The effect of silicon ion implantation on the structure of tantalum–silicon contacts (original) (raw)

Analysis of annealing and ion implantation effects in Ti/TiN contacts on silicon

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1990

The effects of thermal annealing and 350 keV As+ ion implantation on interdiffusion processes in a c-Si/Ti/TiN system were analysed. The Ti/TiN contacts were deposited by sputtering (Ti, 100 nm) and by reactive sputtering (TiN, 50 nm) on (111) n-Si wafers. Characterization included RBS, SEM and XRD analysis and electrical measurements. During vacuum annealing, interdiffusion is observed at the Si/Ti

Characterization of ion-implanted Si by electronic and structural data

Nuclear Instruments and Methods in Physics Research, 1983

Si ~111) was ion implanted with ions of various masses (11B +, 2~Si ~ 31p. 75As~ and I zLSb') with different energies. The damaged layer was measured by UPS, RBS and optical methods. The electronic structure of ttB + and 31 p+ differed. The damage profile of the ion implanted layer is not stepqike for all implanted ions and it has a double peak for liB ~ as given by electronic data. These results are only partly consistent with the structural results given by RBS.

Effects of C+ ion implantation on electrical properties of NiSiGe/SiGe contacts

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2013

We have investigated the morphology and electrical properties of NiSiGe/SiGe contact by C + ions preimplanted into relaxed Si 0.8 Ge 0.2 layers. Cross-section transmission electron microscopy revealed that both the surface and interface of NiSiGe were improved by C + ions implantation. In addition, the effective hole Schottky barrier heights (U Bp ) of NiSiGe/SiGe were extracted. U Bp was observed to decrease substantially with an increase in C + ion implantation dose.

Investigation of inhomogeneous structures of near-surface-layers in ion-implanted silicon

The ion implantation as a subject of investigations attracts increasing interest because of its technological applications. For example, the ion implantation and the adequate thermal treatment are the basic processes for fabrication of a new so-called delta-BSF solar cell. In this silicon solar cell, the continuous sub-structure of modified material _planar amorphous-like layer of nanometric thickness with very thin transition zones. is inserted into the single-crystal emitter. From earlier high resolution electron microscopy studies, it is evident that these two Si phases coexist in the form of well-defined layers separated by sharp heterointerfaces wZ.T. Kuznicki, J. Thibault, F. Chautain-Mathys, S. De Unamuno, Towards ion beam processed single-crystal Si solar cells with a very high efficiency, E-MRS Spring Meeting, Strasbourg, France, First Polish–Ukrainian Symposium, New Photovoltaic Materials for Solar Cells, October 21–22, Krakow, Poland, 1996.x. The aim of this paper is the further structural characterisation of silicon single crystal with buried ‘amorphous’ layer. The non-destructive X-ray diffraction methods as well as the transmission electron microscopy were used to investigate the quality of the a-Sirc-Si heterointerfaces, structural homogeneity of the layers and distribution of the stress field. The measurements were carried out on an initial, as-implanted and annealed material. The _100:-oriented Si single crystals were implanted with 180 keV energy P ions at room temperature.

Silicided Shallow Junction Formation Using Ion Implantation and Thermal Annealing

