Evaluating the effects of thin film patterns on the temperature distribution of silicon wafers during radiant processing

A numerical model was developed to find the temperature distributions durin g radiant heating of a silicon wafer with SiO2 thin film patterns. The radi ative properties of silicon and the film structure were found by considerin g the effects of partial transparency and thin film interference. The avera ge total properties over simple patterns with feature sizes of the order of a few micrometers were found, using an average of the properties of each r egion within the pattern, weighted by their relative areas. In general, waf ers with a single SiO2 film or pattern reach a higher steady state temperat ure than a plain Si wafer due to higher total absorptivity. This applies to thin films of any thickness below several micrometers, where coherent effe cts are dominant. The temperature of patterned wafers vary nonlinearly with film thickness, with the highest temperature discrepancy from Si wafer occ urring at film thickness of similar to 0.2 mu m. For wafers with complex pa tterns, the temperature distributions can be estimated by the average of te mperatures for simpler patterns, weighted by their respective areas. Due to limitations in the computational domain, the radiative processing of 3-in, wafers was modeled; however, results were confirmed for the 12-in. wafer f or limited cases. (C) 2000 Society of Photo-Optical Instrumentation Enginee rs. [S0091-3286(00)01308-8].