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Abstract
Inhomogeneous films pose difficulties in obtaining accurate optical thickness measurements. Added to this problem is that outside the process system, a film adsorbs hydrocarbons and moisture from the cleanroom atmosphere - approximately 1 angstrom unit over an hour period. According to Gary Bultman of KLA-Tencor's Film and Surface Technology Division, surface adsorption will complicate process control procedures. Strong technical and economic drivers exist for combining multiple measurement techniques. New materials will need monitoring of parameters other than thickness and refractive index. Combining FTIR, spectroscopic ellipsometry and spectroscopic reflectometry, increasing information content by providing thickness, index of refraction, extinction coefficient, cure rate and dopant concentration, seems a design imperative.