Full-Flow Sulfuric Ozone System

The Sulfuric Ozone System consists of an Ozone Module and a Pumping Module. Working together, the two modules enhance the removal of organics from wafers by supplying a high temperature, concentrated sulfuric acid solution sparged with ozone gas. Sulfuric Ozone Mixture (SOM) processing in CFM's system provides unsurpassed Cost of Ownership (CoO) benefits. Less frequent bath turnover, lower process temperatures, and lower consumables costs result in superior CoO.

The Ozone Module contains a generator which creates ozone (O3) gas using oxygen (O2) and nitrogen (N2) and delivers it to the Pumping Module, where it is sparged into the sulfuric acid (H2SO4), reacting to create peroxydisulfuric acid (H2S2O8). This process is user-specified through the software interface to occur either continuously or during the soak step of the recipe. Continuous ozone sparging of sulfuric acid increases bath life and eliminates the use of hydrogen peroxide (H2O2), reducing chemical costs and operating temperature.

The Pumping Module continuously circulates, filters, and heats the SOM mixture. The continuous circulation guarantees complete mixing of the H2SO4 and the ozone. The filter removes residual particles from the mixture, ensuring cleaner processing. The heater carefully maintains a steady state temperature control of SOM, maintaining process efficiency of the chemical.

The Pumping Module contains two (pumping) cylinders to hold and circulate the SOM. Sulfuric acid is delivered by bulk chemical supply at the user-defined level to the pumping cylinders, where it continuously circulates through filters under N2 pressure. In the pumping process, one cylinder is pressurized with regulated nitrogen to transfer the chemical out the bottom of the cylinder and through a filter into the second (vented) cylinder. After transfer and filtration of the solution from the first cylinder to the second cylinder is completed, the first cylinder is then vented and the second cylinder is pressurized to transfer and filter the solution back to the first cylinder. This cycling occurs continuously to provide a well filtered and uniformly heated sulfuric ozone bath for wafer processing and ensure complete mixing and residual particle removal.

CFM Technologies, Inc., 150 Oaklands Blvd., Exton, PA 19341. Tel: 610-280-8300; Fax: 610-280-8309.