Thomas Anderson
February 1st, 2001, 02:05 PM
The semiconductor industry processes lots (batches) of silicon wafers. Current wafer diameters limit the lot size to a typical quantity of 24 - 8 inch wafers. For accelerated life testing at least three separate lots are used to provide some scope of lot-to-lot variation in reliability. The question then becomes one of determining the number of wafers to choose from each lot to provide the lot samples. Typically a wafer may have anywhere from a few hundred to thousands of candidates. It seems to me that one wafer is not enough, but requiring samples drawn from the entire 24 wafers is also inappropriate. Would like to here comments.