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

1993-09-02

1995-08-29

Lerner, Martin

Optical: systems and elements

Diffraction

Using fourier transform spatial filtering

355 53, 356401, 359564, 430 5, G02B 2744, G03B 2742, G01B 1100, G03F 900

Patent

active

054465877

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: 5184196 (1993-02-01), Nakagawa et al.
patent: 5200798 (1993-04-01), Katagiri et al.
patent: 5208629 (1993-05-01), Matsuo et al.
patent: 5247329 (1993-09-01), Oshida et al.
patent: 5272501 (1993-12-01), Nishi et al.
patent: 5320918 (1994-06-01), Raab et al.
patent: 5331369 (1994-07-01), Terasawa et al.

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