Epitaxial regrowth of Ge/GaAs heterostructures by scanned laser annealing of amorphous Ge films on GaAs substrates has been studied as a function of laser power and scan rate. At least eight regimes representing different film regrowth characteristics were observed. Of these, two were of primary interest. At low powers (between~1.6 and 3.2 W for a beam diameter of~40 μm) and scan rates between 1 and 400 cm/sec, polycrystalline Ge with a (100) preferred orientation was formed by an “explosive” crystallization mechanism. At higher powers, and over a scan rate range of 25 to 400 cm/sec, single crystal metastable (GaAs)1−x Gexalloys were obtained by liquid phase regrowth. Typical film resistivities, ρ, were as follows: as-deposited ρ=180Ωcm; polycrystalline films, ρ=3 × 10−2 Ωcm; single crystal films,ρ=9×10−4Ωcm.

We have compared the electrical properties of laser and furnace annealed selenium implanted InP. Both annealing methods produce high activities, the best being for anneals in a phosphine ambient which also produces a better surface finish. Reasons for the poorer results from the laser annealed samples have been deduced from Rutherford backscattering experiments.

Characteristics of CW Ar-ion laser annealed InSb has been studied; properties include stoichiometric composition analysis and electrical C-V measurements. The stoichiometry compositions of laser-annealed samples at different power levels and scan speeds have been studied using an electron microprobe technique. Results were compared with electrical C-V measurements using MOS structures.

The preparation of AlSb thin films by pulsed laser annealing of Al/Sb sandwiches is studied in order to resolve some past controversy about the temperature rise induced by the laser pulse. Using 1000 Ȧ thick two layer films supported by TEM grids, we investigate the energy threshold for complete transformation as a function of pulse duration from 15 nsec to 100 msec, and of ambient temperature from −100°C to 250°C.

We thence calculate the temperature effect directly induced by the laser to be about 930°C, or approximately the melting point of the metals, whereas inert gas furnace anneals of comparable films show transformation at this temperature occuring only in about 100 sec. We discuss the isoenergetic nature of the system for short laser pulses and the role of the heat of transformation, and thus conclude that the reaction is thermally triggered by the laser pulse but is to some extent self-sustaining via the heat of transformation locally distributed. This model is also shown to have equal validity for the systems CdTe, CdSe and AlAs.

We have developed a novel technique for improving the morphology of as-grown monocrystalline thin films on foreign substrates. A pulsed electron beam briefly heats the surface of the film above its melting temperature, allowing surface tension in the liquid to erase irregular features. Crystallinity of the layer is preserved by rapid resolidification with the underlying material acting as a seed. Pulse polishing has been applied to two heteroepitaxial systems exhibiting rough as-deposited surfaces: germanium on silicon and cadmium telluride on mica. In both cases the surface morphology was dramatically improved while crystallinity and other critical properties of the layers were maintained. We believe this technique has potentially wide application to many thin film systems and should allow a greater degree of freedom in the growth conditions for heteroepitaxial thin films.

Low resistance Ohmic contacts were produced by evaporating nickel and aluminum films on barium titanate substrates, and subsequently irradiating them with Q-switched ruby laser pulses (λ = 0.694 μm, τ = 15×10−9 s, pulse energy density 1.0 − 1.2 J cm−2). Stability and aging behavior of these contacts were comparable to those of conventional contacts, i.e. flame sprayed aluminum, In-Sn solder, fritted silver and electroless nickel under test conditions (ambient temperatures in air, in boiling water and organic liquids at 150°C, 100 psi).

The temperature induced at the surface of a silicon wafer is calculated for both circular and rectangular scanning beams, assuming both a thermally isolated and heat sunk back surface. In the former case, the problem is one of simple uniform heating with radiative cooling at slow scan speeds. A significant thermal gradient is produced across the wafer at high scan speeds. In the latter case, a one-dimensional analysis suffices except for beam diameters less than about twice the wafer thickness, when lateral heat diffusion effects are present.

