We developed pattern inspection techniques for simultaneously measuring both the width and
the thickness of conductive patterns printed on ceramic green sheets.
The measuring optics use a He-Ne laser scanner. Thickness is measured by beam splitting,
and width, by light diffusion. The beam-splitting optics measure the height by determining the
ratio of reflected to transmitted light intensity. By optimizing the arrangement of the optics, we
attain a resolution of 5 im and a height measurement range of [70 pm. Pattern width measurement
is based on the fact that a beam of light diffuses when it strikes the substrate, but does not
diffuse when it strikes the conductive pattern. A spatial ifiter in the focal plane raises the S/N
ratio to four regardless of the state of the conductor surface.
We used these techniques to inspect the conductive patterns on green sheets. Our system inspects
conductor patterns 3-dimensionally at 12 Mplxels per second with a 5 i.m resolution.