Exploiting Si/CoSi2/Si heterostructures grown by mesotaxy

doi:10.1016/0168-583X(91)95305-W

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Volumes 59–60, Part 1, 1 July 1991, Pages 693-697

https://doi.org/10.1016/0168-583X(91)95305-W Get rights and content

Abstract

Buried single-crystal silicide layers in silicon formed by ion implantation and annealing have many potential applications (some more practical than others!) including metal base transistors (operating at 77 K), buried collector contacts for bipolar transistors and buried groundplanes for ultrahigh-speed electronics. Fabrication of prototype devices is complicated by the presence of defects in the overlayer silicon, but preliminary results are reported.

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Cited by (20)

Formation of cobalt silicide films by ion beam deposition
2006, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Citation Excerpt :
Cobalt disilicide (CoSi2) has been the topic of much attention for metallization in Si devices [1–8], because of its low resistivity (14 μΩ cm), good mechanical properties and thermodynamic equilibrium in contact with Si, as well as its cubic structure with −1.2% lattice mismatch to Si [9–11].
Thin films of cobalt silicide are widely used as metallization in very large-scale integrated electronic circuits. In this study, Co ions were deposited on Si(1 1 1) wafers by a high beam current filter metal vacuum arc deposition (FMEVAD) system. Surface silicide films were formed after annealing from 500 to 700 °C for 30 min. The results show that a thin CoSi₂ surface layer with both a smooth surface topography and sharp interface can be achieved by annealing at 700 °C. The CoSi phase and O contamination were observed in the samples that were annealed at lower temperatures.
Synthesis of CoSi<inf>2</inf>-structures using ion microprobes
2000, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
The superconducting microbeam system at Bochum demonstrates that microbeam systems can be successfully used as an implantation tool. The system, served by a 4 MV-tandem accelerator, is able to produce a wide range of ion species with high purity. The advantage of a microprobe facility as an implanter is the possibility to produce buried structures at a lateral resolution in the submicron range with a penetration depth between 100 nm and a few μm without the use of any resist. Because of the high demagnification of the microprobe system the ion current density is increased two orders of magnitude compared to conventional MeV implantation. In combination with the newly developed high energy ion projection technique, the system yields a very fast implantation of structures at stoichiometric doses, thus allowing to optimize the process of ion beam synthesis within reasonable time. This contribution gives an introduction to the technique of high energy ion projection and reports some first results of CoSi₂ structures synthesized by implantation of 1 MeV Co into Si. The experiments are performed using different implantation temperatures, currents, and doses, and will be discussed in comparison to the conventional implantation technique.
Topics in solid phase epitaxy: Strain, structure and geometry
1996, Materials Science and Engineering R: Reports
The effects of some experimental parameters on the solid-phase crystallization of amorphous films on single crystals, a process known as Solid Phase Epitaxy (SPE), are examined. Results from a large community of researchers concerning SPE of alloys and compounds, strained films, films in constrained geometries and films with unusual amorphous/crystal interfaces are reviewed. Our present understanding of mechanisms involved in SPE is given, and the implications of the wide range of experimental results are discussed.
High-dose oxygen ion implanted heterointerfaces in silicon
1995, Nuclear Inst. and Methods in Physics Research, B
Emitter-base band gap differentials realized with alloys such as Si_xGe_1−x, SiC_x and μc-Si:H have been widely investigated for stretching the performance of Si bipolar transistors. We report on the properties of wide-gap surface regions generated in crystalline Si (c-Si) by high-dose oxygen ion implantation. The electrical and physical property changes of crystalline Si after substoichiometric O ion implantation have been investigated using current-voltage, capacitance-voltage, spreading resistance, secondary ion mass spectroscopy, spectroscopic ellipsometry and Fourier transform infrared spectroscopy. A key finding is the presence of donors in the vicinity of the implanted region, resulting in extensive counterdoping of p-type c-Si. Redistribution of the oxygen atoms during the high-temperature (1200°C) anneal results in sharp interfaces aiding the formation of the heterojunction. Mesa-type diodes on the implanted sample exhibit excellent rectification with diode ideality factor of 1.2, and a room temperature reverse saturation current density of 1 × 10⁻⁸ A/cm² with a thermal activation energy of 0.92 eV.
Electrical and structural properties of buried CoSi<inf>2</inf> layers in Si(100) grown by molecular beam allotaxy
1994, Thin Solid Films
Buried, single-crystal CoSi₂ layers in Si(100) were fabricated by molecular beam allotaxy, a new two-step method to fabricate buried epitaxial layers. At first CoSi₂ precipitates embedded in Si(100) were grown in a molecular beam system. In a second step a continuous, buried silicide layer was formed by rapid thermal annealing. Buried layers with thicknesses ranging from 27 to 224 nm were fabricated and investigated by transmission electron microscopy, Rutherford backscattering, He ion channelling and various electrical methods. Electrical resistivity measurements between 4.2 and 300 K revealed a specific resistivity of 14 μΩ cm at room temperature and 1 μΩ cm at 4.2 K. The temperature dependence follows the Bloch-Grüneisen relation. The resistivity increases with decreasing layer thickness. Schottky diodes were fabricated and characterized using I-V and I-T methods. Excellent diodes were produced with barrier heights of 0.64 ± 0.03 eV and idealities of 1.08.
Phosphorus redistribution during the formation of buried CoSi<inf>2</inf> layers by ion beam synthesis
1994, Nuclear Inst. and Methods in Physics Research, B
To investigate the phosphorus profile in n-doped Si after the formation of buried monocrystalline CoSi₂ layers by ion beam synthesis (IBS) electrical measurements at PBTs and Schottky diodes and secondary ion mass spectrometry (SIMS) have been performed. A discrepancy in the drain current and the pinch-off voltage between dc measurements and simulations of Si PBTs with buried monocrystalline CoSi₂ gates suggests a lower doped intermediate layer around the CoSi₂ gate fingers. Also a shift of intercept voltages to higher values in C-V evaluations of Si/CoSi₂ Schottky diodes may be caused by a process-induced change of the doping profile during IBS. The calculations indicate a decrease or a compensation of dopants near the CoSi₂/Si interface. Investigations by standard SIMS and the ¹⁶⁴PCs⁺ molecule-ion technique, which suppresses the matrix effects considerably, confirm the interpretation of the electrical data in terms of a dopant redistribution by showing a push-out of the phosphorus from the buried CoSi₂ layers during silicide formation.

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¹: Permanent address: IMEC, Leuven, Belgium.

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Exploiting Si/CoSi2/Si heterostructures grown by mesotaxy

Abstract

Nucl. Instr. and Meth.

Nucl. Instr. and Meth.

J. Appl. Phys.

Appl. Phys. Lett.

Appl. Phys. Lett.

Phys. Rev. Lett.

Appl. Phys. Lett.

Exploiting Si/CoSi₂/Si heterostructures grown by mesotaxy