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14 September 1994 Single-photon ionization: laser optical probe technique for semiconductor growth
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Single Photon Ionization Time-of-Flight Mass Spectroscopy (SPI-TOFMS) is used as an in situ optical characterization technique to monitor chemical reactions occurring at semiconductor surfaces during molecular beam epitaxial (MBE) growth be detecting gaseous species. In this approach, 118 nm (10.5 eV) laser photons are generated and passed on front of a semiconductor substrate in the ultra-high vacuum (UHV) chamber. Here, the photons ionize the gaseous scattered and desorbed growth species which are detected by time-of-flight mass spectroscopy. The photons are produced by frequency tripling the fundamental Nd:YAG output to 355 nm and tripling again in a static cell of Xe/Ar to 118 nm. The 10.5 eV photons have sufficient energy to ionize III-V species of interest, but not fragment them, allowing simple interpretation of mass spectra. Gated boxcars allow for rapid data acquisition of growth species in real time. SPI-TOFMS has been used to study Asn/Si(100) desorption kinetics and, more recently, MBE growth of GaAs. Results are presented on the real-time monitoring of Gan and Asn growth species. Simultaneous monitoring of growth with Reflection High-Energy Electron Diffraction (RHEED) is also discussed. Future work includes SPI_TOFMS studies of Si delta-doping in GaAs and surfactant-enhanced epitaxy of Ge on Si. SPI-TOFMS is an in situ UHV optical probe used to study the growth chemistry of semiconductor surfaces. This noninstrusive, species-specific real-time monitor of growth can be applied to increase the quality of device manufacturing.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Adina K. Kunz, April L. Alstrin, Sean M. Casey, and Stephen R. Leone "Single-photon ionization: laser optical probe technique for semiconductor growth", Proc. SPIE 2337, Optical Characterization Techniques for High-Performance Microelectronic Device Manufacturing, (14 September 1994);


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