An expert system for process diagnosis (MOS product testing)

At INMOS, wafer parametric data for all MOS products are produced using a Keithley parametric test system and stored in a VAX database. A VAX program accesses this database and identifies parametric data to be analyzed. This information is used by another VAX program to run the process diagnosis software on the data. A description of the diagnosis program is given. The system is economical in terms of computer resources, requiring roughly one CPU-minute for the analysis and diagnosis of a zero-yield wafer, and can be run as a low-priority batch job during off-peak periods. Manual input to the system is limited to two components, namely, the regular probing of zero-yield product, and the updating of diagnosis tables when a new failure mechanism is identified.<
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