Width and Overlay Narrow Kerf Test Site
Original Publication Date: 1978-Apr-01
Included in the Prior Art Database: 2005-Feb-20
Fig. 1 illustrates a width and overlay test site which can be used with the system described in U. S. Patent 3,957,376 with, for example, the technique set out in the IBM Technical Disclosure Bulletin 20, 1032-1033 (August 1977). The effective spot size of the tool is 4 mils with a plus or minus 1 mil tolerance of position. Shrinking the kerf width brings the adjacent product topography within the measurement spot, producing spurious diffraction patterns which resist analysis. Additionally, the test site must occupy as little real estate within the kerf as possible because of other housekeeping and electrical test requirements.