Method of Measuring Overhanging Photoresist Lift Off Patterns in Scanning Electron Microscope
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Fig. 1 shows a profile of a photoresist lift-off pattern used to form metal lands in VLSI (very large-scale integrated) circuits. The profile of the photoresist is used to determine the amount of overhang and how much of the toe sticks out, and is important in characterizing how well the lift-off operation will be performed. Typically, a monitor wafer (blank wafer with photoresist pattern) and a product wafer are sent for SEM (Scanning Electron Microscope) micro photos on a regular basis. The wafer is fractured through the pattern on a single chip, and an SEM micrograph is made. From the amount of overhang and how much the toe sticks out from the edge, an estimate of the lift-off capability can be made.