Solid state: Superfast annealing: Application of laser and electron-beam annealing portends three-dimensional ICs and economical photoelectric cells

Laser or electron beam annealing can be carried out with either pulsed or steady beams. The beams may be large or small, may persist for only nanoseconds or dwell on a spot for many milliseconds. However, in all cases, the power of the beam must be high enough to raise the material´s temperature to the melting point, or at least to within a few hundred degrees of it. The range of applications for these clean, fast-heating methods has gone far beyond annealing of defects to a variety of other materials manipulation possibilities. For years, lasers have been used in the processing of metals and ceramics: to weld metals and flash-melt alloys, for surface hardening and drilling holes in metals and hard insulators, for example. They have also been used in the electronics industry for silicon wafer scribing and labelling, wire bonding, resistor trimming, and interconnection path selection by pulsed laser erosion. The new field addresses the manipulation of semiconductor material properties themselves.