Bidirectional reflectance distribution function of rough silicon wafers

The trend towards miniaturization of patterning features in integrated circ uits (IC) has made traditional batch furnaces inadequate for many processes . Rapid thermal processing (RTP) of silicon wafers has become more popular in recent years for IC manufacturing. Light-pipe radiation thermometry is t he method of choice for real-time temperature monitoring in RTP. However, t he radiation environment can greatly affect the signal reaching the radiome ter. The bidirectional reflectance distribution function (BRDF) of rough si licon wafers is needed for the prediction of the reflected radiation that r eaches the radiometer and for reflective RTP furnace design. This paper pre sents the BRDF measurement results for several processing wafers in the wav elength range from 400 to 1100 nm with the spectral tri-function automated reference reflectometer (STARR) at the National Institute of Standards and Technology (NIST). The rms roughness of these samples ranges from 1 nm to 1 mum. as measured with an optical interferometric microscope. Correlations between the BRDF and surface parameters are obtained using different models by comparing theoretical predictions with experiments.