Microelectronics And Semiconductor Engineering

Temperature dependent current-voltage (IV) characteristics of Au/n-Si (1 1 1) Schottky barrier diodes with PVA (Ni, Zn-doped) interfacial layer

by Prof.Dr. İbrahim USLU

Materials Science in Semiconductor Processing
Volume 14, Issue 2, June 2011, Pages 139-145

Tuncay Tunc, şemsettin Altindal, iIbrahim Uslu, ilbilge Dökme, Habibe Uslu

Current–voltage (I–V) characteristics of Au/PVA/n-Si (1 1 1) Schottky barrier diodes (SBDs) have been investigated in... more Current–voltage (I–V) characteristics of Au/PVA/n-Si (1 1 1) Schottky barrier diodes (SBDs) have been investigated in the temperature range 80–400 K. Here, polyvinyl alcohol (PVA) has been used as interfacial layer between metal and semiconductor layers. The zero-bias barrier height (ΦB0) and ideality factor (n) determined from the forward bias I–V characteristics were found strongly dependent on temperature. The forward bias semi-logarithmic I–V curves for different temperatures have an almost common cross-point at a certain bias voltage. The values of ΦB0 increase with the increasing temperature whereas those of n decrease. Therefore, we have attempted to draw ΦB0 vs. q/2kT plot in order to obtain evidence of a Gaussian distribution (GD) of the barrier heights (BHs). The mean value of BH and standard deviation (σ0) were found to be 0.974 eV and 0.101 V from this plot, respectively. Thus, the slope and intercept of modified vs. q/kT plot give the values of and Richardson constant (A⁎) as 0.966 eV and 118.75 A/cm2K2, respectively, without using the temperature coefficient of the BH. This value of A* 118.75 A/cm2K2 is very close to the theoretical value of 120 A/cm2K2 for n-type Si. Hence, it has been concluded that the temperature dependence of the forward I–V characteristics of Au/PVA/n-Si (1 1 1) SBDs can be successfully explained on the basis of the Thermionic Emission (TE) theory with a GD of the BHs at Au/n-Si interface.

Diffusion and Desorption of SiH3 on Hydrogenated H: Si (100)-(2x1) From First Principles

by Michele Ceriotti

Diffusion and Desorption of SiH_ {3} on Hydrogenated H: Si (100)-(2× 1) From First Principles

by Michele Ceriotti

Diffusion and Desorption of SiH~ 3 on Hydrogenated H: Si (100)-(2 X 1) From First Principles (12 Pages)

by Michele Ceriotti

The Au/polyvinyl alcohol (Co, Zn-doped)/n-type silicon Schottky barrier devices

by Prof.Dr. İbrahim USLU

Synthetic Metals 161 (2011) 474–480

ibilge Dökme, T. Tunc¸ ibrahim Uslu, S. Altındal

Metal/polyvinyl alcohol/n-type silicon Schottky barrier (SB) devices have been fabricated in this study. The... more Metal/polyvinyl alcohol/n-type silicon Schottky barrier (SB) devices have been fabricated in this study. The importance of this study is that PVA (Co, Zn doped) nanofiber film as an interfacial layer was formed by the electrospinning technique on n-type silicon substrate. The forward and reverse bias current–voltage (I–V) characteristics of this device were measured at room temperature. The ΦBo value of about 0.749 eV obtained from I–V characteristics indicates that the contact potential barrier exists at the interface between organic and inorganic semiconductor layer, that is, PVA/n-Si interface. The variation in the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of the Au/PVA (Co, Zn doped)/n-Si SB devices have been systematically investigated as a function of frequencies in the frequency range of 2 kHz–2 MHz at room temperature. The effects of density of interface states (Nss) and series resistance (Rs) on I–V, C–V and G/ω–V characteristics were investigated. The high-frequency capacitance (Cm) and conductance (Gm/ω) values measured under reverse bias were corrected to decrease the effects of series resistance. These results show that the locations of interface states between Si/PVA and series resistance have a significant effect on electrical characteristics of the Au/PVA (Co, Zn doped)/n-Si SB devices.

