SBIR-STTR Award

In response to customer demand for an in situ, accurate, and repeatable temperature measurement of Silicon (Si) and Gallium Arsenide (GaAs), researchers are using a new temperature sensor to measure the temperature of Si and GaAs above 800øC, and as high as 1100øC. The technique uses a system called Diffuse Reflectance Spectroscopy (DRS). The principal behind DRS is that it measures the changing band gap energy of the semi-conductor as a function of temperature. The sensor uses a light source located out of the growth chamber. The light is modulated so that it can be detected in the presence of other light sources, such as the heater source.The diffuse reflectance from the substrate carries band gap absorption information that is analyzed by software based algorithms to determine temperature. Preliminary measurements of GaAs using DRS show a smooth variation of the optical wavelengths associated with the absorption threshold between 4øK and 1000øK. The laws of physics and thermodynamics suggest that the band gap measurement can be made above these temperatures. Researchers are developing techniques and improvements to the DRS sensor technology to measure above 1100øC.Commercial Applications:Research will result in an advanced temperature measurement sensor for silicon and gallium arsenide wafers for research and Commercial use.

This Small Business Innovation Research Phase 11 project will conduct the necessary research required to produce the Diffuse Reflectance Spectroscopy (DRS) technology for use as semi-conductor wafer temperature measurement. Phase I successfully demonstrated the DRS technique. Phase 11 will adapt and extend the DRS technology and: 1) build a DRS temperature measurement materials data base, 2) develop the DRS technology for a process control interface, and 3) add other process monitoring capabilities to the DRS spectrometer. Research will be conducted in three research venues. First, national laboratory collaborators will collect data on GaAs wafer materials. Second, the University of Washington will collect data on surface morphology, and epilayer growth. Third, Thermionics Northwest will: analyze the data received from the research partners, construct a low cost improved performance DRS wafer temperature sensor, collect and analyze data on Si wafers, and increase the temperature measure range of the DRS technique for Si. The control of wafer temperature is critical to film thickness, uniformity and quality. Most wafer processes require temperature measurement and control to increase yield and device density. In-situ temperature sensing with real-time data acquisition is needed for process control. The research conducted in Phase 11 will support product development of one or more process control products using the DRS technology for semi-conductor research and production facilities