Laser Annealing of Semiconductor Devices

Abstract

Conventional isothermal heat treatment techniques have served for semiconductor fabrication very well up until now. Most of the physical processes involved in fabrication are rate-determined by a solid state diffusion process (e.g. oxidation, dopant redistribution, anneal of implantation damage) and such processes have activation energies typically in the range 2–5 eV. The resulting sensitivity to temperature has required temperature control to ±1°C on modern semiconductor furnaces, and this is routinely met. What, then, is the place of radiant beam processing? This technique opens up the possibility of non-isothermal heat treatment, in which we have control over the spatial and temporal extent of the temperature profile inside the silicon over a very wide range of times (100 picosecs to 100 sees) and distances (0.1 micron to 1000 microns). This selectivity and control of beam annealing makes completely new types of processing possible, and the purpose of this paper is to examine these new possibilities in the light of their usefulness for device fabrication and particularly for silicon integrated circuit processing. New developments are occurring monthly, however, and this overview can only hope to be an accurate snapshot of a rapidly moving field of work.