Modulated Interference Effects and Thermal Wave Monitoring of High-dose Ion Implantation in Semiconductors

Under sufficiently high dose and energy, ions implanted into a semiconductor will produce an amorphous layer throughout the range in which nuclear stopping is the dominant mechanism for slowing the ions. In arsenic implanted silicon, for example, this corresponds to doses greater than 1014ions/cm2 and energies above 10 keV. Using a model for thermal and plasma wave-induced modulated reflectance effects in semiconductors, we show that an optical probe beam will exhibit modulated interference effects which are directly related to the thickness of the amorphous layer and therefore, to the level of ion implantation. We also show experimental data which support the model and demonstrate the use of this thermal wave technique as a method for monitoring the ion implantat ion process in the high dose limit.