Browse Prior Art Database

Light Scanners

IP.com Disclosure Number: IPCOM000080289D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 84K

Publishing Venue

IBM

Related People

Seebe, NB: AUTHOR

Abstract

Scanner 10, Fig. A, provides an intense lineal beam of light at a near grazing angle alpha. It is particularly useful for illuminating a semiconductor wafer W being inspected for particulate (e.g. foreign) matter.

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Light Scanners

Scanner 10, Fig. A, provides an intense lineal beam of light at a near grazing angle alpha. It is particularly useful for illuminating a semiconductor wafer W being inspected for particulate (e.g. foreign) matter.

Beam-forming optics shown schematically as lens Ll, focuses collimated light on the wafer surface via the four faces of the equilateral reflector prism R1. Prism R1 reflects the light into four separate beam paths. Each section of the light beam is reflected by a pair of planar upper and lower reflectors Ru and Rl. The light, which is converging to a focus on the wafer, is passed through a cylindrical lens L2 to spread the focus to a line. At the intersection X of the four spread light beams, there is produced the desired lineal beam used to inspect the wafer W.

The wafer W is mounted on a vacuum type chuck C. Chuck C is movable, e.g., reciprocates (or alternatively rotates) as shown by bidirectional arrow A, so as to orient different portions of the upper surface of wafer W with respect to the inter1ection X.

Readout optics, e.g., reflector R, lens system O and linear detector array D, sense light scattered at the upper surface of the wafer W.

The system of Fig. B provides a light-beam spot for illuminating the wafer W. As such, lens L1 focuses collimated light on the conical reflector prism R1. It in turn reflects the light via the inner surfaces of the pair of concentric conical ring reflectors R2 and R3. The light is focused to an int...