As part of AMD's on-the-job training internal coursework, technicians are asked to write a project report that describes the regulation of gas-tray solenoid voltage on Fab 10 diffusion furnaces.

Excerpt of a project report that met the requirements of AMD's internal coursework for technicians:

Project Report
During this project, solenoids showing excessive wear from operation with the unregulated voltage will be replaced. The unregulated voltage is outside upper control limits for gas tray solenoids, which causes premature failure of solenoids and process aborts. This project was selected because once implemented, it will reduce diffusion furnace aborts, thereby reducing scrap for Fab 10. The cost of the project is minimal compared to the cost of scrapped wafers as a result of solenoid induced furnace aborts.

The goal of the project is to further AMD profits by bringing solenoid voltage within control limits to prevent unnecessary diffusion furnace aborts. There are four components to the report:

• Measurement and Responses
• Capability Study
• Experiments
• Results

Measurements and Responses
There are four critical measurements for this project which require response:

1. Measurement of the DC supply voltage used to power the diffusion furnace gas tray solenoids (found in furnace regulator modification tables)
2. Visual inspection of the gas tray solenoids
3. Analysis of furnace regulator modification costs
4. Reduction in solenoid induced diffusion furnace aborts

Capability Study
For this project, 24 VDC regulators and replacement gas tray solenoids need to be sourced. Coordinating this project in a production Fab is also a consideration[…].

Experiments
(Note: This section of the report refers to tables, also compiled by the technicians.) Thirty-three diffusion furnaces require the 24 VDC regulator modification. The success of the initial modifications proved a more aggressive modification schedule to be appropriate. None of the furnaces within this sample have aborted due to solenoid failures.

Results
This project is a success. The Furnace Regulator Modification Table 1 demonstrates the gas tray solenoids to be operating within control limits. Gas tray solenoid life cycles are now more stable. There have been no aborts due to premature solenoid failure on any diffusion furnaces with the 24 VDC regulator project complete. Furthermore, data in Table 2 shows that the cost to modify each furnace is very low in comparison to the cost of wafer scrap due to an abort.

By monitoring diffusion furnaces as they were modified, data indicated the 24 VDC modification should be performed on all diffusion furnaces. Of the 33 diffusion furnaces needing the 24 VDC modification, 25 are complete, and 8 are scheduled for completion by the end of the first quarter.