Temperature dependent electrical and dielectric properties of Au/polyvinyl alcohol (Ni, Zn-doped)/n-Si Schottky diodes

by Prof.Dr. İbrahim USLU

Microelectronics Reliability
Volume 50, Issue 1, January 2010, Pages 39-44
T. Tunç, İ.Dökme, Ş. Altındal, ibrahim uslu

The electrical and dielectric properties of Au/PVA (Ni, Zn-doped)/n-Si Schottky diodes (SDs) were studied in the... more The electrical and dielectric properties of Au/PVA (Ni, Zn-doped)/n-Si Schottky diodes (SDs) were studied in the temperature range of 80–400 K. The investigation of various SDs fabricated with different types of interfacial layer is important for understanding the electrical and dielectric properties of SDs. Therefore, in this study polyvinyl alcohol (PVA) film was used as an interfacial layer between metal and semiconductor. The electrical and dielectric properties of Au/PVA (Ni, Zn-doped)/n-Si SDs were calculated from the capacitance–voltage (C–V) and conductance–voltage (G/w–V) measurements. The effects of interface state density (Nss) and series resistance (Rs) on C–V characteristics were investigated in the wide temperature range. It was found that both of the C–V–T and G/w–V–T curves included two abnormal regions and one intersection point. The dielectric constant (ε″), dielectric loss (ε″), dielectric loss tangent (tan δ) and the ac electrical conductivity (σac) obtained from the measured capacitance and conductance were studied for Au/PVA (Ni, Zn-doped)/n-Si SDs. Experimental results show that the values of ε′, ε″ and tan δ are a strong function of the temperature. Also, the results indicate the interfacial polarization can be more easily occurred at high temperatures.

Real-Time Virtual Metrology and Control of Plasma Electron Density in an Industrial Plasma Etch Chamber

by Shane Lynn

18th IFAC World Congress, Aug. 2011.
co-Authored with Niall MacGearailt and John V. Ringwood

Plasma etching is a semiconductor manufacturing process during which material is removed from the surface of silicon... more Plasma etching is a semiconductor manufacturing process during which material is removed from the surface of silicon wafers using gases in plasma form. A host of chemical and
electrical complexities make the etch process notoriously difficult to model and troublesome to control. This work demonstrates the use of a real-time model predictive control scheme to maintain a consistent plasma electron density in the presence of disturbances to the ground path of the chamber. The electron density is estimated in real time using a virtual metrology model based on plasma impedance measurements. Recursive least squares is used to update the controller model parameters in real time to achieve satisfactory control of electron density over a wide operating space.

Photorefractive multiple quantum wells planar waveguide

by Andrzej Ziółkowski

E. Weinert-Rączka, J. Gajda, M. Wichtowski, A. Ziółkowski, PAK 53, 34, (2007).

New type of planar optical waveguide with a guiding layer consisting of photorefractive multiple quantum well... more New type of planar optical waveguide with a guiding layer consisting of photorefractive multiple quantum well structure is investigated. Results of optical and electro-optical measurements and possible applications for all-optical switching of guided signals are presented

Temporal analysis of solitons in photorefractive semiconductors

by Andrzej Ziółkowski

Andrzej Ziółkowski, Journal of Optics, 14, 035202, (2012)

Temporal analysis of both the photorefractive mechanism and soliton propagation in a slab semiconductor waveguide is... more Temporal analysis of both the photorefractive mechanism and soliton propagation in a slab semiconductor waveguide is presented. As an example, a structure based on GaAs/AlGaAs
MQWs was investigated. Both a numerical and simple analytical approach based on the bipolar band-transport model is used to derive a temporal photorefractive response on localized illumination. The corresponding propagation problem describing the evolution of screening soliton profiles in media with quadratic electro-optic effect was also discussed.

