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

Abstract

Articles you may be interested inIncorporation of tin in boron doped silicon for reduced deactivation of boron during post-laser-anneal rapid thermal processing J. Appl. Phys. 102, 093717 (2007); 10.1063/1.2812565 Groups III and V impurity solubilities in silicon due to laser, flash, and solid-phase-epitaxial-regrowth anneals Appl. Phys. Lett. 89, 071915 (2006); 10.1063/1.2337081 Dopant deactivation in heavily Sb doped Si (001): A high-resolution x-ray diffraction and transmission electron microscopy studyLaser 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 Sb͒ 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.

Deactivation of metastable single-crystal silicon hyperdoped with sulfur

“…41,42 In contrast, and as expected, no such increase in n s has been observed upon annealing silicon hyperdoped with shallow dopant impurities (B, P, As, Sb). 4,15,16,20,21 The ionization energies of isolated impurities for these shallow dopants are so small that they are essentially all ionized at room temperature, so producing clusters with smaller ionization energies would not result in an increase in n s . Thus, the deep-level defects studied here provide a unique opportunity for insight to the formation of impurity complexes in supersaturated material.…”

“…Studies on silicon hyperdoped with shallow dopants have correlated dopant deactivation (i.e., reductions in conductivity) with the formation of inactive dopant clusters or precipitates, depending upon the dopant element. 17,20,21 Studies on the deactivation of sub-band gap absorptance in silicon made polycrystalline and hyperdoped with chalcogens by femtosecond laser irradiation attributed the deactivation to long-range dopant diffusion to and precipitation on grain boundaries. 22,24 In this work, we examine the annealing-induced deactivation of single-crystal, sulfur-hyperdoped silicon.…”

“…As such, its enhanced properties-increased conductivity in the case of shallow dopants and sub-band gap optical absorption in the case of deep-level dopants-deactivate upon subsequent thermal treatment. 4,10,[14][15][16][17][18][19][20][21][22][23] There has been much interest in studying the nature of this deactivation. Studies on silicon hyperdoped with shallow dopants have correlated dopant deactivation (i.e., reductions in conductivity) with the formation of inactive dopant clusters or precipitates, depending upon the dopant element.…”

Deactivation of ultrashallow boron implants in preamorphized silicon after nonmelt laser annealing with multiple scans

“…[6][7][8][9][10][11][12] This deactivation is thought to be driven by the release of silicon interstitials from end-of-range ͑EOR͒ defects that evolve through nonconservative Ostwald ripening during annealing. 13 The interstitials flow towards the surface and decorate the boron profile, producing boron interstitial clusters.…”

“…[2][3][4][5] A problem exists with creating highly active profiles when boron is implanted in conjunction with a preamorphizing germanium implant; deactivation occurs during postactivation thermal processes. [6][7][8][9][10][11][12] This deactivation is thought to be driven by the release of silicon interstitials from end-of-range ͑EOR͒ defects that evolve through nonconservative Ostwald ripening during annealing. 13 The interstitials flow towards the surface and decorate the boron profile, producing boron interstitial clusters.…”