US6406818B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing photomasks by plasma etching with resist stripped
Assignee: Photronics Inc
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Filing: 1999-03-31
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Granted: 2002-06-18
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Expires: 2019-03-31
Abstract
Abstract A method for adjusting out of tolerance critical dimensions of an under processed photomask to be within predetermined defined limits after the photosensistive resist material has been removed from the exposed photomask. The method includes measuring the critical dimensions of the opaque material of the under processed photomask after the photosensitive resist material has been removed, and exposing the photomask to electrified plasma gases for removing excess opaque material without degrading the reflectivity of the photomask beyond specified limits.
Inventors
- 👤 Rick Zemen
- 👤 Tiecheng Zhou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:14
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/54; G03F1/58; G03F1/38; G03F1/46; G03F1/68; G03F1/72; G03F1/80
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
182 words
A process for removing excess portions of opaque material from an under processed photomask thereby adjusting out of tolerance critical dimensions to within predetermined limits, said under processed photomask comprising a substantially transparent substrate and selected areas of opaque material and anti-reflective material covered by resist material, said anti-reflective material having an initial thickness with a reflectivity value reflecting a first percentage of incident energy, said process comprising the steps of: (a) removing said resist material; (b) measuring at least one critical dimension of said opaque material; (c) determining the amount of excess opaque material to be removed to bring said at least one critical dimension within predetermined limits; and (d) exposing said under: processed photomask to electrified plasma gases for a period of time, said period of time corresponding to the desired amount of excess opaque material to be removed, said anti-reflective material after said exposure to electrical plasma gases having a second thickness with a reflectivity value reflecting a second percentage of incident energy less than a predetermined value that an imaging device can accommodate without adversely impacting its operation.
Claim 2
Dependent Claim
182 words
A process for removing excess portions of opaque material from an under processed photomask thereby adjusting out of tolerance critical dimensions to within predetermined limits, said under processed photomask comprising a substantially transparent substrate and selected areas of opaque material and anti-reflective material covered by resist material, said anti-reflective material having an initial thickness with a reflectivity value reflecting a first percentage of incident energy, said process comprising the steps of: (a) removing said resist material; (b) measuring at least one critical dimension of said opaque material; (c) determining the amount of excess opaque material to be removed to bring said at least one critical dimension within predetermined limits; and (d) exposing said under: processed photomask to electrified plasma gases for a period of time, said period of time corresponding to the desired amount of excess opaque material to be removed, said anti-reflective material after said exposure to electrical plasma gases having a second thickness with a reflectivity value reflecting a second percentage of incident energy less than a predetermined value that an imaging device can accommodate without adversely impacting its operation.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein said opaque material is comprised of chrome and said anti-reflective material is comprised of chrome oxide.
Claim 4
Dependent Claim
16 words
The process of claim 2 wherein said electrified plasma gas is comprised of chlorine and oxygen.
Claim 5
Dependent Claim
44 words
The process of claim 3 wherein the ratio of said chlorine to said oxygen comprising said plasma gas is chosen such that the etch rate of the chrome opaque material is increased with respect to the etch rate of the chrome oxide anti-reflective material.
Claim 6
Dependent Claim
26 words
The process of claim 4 wherein said ratio of said chlorine to said oxygen in said plasma gas is 15 percent to 85 percent by volume.
Claim 7
Independent Claim
193 words
A method improving the yield of photomasks by enabling out of tolerance critical dimensions of opaque material on an under processed photomask to be adjusted within specified limits after resist material has been removed from said under processed photomask, said under processed photomask comprising a substantially transparent substrate and patterned areas of opaque material and anti-reflective material, said anti-reflective material having an initial thickness with a reflectivity value reflecting a first percentage of incident energy, said method comprising the steps of: (a) measuring at least one critical dimension of said patterned areas of opaque material to determine the amount of excess opaque material to be removed; and (b) exposing said under processed photomask to electrified plasma gases for a period of time corresponding to the desired amount of excess opaque material to be removed, said electrified plasma gases reacting with and removing at least a portion of said excess opaque material, said and-reflective material after said exposure to said electrified plasma gases having a second thickness with a reflectivity value reflecting a second percentage of incident energy less than a predetermined value that an imaging device can accommodate without adversely impacting its operations.
