Implant redistribution in high-dose ion implanted and annealed silicon

Abstract

Diffusion constants of helium in gold, silver and aluminium are determined from thermal desorption experiments, giving:

Au: D ₀ = 10^?1.0 cm²/sec, ΔH = 1.70 eV

Ag: D ₀ = 10^?1.2 cm²/sec, ΔH = 1.50 eV

Al: D ₀ = 10^+0.1 cm²/sec, ΔH = 1.35 eV

The results are compared to self-diffusion and to the diffusion of other light elements in metals. Possible diffusion mechanisms are discussed.     

Impurity redistribution in Pb implanted and annealed silicon

Reordering of 〈111〉 silicon, implanted with Pb ions at energies >100 keV and fluences ～5 × 10¹⁵ cm^?2 is accompanied by substantial impurity indiffusion in addition to pronounced outdiffusion and accumulation at the near surface region.     

Defects in pulsed laser and thermal processed ion implanted silicon

The evolution of the nature and concentration of the defects produced by 100 or 300 keV As ions at fluences 1 to 4×10^–12 cm^–2 inn-type, Fz Silicon doped with 10¹⁵ to 10¹⁶ cm^–3 has been studied as function of thermal treatments (in the range 500°–900 °C) and of the energy density (in the range 0.3–0.6 J cm^–2) of a light pulse from a ruby laser (15 ns, 0.69 m). Deep-level transient spectroscopy (DLTS) combined with capacitance — voltage (C-V) measurements were used to get the characteristics (energy level, crosssection for the capture of majority carriers) of the defects and theirs profiles. The difficulties encountered in the analysis of the results, due to the large compensation of free carriers in the implanted region and to the abrupt defect and free carrier profiles, are discussed in detail and the corrections to apply on the C-V characteristics and the DLTS spectra are described. The defects resulting from the two types of treatments are found to be essentially the same. Only, for laser energies higher than 0.5 J cm^–2, the laser treatment appears to introduced new defects (atE0.32 eV) which should result from a quenching process. The fact that a laser energy smaller than the threshold energy for melting and recrystallization is able to anneal, at least partially, the defects produced by the implantation, demonstrates that the annealing process induced by the laser pulse is not a purely thermal process but is enhanced by a mechanism involving ionization.     

Impurity doping in silicon nanowires synthesized by laser ablation

Boron (B) or phosphorus (P) doped silicon nanowires (SiNWs) were synthesized by laser ablation. Local vibrational modes of B were observed in B-doped SiNWs by micro-Raman scattering measurements at room temperature. Fano broadening due to a coupling between the discrete optical phonon and a continuum of interband hole excitations was also observed in the Si optical phonon peak for B-doped SiNWs. An electron spin resonance signal due to conduction electrons was observed only for P-doped SiNWs. These results prove that B and P atoms were doped in substitutional sites of the crystalline Si core of SiNWs during laser ablation and electrically activated in the sites.     

Recrystallization of hexagonal silicon carbide after gold ion irradiation and thermal annealing

Silicon carbide (SiC) single crystals with the 6H polytype structure were irradiated with 4.0-MeV Au ions at room temperature (RT) for increasing fluences ranging from 1?×?10¹² to 2?×?10¹⁵ cm^?2, corresponding to irradiation doses from ~0.03 to 5.3 displacements per atom (dpa). The damage build-up was studied by micro-Raman spectroscopy that shows a progressive amorphization by the decrease and broadening of 6H-SiC lattice phonon peaks and the related growth of bands assigned to Si–Si and C–C homonuclear bonds. A saturation of the lattice damage fraction deduced from Raman spectra is found for ~0.8?dpa (i.e. ion fluence of 3?×?10¹⁴ cm^?2). This process is accompanied by an increase and saturation of the out-of-plane expansion (also for ~0.8?dpa), deduced from the step height at the sample surface, as measured by phase-shift interferometry. Isochronal thermal annealing experiments were then performed on partially amorphous (from 30 to 90%) and fully amorphous samples for temperatures from 200 °C up to 1500 °C under vacuum. Damage recovery and densification take place at the same annealing stage with an onset temperature of ~200 °C. Almost complete 6H polytype regrowth is found for partially amorphous samples (for doses lower than 0.8 dpa) at 1000 °C, whereas a residual damage and swelling remain for larger doses. In the latter case, these unrelaxed internal stresses give rise to an exfoliation process for higher annealing temperatures.     

