Chip Manufacturer Increases Wafer Production by Using Custom Heating Blanket

Challenge

Heating Blanket Graph
A semiconductor company was given a large government contract to manufacture a special chip for a night vision application. They sought help from Valin when they needed to speed up the extensive process of wafer cleaning, which utilized liquid CO2. Their engineers had a problem keeping the cylinder pressure high enough to create the needed “snow” for cleaning the wafers. The flow rate was so high that the pressure would drop below an acceptable level causing the process to abort. The cylinders were housed in a controlled room with a constant temperature of 68°F. Valin determined if we could heat the cylinders to 72°F - 74°F, we could increase the cylinder pressure by 175 psig. By increasing the pressure in the cylinders we would be able to run more wafers prior to the process aborting. The semiconductor company’s goal was to be able to run at least 10 wafers back to back before shutdown.

Solution

Valin’s technical specialists worked with the manufacturer to design a custom heating blanket that included its own independent temperature controller to wrap around the cylinder. This design allowed us to heat the cylinders and control the temperature +/- 1°F. By increasing the temperature to 73°F, we reached a cylinder pressure of 875 psig. This increase in pressure allowed the customer to complete an entire run of 25 wafers without interruption. As a side benefit, they were able to utilize more of the liquid CO2 in the cylinder prior to cylinder change out. The installation was very straight forward and easy and within 4 hours of receiving the blankets, the wafers were running successfully.

Customer Benefits

The benefits to our customer were staggering! Prior to our solution, they could only run a maximum of 3-4 wafers at a time. They would then have to wait for the system to rebuild enough pressure (30-45 minutes) to resume the process. Their goal was to run 10 wafers back to back, but we exceeded their goal by completing 25 wafers. They can now run the wafers without process interruption and consume more of the liquid CO2, which dramatically increases production and saves money.