End point control in plasma etching
First Claim
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1. A process for the uniform application of a pattern to a plurality of workpieces by selective etching, comprising the steps of:
- (a) exposing a plurality of workpieces in a reaction space to a chemically reactive plasma which etches the exposed surface of each workpiece by chemically reacting with the material from which said surface is comprised;
(b) monitoring the variation over time of the amplitude of at least one atomic emission line of the atomic emission spectrum of said plasma during the reaction of said plasma with said workpieces, said emission line having an amplitude which is sensitive to the concentration in said plasma of a member selected from a product of said reaction or an etching radical; and
(c) determining the end point of said selective etching by a change in said amplitude.
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Abstract
The end point in plasma etching is detected by monitoring the optical emission from the plasma, selecting a particular optical emission line and detecting a substantial variation in the intensity of the emission. This indicates a change in material being etched and thus the completion of etching of one material, or the beginning of etching of another material. It is also applicable to removing, or etching, photoresist material.
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Citations
16 Claims
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1. A process for the uniform application of a pattern to a plurality of workpieces by selective etching, comprising the steps of:
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(a) exposing a plurality of workpieces in a reaction space to a chemically reactive plasma which etches the exposed surface of each workpiece by chemically reacting with the material from which said surface is comprised; (b) monitoring the variation over time of the amplitude of at least one atomic emission line of the atomic emission spectrum of said plasma during the reaction of said plasma with said workpieces, said emission line having an amplitude which is sensitive to the concentration in said plasma of a member selected from a product of said reaction or an etching radical; and (c) determining the end point of said selective etching by a change in said amplitude. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16)
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11. A method for providing end point control in a plasma etching process for removing a material from a workpiece, comprising the steps of:
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(a) selectively removing material from a workpiece by chemical reaction between etching radicals in a plasma and the material being removed; (b) monitoring an atomic emission line having an amplitude which is sensitive to the concentration in said plasma of a product of said reaction; (c) determining the end point of said plasma etching process by a change in said amplitude; and (d) terminating said chemical reaction at a predetermined time after said detected end point.
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Specification