Surface modification of silicon with single ion irradiation

In order to solve the issues in Si nanoelectronics such as fluctuation in the device functions and poor reliability of devices due to relative increase in mass transport in nm size structures and to yield novel functions by rather taking advantage of the nm size, we need to understand the phenomena peculiar to nm size structures. Based on the fact that a practical method to fabricate nm structures in terms of throughput, process time, and cost is to combine modification of solid surfaces with energetic particles (especially with single ions) and subsequent chemical processing in solutions, we describe single ion irradiation effects as a tool to modify solid surfaces in nm scale, a method for nm scale in-situ observation of solid surfaces, and some examples of the acquired knowledge.     

Implications of ion implantation technology on ion implanted active devices in silicon

The use of ion implantation to make integrated devices in silicon implies a good knowledge of the behavior of various parts of the device. This paper deals with three main topics: First the electrical characteristics of implanted diodes are described and their variations as a function of annealing temperature lead to a physical model taking into account the anisotropy of impurity concentration gradients. Second, experimental conditions before, during and after implantation are shown to have a strong influence on the quality of the final device, particularly on the value of the reverse leakage current. Third, effects of bombardment on silicon dioxide layers are studied. It is found that recovery of the layers is generally complete after a 300°C annealing.

Contributions of these various parameters to the overall electrical characteristics of ion implanted self-aligned MOS transistors are finally considered. Substantial increase in the maximum oscillation frequency and reduction of the active surface areas of the device are the most evident advantages of using ion implantation technology.     

F and F2 centres in LiF induced by ion implantation

Abstract

COMPUTER IMAGE PROCESSING AND RECOGNITION, by Ernest L. Hall, Academic Press, New York, 1979. Price: $41.35.

SAFETY IN THE CHEMICAL LABORATORY, by N. T. Freeman and J. White-head. Academic Press, London, 1982. ISBN 0 12 267220 8. 244 pages. $43.10.

A DICTIONARY OF SPECTROSCOPY, by R. C. Denney. Macmillan Reference Books, London. Second Edition, 1982. ISBN 0 333 31670 3. 205 pages. €15.

WOMEN SCIENTISTS: THE ROAD TO LIBERATION, Edited by Derek Richter, McMillan, London, 1982. 219 pp. €10.00.

ION ASSISTED SURFACE TREATMENTS, TECHNIQUES AND PROCESSES. Conference Proceedings, Warwick, U.K., 14–16 September 1982. 1982, The Metals Society, ISBN 0 904357 48 1, €00.0     

Optical reflectivity study of silicon ion implanted poly(methyl methacrylate)

The optical reflectivity (both specular and off-specular) of poly(methyl methacrylate) (PMMA) implanted with silicon ions (Si⁺) at energy of 50 keV, is studied in the spectral range 0.25-25 μm. The effect from the Si⁺ implantation on the reflectivity of two PMMA materials is examined in the dose range from 10¹⁴ to 10¹⁷ ions/cm² and is linked to the structure formed in this ion implanted plastic. As compared to the pristine PMMA, an enhancement of the reflectivity of Si⁺ implanted PMMA is observed, that is attributed to the modification of the subsurface region of PMMA upon the ion implantation. The ion-produced subsurface organic interface is also probed by laser-induced thermo-lens.     

准分子激光束的喇曼组束

受激喇曼散射可以将紫外准分子激光辐射频移到特定的近紫外或可见光波长,采用喇曼整形技术可以改善斯托克斯光的光束质量,本文报道喇曼组束提高喇曼整形效率的实验结果.     