Epitaxy and chemical reactions during thin-film formation from low-energy ions: new kinetic pathways, new phases, and new properties

by Nicole Herbots

Nicole Herbots, O.C. Hellman
ARIZONA STATE UNIVERSITY, Departmentof PhysicsandAstronomy, Tempe AZ 85287
0. Vancauwenberghe* MASSACHUSETTS INSTITUTE OFTECHNOLOGY, DepartmentofMaterialsScience & Engineering,Cambridge, MA 02139

Ref: Mat. Res. Soc. Symp. Proc. Vol. 235. pp. 749-762 (1992)

ABSTRACT
Three important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of... more ABSTRACT
Three important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption. The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(lOO) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.

Kinetics of formation and properties of silicon and silicon-germanium-alloy-based insulators grown using low-energy ion beam nitridation

by Nicole Herbots

Ion beam oxidation of GaAs: The role of ion energy

by Nicole Herbots

O. Vancauwenberghe, N. Herbots. H. Manoharan,a) and M. Ahrens

Massachusetts Institute of Technology, Cambridge,
Maassachusetts 02139

J. Vac. Sci. Technot A 9 (3), May/Jun 1991, pp. 1035-1039

In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam... more In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam is used to introduce oxygen athermally into the substrate, in this case GaAs. GaAs bonds are broken upon collision with the ions, making gallium and arsenic atoms readily available to react with the oxygen species. Ion beam oxidation of GaAs at room temperature was studied as a function ofoxygen ion energy between 500 and is keY. The ion beam oxidized GaAs was characterized in situ by Auger electron spectroscopy (AES) and ex situ with x-ray photoelectron spectroscopy (XPS) for accurate determination of the film chemical composition. Below 1 keY, a thin oxide film is formed: it is composed of Ga20 3 and AS20 3 with almost no metallic arsenic, and presents insulating properties.
As the ion energy increases, preferential sputtering of As and decomposition of AS203 increase and prevent formation of an
insulating film. No damage was detected by Rutherford backscattering spectrometry (RES) combined with ion channeling, in the substrate subjected to IBO below 1 keV.

A New 3D Multistring Code to Identify Compound Oxide Nanophase With Ion Channeling

by Nicole Herbots

James Douglas Bradley, Nicole Herbots, Robert Culbertson, Justin Shaw and Vasu Atluri

MRS Online Proceedings Library / Volume 996

a1 james.bradley@medtronic.com, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States

a2 herbots@asu.edu, Arizona St. University, Physics and Astronomy, ASU Dept. of Physics and Astronomy, Box 1530, Tempe, AZ, 85287, United States

a3 robert.culbertson@asu.edu, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States

a4 justin.shaw@nist.gov, NIST Magnetics Group, Magnetics Group, 325 Broadway, Mailstop 818.03, Boulder, CO, 80305, United States

a5 vasu.atluri@asu.edu, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States

A new 3DMultiString computer code of Ion Beam Analysis (IBA) using 4He++ ion channeling combined with Nuclear... more A new 3DMultiString computer code of Ion Beam Analysis (IBA) using 4He++ ion channeling combined with Nuclear Resonance Analysis (NRA) is used to analyze controlled formation of order in continuous layers of silicon dioxide nucleated on (1×1) Si(100) via the Herbots-Atluri clean (U.S. patent 6,613,677 (9/3/2003)) in air at 300 K. In our most recent work, this new 3DMultiString simulations combined with IBA leads to the identification of a new two-dimensional nanophase of tetragonally distorted β-cristobalite SiO2 (annotated b-c SiO2) with a critical thickness of 2 nm from the (1×1) Si (100)/b-c SiO2 interface to the b-c SiO2 /amorphous SiO2 interface (annotated b-c SiO2/a-SiO2). 3DMultiString simulations of IBA data taken on this new b-c SiO2/(1×1) Si(100) interphase includes channeling along the three <100>, <110>, and <111> axes of Si (100) in combination 16OO(α, α)16O 3.045 MeV NRA to measure oxygen areal densities corresponding to nm-thick films. In this way, the critical thickness of the β-c SiO2 nanophase can be established as a function of oxygen coverage. This new 3DMultiSTRING computer code is derived from the original 3DSTRING program that originated at Bell Labs, NJ.coverage.

