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Wafer Warp Elimination Through Control of Process Gas System

IP.com Disclosure Number: IPCOM000062572D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Jacobowitz, L: AUTHOR [+2]

Abstract

A technique for eliminating film stress and wafer warping when films are deposited on wafers via low pressure chemical vapor deposition is provided. The technique comprises optically monitoring the index of refraction of the growing film, and feeding the index of refraction results back to a system which dynamically controls the gas composition ratio during deposition such that the refractive index of the depositing film is maintained at a value constantly equal to the characteristic refractive index for the temperature being used. Stresses due to film tension are created on a silicon wafer when nitride process films are applied to the wafer. The stresses are known to cause warpage of the wafer. The warpage results in the magnification error during lithographic exposure which causes overlay and linewidth error.

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Wafer Warp Elimination Through Control of Process Gas System

A technique for eliminating film stress and wafer warping when films are deposited on wafers via low pressure chemical vapor deposition is provided. The technique comprises optically monitoring the index of refraction of the growing film, and feeding the index of refraction results back to a system which dynamically controls the gas composition ratio during deposition such that the refractive index of the depositing film is maintained at a value constantly equal to the characteristic refractive index for the temperature being used. Stresses due to film tension are created on a silicon wafer when nitride process films are applied to the wafer. The stresses are known to cause warpage of the wafer. The warpage results in the magnification error during lithographic exposure which causes overlay and linewidth error. To eliminate these errors, the films must be applied in such a way as to prevent tension. A system for applying films to a wafer via low pressure vapor deposition without resulting wafer warpage is seen in the figure. The system comprises a dynamic gas system (10, 15, 20) for causing gases of determined gas composition ratio to be deposited as a film on wafers 25 via conventional flow control techniques, an optical system (30, 35) for monitoring the index of refraction of the film on the wafers 25, and feedback 40 from the optical system to the dynamic gas system. In particular, wafers 25 on which nitride films are to...