US5905019A
Expired / Lapsed
US
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Thin resist process by sub-threshold exposure
Assignee: International Business Machines Corp
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Filing: 1997-09-26
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Granted: 1999-05-18
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Expires: 2017-09-26
Abstract
Abstract The present invention utilizes a sub-threshold exposure step on an optically sensitive resist that is applied to a semiconductor wafer to thin the resist below the thickness which can be achieved by normal spinning and/or thinning techniques. Furthermore, the thinned resist can be re-expose to UV energies so as to develop patterns on the surface of the semiconductor wafer. An apparatus for vibrating and rotating the resist during the sub-threshold step is also disclosed herein.
Inventors
- 👤 Christopher E. Obszarny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:00
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0421; G; G03; G03F; G03F7/00; G03F7/16; G03F7/168; G03F7/20; G03F7/2022; G03F7/2024; G03F7/2026
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
79 words
A method of thinning an optically sensitive resist comprising the steps of: (a) applying a resist to at least one surface of a semiconductor wafer; (b) subjecting the resist provided in step (a) to sub-threshold blanket exposure under conditions effective to thin predetermined areas of the resist but insufficient to remove the resist; and (c) developing the sub-threshold exposed areas of the resist to provide a thinned resist that has regions of reduced thicknesses while maintaining its optical sensitivity.
Claim 2
Independent Claim
79 words
A method of thinning an optically sensitive resist comprising the steps of: (a) applying a resist to at least one surface of a semiconductor wafer; (b) subjecting the resist provided in step (a) to sub-threshold blanket exposure under conditions effective to thin predetermined areas of the resist but insufficient to remove the resist; and (c) developing the sub-threshold exposed areas of the resist to provide a thinned resist that has regions of reduced thicknesses while maintaining its optical sensitivity.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said semiconductor wafer is composed of Si, SiGe or GaAs.
Claim 4
Dependent Claim
13 words
The method of claim 2 wherein said semiconductor wafer is composed of Si.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein said semiconductor wafer is of the p- or n-type.
Claim 6
Dependent Claim
33 words
The method of claim 1 wherein said semiconductor wafer is cleaned, treated or both cleaned and treated prior to conducting step (a) to enhance the surface adhesion of the wafer for said resist.
Claim 7
Dependent Claim
22 words
The method of claim 5 wherein said semiconductor wafer is treated by mechanical roughening, chemical roughening or with a chemical adhesion promotor.
Claim 8
Dependent Claim
15 words
The method of claim 6 wherein said chemical adhesion promotor is a silane coupling agent.
Claim 9
Dependent Claim
12 words
The method of claim 7 wherein said silane coupling agent is hexamethyldisalizane.
Claim 10
Dependent Claim
14 words
The method of claim 1 wherein said resist is an optically sensitive, positive resist.
Claim 11
Dependent Claim
23 words
The method of claim 9 wherein said optically sensitive, positive resist comprises a polymeric resin and a photoactive compound dissolved in a solvent.
Claim 12
Dependent Claim
14 words
The method of claim 1 wherein said resist is applied by a spin coating.
Claim 13
Dependent Claim
30 words
The method of claim 11 where said spin coating is carried out under conditions effective to provide a resist having a thickness of from about 5000 to about 45,000 Å.
Claim 14
Dependent Claim
30 words
The method of claim 12 wherein said spin coating is carried out under conditions effective to provide a resist having a thickness of from about 10,000 to about 11,000 Å.
Claim 15
Dependent Claim
41 words
The method of claim 1 wherein step (b) is carried out using a UV light energy source operating at an energy of from about 0.01 to about 2.0 Joules/cm 2 and a dosage of from about 10 to about 130 msec.
Claim 16
Dependent Claim
41 words
The method of claim 14 wherein step (b) is carried out using a UV light energy source operating at an energy of from about 0.06 to about 0.2 Joules/cm 2 and a dosage of from about 45 to about 120 msec.
Claim 17
Dependent Claim
25 words
The method of claim 15 wherein step (b) is carried out using a UV light energy source having a wavelength of 248 or 365 nm.
Claim 18
Dependent Claim
32 words
The method of claim 16 wherein step (b) is carried out using a 365 nm UV light energy source having an energy of from about 0.04 to about 2.0 Joules/cm 2 .
Claim 19
Dependent Claim
31 words
The method of claim 17 wherein step (b) is carried using a 365 nm UV light energy source having an energy of from about 0.06 to about 1.0 Joules/cm 2 .
Claim 20
Dependent Claim
32 words
The method of claim 16 wherein step (b) is carried out using a 248 nm UV light energy source having an energy of from about 0.6 to about 1.2 Joules/cm 2 .
Claim 21
Dependent Claim
32 words
The method of claim 19 wherein step (b) is carried out using a 248 nm UV light energy source having an energy of from about 0.8 to about 1.0 Joules/cm 2 .
Claim 22
Dependent Claim
23 words
The method of claim 1 wherein step (c) is carried out using propylene carbonate, gamma butyrolactone, an ammonium hydroxide, diglyme or mixtures thereof.
Claim 23
Dependent Claim
39 words
The method of claim 1 further comprising the step of: (d) exposing the developed structure provided in step (c) under conditions effective to provide patterns on the surface of the semiconductor wafer; and (e) developing the fully exposed resist.
Claim 24
Dependent Claim
35 words
The method of claim 22 wherein said exposure step is a full blanket exposure step that is carried out using UV light having an energy of from about 0.01 to about 0.06 Joules/cm 2 .
Claim 25
Dependent Claim
35 words
The method of claim 23 wherein said exposure step is a full blanket exposure step that is carried out using UV light having an energy of from about 0.02 to about 0.04 Joules/cm 2 .
Claim 26
Dependent Claim
14 words
The method of claim 22 wherein a pattern mask is employed in step (d).
Claim 27
Dependent Claim
21 words
The method of claim 1 wherein step (b) is carried out by rotating and vibrating said semiconductor wafer containing said resist.
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