bluuebunny/crossref_metadata_2025 huggingface dataset:
GaAs Heterojunction Bipolar Transistor Device and IC Technology
Authors: Kim Michael E. , Oki Aaron K. , Camou James B. , Gorman Gary M. , Umemoto Donald K. , Hafizi Madjid E. , Pawlowicz Leszek M. , Stolt Kjell S. , Mulvey Virginia M.
Published: March 2011

GaAs/AlGaAs N-p-n heterojunction bipolar transistor (GaAs HBT) device and integrated circuit technology which offers key advantages over advanced silicon bipolar and III-V compound field-effect transistors is maturing towards system insertion. The TRW device and IC fabrication process, basic HBT dc and RF performance, examples of device and IC applications, and technology qualification work are presented and serves as a basis for discussing overall technology issues and impact. A relaxed 3-μm emitter-up, self-aligned base ohmic metal (SABM) HBT process and simplified molecularbeam epitaxial profiles are used for near-term producibility. The HBTs have simultaneous fT, fmax≈20–40 GHz and dc current gain ß≈50–100 at collector current density JC=3 kA/cm2 and Early voltage VA≈200–300 with capability for MSI-LSI integration levels. Versatile dc-20 GHz analog, 3–6 Gb/s digital, and 2–3 Gs/s A/D conversion functions are demonstrated with a common 3-μm SABM HBT process which facilitates single-chip multifunctional capability. Key improvements are realized over Si bipolar and GaAs-related FET (e.g. MESFET and HEMT) approaches in operational frequency, gain-bandwidth product, harmonic distortion, 1/f noise, power consumption, and size reduction.
Redistribution Effects for OMVPE InP/GaAs
Authors: Tae-IL OH , Leigh Wallace B.
Published: March 2011

We have analyzed the redistribution parameters for InP grown by organometallic vapor phase epitaxy (OMVPE) on GaAs substrates. The layers, grown using (trimethyl Indium) TMIn at atmospheric pressure, have been characterized for epitaxial quality using photoluminescence, energy dispersed x-ray analysis, and optical microscopy. In order to better understand the effects of inter-diffusion and inter-mixing for the GaAs into the InP epitaxial layer, the layer-substrate interface was first probed by growing consecutive samples of InP for increasingly longer growth times, and thus characterizing the layers as one moves away from the interface. For more detailed analysis, cross-sections of the InP/GaAs interface were prepared for scanning transmission electron microscopy (STEM). Energy dispersed x-ray analysis has shown that all elements In, Ga, As, and P, are present on the epitaxial side of the interface, while only Ga and As are present on the substrate side. A combination of electron diffraction and luminescence measurements show the epitaxy is at least 80% InP at the interface and essentially 100% InP at a distance of 6000Å into the epilayer. Electron diffraction and bright field investigation at the interface show the existence of a second phase, existing in a mostly InP matrix. The effects of redistribution in heteroepitaxial InP/GaAs will be discussed.
X-Ray, Photoluminescence and Etching Studies of Indium-Doped LPE GaAs Layers
Authors: Chen J.F. , Wie C. R. , Junga F. A.
Published: March 2011

The effects of In doping on the structural properties of liquid phase epitaxially (LPE) grown GaAs layers are studied. The distribution coefficient of In in the GaAs at 800 ° C was determined to be 0.033 which was consistent with the value calculated from the pseudobinary phase diagram of the ternary system at a dilute In concentration. The full widths at halfmaximum (FWHM) of x-ray double crystal rocking curves show that a GaAs epi-layer of good crystalline quality can be obtained by doping In to a concentration up to 4.3 × 1019 cm−3, beyond which a sharp increase in the FWHM is observed. Etch pit density (EPD) measurement shows that the dislocation density is reduced by doping the epi-layer with In. At the optimal In concentration of 2.4 × 1019 cm−3, the EPD is reduced by a factor of 20 when measured at the surface of a 9 um thick epilayer.

Photoluminesce measurements made at 15 K show two sharp emission spectra near the bandedge. The relative intensities of the two emissions, I(l.49eV)/I(l.5eV) are reduced with increasing In content. This suggests that incorporation of Carbon acceptors is suppressed by In doping in the GaAs epilayers. The FWHM as small as 5 meV of the bandedge transition was obtained for the epi-layer doped with In concentration of 2.4 × 1019 cm−3.
Determination of as Sticking Coefficients Using Reflection high Energy Electron Diffraction Intensity Oscillations on GaAs
Authors: Chow Robert , Fernandez Rouel
Published: March 2011