MRS Proceedings, 1988

The combination of arsenic and boron implantation with rapid thermal annealing (RTA) has been investigated to form shallow p-n junctions under a titanium silicide (TiSi 2 ) metallization. The use of TiSi 2 as a connection material can lead to the destruction of the junction if the kinetics of silicidation and doping are not well controlled. The purpose of this study is to better understand and control these kinetics, using far-from equilibrium processing such as ion implantation and RTA. The structures were characterized by Rutherford Backscattering Spectometry (RBS) for arsenic and silicide profiling, Secondary Ion Mass Spectometry (SIMS) for boron profiling, Scanning Electron Microscopy (SEM), and electrical sheet resistance measurements. Two procedures were investigated. Both involved the thermal reaction of Ti thin films, sputter-deposited with thicknesses ranging between 40 and 80 nm. In the first experiment, the as-deposited films were implanted with either 115 keV arsenic or 28 keV boron to form the junction, disperse the native oxide, and ion beam mix the Ti and Si. The films were then subjected to an RTA at 750'C for 15 to 60 seconds, which leads to TiSi 2 formation in unimplanted films. Implantation was found to actually prevent TiSi 2 formation. Ion transport calculations indicated that dopant pile-up at the interface might inhibit silicidation while higher energies and larger implant doses can more effectively ion beam mix Ti and Si. A more attractive solution consists of first forming TiSi 2 from the as-deposited Ti by RTA, and then implanting to form the junction. This resulted in better control of the junction thickness. A sharp increase in the TiSi 2 resistivity was found after implantation but the original value could be restored by a second RTA. This RTA also electrically activated the dopants and recrystallized the junction. The material properties of Ti/Si and TiSi 2 /Si under ion bombardment, RTA, doping, and conventional furnace annealing will be discussed.

Study of structure and surface modification of silicon-on-insulator (SOI) devices synthesized by dual ion implantation

Surface and Coatings …, 2009

Silicon oxynitride (Si x O y N z) buried layers were synthesized by high fluence (≥ 1 × 10 17 ions-cm − 2) ion implantation of O + and N + sequentially into single crystal silicon at 150 keV to produce silicon-on-insulator (SOI) structures. The structures of the SOI devices were analyzed by FTIR and XRD measurements and the surface modification by using atomic force microscopy (AFM). The FTIR measurements on the implanted samples (≤ 1× 10 18 ion-cm − 2) show a single absorption band in the wavenumber range 1300-750 cm − 1 attributed to the formation of silicon oxynitride bonds in silicon. The integrated absorption band intensity is found to increase with increase in the fluence. The samples with nitrogen-oxygen sequence of implantation showed nitrogen-rich oxynitride formation whereas samples with oxygen-nitrogen sequence resulted in oxygen-rich oxynitride. The formation of separate phases of Si-O and SiN bonds was observed at high fluence level (≅ 2 × 10 18 ions-cm − 2). The XRD studies show the formation of mixed phases of Si 2 N 2 O and SiO 2 in the sample. The structures of the ion beam synthesized silicon oxynitride layers are found to be strongly dependent on the sequence of implantation. The surface roughness is observed to be very small at lower fluences and it increases as we go to high fluence levels due to heavy damage caused by implantation. The conical hill like structures on the silicon surface is seen due to heavy surface swelling and sputtering phenomena.

Titanium doped silicon layers with very high concentration

Journal of Applied Physics, 2008

Ion implantation of Ti into Si at high doses has been performed. After laser annealing the maximum average of substitutional Ti atoms is about 10 18 cm −3 . Hall effect measurements show n-type samples with mobility values of about 400 cm 2 / V s at room temperature. These results clearly indicate that Ti solid solubility limit in Si has been exceeded by far without the formation of a titanium silicide layer. This is a promising result toward obtaining of an intermediate band into Si that allows the design of a new generation of high efficiency solar cell using Ti implanted Si wafers.

Titanium Silicide on Si:P With Precontact Amorphization Implantation Treatment: Contact Resistivity Approaching 1times10−91 \times 10^{-9}1times109 Ohm-cm2

IEEE Transactions on Electron Devices, 2016

In recent CMOS technology, extreme shrinking of contact area at source/drain regions raises serious concerns of high metal/semiconductor contact resistance. Confronting this problem, we introduce a precontact amorphization implantation plus Ti silicidation technique (PCAI + TiSi x) and achieve ultralow contact resistivity (ρ c) of (1.3 − 1.5) × 10 −9 • cm 2 on Si:P. This PCAI + TiSi x technique utilizes light amorphization (low-energy implantation), thin Ti and TiSi x film, and moderate thermal budget (500°C-550°C): these features are compatible with modern CMOS manufacturing. Moreover, the PCAI + TiSi x-induced ρ c reduction is proved universal on both n-and p-Si. With additional characterizations, we find that the silicidation-induced ρ c variation is not merely a Schottky barrier height tuning effect. The electrical and physical characterizations suggest that the low ρ c is strongly correlated with the formation of interfacial TiSi x crystallites between amorphous TiSi alloy and Si.

