US5660956A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reticle and method of fabricating reticle
Assignee: Toshiba Corp
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Filing: 1996-02-29
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Granted: 1997-08-26
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Expires: 2016-02-29
Abstract
Abstract In a reticle, a semi-transparent film pattern in place of a light blocking film pattern is used as a mask pattern having a size within a certain range, whereby an exposure system can be improved in resolution limit and faithful pattern transfer can be realized with a constant light quantity. A reticle may be of a stacked layer structure which comprises a shift film for providing a different optical path to exposure light, a mask substrate formed on the top or bottom of the shift film, and a transmissivity ratio adjustment layer having a predetermined transmissivity ratio to the exposure light. The material of a phase shifter may be adjusted in amplitude transmissivity ratio so that a shifter width for effectively improving a contrast can be made large and an accuracy necessary for a shifter width can be loosened. The mask pattern may include a semi-transparent film pattern which is made of silicon, a silicon compound, a mixture containing silicon, germanium, a germanium compound or a mixture containing germanium to provide a different optical path from that of the transparent part with respect to lithographic light. A silicon compound, a mixture containing silicon, germanium, a germanium compound or a mixture containing germanium is controlled in its composition ratio to form a semi-transparent film pattern on a transparent substrate.
Inventors
- 👤 Yoko Tomofuji
- 👤 Makoto Nakase
- 👤 Takashi Sato
- 👤 Hiroaki Hazama
- 👤 Haruki Komano
- 👤 Shinichi Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:49
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/32
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
164 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including a semi-transparent film for causing the light beam passing therethrough to be phase-shifted by about 180 degrees from the light beam passing through the light-transmissible substrate, wherein, an amplitude transmissivity ratio of the semi-transparent film is a value determined according to the pattern width and is less than or equal to about 50% when the pattern width divided by a quotient λ/NA is equal to or less than 0.61 so that lithographic light passed through the semi-transparent film pattern is phase-shifted by 180 degrees and then added to the lithographic light not passed through the semi-transparent film pattern, whereby light intensity is sharpened at pattern boundaries.
Claim 2
Dependent Claim
164 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including a semi-transparent film for causing the light beam passing therethrough to be phase-shifted by about 180 degrees from the light beam passing through the light-transmissible substrate, wherein, an amplitude transmissivity ratio of the semi-transparent film is a value determined according to the pattern width and is less than or equal to about 50% when the pattern width divided by a quotient λ/NA is equal to or less than 0.61 so that lithographic light passed through the semi-transparent film pattern is phase-shifted by 180 degrees and then added to the lithographic light not passed through the semi-transparent film pattern, whereby light intensity is sharpened at pattern boundaries.
Claim 3
Dependent Claim
86 words
A reticle as set forth in claim 1, wherein the mask pattern is of a laminated structure which comprises a phase shift film for causing length of an optical path for a light beam passing therethrough to be different from length of an optical path for a light beam passing through the light-transmissible substrate, and a semi-transparent film formed on the top or bottom surface of the phase shift film, and having a predetermined transmissivity ratio, the semi-transparent film serving as a transmissivity ratio adjustment layer.
Claim 4
Dependent Claim
38 words
A reticle as set forth in claim 1, wherein the semi-transparent film pattern has an amplitude transmissivity ratio of substantially zero when a pattern size thereof divided by λ/NA on a light exposure condition is larger than 0.61.
Claim 5
Dependent Claim
157 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including a semi-transparent film pattern for causing a length of an optical path for a light beam passing therethrough to be different from a length of an optical path for a light beam passing through the light-transmissive substrate, wherein the semi-transparent film pattern includes a plurality of minute regions which are unresolved by an exposure light and have different amplitude transmissivity ratios, and the light beam passing through the semi-transparent film pattern is a phase-shifted light beam which is added to a light beam passing through the minute regions so that light intensity is sharpened at the mask pattern boundaries.
