Summer 1983
Quantitative Examination of Photofabricated Profiles (part 6)
INTRODlJCTlON
Until recently the thickness or lineness of structures that
could be produced by etching through an adherent photographic
stencil has been severely limited by undercut. A
significant breakthrough has resulted from discoveries made
during Ihe processing of semiconductors for production of
microelectronic circuits. During the wet etching of silicon, it
was discovered that etching in a potassium hydroxlde solution
caused various planes in the crystal structure to etch at different
rates under the same etching conditions. This type of phenomenon
is known as anisotropic etching. With single crystal
silicon of orientation (110) and with the aperture in a photoetched
silicon dioxide mask orientated parallel to a : III : slowetching
plane. downwards etching was 400 600 times faster
than side-ways etching.’ The resultant slots had straight
parallel edges and sidewalls perpendicular to the silicon surface
(Fig. I).
This paper describes a study of the applicatiun of this process
to produce deep narrow slots. Such slots have been used for
monitoring the sharpness of diamond styluses used in surface
texture instruments.
