Electrical Behavior of Group III and V Implanted Dopants in Silicon

Abstract

The anneal behavior of layers implanted with dopants from column III (B, Al, Ga, and Tl) and column V (As, Sb, and Bi) in silicon substrates has been investigated. The ranges of implant conditions were energy 20–50 keV, dose 1013–1015/cm2, and substrate temperature 23°–500°C. Hall-effect and sheet resistivity measurements were used to determine the effective number of carriers/cm2 (Ns)eff and the effective mobility μeff. Analysis of nonuniform distributions of carrier densities and mobilities on these measurements shows that the values of (Ns)eff and μeff can be misleading unless the effect of the depth distributions is allowed for. These distributions have been determined in some cases by the use of layer removal techniques combined with Hall-effect and sheet resistivity measurements. We find in well-annealed implanted samples that the dependence of the mobility on carrier density follows that determined for bulk silicon. In many cases deviation from this relation can be accounted for on the basis of compensation. In the case of aluminum we suggest that this compensation may be accounted for by the presence of interstitial aluminum atoms acting as donors. We have found that interstitial thallium can behave as a donor. The anneal behavior of the implanted layer is influenced by ion species, dose, and substrate temperature. The carrier concentration measured in implantations of column III elements did not exceed the limits of thermal equilibrium solubility as is found for column V elements. In the former case, enhanced diffusion effects are observed. From the known substitutional behavior of column V elements, it is suggested that the anneal behavior in the 600°–800°C range is due to the dissociation of radiation damage complexes.

Bismuth ion-implanted solid-phase epitaxially grown shallow junction for metal–oxide–semiconductor field-effect transistors

“…Angular scans with Rutherford backscattering spectrometry of Biimplanted Si revealed that a fraction of Bi atoms ͑after hot implants or annealed after implantation͒ are slightly displaced from the lattice rows 6 and are electrically inactive. 7,8 Despite these findings, de Souza and Fichtner 8 showed that the electrical activation yield ͑EAY: ratio of sheet carrier concentration to implanted dose͒ of Bi implanted Si ͑100͒ was about 90% after annealing at 600°C. They also showed that the maximum EAY for rapid thermal annealed ͑RTA͒ samples at T ജ 700°C was achieved after the shortest annealing time and reduced from the initial values.…”

“…This was attributed to the degree of amorphization and dynamic annihilation of Si during HT implantation. 7 Sheet resistance of the junctions ͑in LT and RT implants͒ increased with an increasing thermal budget after 700°C ͑30 s͒ due to deactivation and/or precipitation. 7 It is evident that the process window for activation of the junctions lies within T ഛ 700°C in an acceptable annealing time.…”

Deactivation of metastable single-crystal silicon hyperdoped with sulfur

“…2(a)), n s and l e represent effective quantities, or weighted averages of the depth-dependent carrier concentration and mobility. 29 The error bars in (b) and (c) are determined by the finite size and placement of the contacts on the cloverleaf van der Pauw structure according to Ref. 30.…”

Hyperfine clock transitions of bismuth donors in silicon detected by spin-dependent recombination

“…These conditions yielded a maximum bismuth concentration of 1.8 × 10 18 cm −3 (above the solubility limit [25]) in the depth of 90 to 150 nm from the surface. The post-implantation annealing, performed at 650 • C for 30 min in an evacuated quartz tube, led to an activation efficiency [7,[26][27][28] below 60%, resulting in the Bi donor concentration less than 1.1 × 10 18 cm −3 (below the metal-insulator transition [29]). This process was designed to maximize the number of D-R pairs, instead of fully activating all the implanted Bi atoms [30].…”