Reliability of LSI Memory Circuits Exposed to Laser Cutting

Abstract

Laser activation of spare row or column elements of VLSI memories is a powerful tool for yield enhancement, and is presently in use on a 64K-bit MOS RAM. In order to learn as much as possible about the application and reliability of this new technology in advance of its use in manufacture, experiments were carried out on the effects of the laser on materials and structures of the device. Also, laser-cut 16K RAM testers and polysilicon resistors were bias-temperature aged, with particular attention paid to electrical drifts which might indicate penetration of contaminants at the laser-cut site. So far there is no indication of a reliability problem associated with laser processing.