Gettering Efficiency Of Au To Nanocavity Induced By He～+ Implantation

Metal contamination in a silicon wafer is unavoidable during the many steps required for the fabrication of microelectronics devices. High leakage currents and soft reverse current-voltage characteristics are some of the detrimental effects produced by the metal atoms dissolved in the silicon matrix. Gettering procedures can reduce metal contamination. Many gettering techniques have been widely studied to overcome this problem by removing metal impurities from active regions of device.One new gettering method that has recently received growing interest is the use of nanocavities resulting from helium or hydrogen implantation. The gettering processes usually are estimated by gettering of Au to nanocavity in silicon. In this paper, the characteristics of nanocavity gettering mechanism, diffusion and distributing of aurum and ion implantation in silicon were described.In this work, many bumps on the polishing surface of the silicon, after a He+ impantation in and subsequently a hot-treatment, were observed using atomic force microscope(AFM). But this phenomena could not be observed without He+ impantation.The diodes manufactured using back-side and double-side Au-doped waferswere studied in this work. The effects of the nanocavity-gettering technique were monitored by the leakage current. The experimental results showed that the thermal treatment of the gettering-process was very important to the gettering efficiency. After gettering thermal treatment at 800 for 6 hours, the leakage-current density of the diodes were decreased. The experiments also showed that the gettering efficiency of the diods with a rough-back-side were a little bit better than those with a polished-back-side for the first time. In addition, integrated circuits and semiconductor devices are generally made with single-side polished wafers, therefore the results of this work indicate that nanocavity-gettering technique is practical in manufacture of devices. Finally, the gettering uniformity is demonstrated directly on samples.The gettering results of Au to oxygen intrinsic precipitation and to the nanocavity formed by helium ion implantation were compared and discussed in this paper.