RBS STUDY OF THE EFFECT OF ARSENIC AND PHOSPHORUS INTERFACIAL SEGREGATION UPON THE SINTERING OF CONTACTS BETWEEN IMPLANTED POLYCRYSTALLINE SILICON AND ALUMINUM -SILICON(1%)

by Nicole Herbots

Nicole HERBOTS *, Maurice LOBET and Femand Van de WIELE
Microekxtronics Lab, Uniwrsite Catholique de Lmamin, 3, place du Levant. B - 1348 Louvain -la - Neuve, Belgium
Nuclear Instruments and Methods in Physics Research B7/8 (1985) 278-286 North-Holland, Amsterdam

The sintering behavior of the interface between Al :Si(l%) alloy and polycrystalline Si (poly-Si) was studied as a... more The sintering behavior of the interface between Al :Si(l%) alloy and polycrystalline Si (poly-Si) was studied as a function of the poly-Si implantation dose by combining RBS, SEM, TEM and X-ray microanalysis. Two different N-dopants were used: arsenic and phosphorus. The dopants were implanted in the poly-Si layer and thermal annealing was used to obtain dopant segregation towards the poly-Si interfacea.
After sir&ring, two main effects were detected: (1) Al-Si eutectic phase precipitates and Si crystallites are formed at the interface. (2) The density of precipitates is a function of the implantation dose. For doses above 1 x lOI5 at./cm2. segregated arsenic and phosphorus are found to completely inhibit this precipitation process, provided that the segregation peak of the dopant profile is preserved before metallization.
Several conclusions can be drawn: for surface concentrations higher than 8~10’~ at./cm3, arsenic and phosphorus inhibit the precipitation of the Al-Si eutectic phase, and thus inhibit interactions between the films at the interface. Moreover, argon gas, usedfor sputtering deposition of aluminum, segregated at the poly-Si/Al: Si(l%) interface and may also inhibit the metal-semiconductor interdiffusion.

Stability of C49 and C54 phases of TiSi2 under ion bombardment

by Nicole Herbots

S. Motakef, J. M. E. Harper, F. M. d’Heurle, and T. A. Gallo IBM Research Division, Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598
N. Herbots Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
J. Appl. Phys. 70 (5), 1 September 1991, p. 2660

The transformation of C49 phaseTiSiz to the low resistivity C54 phaseis necessaryfor many microelectronic... more The transformation of C49 phaseTiSiz to the low resistivity C54 phaseis necessaryfor many microelectronic applications. Here, we report on attempts to decreasethis transformation temperature by low-energy ion bombardment at elevated temperature. Ion irradiation was performed using a broad beam Kaufman ion sourceoperatedin Nz or Ar gasbetween
0.1 and 2 keV beamenergy,with ion dosesranging from 2.0X 1016to 1.9X lo** ions/cm’, and sampletemperaturesfrom 480“C!to 735“C. For comparison,room-temperatureAr + implantation at higher energy (105-210 keV) was performed with a doseof lOI ions/cm2 with projected ranges within and beyond the TiS& layer thickness. Resistivity measurementsas a function of temperature,x-ray diffraction, and Rutherford backscattering s p e c t r o m e t r y w e r e u s e d t o d e t e r m i n e t h e c o m p o s i t i o n a n d p h a s e s .R e s u l t s s h o w t h a t l o w - energyion bombardment doesnot promote the C49-C54transformation at the temperatures studied, while ion implantation actually raisesthe temperaturefor the transformation.
In addition, bombardment of C54 TiSi, doesnot causeit to revert to the C49 phase,indicating that both phasesappearto be surprisingly stableunder ion bombardment.Simulationsof defect production using the TRIM code indicate the formation of a higher number of displaced atoms than are usually required to initiate a transformation. We conclude that the defectsintroduced into C49 TiSi, by ion bombardment at energiesup to 2 keV are either not sufficient to nucleate the C54 phaseor they are annealedout too quickly at the temperatureneededfor C54 phasegrowth.

