From crater eruption to surface purification of raw silicon: A treatment by pulsed electron beam

The high-current pulsed electron beam treatment can induce crater eruption at the impurity particle sites, thus providing an efficient method for surface purification. In the present work, raw silicon materials of 2N-, 5N- and 6N-purity levels are treated by this method for the objective of testing the surface purification effect through the crater eruption mechanism on silicon. The surface morphology evolution is followed to trace the crater development in relation to treatment parameters such as energy density (1.8, 2.0 and 3.0 J/cm2) and pulse number (1, 3, 5 pulses), and to the sample purity levels. It is confirmed that the amounts of craters reflect the purity level of the initial samples. Raman spectroscopy shows red shifts, up to 2.2 cm−1, caused by the tensile stress due to impurity re-dissolution. The accompanied transient temperature field is also simulated, which supports the crater eruption mechanism.