Surface examining apparatus and method
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorKoichi Kugimiya
Life of this patent
Estimating the term…
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.
Claims26
A surface examining apparatus, comprising:
- a substantially point light source for emitting light rays,
- an image-receiving means for receiving images,
- first optical means for converging said rays and for making them impinge as evenly distributed rays on a surface to be examined, and
- second optical means for converging rays reflected from said surface and for projecting said converged reflected rays substantially undiminished to said image-receiving means, said second optical means projecting an image to said image-receiving means constituting a defocussed image of said surface to be examined.
A surface examining apparatus, comprising:
- a substantially point light source for emitting light rays,
- an image-receiving means for receiving images,
- first optical means for converging said rays and for making them impinge as evenly distributed rays on a surface of a semiconductor wafer, and
- second optical means for converging rays reflected from said surface and for projecting said converged reflected rays substantially undiminished to said image-receiving means, said second optical means projecting an image to said image-receiving means constituting a defocussed image of said surface of said semiconductor wafer.
A method for examining a surface, comprising the steps of:
- shining light rays from a substantially point light source,
- making said rays impinge on a surface to be examined, and reflect therefrom,
- converging the rays reflected from said surface and projecting them substantially undiminished onto an image-receiving means to form a defocussed image with respect to said surface to be examined, and
- obtaining a shading pattern in said defocussed image which corresponds to an unevenness on said surface to be examined.
A method for examining a surface, comprising the steps of:
- shining light rays from a substantially point light source;
- making said rays impinge on a surface of a semiconductor wafer, and reflect therefrom,
- converging the rays reflected from said surface and projecting them substantially undiminished onto an image-receiving means to form a defocussed image with respect to said surface of a semiconductor wafer, and
- obtaining a shading pattern in said defocussed image which corresponds to an unevenness on said surface of said semiconductor wafer.
Dependencies are inferred from the claim text.