IBMM of OH adsorbates and interphases on Si-based materials

by Nicole Herbots

N. Herbots , Qian Xing, M. Hart, J.D. Bradley, D.A. Sell, R.J. Culbertson, Barry J. Wilkens
Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA
FINAL REFERENCE:
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Volume 272, 1 February 2012, Pages 330-333

Proceedings of the 17th International Conference on Ion Beam Modification of Materials (IBMM 2010)

Please cite this article as

N. Herbots. Q. Xing et al., IBMM of OH adsorbates and interphases on Si-based materials, Nucl. Instr. and Meth. , Vol 272, pp 330-333 (2012),
doi:10.1016/j.nimb.2011.01.094

Using ion beam modification, films composed of synthesized
‘‘interphases’’ of ordered silica on OH-passivated (1... more Using ion beam modification, films composed of synthesized
‘‘interphases’’ of ordered silica on OH-passivated (1 X 1) Si(100) underwent surface electro-chemical changes quantified by surface free energy via Sessile drop method and contact angle analysis using Young’s equation and Van Oss theory. IBMM caused the surface free energies initially ranging from 26.0 mJ/m2 to 57.3 mJ/m2 to converge to 43.1–45.4 mJ/m2 for various passivated and as-received wafer samples alike. Although TMAFM also identified topographic changes, these changes did not correlate to the change of surface free energies. Ion beam modification of the ordered silica film on Si(100) surface is analyzed using 3.045 MeV 16O(a, a)16O nuclear resonance scattering (NRS) in conjunction with channeling in (1 1 1) direction, which demonstrated the convergence of the partially ordered oxygen to amorphous at about 55 microCoulombs/mm2 He++ flux. Additionally, Si surface peak channeling in (1 0 0) and (1 1 1) directions also experienced an uptrend in areal density as incident ion flux increased, while the rotating random Si signal height remains stable, showing a disruption in the surface order during IBMM.

Atomic collisions, elastic recombination, and thermal diffusion during thin-film growth from low-energy ion beams

by Nicole Herbots

N. Herbots *, 0. Vancauwenberghe **, O.C. Hellman + and Y.C. Joo ++
Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
Volumes 59-60, Part 1, 1 July 1991, Pages 326-331
doi:10.1016/0168-583X(91)95233-4 |

Low-energy (< 1 keV) ions are used in a variety of thin-film techniques. When low-energy ions are used during... more Low-energy (< 1 keV) ions are used in a variety of thin-film techniques. When low-energy ions are used during growth, the atomic mobility is athermally enhanced. This can lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. Athermal enhancement of atomic mobility in semiconductors can be described below the temperature for plastic deformation (T = 540-degrees-C in Si) by classifying the mechanisms involved into three categories according to their respective timescale: collisions, elastic recombination, and thermal diffusion. A quantitative model can then be derived to predict the conditions of temperature, dose rate, and energy to obtain thin film growth, and oxidation in techniques such as ion beam deposition (IBD), and ion beam oxidation (IBO). Using computer simulations, the dynamics of defect generation and redistribution, and the resulting thin-film growth rate can be investigated. Energies below 200 eV are found not only to minimize damage and sputtering, but also create defect distributions that favor surface recombination and hence growth. This elucidates the mechanism of thin-film formation with high atomic density, oxidation with a sharp inteface with the substrate and epitaxial growth, and experimental findings on the energy dependence of IBD and IBO.

