Carrier Lifetime Reduction by Ion Implantation into Silicon
- PDF / 356,816 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 33 Downloads / 227 Views
CARRIER LIFETIME REDUCTION BY ION IMPLANTATION INTO SILICON
A. MDGRO-CAMPERO AND R.P. LOVE General Electric Research and Development Center,
Schenectady,
NY 12301
ABSTRACT Ion implantation is emerging as a versatile tool for We present the control of carrier lifetime in silicon. results on the use of argon and proton implantations to reduce lifetime. Particle energies used imply submicron penetration depths into the silicon. We find that within the first micrometer from the surface, the generation lifetime can be reduced by several orders of magnitude, and varies inversely with dose. A change in doping coHent ation was found only at the highest dose used (10 cm Effects of the implantations on surface generation velocity and oxide charges were also studied.
INTRODUCTION Ion implantation is used extensively in silicon device processing. The most common application at present is probably the introduction of dopants into silicon, but other uses of ion beams are also practiced or are being developed [1]. Ion implantation can be used indirectly to increase carrier lifetime by gettering impurities. In this case, impurities which decrease the lifetime are removed from the region of interest and gathered at a damaged portion of the silicon wafer. This damaged region can be created by ion implantation [1]. This paper is not directly concerned with this effect of implantation. Our study involves the use of ion implantation to decrease carrier lifetime in silicon; we present here some results on the effects of proton and argon ion beams. At low carrier injection levels the dominant mechanism for carrier generation and recombination is phonon-assisted events via deep level defects [2]. These defects can be crystalline imperfections, impurities (e.g., gold atoms), and/or a combination of both such as the oxygen-vacancy complex. In the case of ion implantation all of these can be important, since crystalline imperfections result from ion implant damage, and the implanted species itself may act as a deep level impurity. The techniques in common use to reduce carrier lifetime in silicon (the diffusion of gold or platinum, and electron irradiation) result in a reduction of lifetime throughout the wafer. On the other hand, due to the well defined range of ions, ion implantation makes possible the spatial localization of regions of reduced lifetime. Masking can be used effectively to provide planar selectivity. Depth control can be achieved by varying the energy of the incident ion or by burying the implanted region by epitaxial overgrowth. The effect of the ion implantation on other material properties is also of concern. The thermal stability of the ion implantation effects is important depending on thermal requirements of subsequent processing steps or device operating temperatures.
Mat.
Res. Soc. Symp.
Proc. Vol.
27 (1984)GElsevier Science Publishing Co.,
Inc.
538
EXPERIMENTAL PROCEDURES Silicon waf5rs of orientation (111) and doping density of 1015 phosphyrus itoms cm were used. The backs of the wafers were implanted
Data Loading...
