Wafer temperature non-uniformity due to volumetric absorption of radiation

Until recently, the semiconductor production wafer processed in a rapid thermal processing system was considered to be an opaque material where all of the incident irradiation is absorbed by the surface and volume absorption has no significance. Such an approach cannot explain several experimentally observed effects such as the different emissivity of doped and un-doped regions, difference in temperatures between die and its boundary, etc. This paper describes a method of solution of heat transfer in semitransparent medium. An example illustrates the impact of semitransparency on the wafer temperature distribution