The reaction CoSi+Si→CoSi2 has been investigated in the temperature range of 500–600 °C, using Rutherford backscattering, x-ray diffraction, transmission electron microscopy, and four-point sheet-resistance measurements. The reaction is very slow at 500 °C and extremely fast at 600 °C, and appears to occur in four stages: (a) nucleation of the CoSi2 phase at the grain-boundary triple points, (b) lateral growth from nucleation sites to form a continuous layer on the silicon surface, (c) growth in thickness by diffusion through this disilicide layer, and (d) the lateral epitaxial growth by eliminating the grain boundaries. The diffusion through the disilicide layer seems to be a rate-limiting process with high activation energy.

The crystallization of low pressure chemical vapor deposition amorphous silicon films was studied by transmission electron microscope observations. The results demonstrate the interdependence of the silicon deposition rate, the incubation time for nucleation, and the crystalline growth rate. At temperatures below 600 °C the deposited films are amorphous, but partial crystallization can occur the deposition time is longer than the incubation time. Crystallization occurs through an epitaxial-like growth from nucleates near or at the substrate interface; the crystalline phase will reach the depositing interface for thick films if the growth rate exceeds the deposition rate. The crystallized fraction of the deposited layer can be controlled by regulating the deposition temperature and rate and by in situ addition of dopant impurities. At temperature higher than 600 °C the deposited films are polycrystalline and columnar in structure. The surface texture is much smoother for films whose surfaces are amorphous.

No abstract

It is shown that local tetragonal distortion in a Si Ge0.05Si0.95 strained-layered structure can be detected and quantified from analyses of the high-order Laue zone lines which are present in the bright-field disks of [001] convergent-beam electron diffraction patterns. The detection of a tetragonal distortion is based on symmetry arguments, whereas the quantification requires a detailed analysis which is based on computer simulated patterns, assuming a kinematical approximation of the scattering process and including surface relaxation. The result of this quantitative analysis is in good agreement with the tetragonal distortion which is predicted by isotropic elasticity theory.

The rapid thermal annealing behavior of BF+2 and As+ +BF+2 implanted into crystalline and preamorphized silicon is studied. After solid phase epitaxy nearly complete electrical activity is obtained without channeling tails (for the preamorphized silicon) or significant thermal diffusion. Dislocation loops always appear near the amorphous-crystalline (α/c) interface of the preamorphized layer after solid phase epitaxy annealing (called ‘‘deep disorder’’). For preamorphization using Si+ damage into room-temperature silicon targets, dislocations also span between the deep disorder and the surface, called ‘‘spanning dislocations.’’ The spanning dislocations are eliminated by preamorphization using Ge+ implanted into room-temperature silicon targets. Transmission electron microscopy studies show the spanning dislocations move to the surface under thermal treatment, while the deep disorder remains to act as a getter region. The deep disorder is shown to getter F, or Au when Au is intentionally diffused from the wafer backside. The same kind of disorder correlates the limited diffusion behavior of B for BF+2 implants into crystalline Si. Otherwise, for the cases studied, the secondary ion mass spectrometry and Rutherford backscattering spectrometry profiles show nearly normal diffusive behavior for B or As dopants for 10-sec rapid thermal anneal. General physical interpretations are noted.