AMORPHIZATION OF SILICON BY HIGH-DOSE GERMANIUM ION-IMPLANTATION WITHNO EXTERNAL COOLING MECHANISM

Si(100) wafers were implanted by using three different methods: single -energy Ge+ ion implantation, double-energy Ge+ and Ge2+ ion implantat ion, and double-energy Si+ and Ge+ ion implantation. The single-energy implantations were performed at energies from 50 to 180 keV, over the range of 8.38 x 10(15) to 5.80 x 10(16) ions/cm2. By keeping the ion beam power density below 0.09 W/cm2, full surface amorphization could be achieved in the single-energy Ge+ implanted samples. Also beam heat ing was suppressed during implantation, although the implanter had no external cooling. In addition, a two-step single-energy implant techni que using sequentially high and low power densities was further develo ped in order to reduce implantation times. In order to locate the amor phous/crystalline (a/c) interfaces far away from the concentration pea k positions of the implanted Ge+ ions, the double-energy Ge+ and Ge2+, and Si+ and Ge+ implantations were carried out. Three Ge+ implanted w afers were either pre-implanted with 180 keV Si+ ions, or post-implant ed with 360 keV Ge2+ ions, respectively, in order to locate deeper a/c interfaces. Channelling effect measurements indicate that the double- energy Ge+ and Ge2+ implantation is a preferable technique for wilfull y tailoring the amorphous depth and the Ge peak position.