Absolute Non-contact Temperature Measurements With A New Polarizing Radiation Pyrometer

A completely new method is proposed to remotely measure the true temperature of substrates during chemical vapor deposition (CVD) processes. Conventional radiation pyrometry is not adequate since requires only that the sample be optically polished (specular) and opaque at the measurement wavelengths. These conditions are met for semiconductor and metallic substrates and coating materials of interest in CVD. The method requires a special photometer incorporating a rotating a rotating linear polarizer, and a lamp with a black body calibration, both external to the chamber. True surface temperatures are obtained, which permit tracking of wafers an othersubstrates during CVD deposition, which in general results in significant variations in spectral emissivity. The signal, noise sources, and observation times lead to an expected repeatability and precision better than 1oC are feasible as well. A modified mode of operation can provide surface temperature profile scans with 0.1oC precision. These parameters are a major improvement in radiation pyrometry, and suggest (1) applicatoin to feedback control of CVD for intelligent processing of materials, and (2) a very likely commercial instrument for worl wide sales. ANTICIPATED BENEFITS: This technique overcomes inaccuracies in conventioanl radiation pyrometry. Consequently, there are numerous potential applications in industry and science, which now utilize a range of commercial non-contact instruments. The method is perfectly general and can be applied at longer wavelengths and colder temeperatures by suitable adaptation of the instrument parameters.