Browse Prior Art Database

Dark Field Illumination Device

IP.com Disclosure Number: IPCOM000083181D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Makosch, G: AUTHOR

Abstract

A dark field illumination device illuminates alignment targets from selected sections of a viewing area in a projection printing apparatus.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Dark Field Illumination Device

A dark field illumination device illuminates alignment targets from selected sections of a viewing area in a projection printing apparatus.

Fig. 1 illustrates the illumination device 1, which has finger 2 mounted above surface 3 on movable stage 4 driven by motor 5. Fiber bundle 6 supplies light from lamphouse 7 to finger 2. Stage 4 permits moving finger 2 for dark field illumination of one alignment target area to another of workpiece 11, such as a light-sensitive resist coated semiconductor wafer. Projection printing lens 8 is used to form exposure mask images on the workpiece, and to form the alignment images for viewing. Stage 4 moves the finger 2 out of the path of the projection printing system during exposure.

Fig. 2 illustrates the structure of finger 2. Finger 2 contains fiber bundle 6 cast in epoxy. Bundle 6 splits into four fibers 6a, 6b, 6c, and 6d which are arranged around cone-shaped aperture 9 at the end of finger 2. The dark field image is formed through aperture 9. Interference filters, not shown, are placed at the fiber input. The device can be modified for a two-field alignment by providing a second illumination cone in finger 2, or by employing a second finger.

1

Page 2 of 2

2

[This page contains 3 pictures or other non-text objects]