IND ENG 130 Midterm: ieor130-sp2004-mt1-Leachman-exam
8 Jan 2019
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20 points each problem, 60 points total: the number of particles deposited on wafers at a particular process step is subject to statistical process control. Suppose the die size is 0. 5 sq cm. Predict the new maximum observed yield: a diffusion furnace performs polysilicon depositions on four lots of wafers in one machine cycle. At the start of the machine cycle, the load lock of the furnace is pumped down to vacuum. The load lock to the furnace incorporates an unreliable o ring. When the o ring fails, all four lots become contaminated and must be thrown out. It is not possible to determine if the o ring has failed until after the machine cycle is completed, at which point it is obvious if the o ring failed or not. When the o ring fails or when it is replaced before failure, it takes 2 hours to replace it and re-qualify the furnace for more production.
