Determination of heat and ion fluxes in plasma immersion ion implantation by in situ measurement of temperature using laser interferometry

Temperature rises of a birefringent substrate (LiNbO3) with repetitive negative pulse bias have been measured in a capacitively coupled RF argon plasma. The measurement method is based on monitoring the variation in natural birefringence due to the changed temperature by interferometry. Using this method, the dependence of the substrate temperature rise upon the repetition rate of the pulse bias has been investigated. A negative bias of −800 V was applied in a series of pulses with repetition rates of 400–800 Hz and a duration of 35 μs using a pulse modulator. The heat flux increases with the repetition rate of the bias pulse. At 800 Hz the value is nearly equal to 40% of the power applied to the pulse modulator.