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Preparing Thin (< 100 Angstrom) SiO(2) Films

IP.com Disclosure Number: IPCOM000083068D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Irene, EA: AUTHOR

Abstract

Conventionally SiO(2) films are prepared by thermal oxidation of Si slices in O(2), steam + O(2), and other oxidants such as CO(2), NO, etc., or by chemical vapor deposition (CVD) techniques (i.e., reaction of SiH(4) + O(2)). Experience dictates that the Si-SiO(2) interface properties are best for thermal oxides (rather than CVD SiO(2)) prepared at elevated temperatures (> 700 degrees C) in clean gases (O(2), H(2)O, etc.).

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Preparing Thin (< 100 Angstrom) SiO(2) Films

Conventionally SiO(2) films are prepared by thermal oxidation of Si slices in O(2), steam + O(2), and other oxidants such as CO(2), NO, etc., or by chemical vapor deposition (CVD) techniques (i.e., reaction of SiH(4) + O(2)). Experience dictates that the Si-SiO(2) interface properties are best for thermal oxides (rather than CVD SiO(2)) prepared at elevated temperatures (> 700 degrees C) in clean gases (O(2), H(2)O, etc.).

It is within the state of the art to obtain clean O(2) and H(2)O, but difficult and costly to obtain other oxidant gases (CO(2), NO, etc.) of sufficient purity and quantity. Therefore, O(2) and/or H(2)O are used commercially for the preparation of SiO(2) films. Either O(2) or O(2) + steam has proven to be adequate to prepare controlled thicknesses of SiO(2) on Si for thick films, i.e.,> 100 Angstroms. O(2) + steam is usually only used for growing SiO(2) films > 1000 Angstroms. For films of 0 to 100 Angstroms at temperatures > 70 usual to use O(2) + N(2) (or another inert gas) with ~ .5 to 10% O(2).

This technique lengthens the time needed to oxidize Si to a desired thickness, thereby facilitating reproducibility of the thickness of the film from run- to-run. The problem with this technique is that careful control of the O(2) percentage must be maintained. To do this precisely, requires accurate mass flow meters and careful monitoring and control of the H(2)O content of the O(2) and the inert gas.

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