Claims
- 1. A method of eliminating proximity effects in a photoresist image having a critical dimension, comprising:providing an imaging system having an adjustable numerical aperture and a variable partial coherence value; determining optimum values for the numerical aperture and the partial coherence value whereby proximity effects of optical origin are eliminated; determining an optimum value for a post exposure bake temperature, whereby proximity effects related to photoresist are eliminated; and using said optimum values of the numerical aperture, partial coherence value, and post exposure bake temperature, forming said photoresist image.
- 2. The method of claim 1 wherein the optimum numerical aperture is between about 0.5 and 0.7.
- 3. The method of claim 1 wherein the optimum partial coherence value is between about 0.6 and 0.8.
- 4. The method of claim 1 wherein the optimum post exposure bake temperature is between about 60 and 100° C.
- 5. The method of claim 1 wherein the step of determining optimum values for the numerical aperture and the partial coherence value is achieved through simulation.
- 6. The method of claim 1 wherein use of the optimum partial coherence value is achieved by modifying the aerial image in an ASM stepper or by enlarging the filter size in a Nikon stepper.
- 7. The method of claim 1 wherein said critical dimension is between about 0.18 and 0.35 microns.
- 8. The method of claim 1 wherein said imaging system uses actinic radiation having a wavelength between about 1,830 and 3,650 Angstroms.
- 9. The method of claim 1 wherein the photoresist is selected from the group consisting of the t-BOC series of photoresists.
Parent Case Info
This is a division of patent application Ser. No. 09/049,213, filing date Mar. 27, 1998, Elimination Of Proximity Effect In Photoresist, assigned to the same assignee as the present invention.
US Referenced Citations (5)