Hamamatsu Systems, Inc.

Inspex, Inc.

Hitoshi Iida

Charly D Allemand

Mario A Maldari

David L Brewer

Pay-Shin King

Gary P Green

An apparatus and method are disclosed for detecting the presence of particles on the surface of an object such as the front side of a patterned semiconductor wafer. A vertically expanded, horizontally scanning, beam of light is directed onto an area on the surface of the object at a grazing angle of incidence. A video camera positioned above the surface detects light scattered from any particles which may be present on the surface, but not specularly reflected light. The surface is angularly prepositioned (rotated) relative to the incident light beam so that the diffracted light from the surface and the pattern of lines on the surface is at a minimum. The object is then moved translationally to expose another area to the incident light beam so that the entire surface of the object or selected portions thereof can be examined, an area at a time.

Particle detection method and apparatus

A video system having a television camera, a digital video signal processor coupled to the output of the television camera and a television monitor coupled to the output of the digital video signal processor is disclosed. The digital video signal processor includes an analog to digital converter for converting analog video signals into video data, a frame memory processor for processing and temporarily storing the video data, a random access memory device in which the video data is altered in accordance with the contents of a table-look-up temporarily written therein, a read only memory device containing a plurality of different table-look-ups, each table-look-up containing data representing a different gamma correction, a central processing unit for obtaining a table-look-up from the read only memory device and then writing the table-look-up into the random access memory device and a manually operated control device coupled to the central processing unit for selecting which table-look-up is read out from the read only memory device and then written into the random access memory device and a digital to analog converter for converting the processed video data into analog video signals.

Video system having an adjustable digital gamma correction for contrast

A method and apparatus for detecting and measuring the number and sizes of impurities on the surface of a material, such as a semiconductor wafer, wherein high intensity collimated light is directed onto the surface, in the absence of any extraneous light, through a collimating mirror, and employing a point source, whereat the particles will scatter the light, and wherein the surface is viewed by a highly light sensitive TV camera which picks up the scattered light and displays same on a viewing screen. The intensity of scattered light will indicate the size of the particles when compared with a calibrated model. Advantageously, a broad range of light waves is employed and thus enables a range of sizes of particles to be detected by the light scattered thereby. Also, advantageously, with the use of ordinarily available equipment, the system can inspect wafer surfaces for particles having sizes as small as 0.3 microns. The system also enables detection and identification of moving particles as distinguished from stationary particles.

Growing community of inventors

Bedford, MA, United States of America

Hitoshi Iida