Claim 8
Independent Claim
193 words
A method improving the yield of photomasks by enabling out of tolerance critical dimensions of opaque material on an under processed photomask to be adjusted within specified limits after resist material has been removed from said under processed photomask, said under processed photomask comprising a substantially transparent substrate and patterned areas of opaque material and anti-reflective material, said anti-reflective material having an initial thickness with a reflectivity value reflecting a first percentage of incident energy, said method comprising the steps of: (a) measuring at least one critical dimension of said patterned areas of opaque material to determine the amount of excess opaque material to be removed; and (b) exposing said under processed photomask to electrified plasma gases for a period of time corresponding to the desired amount of excess opaque material to be removed, said electrified plasma gases reacting with and removing at least a portion of said excess opaque material, said and-reflective material after said exposure to said electrified plasma gases having a second thickness with a reflectivity value reflecting a second percentage of incident energy less than a predetermined value that an imaging device can accommodate without adversely impacting its operations.
Claim 9
Dependent Claim
61 words
The method of claim 6 wherein said under processed photomask is subjected to a series of exposures to electrified plasma gases, each of said exposures removing at least a portion of said excess opaque material, and wherein after each of said exposures at least one critical dimension of the opaque material is measured to determine whether it is within predetermined limits.
Claim 10
Dependent Claim
22 words
The method of claim 6 wherein said opaque material is comprised of chrome and said anti-reflective material is comprised of chrome oxide.
Claim 11
Dependent Claim
19 words
The method of claim 8 wherein said under processed photomask is exposed to plasma gases comprising chlorine and oxygen.
Claim 12
Dependent Claim
37 words
The method of claim 9 wherein the ratio of chlorine and oxygen gases is selected such that the relative etch rate of said opaque material is increased with respect to the etch rate of said anti-reflective material.
Claim 13
Dependent Claim
20 words
The method of claim 10 wherein the ratio of chlorine to oxygen is 15 percent to 85 percent by volume.
Claim 14
Independent Claim
244 words
A method for creating a photomask from a blank photomask, said blank photomask comprising (1) a substantially transparent substrate, (2) a Layer of opaque material covering substantially all of said substantially transparent substrate, (3) a layer of anti-reflective material covering substantially all of said layer of opaque material and having a first thickness reflecting a first percentage of incident energy less than a predetermined value, and (4) a layer of photoresist material covering substantially all of said layer of anti-reflective material, comprising the steps of: (a) creating a pattern of said photoresist material thereby exposing selected areas of said anti-reflective material layer, (b) etching said selected areas of said anti-reflective material layer and substantially all of said opaque material layer underlying said selected areas of said anti-reflective material layer, thereby creating a pattern of anti-reflective material and a pattern of said opaque material substantially corresponding to said pattern of said photoresist material, (c) removing said pattern of said photoresist material, (d) measuring at least one critical dimension of said pattern of opaque material and comparing said measured critical dimension to a predetermined value thereby determining the presence of excess opaque material, (e) performing a second etching process thereby removing a first portion of said excess opaque material, said pattern of said anti-reflective material after said second etching process having a second thickness reflecting a second percentage of incident energy below a predetermined value that an imaging device can accommodate without adversely impacting its operations.
