Enhanced diffusion phenomena during rapid thermal annealing of preamorphized boron-implanted silicon

Abstract

The diffusion of boron implanted in preamorphized silicon and rapid thermal annealed with an electron beam is analyzed. For an implanted dose of 5× 1015 B+/cm2 an enhanced diffusion in the early phase of the annealing is clearly observed. The enhancementof the diffusivity is of about a factor 30 at t  0 and exponentially decreases with a constant time of 0.5 s at the temperature of 1100 °C. For lower implanted dose (1 × 1015 B+/cm2) the phenomenon is less remarkable and no conclusive evidence on the existence of enhanced diffusion can be drawn. It is also observed that a recrystallization preannealing step at 550 °C for 1 h does notavoid enhanced diffusion during the rapid thermal annealing. The mechanismswhich could give rise to these effects are reported and discussed.

Temperature and Time Dependence of Dopant Enhanced Diffusion in Self‐Ion Implanted Silicon

“…In these previous studies, the EB resist used was poly(glycidyl methacrylate) (PGMA) which had high sensitivity but low dry etch resistance. On the other hand, polystyrene type EB resists such as chlorinated polymethylstyrene (CPMS) (6)(7)(8), chloromethylated polystyrene (CMS) (9,10), and iodinated polystyrene (IPS) (11) have been known as dry etch resistant EB resists. This paper reports EB exposure characteristics of highly sensitized CMS, and dry etching processes of mask fabrication.…”

“…In this condition, only a theoretical approach of the kinetics involved in the process can be helpful to describe the experimental results. Several authors (2,5,8,9,12) have in fact simulated the evolution of the doping profiles by hypothesizing an exponential decay with time of the enhanced diffusion coefficient.In this work investigations on B, P, As, and Sb diffusivities were made also at low temperature, and the time dependence of the diffusion coefficient D was accurately determined in the B case. The results show that D is nearly constant until a time value is reached which diminishes with the annealing temperature, beyond which it tends asymptotically to the equilibrium value.…”

“…Recent works showed that the evolution with temperature of the point defects induced by ion implantation led to a marked transient enhanced diffusion for the elements like phosphorus (1)(2)(3)(4) and boron (3)(4)(5)(6)(7)(8)(9), while minor effects were observed for arsenic (3-5, 10, 11) and antimony (3,4). Most of the described experiments were made by rapid thermal annealing (RTA) of the implanted samples, so that the diffusivity phenomena were evidenced at their final steps and poorly followed during their time evolution, owing to the short duration of the heating.…”

Reduction in number of crystal defects in a p+Si diffusion layer by germanium and boron cryogenic implantation combined with sub-melt laser spike annealing

“…In the case of activation by a nonthermal equilibrium state, impurities beyond the solubility limit of Si will be incorporated. 30) Impurities beyond the solubility limit of Si will be released from lattices with increasing annealing temperature and annealing time, and eventually the concentration returns to a value at the solubility limit. 31) As in double-pulse irradiation, activation by a nonthermal equilibrium state also occurs.…”

Boron diffusion layer formation using Ge cryogenic implantation with low-temperature microwave annealing

“…Usually, in recrystallization from an amorphous layer, solid phase growth is induced by low-temperature annealing at about 500 °C or lower, and impurities with the solubility limit higher than that of Si will be incorporated. 38) In addition, the impurities beyond the solubility limit in Si will be released from the lattice position with increasing annealing temperature and passage of annealing time, and eventually the concentration returns to the solubility limit. 39) From these results, it is shown that the crystallized state of the amorphous layer formed by cryogenic Ge implantation clearly differs from that formed by room-temperature and cryogenic B implantations.…”