Claim 6
Dependent Claim
157 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including a semi-transparent film pattern for causing a length of an optical path for a light beam passing therethrough to be different from a length of an optical path for a light beam passing through the light-transmissive substrate, wherein the semi-transparent film pattern includes a plurality of minute regions which are unresolved by an exposure light and have different amplitude transmissivity ratios, and the light beam passing through the semi-transparent film pattern is a phase-shifted light beam which is added to a light beam passing through the minute regions so that light intensity is sharpened at the mask pattern boundaries.
Claim 7
Dependent Claim
40 words
A reticle as set forth in claim 4, wherein amplitude transmissivity ratio of the semi-transparent film pattern is controlled according to a ratio of an area occupied by the minute regions with respect to an area of the semi-transparent film.
Claim 8
Dependent Claim
25 words
A reticle as set forth in claim 4, wherein the semi-transparent film pattern includes a region whose amplitude transmissivity ratio is varies through ion implantation.
Claim 9
Dependent Claim
159 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; a mask pattern disposed on the light-transmissible substrate and having at least one pattern width; and a phase shifter disposed on a periphery of the mask pattern, for causing a length of an optical path for a light beam passing therethrough to be different from a length of an optical path for a light beam passing through the light-transmissible substrate, wherein an amplitude transmissivity ratio of the phase shifter is set to be equal to or less than 100% when a value of the pattern width of the mask pattern divided by λ/NA on a light exposure condition is in a range between 0.34 and 0.68, and a width of the phase shifter is determined according to its amplitude transmissivity ratio.
Claim 10
Dependent Claim
159 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; a mask pattern disposed on the light-transmissible substrate and having at least one pattern width; and a phase shifter disposed on a periphery of the mask pattern, for causing a length of an optical path for a light beam passing therethrough to be different from a length of an optical path for a light beam passing through the light-transmissible substrate, wherein an amplitude transmissivity ratio of the phase shifter is set to be equal to or less than 100% when a value of the pattern width of the mask pattern divided by λ/NA on a light exposure condition is in a range between 0.34 and 0.68, and a width of the phase shifter is determined according to its amplitude transmissivity ratio.
Claim 11
Dependent Claim
170 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including line-based patterns, wherein each line-based pattern comprises a semi-transparent film for causing the light beam passing therethrough to be phase-shifted by about 180 degrees from the light beam passing through the light-transmissible substrate, and an amplitude transmissivity ratio of the semi-transparent film is a value determined according to the pattern width and is less than or equal to about 50% when the pattern width divided by the quotient λ/NA is equal to or less than 0.61, so that lithographic light passed through the semi-transparent film pattern is phase-shifted by 180 degrees and then added to the lithographic light passed through the semi-transparent film pattern, whereby light intensity is sharpened at pattern boundaries.
Claim 12
Dependent Claim
170 words
A reticle for fabrication of semiconductor circuits by a photolithography technique using a light beam having a predetermined wavelength (λ) and numerical aperture (NA), wherein the light beam passes through the reticle, the reticle comprising: a light-transmissible substrate; and a mask pattern disposed on the light-transmissible substrate and having at least one pattern width, the mask pattern including line-based patterns, wherein each line-based pattern comprises a semi-transparent film for causing the light beam passing therethrough to be phase-shifted by about 180 degrees from the light beam passing through the light-transmissible substrate, and an amplitude transmissivity ratio of the semi-transparent film is a value determined according to the pattern width and is less than or equal to about 50% when the pattern width divided by the quotient λ/NA is equal to or less than 0.61, so that lithographic light passed through the semi-transparent film pattern is phase-shifted by 180 degrees and then added to the lithographic light passed through the semi-transparent film pattern, whereby light intensity is sharpened at pattern boundaries.
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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) | 2000-08-25 | 2001-02-24 | 2001-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-25 | 2005-02-24 | 2005-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-25 | 2009-02-24 | 2009-08-26 | $7700.00 | Window Closed / Lapsed |