Technique for determining concentration profiles of boron impurities in substrates

Abstract

A new technique is described in detail which can be used to profile boron impurities in almost any substrate to a depth of a few microns. It uses the reaction 10B (n,4He)7Li to convert boron atoms to monoenergetic α particles which are detected after they leave the target. The technique is sensitive to boron at levels as low as 3 ppm, with a depth resolution of ±20/nm for boron in silicon. A new technique of deconvoluting this type of experimental data is described in detail. Methods are presented which eliminate the problem of spurious oscillations in deconvoluted data. Examples are shown in which the technique is used to analyze various distributions of boron in silicon.