ULTRA-HIGH DOSE BORON ION-IMPLANTATION - SUPERSATURATION OF BORON ANDITS APPLICATION

Super-saturation of dopant atoms in silicon has been attracting intere st because a high concentration of carriers in silicon is required in practical applications and is scientifically important. A high hole co ncentration of about 1 x 10(21) cm(-3) is obtained by implanting boron into silicon substrate with a dose of 1 x 10(17) cm(-2). In such supe r-saturated boron in silicon, it was found that the clustered boron at oms (B-12) substitute silicon atoms. The results of a first-principles calculation indicated that the icosahedral boron cluster is energetic ally preferable to the cube-octahedral cluster. As a practical applica tion, low resistivity contact between aluminum and silicon of lower th an 1 x 10(-8) Omega cm(2) was demonstrated by this high dose boron imp lantation technique with co-implantation of germanium. (C) 1998 Elsevi er Science S,A. All rights reserved.