Accession Number : ADA019422

Title :   Optimal Summation of Gaussians for Ion Implantation Profile Control.

Descriptive Note : Technical rept.,

Corporate Author : ILLINOIS UNIV AT URBANA-CHAMPAIGN COORDINATED SCIENCE LAB

Personal Author(s) : Zaremba,Andrew Joseph

Report Date : NOV 1975

Pagination or Media Count : 75

Abstract : The fact that the number of implanted ions can be accurately determined and controlled is used in the processing of numerous semiconductor devices. By contrast, there is very little fabrication of solid state devices which effectively uses the spatial impurity distribution of implanted ions. To a large degree, this is because the distribution of a particular implant is Gaussian, which is not a particularly useful profile. However, by using multiple implants the individual Gaussians may be effectively summed to approximate a wide range of desired impurity distributions. The summation of Gaussian distributions to achieve arbitrary functions is a mathematical problem of general interest, and the usefulness of solving the problem extends far beyond the desire to approximate impurity distributions in semiconductors. Unfortunately, the solution here is complicated by the physics of the situation which limits the available Gaussian expansion functions. Under this condition it will be shown that the analytical solution of the problem is not feasible. A numerical solution is presented for a number of profiles, indicating that many desirable impurity distributions may be satisfactorily approximated.

Descriptors :   *SEMICONDUCTOR DOPING, *ION IMPLANTATION, IMPURITIES, NUMERICAL ANALYSIS, COMPUTER PROGRAMS, DIFFUSION, GALLIUM ARSENIDES, SILICON, GALLIUM PHOSPHIDES, NORMAL DISTRIBUTION, THESES

Subject Categories : Electrical and Electronic Equipment
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE