive ion etch process, a smooth tapering effect is created when fabricating a trench in a silicon substrate. A tapering effect from approximately a 90 degree slope to an 80 degree slope is achieved with a silicon loading of less than 1% to 50% of the total cathode area, respectively. Silicon loading can be accom- plished by changing the typically inert cathode plate material of a reactive ion etch reactor, e.g., Al2O3, to a material which consumes some of the available etchant species. Electrode loading can be effected by coating an electrode tray with polysilicon in a chemical vapor deposition pancake reactor. A more intermediate loading may be accomplished by either changing a portion of the electrode plates from a refractory material to a silicon mate- rial, or by adding silicon to auxiliary recesses machined into the cathode plates. Intermediate silicon loadings result in a correspondingly tapered trench sidewall variation which can meet the design specification...