Projection method and projection system and mask therefor

Details Projection method and projection system and mask therefor Projection method and projection system and mask therefor

1995-06-06

1997-08-26

Henry, Jon W.

Optical: systems and elements

Diffraction

Using fourier transform spatial filtering

359566, 359569, G02B 518, G03B 2754

Patent

active

056616015

ABSTRACT:
A projection method uses a modified illumination method for a lithography process of semiconductor device, and a projection system and mask use the projection method. An object is exposed by removing the vertical incident component of light passed through a condenser lens. Zero-order diffracted light interferes destructively and the oblique component of .-+. first-order diffracted light, interferes constructively. The obliquely incident component light illuminates a mask having a pattern formed thereon. The vertical incident component of the light is removed by a phase difference of light due to a grating mask or a grating pattern formed on the back surface of the conventional mask. The resolution of a lithography process is improved due to the increased contrast, and the depth of focus is also increased. Thus, patterns for 64 Mb DRAMs can be formed using a conventional projection exposure system.

REFERENCES:
patent: 5208629 (1993-05-01), Matsuo et al.
patent: 5394219 (1995-02-01), Hirosue
patent: 5418092 (1995-05-01), Okamoto
patent: 5438204 (1995-08-01), Von Bunau et al.
patent: 5446587 (1995-08-01), Kang et al.

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