A NOVEL INTEGRATED PYROMETER - EMISSOMETER WHICH ENABLES ACCURATE TEMPERATURE MEASUREMENTS OF SURFACES WITH UNKNOWN EMISSIVITIES

摘要

Rapid thermal processing (RTP) is used for many steps during the manufacturing process of microelectronic circuits. The electrical properties of semiconductor devices are very sensitive to thermal process control. For example some processes require thermal ramp rates of up to hundreds of degrees Celsius per second, temperature repeatability of as little as 2 °C (@ 1000 °C), while maintaining temperature uniformity to within a few degrees across the wafer. To meet these requirements without introducing contaminants, radiation pyrometers are used to measure and control wafer temperatures. However, wafer emissivities vary greatly requiring active measurement and compensation of emissivity during wafer processing. This paper describes the development of a pyrometer with an integrated emissometer. This novel instrument determines the effective emittance of a wafer by measuring changes in radiance as a function of view angle when the wafer is in an RTP chamber. Models of the functional emissivity dependence have been determined by Monte-Carlo methods that describe the relationship of the pyrometer optics, processing chamber, and the wafer surface. Measurements of the bi-directional reflectance distribution function (BRDF) of the critical surfaces were incorporated into the model. This technique has been successfully implemented into the current generation of high performance production RTP tools