Surface examining apparatus and method

Details Surface examining apparatus and method Surface examining apparatus and method

1982-02-11

1985-10-15

McGraw, Vincent P.

Optics: measuring and testing

By polarized light examination

With light attenuation

356445, 356237, G01B 1130, G01N 2188

Patent

active

045470731

ABSTRACT:
The surface of a polished semiconductor wafer is examined by an apparatus comprising a light source, a first optical means for converging the light to a parallel light and projecting it onto the surface to be examined and a second optical means for converging the light reflected by the surface and projecting it onto a light receiving screen. If the surface has a defect, such as a crystal imperfection, the surface forms a very slight recess or wave, for example, having a sub-micron depth and having an opening diameter of several mm. When such surface is examined by the above-mentioned apparatus, specific shading patterns, lines, stripes or dots are projected on the light-receiving screen, thereby making detection of wafer defects easy and even subject to automation.

REFERENCES:
patent: 3176306 (1965-03-01), Burns
patent: 3815998 (1974-06-01), Tietze
patent: 3964830 (1976-06-01), Ikeda et al.
patent: 4215939 (1980-08-01), Miller et al.
patent: 4290698 (1981-09-01), Milana
patent: 4330205 (1982-05-01), Murakami et al.

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