LIFETIME CONTROL IN SILICON DEVICES BY VOIDS INDUCED BY HE ION-IMPLANTATION

A method to control carrier lifetime in silicon locally and efficientl y is presented. Voids, farmed by high dose He implants, have been char acterized by transmission electron microscopy demonstrating they are w ell localized in depth within layers thinner than 100 nm while their l ateral extent is limited only by the masking capability during He impl antation. Deep level transient spectroscopy measurements, performed on diodes containing different void densities, revealed the presence of two well defined trap levels, independent of void characteristics, at E(nu)+0.53 for holes and E(c)-0.55 for electrons. These characteristic s make them ideal for lifetime control in reducing parasitic transisto r gain, Gummel plots on transistors have shown that when voids are for med the gain decreases from 1 to 10(-3). The other transistor characte ristics are only slightly influenced by the presence of voids. (C) 199 6 American Institute of Physics.