Formation of TiSi2/n+ /p-Silicon Junctions by Implantation through Metal Technique

Physica Status Solidi (a), 1993

N. M. RAVINDRA (a), YING Wu (a), B. SHAH^) (a), W. SAWN (a), T. FINK (a), R. T. LAREAU (b), and R. L. PFEFFER (b) Experimental studies of the formation and electrical characterization of TiSi,/n+/p-Si shallow junctions are presented. The formation of shallow nip junction, by ion implantation of As' through Ti films evaporated on p-Si substrates followed by rapid thermal annealing (RTA) and conventional furnace annealing, is performed in these experiments. Structural techniques such as secondary ion mass spectroscopy (SIMS) and Rutherford backscattering (RBS) experiments are employed to characterize these devices. RUMP simulations are deployed to analyze and interpret the RBS data. Temperature dependent current-voltage measurements of these junctions are performed in the temperature range of 250 to 400 K. Interpretations for these results are sought from conventional p-n junction theory.

Defect Structures and Electrical Behavior of Rapid Thermally Annealed Ion Implanted Silicon

MRS Proceedings, 1987

ABSTRACTThe importance of the knowledge of implantation induced damage structures in annealing studies is emphasized. The existence of various observed microstructures is reviewed and their distributions are presented schematically. It was found that although the usefulness of RTA in controlling dopant profiles is indisputable, the control of microstructure by RTA especially in “non-amorphized” or incompletely amorphized Si samples is questionable. Significance of complete surface amorphization to achieve better structural perfection on subsequent RTA or FA is discussed. An attempt was made to explain the published electrical data on rapid thermally annealed B+ and As+ implanted Si based on expected location and annealing behavior of defects for such implants. Recent structural and electrical results from B implanted pre-amorphized Si are presented.

Anneal behaviour of compositional and electrical characteristics of vanadium implanted silicon

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989

High dose ion implantation to a dose of 1-5~10~' ions/m2 of " V4 ions into single crystal silicon has been used to form vanadium silicides. RBS, XRD and sheet resistance measurements were employed to characterise the as-implanted and annealed layers. Various sihcide phases in different proportions are seen in the implanted substrates. After a 750°C anneal we observe a marked silicon diffusion into the implanted layer, though annealing up to 500 * C produces little intermixing. The broadening of the V profile after a 750 o C anneal is much more for the higher dose samples, than for the lower dose samples. The sheet resistance of the as-implanted sample decreases on annealing up to 75O'C. However, the resistivity values are quite large compared to the values reported for silicides prepared by other techniques.

Effects of silicon negative ion implantation in SiO2

Nucleation and Atmospheric Aerosols, 2018

In the present work, effects of silicon negative ion implantation into semi-insulating gallium arsenide (GaAs) samples with fluences varying between 1 × 10 15 and 4 × 10 17 ions cm −2 at 100 keV have been described. Atomic force microscopic images obtained from samples implanted with fluence up to 1 × 10 17 ion cm −2 showed the formation of GaAs clusters on the surface of the sample. The shape, size and density of these clusters were found to depend on ion fluence. Whereas sample implanted at higher fluence of 4 × 10 17 ions cm −2 showed bump of arbitrary shapes due to cumulative effect of multiple silicon ion impact with GaAs on the same place. GXRD study revealed formation of silicon crystallites in the gallium arsenide sample after implantation. The silicon crystallite size estimated from the full width at half maxima of silicon (111) XRD peak using Debye-Scherrer formula was found to vary between 1.72 and 1.87 nm with respect to ion fluence. Hall measurement revealed the formation of n-type layer in gallium arsenide samples. The current-voltage measurement of the sample implanted with different fluences exhibited the diode like behavior.

