hw1_solutions_new

# hw1_solutions_new - Solutions to IEOR 130 HW 1 Spring 2009...

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1 Solutions to IEOR 130 HW 1 Spring 2009 Prof. Leachman 1. Line yield (LY) is the fraction of wafers started that become wafer outs from the wafer fabrication (wafer fab) factory. Die yield (DY) is the fraction of chips (dice) printed on wafers coming out of wafer fab that electrically work. That is, it is the ratio of good die out to total die out. Defect density is an equivalent metric to die yield, expressing the average number of fatal defects per square centimeter of wafer surface. There are different mathematical models for inducing the underlying defect density from the observed die yield. The various models make varying assumptions about the clustering of defects. Stepper throughput expresses the average number of wafer operations completed per stepper per day. Overall equipment efficiency (OEE) is a ratio A/B, where A is the theoretical time required to complete the good units of product actually processed by the equipment during an observation period, and B is the total time in the observation period. On-time delivery (OTD) is a metric expressing the fraction of targeted output for a fabrication plant actually completed in an observation period. Line-item performance against schedule (LIPAS) is the most common OTD metric in the semiconductor industry.

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