The Effect of Ion Implantation on Carbon Diffusion Through Si/SiOx Layer

The mechanism of carbon (C) diffusion in Silicon Oxide (SiOx) that is deposited on silicon (Si) wafer through the furnace oxidation process, has been investigated in different pre-conditions (with and without ion implantation & with and without O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> leak during thermal treatment). The diffusive behaviour of C through SiOx was monitored by X-Ray Photoelectron Spectroscopy (XPS). The C in SiOx on ion-implanted Si wafer is 6.04 at% at & 2.4 at% for bulk & interlayer respectively. While under O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> leakage condition during thermal treatment, the concentration of C is 0.63 at% and 0.8 at% in the upper and lower part of the SiOx bulk layer respectively. However, the concentration of C in SiOx on ion implantation-free Si wafers are 7.54 at% and 6.0 at% for bulk & interlayer respectively. Under O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> leakage conditions during thermal treatment, the C concentration of ion implantation-free wafer is also relatively high at 2.14 at% and 1.89 at% for upper & lower SiOx bulk respectively. The C diffusion profiles show that ion-implanted Si wafers have lower C impurities due to faster out-diffusion of C from the Si substrate in both O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> leaked & and O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> leaked conditions during thermal treatment. On the other hand, ion implantation-free Si wafer has higher C impurities due to slower out-diffusion of C. This suggested that the implantation process can cause certain damage on the Si wafer surface, leading to faster out-diffusion of C during the thermal treatment step.