Analysis of second-harmonic generation by unamplified, high-repetition-rate, ultrashort laser pulses at Si(001) interfaces

State-of-the-art femtosecond lasers have the potential to dramatically improve the effectiveness of interface nonlinear optics for diagnosing Si(001) interface characteristics that are relevant to Si microelectronics manufacturing. We present an analysis of signal acquisition rate and parasitic surface heating for SHG by ultrashort laser pulses at Si(001) interfaces, emphasizing their dependence on the pulse duration, energy, repetition rate, wavelength and focal geometry of the pulses. The results of the analysis are illustrated by several experimental examples of SHG by a Ti: sapphire femtosecond laser from a buried Si(001)-SiO/sub 2/ interface or a Si(001) surface during chemical vapor deposition.