Situ rate and depth monitor for silicon etching
First Claim
1. A process for monitoring changes in thickness of a layer of product material in an environment arranged to produce such changes, comprising the steps of;
- selecting a reference material which exhibits thickness changing characteristics in said environment correlatable to those of the product material in said environment;
depositing said reference material on a substrate therefor to form a monitor device that exhibits an optical discontinuity between said reference material and substrate;
positioning said monitor device in the said environment with said product material so that said reference material and product material undergo changes in thickness; and
directing light to said monitor device so as to obtain reflected light therefrom to monitor the thickness of said reference material, whereby changes in thickness of said reference material may be correlated to changes in thickness of said product material.
1 Assignment
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Accused Products
Abstract
An in situ thickness change monitor for determining thickness change in opaque product material, such as silicon, in chamber apparatus, such as reactive ion etching apparatus, operative to produce such thickness change. Reference material having thickness change properties, such as etch-rate, correlatable to the product material thickness change properties is deposited upon a substrate having an index of refraction such as to form a monitor exhibiting an optical discontinuity. With the monitor positioned within the chamber with the product material, light directed thereto acts to provide reflected beams producing light having an intensity variation due to interference indicative of the thickness of the reference material. Changes in the thickness of the reference material are correlated to changes in thickness of the product material.
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Citations
22 Claims
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1. A process for monitoring changes in thickness of a layer of product material in an environment arranged to produce such changes, comprising the steps of;
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selecting a reference material which exhibits thickness changing characteristics in said environment correlatable to those of the product material in said environment; depositing said reference material on a substrate therefor to form a monitor device that exhibits an optical discontinuity between said reference material and substrate; positioning said monitor device in the said environment with said product material so that said reference material and product material undergo changes in thickness; and directing light to said monitor device so as to obtain reflected light therefrom to monitor the thickness of said reference material, whereby changes in thickness of said reference material may be correlated to changes in thickness of said product material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A process for monitoring changes in thickness of a layer of product material being etched in an etching chamber comprising;
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selecting a reference material which exhibits etch rate characteristics correlatable to those of said product material; depositing said reference material on a substrate so that an optical discontinuity exists between said reference material and substrate; positioning said reference material on said substrate in said etching chamber with said product material; directing light to said reference material in said etching chamber to obtain reflected light therefrom which may be used to determine the thickness of said reference material; and using said reflected light to determine the thickness of said reference material such that changes in thickness of said reference material may be correlated to changes in thickness of said product material. - View Dependent Claims (13, 14, 15, 16, 17)
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18. Apparatus for the in situ monitoring of changes in thickness of product material in a chamber arranged to produce changes in thickness of said product material, comprising;
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monitor means positioned within said chamber with said monitor means including a layer of reference material exhibiting thickness changing properties within said chamber correlatable to the thickness changing properties of said product material, said monitor means further including substrate means for said reference material arranged so that an optical discontinuity exists between said reference material and substrate means;
light source means for directing light tosaid monitor means so that said monitor means produces reflected light from both said reference material and substrate means; and detector means to change said reflected light to a signal having a period indicative of the thickness of said reference material and correlatable to the thickness of said product material. - View Dependent Claims (19, 20, 21, 22)
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Specification