RHEED intensity oscillations were used to investigate As-controlled incorporation rates. The measurements were made under Ga accumulation at the surface of the substrate, and at fluxes and substrate temperatures common for 1.0 micron/hr GaAs growth. The results between the dimer and tetramer As species were compared. The transition between Ga and As controlled incorporation rates was constant within 2.5°C for a constant As flux and was independent of the substrate temperature. Also, the As-controlled incorporation rate curves shows two regions as the substrate temperature increases. At low substrate temperatures, the As incorporation rate is substrate temperature independent. Then at higher substrate temperatures, the As incorporation rate has an arrhenius dependence with a positive activation energy. An interpretation of these results is possible by assigning the maximum sticking coefficient of the tetramer to the region where the As incorporation rate is independent of substrate temperature. This assignment allows one to derive the As (dimers and tetramers) sticking coefficient dependence with substrate temperature. The dimer sticking coefficients are greater that the tetramer sticking coefficients for a given substrate temperature and As flux, and the maximum sticking coefficient of the As dimer was determined to be 0.8 in these experiments.
Element III Segregation During Mocvd Growth on Structured Substrates
Authors: Menu Eric P. , Dzurko Kenneth M. , Dapkus P. Daniel
Published: March 2011

The crystal habits of GaAs and GaAlAs grown on structured substrates by Metalorganic Chemical Vapor Deposition (MOCVD) have been investigated. The growth behavior was delineated by depositing alternating thin layers of AlGaAs and GaAs over grooves and mesas. A strong temperature dependence of facet growth rate and an anisotropy of Al composition with facet orientation are observed. This latter effect so far undocumented in MOCVD has been analysed by Auger Electron Spectroscopy performed on cleaved cross-sections. BCF theory has been used to extract quantitative microscopic data. These observations demonstrate the importance of surface effects and provide an insight into MOCVD growth mechanisms.
Production of GaAs and InP Based Heterostructures
Authors: Jorgensen H. , Schreiner R. K. , Deschler M.
Published: March 2011

The complete requested range of epitaxial deposition from one monolayer to tens of microns is available integrating LP-MOVPE and LP-VPE into wafer fabrication. Uniformity across 2 inch wafers for thickness, composition, and doping show a variation of less than 2 %. Electrical properties of the 1014 cm−3range and less for background doping, carrier mobilities of 210,000 cm2/Vs for AIGaAs and 190,000 cm2/Vs for GalnAs, both HEMT structures, are achieved. FWHM of 3.4 meV and 18.6 meV for 10 nm and 2 nm GaInAsP wells have been measured. GaAsP layers including a “graded” layer reveal FWHM of 15 nm. A new model for the understanding of high growth rates in the hydride system is demonstrated.
Atomic Layer Epitaxy of GaAs and InAs
Authors: Jeong Weon G. , Menu E.P. , Dapkus P.D.
Published: March 2011

The saturation behavior of growth of GaAs and InAs by atomic layer epitaxy is studied. The growth rate is found to be strongly dependent on alkyl exposure time for the same total alkyl exposure per cycle. The longer the exposure time, the higher the saturated growth rate is. For short exposure, the growth rate saturates to a value less than one monolayer (ML)/cycle. Strong saturation of the growth rate to one ML/cycle is achieved for InAs at a growth temperature of 340°C with 3 sec of trimethylindium exposure. For GaAs, saturation of the growth rate to one ML/cycle is achieved at the growth temperature of 400°C with 10 sec of trimethylgallium exposure. At higher growth temperatures, the growth rate does not saturate but increases slowly with increasing exposure. The large physical size and finite decomposition time of the initial adsorbate are suggested as the cause for the dependence of ALE growth rate on alkyl exposure time.
New Group III Precursors for the Movpe of GaAs and InP Based Material
Authors: Hostalhe M. , Pohl L. , Merck E. , Brauers A. , Balk P. , Frese V. , Hardtdegen H. , Hovel R. , Regel G.K. , Molassioti A. , Moser M. , Scholz F. , Schumann H. , Hartmann K.U. , Wassermann W.
Published: March 2011

This paper presents proposals for the synthesis of several group III metal organics (In, Ga, Al compounds) and preliminary results on their use in the MOVPE (metal organic vapor phase epitaxy) of III-V semiconductors. The common feature of all these precursors is that they are saturated by interor intramolecular coordination. They are even non-pyrophoric and air resistant which is an interesting aspect with respect to safe handling. In addition, the compounds are liquid at room temperature with a low but sufficient vapor pressure for MOVPE without additional heating of the source.
Modulation Doped GaAs with Electron Mobilities Exceeding 107cm2/V sec
Authors: Pfeiffer Loren , West K. W. , Stormer H. L. , Baldwin K. W.
Published: March 2011

A modulation doped Al.35Ga.65As/GaAs single interface structure using Si delta doping setback from the two dimensional electron gas (2 DEG) by 700Å, was measured in van der Pauw geometry at 0.35K and showed an electron mobility of 1.17× 107 cm2 /V see at a carrier density of 2.2× 1011electrons/cm2. An Al.30Ga.70As/GaAs single quantum-well 250Å wide of similar structure with a 500Å setback yielded a 2 DEG mobility of 5.1× 106 cm2 /Vsec at 3.0×1011 electrons/cm2under similar measurement conditions. These mobilities exceed those previously published by more than a factor of two for the single interface structure, and by nearly an order of magnitude for the quantum-well. The samples were grown by solid source MBE in a Varian Gen II modified with He closed-cycle cryogenic vacuum pumping, and in other ways, to achieve a base pressure of 1.5× 10−12 torr, as measured on a extractor-type ionization gauge that is not subject to the usual x-ray limited reading.
Growth and Characterization of GaAs on Si by Mbe
Authors: Li A.Z. , Wang J.X. , Qiu J.H. , Liang B.W. , Zheng Y.L. , Wang S.B.
Published: March 2011

