SBIR Phase I: Multi-Pass Impedance Optimized Photoacoustic Sensor for Moisture Monitoring

This Small Business Innovation Research (SBIR) Phase I project will yield highly sensitive photoacoustic spectroscopy (PAS) systems to serve as monitors for the semiconductor industry. Moisture in semiconductor process gases can distort manufacturing processes and thereby compromise device performance. No candidate technologies for moisture monitors have all the necessary characteristics: sensitivity, speed, compactness, quickness to dry, and low cost. This project will enable PAS systems to satisfy all those characteristics by increasing their sensitivity and diminishing their size. The conventional design strategy has been to place the microphone in the center of the acoustic cavity; a technique which we have found to be sub-optimal. The company is working on fundamental methods which optimize sensitivity in small photoacoustic cells using insight developed from electrical/acoustical analogs. During this Phase I SBIR project, the company will design, build, and test a PAS system in accordance with our innovative design. The goal of Phase I is to demonstrate a small PAS system with moisture sensitivity of 10-20 ppb and low manufacturing costs. Commercially, small, inexpensive, highly sensitive moisture monitors based on PAS will help wafer fabs to increase yields, reduce down time, accelerate time to market, decrease time for root cause analysis, optimize maintenance schedules, and optimize the duration of purges of process tools. The company has determined that the market for moisture monitors in wafer fabs is a commercially interesting niche. This market will become increasingly attractive as critical feature sizes continue to shrink, moisture requirements become more demanding, and PAS systems show that they can meet all the market requirements.