Browse Prior Art Database

Scanning Optics

IP.com Disclosure Number: IPCOM000059979D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Batchelder, JS: AUTHOR

Abstract

A high speed, high resolution optical scanner for objective focussing of laser light is used to optically identify contamination on patterned silicon wafers. This optical scanning system is an improvement over using large lenses to image the entire wafer at once for contamination detection. In Fig. 1, a microscope objective 1 similar to that used on a video disk player is mounted on one end of a rotating arm 2. Mirrors 3 and 4 are mounted on the arm that intersects both the rotation axis and the optical axis of the objective at 45 degrees. A glass pipe or tube 5 is coaxial with the objective. The upper end of this pipe 6 is cut, polished, and anti-reflection coated normal to the optical axis.

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 55% of the total text.

Page 1 of 2

Scanning Optics

A high speed, high resolution optical scanner for objective focussing of laser light is used to optically identify contamination on patterned silicon wafers. This optical scanning system is an improvement over using large lenses to image the entire wafer at once for contamination detection. In Fig. 1, a microscope objective 1 similar to that used on a video disk player is mounted on one end of a rotating arm 2. Mirrors 3 and 4 are mounted on the arm that intersects both the rotation axis and the optical axis of the objective at 45 degrees. A glass pipe or tube 5 is coaxial with the objective. The upper end of this pipe 6 is cut, polished, and anti- reflection coated normal to the optical axis. The lower end 7 is beveled at 42 degrees with respect to the optical axis (80OE-laser angle of incidence), and acts as a laser mirror, mirror support, and focussing element. The wafer 10 is scanned in one direction underneath the rotating arm. A cylindrical illumination beam (8 and 9), is directed parallel to the axis of rotation at mirror 4, towards the mirror 3, and into the glass pipe 5. In operation, the illumination (8 and 9) reflects off the two mirrors 3 and 4, enters the glass pipe 5 and is directed towards the field of view of the objective 1. Light, which is not scattered but is reflected by the wafer 10 back into the glass pipe 5, is used to determine the relative wafer height, and thereby determines the correct position of the objective to be in ...