PRO COOL® uses the following yields from TWO COOL® in analysis and reports:
Defect-Limited (Wafer Fab version only)
PRO COOL® also allows definition of an inspection scrap value. Capacity analysis considers the impact of equipment yield and inspection scrap on the volume of work-in-process. Defect-limited yield and parametric yield losses are not considered in capacity analysis.
Equipment yield losses from TWO COOL® are assumed to exit the process at the tool incurring the equipment yield loss. PRO COOL® assumes that defect and parametric yield losses will be identified at an inspection or test step. The impact of defect and parametric yield losses on work-in-process volume can be reflected in PRO COOL® by setting the appropriate inspection scrap value (See the "Process Step Sequence" dialog box in Chapter 4 of the PRO COOL® User's Guide).
Scrap percentages and costs are calculated in TWO COOL®. The PRO COOL® Inspection Scrap % values must be consistent with the TWO COOL® yields for proper allocation of scrap costs. For example, a PRO COOL® analysis of a three step process with the last step including inspection would compare to the three TWO COOL® parametric yields as shown in the table below.
|TWO COOL®||Parametric Yield||PRO COOL®||Inspection Scrap %|
|Tool Group A||99%||Step A using Tool A||0%|
|Tool Group B||99%||Step B using Tool B ||0%|
|Tool Group C||99%||Step C using Tool C (Inspection Step)||3%|
|TWO COOL® Yield||97%||PRO COOL® Yield||97%|
Reporting Yield in PRO COOL®
The Management Summary Report shows Line Yield and Composite Yield for the process. Line Yield is defined as follows:
Yield = Ships/Starts
Composite Yield is the product of Equipment Yield, Parametric Yield, and Defect-Limited Yield for each tool group:
YC = (YE x YP x YD)Tool Group
Tool Group yields are presented on several reports:
| ||Equipment Yield||Composite Yield||Inspection Scrap|
|Tool Group Report||Yes||Yes|| |
|Process Step Report|| ||Yes||Yes|
|Minimum Cycle Time Report||Yes||Yes|| |
|Ships by Process Step Chart||Yes|| ||Yes|
Composite Yield is reported for information only and is not part of the PRO COOL® cost and capacity analysis.