Photocopying – Projection printing and copying cameras – Step and repeat
Patent
1991-12-04
1993-10-19
Rutledge, D.
Photocopying
Projection printing and copying cameras
Step and repeat
355 77, 430397, G03B 2742
Patent
active
052550508
ABSTRACT:
For projecting a photomask pattern on a wafer using a projection optical system having a short wavelength light source and a high numerical aperture, a method for projection exposure is proposed, by which a focal margin may be improved to achieve stable resolution and improved throughput. It is assumed for example that three-stage sequential light exposure is performed by setting an image plane at three positions, namely at a center focal position which is a mean height position of highs and lows of the wafer surface step difference and plus and minus focal positions offset a predetermined amount on each side of the center focal position. If light exposure is performed at each of these positions with an exposure light volume equal to one-third of the total exposure light volume, the focus margin becomes smaller than that in the case of the two-stage light exposure. By using a relatively small exposure light volume at the center focal position according to the present invention, the focal margin may be enlarged, although the synthesized light intensity contrast becomes minimum at the center focal position. The same effect may also be achieved by continuous light exposure with the constant exposure light volume using a relatively high speed of movement of the image plane at the center focal position for improving the throughput.
REFERENCES:
patent: 4239790 (1980-12-01), Bosenberg
patent: 4869999 (1989-09-01), Fukuda et al.
patent: 4904569 (1990-02-01), Fukuda et al.
patent: 4937619 (1990-06-01), Fukuda et al.
Rutledge D.
Sony Corporation
LandOfFree
Projection exposure method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Projection exposure method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Projection exposure method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1355699