TEM investigation of titanium-silicide Schottky contacts on GaAs

Ultramicroscopy, 1985

Titanium silicides were used as Schottky contacts on GaAs. Samples with two different ratios of Ti:Si 1:2 and 1:3 were prepared. The composition with the 1:3 Ti:Si ratio was found to result in good Schottky contact parameters. Structural and analytical' investigations, including high resolution electron microscopy and energy dispersive X-ray spectroscopy, were used to characterize the formed contacts .

Issues in the ion implantation of Si for GaAs applications

III-Vs Review, 1997

The ion implantation of Si is one of the key enabling processes involved in the fabrication of GaAs electronic and optical devices. In this article we discuss some of the issues involved from the ion implanter equipment perspective. A comprehensive study of the mass separation issues between the various isotopes of Si for various dose and energy levels is presented. This data illustrates the tradeoffs that exist between throughput and beam purity in the selection between the isotopes. The possible contaminants that could be introduced during the implantation are discussed, as well as techniques that could be used to reduce them. Data on multiple charged implants for deeper profiles is also presented, as well as equipment designs that have been made to improve the beam currents for these implants.

Formation of Conducting and Insulating Layered Structures in Si by Ion Implantation: Process Control Using FTIR Spectroscopy

Journal of The Electrochemical Society, 2001

Fourier transform infrared ͑FTIR͒ spectroscopy was employed to characterize the formation process of conducting and/or insulating layers in silicon by arsenic or oxygen ion implantation, respectively. Two methods of buried insulating layer formation were studied. The first involved implantation of 200 keV oxygen ions at a dose of 1.8 ϫ 10 18 cm Ϫ2 at implantation temperature in the range 500-550°C followed by annealing at 1300°C for 5 h. The second involved 190 keV oxygen implantation in three cycles, each cycle followed by annealing at 1315°C for 2 h. The Si overlayer of these substrates as well as bulk Si wafers were then implanted with 70 keV As ϩ ions at a nominal dose of 5 ϫ 10 15 cm Ϫ2 . Annealing at 950 or 1150°C led to dopant activation and the formation of conducting layers. The optical multilayer modeling of such inhomogeneous structures is given in detail. Depth profiles of oxygen atomic concentration or free carrier concentration as well as the corresponding refractive index depth profiles are quantified in a fast, cheap, accurate, and contactless way using FTIR spectroscopy. Furthermore, layer thickness, chemical composition, crystallinity, interface quality, and the electrical and transport properties are also evaluated. The results are in good agreement with ion beam analysis and electrical measurements and it is demonstrated that FTIR spectroscopy can act as a complementary technique to ion beam analysis techniques, taking over the role of the electrical methods ͑which are destructive͒ and giving much more information.

Formation of titanium silicides by high dose ion implantation

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1987

We have investigated titanium silicide formation using high dose (-2 X IO*' ions/m2) ion implantation of 30 keV, 48Ti+ ions at room temperature into two different types of Si substrates: (a) n-type (111) single crystals and (b) amorphous Si films (-200 nm thick) vacuum deposited onto a thermally grown SiO, layer. XRD and RBS techniques were employed to characterize various silicide phases and their depth distribution in as-implanted as well as in annealed samples. We find that a mixture of TiSi. TiSi, and TisSi, silicides is formed by high dose implantation. Out of these, TiSi, was found to be the dominant phase. The composition of these silicide layers is practically uniform with depth and remains unaltered on heat treatment up to 750 o C. The electrical properties of silicide layers have also been investigated using sheet resistance measurements. The resistivity of as-implanted layers is rather high (-10 $2 m), but drops sharply by nearly a factor of 20 after a post-implantation anneal above 800' C. The resistivity of silicide layers thus obtained compare well with silicides prepared by other techniques.