Patent ID: 6423601
Filing Date: 2002-07-23
Classification: H01L

Abstract:
A method of forming a boron-doped region in a semiconductor, the boron-doped region having a retrograde-shaped boron concentration distribution profile exhibiting a peak boron concentration at a preselected depth below a surface of the semiconductor, which method comprises the steps of:(a) providing a semiconductor having a surface; (b) implanting nitrogen ions into the semiconductor surface, the implantation conditions chosen for providing a preselected, approximately parabolically-shaped nitrogen concentration distribution profile within said semiconductor with a peak nitrogen concentration at a depth below the semiconductor surface substantially corresponding to said preselected depth; (c) implanting boron or boron-containing ions into the semiconductor surface, the implantation conditions chosen for providing a preselected, approximately parabolically-shaped boron concentration distribution profile within said semiconductor with a peak boron concentration at a depth below the semiconductor surface which is above, below, or substantially at said nitrogen concentration peak; and (d) thermally treating the nitrogen and boron-implanted semiconductor at a temperature and for an interval sufficient to convert said parabolically-shaped boron concentration distribution profile into a retrograde-shaped profile comprising, in order from the semiconductor surface, a first, substantially constant concentration portion, a second, substantially parabolically-shaped varying concentration portion having a peak concentration, and a third, substantially constant concentration portion, wherein said peak of said second, parabolically-shaped varying concentration portion substantially corresponds to said preselected depth below the semiconductor surface.