Evaluation of the Damage for Gettering in Silicon Wafer Introduced by a Cavitating Jet

Abstract

Damage for gettering can be introduced by a high speed submerged water jet with cavitation, i.e., a cavitating jet, into a silicon wafer. Gettering is an important technique for removing unwanted impurities from the surface of the silicon wafer that is active device region. Metal contaminations diffuse in bulk of the wafer and adhere to the defects through the thermal treatments in semiconductor processes. If the damage was intentionally introduced into the silicon wafer, these contaminations can be gathered within the intended region. Consequently, the surface of the wafer can be kept free from impurities. The method presented here utilizes cavitation impacts to introduce the damage for gettering. By using cavitation impacts, the damage can be introduced without the use of particles which form sources of contamination during farther wafer handling, as in shot blasting that is a popular technique. The cavitation impacts caused by a cavitating jet were used since the intensity of cavitation impacts can easily be controlled by controlling hydraulic parameters. The gettering effect of the damage introduced by the cavitating jet was already confirmed, but the detail information of the introduced damage has not been obtained. After applying thermal treatment to the wafer treated by the cavitating jet, there are Oxidation-induced stacking faults (OSF) which would be gettering sites. However, the source of OSF is not yet confirmed. In this paper, the damage on the silicon wafer surface introduced by the cavitating jet for gettering is observed to evaluate the source of OSF.