Solid-phase Recrystallization Research Articles

Solid phase recrystallization in molecular beam deposited gallium arsenide

A series of experimental investigations on the solid phase recrystallization of molecular beam deposited gallium arsenide films on silicon dioxide/tantalum/nickel substrates has been performed. The activation energy for recrystallization is unexpectedly small (0.55 eV) in the temperature range 450–600 °C. When a thin amorphous germanium layer was grown before gallium arsenide deposition, an enhanced grain growth of gallium arsenide occurs together with anomalous germanium diffusion into the gallium arsenide layer in a semieutectic phase reaction. An enhancement of grain growth has also been observed by the utilization of a graphoepitaxy substrate having inverted pyramidal relief.

Solid-phase recrystallization of Si-ion-implanted polycrystalline silicon films

The structure of solid-phase recrystallized polycrystalline Si (poly-Si) films damaged by Si ion implantation was investigated. It was found that the recrystallized poly-Si film has a largest grain size of about 2 μm and has a strong texture when the Si dose is in the critical range for amorphizing the film. Under this implantation condition SSIC (Seed Selection through Ion Channeling) occurs. Poly-Si pn-diodes and MOSFETs were fabricated with the solid-phase recrystallized films. The best characteristics, such as mobility and leakage current, were obtained for the film recrystallized with the SSIC process.

Control of Resistivity of Polycrystalline Si Films by Solid-Phase Recrystallization (SPR)

The effect of the grain size after solid-phase recrystallization (SPR) on the resistivity of polycrystalline Si (poly-Si) films was investigated in detail. SPR poly-si films were obtained by amorphization by Si ion implantation and by subsequent recrystallization by low-temperature furnace annealing. Resistivity could be precisely controlled by choosing the doping concentration and by full amorphization and recrystallization at a fixed temperature. This was due to the controlled increase in grain size and the decrease in trapping state density per unit volume. An advanced model on the resistivity was proposed in which the resistivity dependence on the dopant concentration was well explained. It was indicated that the grain boundary of SPR poly-Si films exhibits the same electrical characteristics as that of as-deposited films.

Recent advances in solid-phase epitaxial recrystallization of SOS with applications to CMOS and bipolar devices

Recent advances in solid-phase epitaxial recrystallization suggest that this technology may dramatically improve the crystallinity of heteroepitaxial silicon-on-insulators, such as silicon-on-sapphire (SOS). Recent improvements of 0.3- and 0.5-μm SOS films using two solid-phase epitaxial recrystallization processes (SPEAR and DSPE) are reported. Both techniques have reduced the total microtwin densities of SOS samples by more than 100-fold, while increasing electron and hole mobilities approximately 50%. The resulting properties are very close to those of bulk silicon. High-performance submicrometer CMOS devices and circuits in 0.3-μm recrystallized SOS films have been fabricated.

Direct evidence of recrystallization rate enhancement during rapid thermal annealing of phosphorus amorphized silicon layers

The solid phase epitaxial regrowth of implanted phosphorus amorphized 〈100〉 silicon during rapid thermal annealing (RTA) in the temperature range 475–600 °C has been studied using Rutherford backscattering and channeling measurements. Within the temperature range 475–550 °C, our results show an enhancement of growth rate (Vg) by a factor of 4 when compared with values reported in literature for processing in a conventional furnace, with an activation energy of 2.7±0.2 eV. For temperatures above 550 °C, a reduction of this enhancement effect sets in, with a fall in the enhancement factor from 4 at 550 °C to about 1.5 at 600 °C. Estimation of the absolute error in temperature measurement in the RTA furnace shows that the accelerated kinetics cannot be completely explained by such errors as they are small compared to the enhancement rate. These results therefore give evidence of RTA induced enhancement of growth rate during solid phase recrystallization of implantation-amorphized silicon.

Formation of Ohmic Contacts to n-GaAs by Solid Phase Epitaxy of Evaporated and Ion Implanted Ge Films

Ge films evaporated on GaAs(100) substrates have been amorphized by ion implantation and recrystallized epitaxially in the solid phase. Ohmic characteristics have been obtained in Ge/n-GaAs heterostructures by implantation of As+ or P+ in Ge and Si+ at the interface. A two-step annealing method was found to be effective to obtain ohmic characteristics. In two-step annealing, the first annealing step at low temperature is for solid phase recrystallization of Ge films; the second step involves rapid high-temperature annealing in order to activate the implanted species. It has also been found that interdiffusion should be minimized in order to obtain good ohmic characteristics.

Artificial epitaxy in an elastic strain field

The mechanism of obtaining oriented films on nonoriented substrates is discussed. It is supposed that various anisotropic elastic stresses can serve as agents leading to the formation of oriented layers. The proposed mechanism has been confirmed by experiments on laser annealing of PbTe and Ge films and solid-phase recrystallization of S.

High Dose Implantation of Nickel into Silicon

ABSTRACTSeveral silicon wafers were implanted with 58Ni+ at an energy of 170 keV and a current density of 12 μA cm-2 to doses between 5 × 1015 and 1.8 × 1018 ions cm-2. The substrates were phosphorus doped n-type <100> Czochralski grown silicon wafers. The wafers were water cooled during implantation and the surface temperatures was monitored with an infrared pyrometer and controlled to < 70°C. Samples were subsequently furnace annealed at 900°C for 30 min in nitrogen. The as-implanted and annealed samples were analyzed using cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering (RBS) spectroscopy, spreading resistance depth profiling (SRP), and scanning electron microscopy (SEM). Micro-crystallites of NiSi2 (2–5nm) buried within an amorphous matrix formed during the 1.5 × 1017 ions cm-2 dose implantation. For higher doses above 3 × 1017 Ni+ cm-2, ion beam sputtering occurred. After annealing, rapid diffusion of nickel and solid-phase recrystallization of the amorphous regions occurred.

Characterization of CMOS Devices in 0.5-μm Silicon-On-Sapphire Films Modified by Solid Phase Epitaxy and Regrowth (Spear)

ABSTRACTComplementary Metal-Oxide-Semiconductor (CMOS) devices and circuits with minimum feature sizes of about 1 μm were fabricated in 0.5-μm-thick epitaxial Silicon-On-Sapphire (SOS) films. The films were modified by ion implantation and subsequent solid phase recrystallization processes which reduced the total microtwin concentrations in the Si layers by more than a hundredfold, while increasing electron and hole channel mobilities between 40 to 50%. Leakage currents were reduced by over 2 orders of magnitude, while drive currents and subthreshold slopes showed significant improvements over as–grown SOS films. Propagation delays of less than 80 psec were obtained for CMOS/SOS inverters with Leff = 0.6 μm.

Thin-film transistors fabricated in solid-phase-recrystallized Si films on fused silica substrates

Solid-phase recrystallization of Si films prepared by chemical vapor deposition on fused silica substrates has been accomplished by transient heating on a graphite strip heater. This process increases the grain size from ∼50 nm to ∼1 μm. Thin-film transistors fabricated in the recrystallized films exhibit surface electron mobilities of 15–20 cm2/V s and on:off current ratios in excess of 105 for a voltage swing of 10 V.

Use of recrystallized Y 3Fe 5O 12 seeds for growing yttrium iron garnets from flux

A method for growing large platelet crystals of Y 3Fe 5O 12 by solid-phase recrystallization of polycrystalline material is considered. Using platelets as seeds, the authors describe the growth of garnet crystals in lead borate fluxes and discuss the characteristics of the crystallization process in the solid phase and in fluxes on seeds. Phase equilibrium data on the system PbO-PbF 2-B 2O 3-Y 2O 3-Fe 2O 3 are also presented.