ANORDNING FOR ANVENDNING I ETT STEG- OCH REPETITIONSSYSTEM FOR DIREKT EXPONERING AV HALVLEDARSKIVOR

摘要

Apparatus for masking operations in processing of semiconductor wafers. A step and repeat system is used to expose the wafer 11 to an image contained on a reticle 13. The reticle also contains an alignment target which is projected onto the wafer adjacent the circuit pattern. The stage holding the wafer is stepped to produce a desired array of circuits and targets on the wafer. Subsequently a reticle 13 is used which contains a different image together with an alignment pattern that is shaped complimentary to the alignment target of the first reticle. When the wafer is stepped to each array location, a low intensity light source 42 illuminates the alignment target on the wafer through the same lens 14 used for the image exposure. The image of the alignment target is viewed on the wafer and the corresponding alignment image on the reticle, simultaneously. The stage is moved to achieve alignment. The reticle image is projected onto the wafer, overlapping the previous image. The wafer is then stepped and the process repeated at other array positions.