Methods for reducing blur and variation in blur in projected...

Details Methods for reducing blur and variation in blur in projected... Methods for reducing blur and variation in blur in projected...

2005-06-14

2005-06-14

Lee, John R. (Department: 2881)

Radiant energy

Irradiation of objects or material

Irradiation of semiconductor devices

C250S492100, C250S492200, C250S492300, C250S3960ML, C250S3960ML, C250S398000, C430S296000, C430S942000

Reexamination Certificate

active

06906336

ABSTRACT:
Exposure methods are disclosed for use in charged-particle-beam microlithography and that yield decreased blur and variation in blur within individual exposure fields (subfields) of a pattern. Blur at a location on the optical axis increases monotonically with increased shift in the focal point of a subfield image on the substrate. In contrast, blur at a subfield edge exhibits comparatively little change over a limited range in focal-point shift, and exhibits sharply increased change as the shift in focal point exceeds a threshold. Variation in blur within individual subfields decreases monotonically with increased shift in the focal point. Consequently, by changing the focal point during exposure, within a range in which maximum blur within the subfield is within an acceptable range, Δblur is decreased more than conventionally, thereby increasing the uniformity of blur within the projected subfield.

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U.S. Appl. No. 09/843,592, filed Apr. 26, 2001, Yamada et al.
U.S. Appl. No. 09/901,766, filed Jul. 9, 2001, Simizu.

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