SUPPLEMENTAL YIELD INFORMATION FOR ALL USERS OF PRO COOL®

PRO COOL® uses the following yields from TWO COOL® in analysis and reports:

• Equipment
• Parametric
• 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.

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