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US5160576A
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Method of end point detection in a plasma etching process
Assignee: Lam Research Corp
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Filing: 1991-03-05
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Granted: 1992-11-03
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Expires: 2011-03-05
Abstract
Abstract A method of optically detecting a change in intensity of an emission peak in a plasma process, such as a plasma etching process, by reflecting an emission spectrum of radiation from the plasma reaction off of a pair of rugate filters. The reflected emission spectrum has increased in-band reflections and decreased out-of-band reflections which provides reduced noise and an easier-to-detect emission peak. The method can be used for end-point detection in a plasma etching process such as etching of SiO 2 .
Inventors
- 👤 Michael Robbins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:15
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/28; G02B5/289; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0683; G01N; G01N21/00; G01N21/62; G01N21/66; G01N21/67; G01J; G01J3/00; G01J3/12; G01J2003/1213; G01J3/28; G01J3/443
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
67 words
A method of end-point detection in a plasma etching process, comprising: etching a specimen by means of glow discharge in a reaction chamber; and optically detecting an intensity of at least one emission peak in emission spectrum of radiation from the glow discharge, the emission spectrum being reflected from at least one rugate filter prior to measuring the intensity of the emission peak in the emission spectrum.
Claim 2
Independent Claim
67 words
A method of end-point detection in a plasma etching process, comprising: etching a specimen by means of glow discharge in a reaction chamber; and optically detecting an intensity of at least one emission peak in emission spectrum of radiation from the glow discharge, the emission spectrum being reflected from at least one rugate filter prior to measuring the intensity of the emission peak in the emission spectrum.
Claim 3
Dependent Claim
34 words
The method of claim 1, wherein the emission spectrum is reflected from the one rugate filter to a second rugate filter prior to detecting the intensity of the emission peak in the emission spectrum.
Claim 4
Dependent Claim
42 words
The method of claim 1, wherein a plurality of emission peaks are optically measured, the rugate filter filtering the emission spectrum such that a plurality of bandwidths are reflected therefrom, each of the bandwidths including a respective one of the emission peaks.
Claim 5
Dependent Claim
26 words
The method of claim 1, wherein the emission spectrum is passed through a window in the reaction chamber prior to being reflected by the rugate filter.
Claim 6
Dependent Claim
25 words
The method of claim 1, wherein the emission spectrum is passed through at least one edge filter prior to being reflected by the rugate filter.
Claim 7
Dependent Claim
23 words
The method of claim 1, wherein the emission spectrum is passed through a collimating lens prior to being reflected by the rugate filter.
Claim 8
Dependent Claim
32 words
The method of claim 1, wherein the emission spectrum is passed into amplification means for amplifying the intensity of the emission peak after the emission peak is reflected by the rugate filter.
Claim 9
Dependent Claim
15 words
The method of claim 1, wherein the emission peak is produced by an etching reaction.
Claim 10
Dependent Claim
29 words
The method of claim 1, wherein the specimen comprises an exposed surface of silicon dioxide and the emission peak is produced by a molecular transition of a CO molecule.
Claim 11
Dependent Claim
22 words
The method of claim 9, wherein the exposed surface is no greater than 1% of a total surface area of the specimen.
Claim 12
Dependent Claim
21 words
The method of claim 3, wherein the emission peaks are produced by molecular transitions of at least one etching reaction product.
Claim 13
Dependent Claim
40 words
The method of claim 1, further comprising a step of adjusting an angle of incidence between the emission spectrum and a normal to a reflecting surface of the rugate filter such that suitable reflection of the emission spectrum is achieved.
Claim 14
Dependent Claim
20 words
The method of claim 12, wherein the rugate filter is oriented such that the angle of incidence is about 45°.
Claim 15
Independent Claim
74 words
A method of optically detecting a change in intensity of an emission peak in a plasma process, comprising: providing a plasma reaction by reacting a plasma reactant with a surface of a specimen in a reaction chamber; reflecting an emission spectrum of radiation from the plasma reaction off at least one rugate filter; and optically detecting an intensity of at least one emission peak in the emission speotrum refleoted off of the rugate filter.
Claim 16
Independent Claim
74 words
A method of optically detecting a change in intensity of an emission peak in a plasma process, comprising: providing a plasma reaction by reacting a plasma reactant with a surface of a specimen in a reaction chamber; reflecting an emission spectrum of radiation from the plasma reaction off at least one rugate filter; and optically detecting an intensity of at least one emission peak in the emission speotrum refleoted off of the rugate filter.
Claim 17
Dependent Claim
34 words
The method of claim 14, wherein the emission spectrum is reflected from the one rugate filter to a second rugate filter prior to detecting the intensity of the emission peak in the emission spectrum.
Claim 18
Dependent Claim
42 words
The method of claim 14, wherein a plurality of emission peaks are optically detected, the rugate filter filtering the emission spectrum such that a plurality of bandwidths are reflected therefrom, each of the bandwidths including a respective one of the emission peaks.
Claim 19
Dependent Claim
26 words
The method of claim 14, wherein the emission spectrum is passed through a window in the reaction chamber prior to being reflected by the rugate filter.
Claim 20
Dependent Claim
25 words
The method of claim 14, wherein the emission spectrum is passed through at least one edge filter prior to being reflected by the rugate filter.
Claim 21
Dependent Claim
23 words
The method of claim 14, wherein the emission spectrum is passed through a collimating lens prior to being reflected by the rugate filter.
Claim 22
Dependent Claim
26 words
The method of claim 14, wherein the intensity of the emission peak in the emission spectrum is detected by passing the emission spectrum into a photomultiplier.
Claim 23
Dependent Claim
40 words
The method of claim 14, further comprising a step of adjusting an angle of incidence between the emission spectrum and a normal to a reflecting surface of the rugate filter such that suitable reflection of the emission spectrum is achieved.
Claim 24
Dependent Claim
20 words
The method of claim 14, wherein the rugate filter is oriented such that the angle of incidence is about 45°.
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| 3.5 Years (Year 4) | 1995-11-03 | 1996-05-04 | 1996-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-11-03 | 2000-05-04 | 2000-11-03 | $3760.00 | Window Closed / Lapsed |
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