Recrystallization of implanted amorphous silicon layers. II. Migration of fluorine in BF+2-implanted silicon

Abstract

Fluorine distribution profiles for silicon implanted with BF+2 have been measured by SIMS as a function of anneal temperature and time. Anomalous migration of fluorine is observed in samples having amorphized layers after implantation. Outdiffusion of fluorine occurs during recrystallization of the amorphous layer, and fluorine collects in regions of residual damage during annealing. This gettering of fluorine by defects illustrates the residual damage below the amorphized layer in samples implanted at room temperature is more difficult to anneal out than that in samples implanted at lower temperture (∼−110 °C).

Depth profiling by secondary ion mass spectrometry

“…An alternative approach is to sputter with 0 (Andersen 1969) or Cs (Storms et al 1977. Oxygen has been popular before for depth profiling in metals and insulators but in the last few years Cs' bombardment has also been applied routinely for SIMS profiling of negative secondaries (Lidow et al 1978a, 1978c, Magee 1979, Tsai et al 1978, 1979b. Since beam ions are implanted at a certain depth, the 0 (or Cs) concentration at the surface is originally low until the erosion reaches the implantation layer and an equilibrium between implantation and sputtering is reached Morabito 1974, Wittmaack 1977~).…”

“…Which process occurs depends on the element, the form in which it is implanted and the implantation temperature. Implantation of B into Si as BF, (Tsai et al 1978, 1979b, Tsai and Streetman 1979 leads to formation of an amorphous layer at lower doses than for implantation of B only. Temperature has an effect because of its influence on the production of lattice defects.…”

Activation behavior of BF₂⁺ implants in RTP annealed silicon

“…6 offers clear evidence that fluorine, retained in silicon, has a major impact on the activation mechanism of BF 2 + implants. This effect was reported previously [2], [6], [7]. Since fluorine accumulates at sites with large crystal damage [6], it is the interaction of fluorine with crystal damage that dominates the boron activation from BF 2 + implant.…”

“…This effect was reported previously [2], [6], [7]. Since fluorine accumulates at sites with large crystal damage [6], it is the interaction of fluorine with crystal damage that dominates the boron activation from BF 2 + implant. Under otherwise identical conditions, a drop in crystal defect density results in a reduction of retained fluorine concentration, and a subsequent increase in boron activation.…”

Fluorine-vacancy complexes in Si-SiGe-Si structures

“…The shallow F peaks were shown to be correlated with the reduction of boron thermal diffusion by El-Mubarek et al 13 The influence of defects on F profiles after annealing at temperatures above 500°C was observed in an early study of Si implanted with BF 2 + . 19 In this work, gettering of F was observed in damaged regions and at the interfaces between crystalline and amorphous regions.…”