Transient heating with graphite heaters has been shown to be very useful in several important semiconductor processing applications. Using stationary and/or movable heaters, we have obtained excellent results in the annealing of ion-implantation damage in Si and GaAs, preparation of epitaxial Ge1−xSix on Si substrates, and recrystallization of Si films on insulators. The advantages of graphite heaters include their ready scalability in area to commercial wafer size and their low capital cost. These heaters are also easily machinable, and their temperature can be rapidly varied. When fully developed, this heating technique should provide an inexpensive and versatile method for commercial processing of many semiconductor materials.

We report an extremely rapid and efficient method for annealing ion-implanted wafers by transient irradiation with tungsten halogen lamps. Several 3-inch wafers are held in an inert atmosphere, thermally isolated from the water cooled base and separated by a quartz plate from the air cooled lamps, which can deliver in excess of 100 kW of power. Heating of the wafers up to 1200°C, or even to the melting point of Si, occurs within seconds. The cooling process can be equally rapid. The temperature is continuously monitored with a pyrometer. The radiative flux in the chamber is uniform within 5% over at least 500 cm 2; however, at temperatures 1200 °C radiative losses at the wafer perimeter may cause crystalline slip if proper countermeasures are not taken.

Irradiation of Si wafers for 5 to 10 sec with high intensity tungsten halogen lamps produces complete recovery of the displacement damage resulting from ion implantation. Data for two different thermal cycles are presented, with As and B implant doses ranging from 1013 to 1016 ions cm−2. Sheet resistance measurements combined with Rutherford backscattering indicate full electrical activation of dopants with very little diffusion. Carrier lifetimes measured by a photoconductive method and by diode reverse recovery compare favorably with furnace annealing data, and capacitance transient spectroscopy reveals a low density of defects in the junction depletion region. These results combined with the inherent advantages of low cost and high efficiency make Rapid Thermal Annealing ideally suited for VLSI device fabrication.

simple radiant light source has been employed to rapidly anneal ion implanted silicon structures at temperatures >1000° C for times of the order of 1–200 sec. Rutherford backscattering and channeling analysis indicated good crystalline lattice recovery and the formation of metastable solid solutions of Sb in Si without observable diffusion broadening of the implanted profile. Diode arrays have been successfully annealed using the technique, with no observable deterioration of the surrounding oxide mask.

Supersaturated substitutional solid solutions of 2×101531P+ /cm2 implanted at 10 keV in (100) Silicon were obtained after solid phase epitaxial regrowth using a scanning beam of incoherent light. The main results are: a) the maximum P+ concentration exceeds of about 5 times the maximum solid solubility at the temperature reached by the sample; b) the carrier concentration profile shows a complete dopant activation without diffusion of the implanted ions; c) an improvement of minority carriers diffusion length in the bulk is often observed; d) the values of carrier mobilities are similar to those obtained after liquid phase regrowth by pulsed ruby laser; e) a very good recovery of the damage is obtained: Rutherford backscattering spectra show that the dechanneling fraction is very close to the value of virgin samples and Trasmission Electron Microscopy analysis shows that the residual damage consists of dislocation loops of about 30 Å diameter confined in a region at about 500 Å depth.

This paper describes a semiconductor processing system using two electron beams. One beam provides uniform heating of the bulk of the specimen, whilst the other performs localized heating, for example as a spot, a line beam, or as an inset scan. The annealing of localized regions in ion-implanted silicon and SOS, by local heating above the bulk temperature, illustrates the application of the system. Other applications of the systems are also considered.

The optimum e-beam anneal conditions for damage free wafer annealing, implant activation uniformity across 3 inch wafers and low dose boron activation have been investigated with reference to the needs of MOS device processing. Some effects of e-beam annealing on MOS gate dielectrics are reported.

A gas discharge system is used to produce a large area electron beam which can be used to angeal ion-implanted semiconductors. The sample temperature rise and amorphousto-single-crystal regrowth were monitored using the change in optical reflectivity.