CHARGED-PARTICLE ENERGY SPECTROMETERS AND THEIR APPLICATIONS IN FUNDAMENTAL-STUDIES OF WAFER CHARGING AND ION-BEAM TUNING PHENOMENA

The measurement of charged particle energies has been a key technique used in fundamental investigations of wafer surface charging phenomena and ion beam propagation at Applied Materials. A previous paper descr ibed the use of a spectrometer incorporating hemispherical energy anal ysers which was used for the measurement of potentials present inside ion beams from the spectroscopy of ''slow ions'' emitted from the beam s, and the determination of relatively high potentials on surfaces fro m the energy spectra of sputtered ions. Extension of this work to meas ure low surface voltages induced on an oxide wafer during implantation has given experimental confirmation that beam potentials influence su rface potentials. Other spectrometer types have also been used. Cylind rical mirror analysers, having the advantages of simplicity and compac tness, have been used for ion spectroscopy inside Precision Implant 95 00 systems. These have given valuable insight into the effects of ion source tuning on beam potential and, in particular, the correlation be tween beam quality and device yield. Retarding field analysers have al so been used for ion energy measurements, but their main application h as been for electron spectroscopy due to their immunity from the probl ems of internally reflected electrons experienced by other spectromete r types. This paper will discuss the operation of these various spectr ometers and review some results relevant to ion beam tuning and wafer surface charge control phenomena.