Help, Please answer this exercise!!!!

6. ( 20 points) A fabrication facility operates a single process flow. The process flow includes four polish steps performed by a particular type of CMP machine. Data about the CMP machines of this type is as follows: Availability: 69.0% Utilization of availability: 75.0% MTTR: 10 hours TTR:40 hours Takt time (TKT): 0.3 hours (for each of the four polish steps) Standard cycle time (SCT): 0.4 hours (for each of the four polish steps) Number of qualified machines: 3 (for each of the four polish steps) After each polish step there is a cleaning step performed by a particular type of single-waferclean (SWC) machine. Data about the SWC machines of this type is as follows: Availability: 93.0% Utilization of availability: 82.0% MTTR: 4.4 hours OTTR: 5.3 hours Takt time (TKT): 0.165 hours (for each of the four clean-after-polish steps as well as for 3 other cleaning steps performed by this machine type) Standard cycle time (SCT): 0.2 hours (for each of the four clean-after-polish steps as well as for 3 other cleaning steps performed by this machine type) Number of qualified machines: 4 (for each of the four clean-after-polish steps as well as for 3 other cleaning steps performed by this machine type) Assume ca2=1 and c02=1 for all steps on both machine types. Recent data show that incoming wafer uniformity at two of the four polish steps has improved considerably, so the process engineering director is considering eliminating those two polishing steps and the subsequent two clean-after-polish steps from the process flow. (a) (8 points) Estimate the reduction in entitlement cycle time if the two polish steps and the two clean-after-polish steps are eliminated from the process flow. (b) (7 points) Assuming the above-mentioned two polish steps and the two clean-after-polish steps are eliminated, estimate the percentage increase in wafer starts (to the nearest percentage point) that could be made such that the new total ECT for the CMP machine type and the SWC machine type above would not exceed the total ECT for those machine types before the steps are eliminated. (c) (3 points) Now suppose there are many other equipment types in the fabrication facility. Briefly explain how to determine the percentage increase in wafer starts that could be made if the above-mentioned two polish steps and two clean-after-polish steps are eliminated such that the new total ECT for the process flow would not exceed the total ECT for the process flow before the steps are eliminated. (d) (2 points) Suppose there is a slight decrease in yield that would occur if the above-mentioned steps are eliminated. Briefly explain how you would determine if fab output would go up or go down if the steps are eliminated and wafer starts are increased by the percentage calculated according to your proposed method in part (c)