US5556726A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photolithographic dose determination by diffraction of latent image grating
Assignee: International Business Machines Corp
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Filing: 1995-06-29
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Granted: 1996-09-17
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Expires: 2015-06-29
Abstract
Abstract A method of determining quantitatively the exposure levels for photoresists in semiconductor photolithography employs a specially designed grating pattern on a mask. The mask is first used to expose a series of LIM image gratings of different dosages. Then a normal plane wave at a longer wavelength is incident on these gratings one by one, and some nonzero order diffraction efficiency of the grating is measured to determine quantitatively the correct dosage to be used. This method can make a determination of exposure dosage, without knowledge of underlying film thickness and refractive index, and handle either resist thickness change or underlying film thickness/refractive index change or both.
Inventors
- 👤 Chi-Min Yuan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:46
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/7055; G03F7/70558; G03F7/20; G03F7/70605; G03F7/70653; G03F7/70675
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
83 words
A method of determining the optimal exposure dosage required for semiconductor photolithography comprising the steps of: providing a photoresist to be bleached; placing a mask over the photoresist, said mask consisting of transparent and semitransparent regions, said semitransparent regions providing partial transmission of light to the photoresist; exposing said photoresist to light through said mask; measuring the exposure of said photoresist to energy until said photoresist is fully bleached; and calculating an optimal exposure dosage required from measurements of exposure of said photoresist.
Claim 2
Independent Claim
83 words
A method of determining the optimal exposure dosage required for semiconductor photolithography comprising the steps of: providing a photoresist to be bleached; placing a mask over the photoresist, said mask consisting of transparent and semitransparent regions, said semitransparent regions providing partial transmission of light to the photoresist; exposing said photoresist to light through said mask; measuring the exposure of said photoresist to energy until said photoresist is fully bleached; and calculating an optimal exposure dosage required from measurements of exposure of said photoresist.
Claim 3
Independent Claim
91 words
A method of exposing product chips to optimal exposure dosage of light comprising the steps of: providing a photoresist to be bleached; placing a mask over the photoresist, said mask consisting of transparent and semitransparent regions, said semitransparent regions providing partial transmission of light to the photoresist; exposing said photoresist to light through said mask; measuring the exposure of said photoresist to energy until said photoresist is fully bleached; calculating an optimal exposure dosage required from measurements of exposure of said photoresist; and exposing product chips to said optimal exposure dosage.
Claim 4
Independent Claim
91 words
A method of exposing product chips to optimal exposure dosage of light comprising the steps of: providing a photoresist to be bleached; placing a mask over the photoresist, said mask consisting of transparent and semitransparent regions, said semitransparent regions providing partial transmission of light to the photoresist; exposing said photoresist to light through said mask; measuring the exposure of said photoresist to energy until said photoresist is fully bleached; calculating an optimal exposure dosage required from measurements of exposure of said photoresist; and exposing product chips to said optimal exposure dosage.
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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) | 1999-09-17 | 2000-03-18 | 2000-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-09-17 | 2004-03-18 | 2004-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-09-17 | 2008-03-18 | 2008-09-17 | $7700.00 | Window Closed / Lapsed |