Claim 15
Independent Claim
244 words
A method for creating a photomask from a blank photomask, said blank photomask comprising (1) a substantially transparent substrate, (2) a Layer of opaque material covering substantially all of said substantially transparent substrate, (3) a layer of anti-reflective material covering substantially all of said layer of opaque material and having a first thickness reflecting a first percentage of incident energy less than a predetermined value, and (4) a layer of photoresist material covering substantially all of said layer of anti-reflective material, comprising the steps of: (a) creating a pattern of said photoresist material thereby exposing selected areas of said anti-reflective material layer, (b) etching said selected areas of said anti-reflective material layer and substantially all of said opaque material layer underlying said selected areas of said anti-reflective material layer, thereby creating a pattern of anti-reflective material and a pattern of said opaque material substantially corresponding to said pattern of said photoresist material, (c) removing said pattern of said photoresist material, (d) measuring at least one critical dimension of said pattern of opaque material and comparing said measured critical dimension to a predetermined value thereby determining the presence of excess opaque material, (e) performing a second etching process thereby removing a first portion of said excess opaque material, said pattern of said anti-reflective material after said second etching process having a second thickness reflecting a second percentage of incident energy below a predetermined value that an imaging device can accommodate without adversely impacting its operations.
Claim 16
Dependent Claim
48 words
The method of claim 12 wherein said second etching process comprises exposing said substantially transparent substrate, said pattern of anti-reflective material, and said excess opaque material to electrified plasma gases for a period of time corresponding to said first portion of said excess opaque material to be removed.
Claim 17
Dependent Claim
148 words
The method of claim 13 further comprising the steps of: (f) measuring at least one critical dimension of said pattern of opaque material after said second etching process and comparing said measured critical dimension to a predetermined value thereby determining the presence of remaining excess opaque material, (g) performing a third etching process by exposing said substantially transparent substrate, said pattern of anti-reflective material, and said remaining excess opaque material to electrified plasma gases for a second period of time, wherein said electrified plasma gases are comprised of chlorine and oxygen, said second period of time corresponding to said portion of said remaining excess opaque material to be removed, said pattern of said anti-reflective material after said third etching process having a third thickness reflecting a third percentage of incident energy less than a predetermined minimum value that an imaging device can accommodate without adversely impacting its operations.
Claim 18
Dependent Claim
40 words
The method of claim 14 wherein the ratio of chlorine and oxygen gases is selected such that the relative etch rate of said excess opaque material is increased with respect to the etch rate of said pattern of anti-reflective material.
Claim 19
Dependent Claim
20 words
The method of claim 15 wherein the ratio of chlorine to oxygen is 15 percent to 85 percent by volume.
Claim 20
Dependent Claim
22 words
The method of claim 12 wherein said opaque material is comprised of chrome and said anti-reflective material is comprised of chrome oxide.
Claim 21
Dependent Claim
14 words
The method of claim 12 wherein said opaque material is comprised of molybdenum silicide.
Claim 22
Dependent Claim
122 words
The method of claim 13 further comprising the steps of: (f) measuring at least one critical dimension of said pattern of opaque material after said second etching process and comparing said measured critical dimension to a predetermined value thereby determining the presence of remaining excess opaque material, (g) performing a third etching process by exposing said substantially transparent substrate, said pattern of anti-reflective material, and said remaining excess opaque material to electrified plasma gases for a second specified amount of time, said second specified amount of time corresponding to said portion of said remaining excess opaque material to be removed, said pattern of said anti-reflective material after said third etching process having a third reflectivity value less than a predetermined minimum value.
Claim 23
Dependent Claim
22 words
The method of claim 19 wherein said electrified plasma gases used in said third etching process are comprised of chlorine and oxygen.
Claim 24
Dependent Claim
47 words
The method of claim 20 wherein the ratio of chlorine and oxygen gases used in said third etching process is selected such that the relative etch rate of said remaining excess opaque material is increased with respect to the etch rate of said pattern of anti-reflective material.
Claim 25
Dependent Claim
20 words
The method of claim 21 wherein the ratio of chlorine to oxygen is 15 percent to 85 percent by volume.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2005-06-17 | 2005-12-17 | 2006-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-06-17 | 2009-12-17 | 2010-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-06-17 | 2013-12-17 | 2014-06-18 | $7700.00 | Window Closed / Lapsed |