Environmentally Safe Solvent Based Wafer Cleaning Process

In fabricating semiconductor wafers, cleanliness of wafers and equipment are critical to obtain a high yield process. A wafer is cleaned many times during its fabrication process to remove a variety of organic materials, such as photo resists, and inorganic particles, such as tool/process generated particles. Hazardous, volatile organic solvents are now used to clean chemically sensitive wafers. As restrictions on the use of hazardous solvents increase, an alternative safe-solvent cleaning technique is needed of comparable performance. ESI proposes to examine a three-step (wash-rinse-dry) process which will meet these requirements. In this process: a. the wafer first immersed in a safe, nonvolatile solvating agent to remove organic films, b. the wafer is then rinsed with a safe, volatile rinse liquid to remove particles and residual solvating agent, c. the vapor is then dried with recovery of the evaporated rinse liquid. The candidate liquids will be chosen on the basis of their solvation parameters, as well as the following criteria: a. not classified as a VOC, HAP, ODC, or long term global warming agent b. be nontoxic c, not be a flammable liquid (Flash Point > 100 degrees F) Parametric studies will be performed to optimize process conditions for the removal of representative films and contaminants from processed silicon and gallium arsenide wafters.