Differences between ruby and Nd:YAG laser annealing of ion implanted silicon

It is shown that the threshold power density for laser-induced epitaxial recrystallization of 2100 Å thick amorphous silicon layers, produced by implantation of As, Sb, Sn and Ga ions, depends on the type and dose of dopants when the 1.06 μm radiation of a pulsed scanned Nd:YAG laser is used and that it is independent of these parameters for the 0.69 μm radiation of a single-pulse ruby laser.     

光解产生的铅原子中受激喇曼散射和共振激光辐射

用2660(?)的紫外激光解离PbCl_2分子时,发现在3740(?)和3734(?)波长上有较强的受激辐射输出.根据它们的光谱特性和铅原子的能级结构判断,这些辐射是基于双光子解离PbCl_2分子得到的铅原子在6p~(23)P_2亚稳能级上的布居而产生的光泵共振激光辐射和受激喇曼散射.提出了描述整个过程的理论模型,通过拟合实验结果,确定了2660(?)激光双光子解离PbCl_2产生6p~(23)P_2亚稳态铅原子的光解系数.当PbCl_2分子密度为N_(00)=6.21×10~(16)cm~(-3)时,光解产生的铅原子在6p~(23)P_2和6p~(21)D_2这两个亚稳态的最大布居数近似相等,称为2.0×10~(16)cm~(-3).     

Photoresponse of ion implanted gallium dopants in silicon

High resolution spectral photoconductivity measurements are reported for a thin Si:Ga layer fabricated by ion implantation. The gallium ions were implanted at an energy of 3 MeV and a dose of 10¹⁴cm⁻². The measured spectral response of the layer was comparable to that of bulk Si:Ga, while the temperature range of the layer's photoresponse showed an increase when compared to that of bulk Si:Ga. These results show that ion implantation can produce useful thin, infrared active layers.     

Damage dependent electrical activation of phosphorus implanted in silicon

Damage profiles for 250-keV self-ion irradiation of gold, determined by (1) stereo electron microscopy measurements of the depth distribution of visible clusters and (2) binary-collision simulations, are presented. Simulations for an amorphous medium, a single crystal (with the ion beam oriented in a nonchanneling direction), and a polycrystal were performed using the MARLOWE code. The calculated damage profiles for the single crystal and the polycrystal both exhibit approximately exponential tails, but have shallower modal depths than the profile for the amorphous medium. The inclusion of room-temperature thermal vibrations in the simulations is found to broaden the profile and suppress long-range channeling. Comparison between simulation and experiment suggests that a screening length somewhat smaller than the Firsov value is appropriate for Au-Au interactions.     

High concentration effects of ion implanted boron in silicon

The diffusion behaviour of implanted boron in silicon was investigated using the¹⁰B(n,α)⁷ Li nuclear reaction. An anomalous behavior with a strong reduction of the diffusivity above an effective solubility limit at 1.5×10¹⁹, 6×10¹⁹, and 1.1×10²⁰ cm⁻³ was found for annealing temperatures of 800, 900, and 1,000°C, respectively.     

Rapid thermal process-induced recombination centers in ion implanted silicon

This work presents direct evidence for a correlation between rapid thermal process-induced recombination centers and co-implanted metallic impurities in ion implanted silicon. Experimental evidence includes the dose dependence of the minority carrier diffusion length measured by the SPV technique, SIMS and RBS analysis of high-dose implantations which show the presence of heavy metals, the dependence of the final diffusion lengths on the mass of the implanted ions, as well as the successful modification of an implantation equipment.     

Track effects in luminescence of LiF during 1 MeV/amu heavy ion irradiation

Luminescence spectra from pure LiF generated with high-energy heavy ions were studied in dependence on exciting density and irradiation temperature.     

In-situ electrical measurement in ion implanted amorphous silicon films

Doping in amorphous silicon has been studied by P, B and Si implantation in evaporated silicon films made by electron beam evaporations. After double implantation of P and B, a compensation effect has been observed in implanted amorphous silicon layer.