Laser infrared photothermal radiometry of electronic solids: Principles and applications to industrial semiconductor Si wafers

The physical principles and application case studies of the novel diagnosti c technique of laser infrared photothermal radiometry (PTR) of semiconducto rs are presented. Following superband gap optical excitation, the signal co nsists of two contributions, one due to the de-exciting carrier density (pl asma wave) and another from direct absorption and heating of the lattice (t hermal wave). Multiparameter Bts to frequency-domain amplitude and phase da ta have been developed to reliably measure recombination lifetime, tau surf ace recombination velocities (front and back surface), electronic, and ther mal diffusivities. Applications case studies are presented, which demonstra te that lifetime measurements using PTR provide a most sensitive, convenien t, and nonintrusive, remote industrial semiconductor metrology. The new met rology combines the features of several, laboratory and commercial techniqu es currently available for industrial wafer (substrate and process) charact erization (e.g., thermoreflectance, microwave reflectance, and surface phot ovoltage). The technology is capable of being used as a sensitive control o f ion implantation, contamination monitor during oxidation and wafer cleans , and photoexcited carrier recombination lifetime measurements. (C) 2000 Am erican Vacuum Society. [S0734-2101(00)07502-3].