Digital Matched Filter Alignment System
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
This article concerns development of an all-digital technique that provides significant improvement over an existing analog pattern positioning system for obtaining precise alignment of semiconductor chips with substrates. The disclosed techniques entails the electronic comparison of the relative positions of a correctly positioned stored pattern with an unaligned scanned pattern. By the introduction of various known offsets into the comparison process, the actual position of the scanned pattern can be determined and it can be then directed to the correct position and remeasured for verification. The disclosed all-digital matched filter alignment system is diagrammed in Fig. 1. A brief description of its essential elements follows: A) Image Sensor: Any device which can convert an optical scene into an electrical signal, i.e.