Gate Hang Over Source-Drain Test Monitor
Original Publication Date: 1988-Sep-01
Included in the Prior Art Database: 2005-Feb-15
A technique is described whereby a monitor, called "gate hang over source-drain test" (GHOST), is a chrome-on-glass pattern which is part of the product circuit pattern which is exposed onto photoresist coated semiconductor wafers. It acts as a visual process monitor and quantifies the length of gate metal which extends beyond a source-drain implant window which is aligned to the gate level. The GHOST monitor photo pattern attached to a testing vehicle provides the ability to determine process variations which occur during photolithography. Fig. 1 illustrates a test site with zero micron deviation from nominal for both the X and Y axis. Fig. 2 illustrates an error of .75 micron for both X and Y, indicating that the overhang is .75 micron less than nominal.