The diffusion of B implanted in Si has been investigated at different concentrations in a wide range of experimental conditions (temperature from 800 to 1000 °C and time from 10 s to 8 h) by using furnace and rapid thermal treatments. In particular, the transient enhanced diffusion induced by the implantation damage in the early phase of the annealing and the precipitation occurring in concomitance with the diffusion for dopant concentration exceeding the solid solubility have been extensively analyzed. A simulation program taking these phenomena into account has been developed by modifying the supreme iii code. A satisfactory agreement with experimental data has been obtained for all the investigated conditions. The model represents a significative improvement of the diffusion simulation of B implanted in crystalline Si. In fact, the more commonly used codes of process simulation do not evaluate adequately the effects of the above considered phenomena.

Diffusion of boron in silicon during post-implantation annealing

Impact of energy filtering and carrier localization on the thermoelectric properties of granular semiconductors

Laser annealing is being investigated as an alternative method to activate dopants and repair the lattice damage from ion implantation The unique properties of the laser annealing process allow for active dopant concentrations that exceed equilibrium solubility limits However, these super-saturated dopant concentrations exist in a metastable state and deactivate upon subsequent thermal processing Previously, this group compared the electrical characteristics of the deactivation behavior of common dopants (P, B, and Sb) across a range of concentrations and annealing conditions Boron and antimony were shown to be stable species against deactivation while P and As deactivate quickly at temperatures as low as 500 °C In this work, we present additional data to understand the underlying physical mechanisms involved in the deactivation process It is proposed that As and P deactivate through the formation of small dopant—defect clusters while B and Sb deactivate through precipitation

Physical processes associated with the deactivation of dopants in laser annealed silicon

A process is disclosed which incorporates implantation of a carbon cluster into a substrate to improve the characteristics of transistor junctions when the substrates are doped with Boron and Phosphorous in the manufacturing of PMOS transistor structures in integrated circuits. There are two processes which result from this novel approach: (1) diffusion control for USJ formation; and (2) high dose carbon implantation for stress engineering. Diffusion control for USJ formation is demonstrated in conjunction with a boron or shallow boron cluster implant of the source/drain structures in PMOS. More particularly, first, a cluster carbon ion, such as C 16 H x + , is implanted into the source/drain region at approximately the same dose as the subsequent boron implant; followed by a shallow boron, boron cluster, phosphorous or phosphorous cluster ion implant to form the source/drain extensions, preferably using a borohydride cluster, such as B 18 H x + or B 10 H x + . Upon subsequent annealing and activation, the boron diffusion is reduced, due to the gettering of interstitial defects by the carbon atoms.

System and method for the manufacture of semiconductor devices by the implantation of carbon clusters

The As diffusion coefficient as a function of its concentration was determined by Boltzmann–Matano analysis of the profiles of the dopant diffusing out of its conjugate phase precipitates during furnace annealing at 900 and 1050 °C of samples heavily doped by ion implantation. This method allowed to assure a constant diffusion source of As and to investigate a doping range attaining 3×1021 cm−3. Along the same lines, the diffusivity versus concentration of specimens heavily implanted with P was determined at 900 and 1000 °C. Dopant profiles were determined by secondary neutral mass spectroscopy. The diffusivity of both As and P increases with dopant content, attaining a maximum at a concentration which closely corresponds to the saturation value of the carrier density, ne, which we previously determined by equilibration annealing of specimens with excess dopant. This finding demonstrates that ne represents the limiting value of the concentration of unclustered dopant at the diffusion temperature. On the c...

High concentration diffusivity and clustering of arsenic and phosphorus in silicon

An extensive investigation on the diffusion of boron implanted at high concentration in preamorphized silicon has been carried out for rapid thermal annealing and conventional furnace annealing. The rapid process of epitaxial regrowth of the amorphous layer brings B atoms into substitutional positions, and thus electrically active, up to a concentration threshold of about 3.5×1020 cm−3. This value is nearly independent of the annealing temperature and of the implanted dose. Since the concentration of dopant in solution is higher than the solubility value, precipitation phenomena occur in concomitance to diffusion during the annealing. The kinetics of precipitation has been investigated at 800, 900, and 1000 °C with isothermal treatments ranging between 10 s and 171 h. A simulation program taking into account precipitation phenomena has been developed modifying the suprem iii code. The density of nuclei of the new phase has been evaluated on the base of the models of classic nucleation theory, while the ra...

F. Baruffaldi

Papers

High‐concentration boron diffusion in silicon: Simulation of the precipitation phenomena