This Small Business Innovation Research (SBIR) Phase I project provides a unique and robust in-situ sensor for detection and control of impurities in microstructures and porous layers associated with manufacturing of semiconductor, MEMS and emerging nano devices. Use of impedance as a measure of contamination in bulk fluids is well established. However, applying it in micro-scale features (potentially down to a few nanometers) is novel, provides high sensitivity, and has many promising applications. This project focuses on development of a unique, low cost, rapid response, integrated sensor that will detect the impurities inside microstructures directly. The project will develop this in two embodiments- integrated with a monitor wafers moving with the product, and as a stand-alone sensor integrated with the process tool. Direct monitoring of residual impurities inside or on the surface of the microstructures will allow more accurate and reliable process control. The technology will also have similar application in some new areas such as supercritical fluids processing where no in-situ sensors are currently available. Because of the exceptional sensitivity and flexible layout, this sensor will also further understanding of the mechanisms involved in chemical transport inside microstructures.
The broader impact from this technology could be significant. The first application, amounting to annual commercial market revenue of $9M to $30M, will be application of the sensor to rinsing and drying of patterned wafers and porous films in IC manufacturing. Currently, these processes are often performed and controlled almost "blindly" based on past experience and post-process control. With shrinking process geometries, a major processing challenge is the presence of very small structures, often with large aspect ratios. Insufficient cleaning and drying have significant negative effects on manufacturing yields and device performance. On the other hand, excessive cleaning, rinsing, or drying results in damage to the microstructures as well as wasting of chemicals, water, energy and time - increasing processing cost. The application of the proposed technology to rinse is expected to reduce water usage by 40-60%. Together with the reduction in the chemical and energy, this could result in $3-5 million savings per year in an average fabrication plant.
