Improving Silicon Wafer Cleaning with the Piranha Etch Process

The Piranha etch process removes organic material from silicon wafers rapidly and thoroughly and is typically used in the silicon wafer cleaning process.

The Piranha process involves using an aggressive mixture of sulfuric acid and hydrogen peroxide to dissolve organic residue on silicon wafers. To improve the strip speed, the temperature of the mixture is increased up to 130 degrees centigrade. Control of the mixing is difficult as the mixture of these two chemicals is exothermic and heats up the solution. As the temperature cools, it has to be heated again to maintain temperature and strip rate.

Modutek can provide high-temperature re-circulating and constant temperature quartz baths and has introduced a new “bleed and feed” program to improve the control of the Piranha process. It uses a two-tank system with a clean and dirty tank. Once the concentration of the hydrogen peroxide goes down, a small amount of mixture from the dirty tank is drained and discarded. The drained amount is replaced from the clean tank. The stripping process and the concentration are maintained at a desired level, and the clean tank has the sulfuric acid and hydrogen peroxide replenished.

The “bleed and feed” control method can save up to 75% of chemical usage and disposal costs are correspondingly lower. It also improves process efficiency with less downtime, and the strip rate is kept constant which leads to improved process results. Modutek is a leading semiconductor equipment manufacturer that provides customers with high-quality silicon wafer cleaning equipment that offers the highest degree of process control.

For more details read the complete article titled “Improving Silicon Wafer Cleaning with the Piranha Etch Process”. Call Modutek for a free quote or consultation to discuss your specific needs at 866-603-1533 or email modutek@modutek.com.