Exposure Field Alignment System
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Advantage is taken of beneficial features of both broadband illumination microscope alignment and of exposure wavelength, through-the-lens alignment to achieve accurate alignment of exposure fields independent of process variations. As shown in the figure, two reference markers L and R, which provide high contrast images in both single wavelength (exposure wavelength) and broadband illumination alignment detection systems, are made a part of wafer chuck 2. Wafer chuck 2, containing wafer-notch locating pin 4 and wafer-edge locating pin 6, is mounted on an X-Y- theta table in a wafer exposure system. An in-process wafer 8 is placed on wafer chuck 2, as shown, for a next level alignment and exposure.