A quantitative model of point defect diffusivity and recombination in ion beam deposition and combined ion and molecular deposition

by Nicole Herbots

O. Vancauwenberghe, N. Herbots, and O. C. Hellman MassachusettsInstituteo/Technology, 77MassachusettsAvenue. Cambridge. jWassachusetts02139
(Received 18 October 1990; accepted 12 February 1991)
J. Vac. Sci. Techno!. B 9 (4), JullAug 1991, p.2027-2033 0134-211X/911042027-07$01.00 @ 1991 American Vacuum Society 2027

We are investigating the use of low energy ions (< 1 keV) in low temperature thin film growth techniques, ion beam... more We are investigating the use of low energy ions (< 1 keV) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function of ion energy to support more quantitatively this physical description of IBD. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the IBD growth process is also investigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

New SiGe dielectrics grown at room temperature by low‐energy ion beam oxidation and nitridation

by Nicole Herbots

Author(s): VANCAUWENBERGHE, O (VANCAUWENBERGHE, O); HELLMAN, OC (HELLMAN, OC); HERBOTS, N (HERBOTS, N); TAN, WJ (TAN, WJ)
Source: APPLIED PHYSICS LETTERS Volume: 59 Issue: 16 Pages: 2031-2033 DOI: 10.1063/1.106122 Published: OCT 14 1991

New dielectric materials based on SiGe have been formed at room temperature by direct ion beam oxidation and... more New dielectric materials based on SiGe have been formed at room temperature by direct ion beam oxidation and nitridation. Si0.8Ge0.2 layers were deposited by molecular beam epitaxy on Si(100) and then exposed to a low-energy ion beam of O-18-2+ to form oxides and N-14-2+ to form nitrides. The ion energies investigated ranged from 100 eV to 1 keV. Thin films of SiGe oxide and SiGe nitride were formed at all energies used as evidenced by in situ x-ray photoelectron spectroscopy analysis. They were found to be insulating by ex situ scanning electron microscopy observations. During the ion beam processing, the Ge content of the alloy layer decreases, due to preferential sputtering of Ge and the Ge compounds. However, as the ion energy is decreased, the concentration of Ge in the alloy remains closer to the original content. The thermal stability of these new SiGe dielectrics was also assessed up to 500-degrees-C.

Microstructure and stoichiometry dependence of ion beam nitrides as a function of energy and temperature: A comparative study between Si and SiGe

by Nicole Herbots

Author(s): HELLMAN, OC (HELLMAN, OC); HERBOTS, N (HERBOTS, N); VANCAUWENBERGHE, O (VANCAUWENBERGHE, O); CULBERTSON, RJ (CULBERTSON, RJ); CROFT, WJ (CROFT, WJ)
Source: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS Volume: 10 Issue: 4 Pages: 1631-1636 DOI: 10.1116/1.577761 Part: Part 2 Published: JUL-AUG 1992

Abstract: The microstructure and stoichiometry of nitrides formed by direct low-energy ion beam nitridation has been... more Abstract: The microstructure and stoichiometry of nitrides formed by direct low-energy ion beam nitridation has been investigated as a function of ion energy and substrate temperature for Si(100) and SiGe/Si(100) films. Cross-sectional transmission electron microscopy, Rutherford backscattering spectroscopy combined with ion channeling and in situ x-ray photoelectron spectroscopy were used. It was established that a substrate temperature of 700 K produces a homogeneous amorphous nitride layer, whereas lower substrate temperatures decrease the incorporation of nitrogen in the film, while causing the formation of a nitrogen-poor amorphous layer beneath the nitride film. The N-to-Si or N-to-(Si + Ge) atomic ratio is found be close to 1.33 at 1 keV and decreases with ion energy. Effects due to chemically enhanced physical sputtering of germanium are observed.