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US006387597B1
(12) United States Patent ao) Patent No.: us 6,387,597 Bi
Gelbart (45) Date of Patent: May 14,2002
(54) METHOD FOR EXPOSING FEATURES ON NON-PLANAR RESISTS
(75) Inventor: Daniel Gelbart, Burnaby (CA)
(73) Assignee: Creo Sri, Hole town (BB)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 70 days.
(21) Appl. No.: 09/654,042
(22) Filed: Sep. 1, 2000
Related U.S. Application Data
(63) Continuation-in-part of application No. 09/093,854, filed on Jun. 5, 1998, now Pat. No. 6,136,509.
(51) Int. C I. G03C 5/00
(52) U.S. CI 430/311; 430/322; 430/328;
430/330; 430/394; 430/397; 430/945
(58) Field of Search 430/311, 330,
430/394, 397, 945, 964, 270.1, 328, 322
(56) References Cited
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FOREIGN PATENT DOCUMENTS
EP 0557138 A2 8/1993
OTHER PUBLICATIONS
Ooki et al. Experimental Study on Non-linear Multiple Exposure Method. SPIE vol. 3051, pp. 85-93 [date unknown].
Neisser et al. Simulation and Experimental Evaluation of Double Exposure Techniques. SPIE vol. 3334, pp. 372-377. [date unknow].
Creo, Trendsetter Data Sheet (Aug. 1997).
Creo, Difine 4LF Thermoresist Data Sheet (May, 1998).
Primary Examiner—Christopher G. Young
(74) Attorney, Agent, or Firm—Oyen Wiggs Green &
Mutala
(57) ABSTRACT
A method for imaging a non-planar resist uses a nonintegrating resist. The resist may be a thermoresist which changes from an unexposed state to an exposed state upon heating to a threshold temperature. The method involves using a variable focus optical system and making a plurality of exposures at different focus settings. The duration and intensity of the exposures is selected so that areas on the resist corresponding to in-focus features are heated to temperatures in excess of the threshold temperature and become exposed whereas areas on the resist corresponding to outof-focus features are heated to temperatures which are insufficient to expose the resist.
21 Claims, 5 Drawing Sheets
