Patent ID: 6580960
Filing Date: 2003-06-17
Classification: H01L

Abstract:
A method for finding a pair of operation/tool's for a failure in a semiconductor fabrication facility having multiple operations and multiple tools for processing a plurality of semiconductor wafer lots, wherein each operation/tool having a lot list representing the process sequence of the lots, and a lot with wafers having the failure is called a bad lot, and a lot without the failure is called a good lot, the method comprising:generating a candidate operation/tool list by selecting all the operation/tool's; assigning a weight value to each lot in the lot list for each operatioon/tool in said candidate operation/tool list, the weight value being a predetermined positive value for a bad lot, and a negative value for a good lot; selecting a pair of operation/tool's from said candidate operation/tool list; for said pair of operation/tool's, naming one of said pair of operation/tool's as the primary operation/tool whose lot list is named as the primary lot list; naming the other of said pair of operation/tool's as the secondary operation/tool whose lot list is named as the secondary lot list; generating a first lot list by removing the lots that are not in said primary lot list from said secondary lot list; generating a second lot list by removing the lots that are not in said secondary lot list from said primary lot list; generating a first cumulative value by sequentially summing the weight value of each lot in said first lot list, and assigning a first peak cumulative value as the maximum first cumulative value during the summation process; generating a second cumulative value by sequentially summing the weight value of each lot in said second lot list, and assigning a second peak cumulative value as the maximum second cumulative value during the summation process; summing said first peak cumulative value and said second peak cumulative value to make a peak combination cumulative value; ranking each pair of operation/tool's according to their corresponding peak combination cumulative values; and assigning the pair of operation/tool's with the greatest peak combination cumulative value the most likely to cause said failure.