Implementing a yield management program to improve die yield

摘要

Because it reflects the amount of product available for sale, die yield is critical to the success of a semiconductor fabrication plant. Yield is also the most important factor in overall processing cost. This article describes a yield improvement project undertaken by Tower Semiconductor, a foundry in Migdal Haemek, Israel, that produces several dozen different products, each with the relatively low volume of a few hundred wafers. Five different technologies (1.0, 0.8, 0.6, and 0.5 μm, and EPROM) are fabricated with variations of dual and triple metal. The same facility also is used to develop such new technologies as analog, 0.35 μm, and 0.5- and 0.35-μm Flash. With this complex product mix, the company needs a yield management program that operates effectively to ensure that high yield levels are consistently maintained.