High quality of Si-doped n-type MBE GaAs grown directly on 4° off (001) towards [0111 Si substrates has been achieved by a multiple step MBE growth procedure. Epilayers have been characterized for the doping range 2x1016 to 3x1018cm-3 with thickness up to lOm by double crystal x-ray rocking curves, Hall mobilities, photoluminescence spectra, dislocation etching pit densities and I-V characteristics of MESFET of GaAs/Si. The results show that the electron mobilities are 2900 to 1430cm2 /Vs while free electron concentration of 3.5x1017 to 2.7x1018cm-3. The FWHM of the DCRC are 175 to 350 arc sec, the EPD are 1x106 to 2x107 cm-2 for most of samples and both of them appear variation with thickness of epilayer. The main peak of PL appears a few meV shift to long wavelength in comparison with GaAs on GaAs. The FWHM of the PL are 21 meV for n-type GaAs/Si in a doping level of 3.5x1017cm-3. MESFET show a acceptable I-V characteristics. All of epilayers with thickness less than 5pm appear good morphology. Some slightly orthogonal cracking was observed in the 5 to 10µm thick films of GaAs/Si.
Narrow Si doping distributions in 6-doped GaAs, Al0.3Ga0.7As and Quantum Wells grown by Gas Source Molecular Beam Epitaxy
Authors: Cunningham J.E. , Chin T.H. , Tell B. , Jan W. , Ditzenberger J. A. , Kuo T. Y. , Fonstad C.
Published: March 2011

We report very small interdiffusion and surface segregation of Si in δ-doped GaAs, A10.3Gao.7As and Quantum Wells grown at 580 C by Gas Source Molecular Beam Epitaxy. Capacitance-Voltage profiles of δ-doped layers are 38 Å wide for growth at 580 C and further, insignificant profile narrowing is observed at 530C and below. Much wider profiles are observed at equivalent substrate temperature for As4 growth. Atomic diffusion of Si in δ-doped Al0.3Ga0.7As is found to have a rate of D0=5× 10−cm2/sec with an activation energy of 1.8 eV.
Comparison of Interface Formation for GaAs-on-Si and ZnSe-on-Si.
Authors: Bringans R. D. , Olmsteadt Marjorie A.
Published: March 2011

A comparison is made between the interface formed when GaAs is grown heteroepitaxially on Si(100) substrates with that formed for ZnSe-on-Si(100) growth. Results of core level photoemission spectroscopy show that the Si(100) surface reacts with As atoms to form a stable monolayer, but reacts with Se atoms to form the compound SiSe2. Annealing treatments can also give rise to a submonolayer coverage of Se atoms on Si(100). The SiSe2 compound is also seen at the interface between ZnSe and Si. Island formation appears to occur at the beginning of growth for both GaAs-on-Si and ZnSe-on-Si
Low Pressure Omcvd Growth of GaAs on InP for Fet and Quantum Well Laser Fabrication
Authors: Bhat R. , Lo Y-H. , Caneau C. , Chang-Hasnain C.J. , Skromme B.J. , Hwang D.M. , Zah C.E. , Koza M.A.
Published: March 2011

Gallium arsenide epitaxial layers with excellent morphology have been grown by organometallic chemical vapor deposition (OMCVD) on (100) and 2-3° off (100) InP substrates by a modified two-step growth commonly used for GaAs on Si. The layers have been characterized by X-ray diffraction, cross-sectional transmission electron microscopy (TEM), low temperature photoluminescence (PL) and Hall measurements. 1 µm gate GaAs metal-semiconductor field effect transistors (MESFETs) with transconductances as high as 220 mS/mm have been fabricated. These MESFETs have been integrated with buried heterostructure and V-groove InGaAsP lasers. The V-groove laser -MESFET OEIC transmitter has been shown to be capable of direct modulation at 5 Gb/sec bit rate. Finally we have also demonstrated GaAs single quantum well lasers with threshold currents as low as 800 A/cm2for 50 µm wide broad area gain guided devices with 1.25 mm long cavities.
Quaternary Phase Equilibria vs. Strain-Energy at the In.53Ga.47As/InP Interface
Authors: Schultz Allan E. , Chang Y. Austin
Published: March 2011

Extensive new data and modeling in the In-Ga-As system has allowed the authors to reexamine the phase equilibria between the melt and the epitaxial solid. A detailed thermodynamic model was constructed with the following improvements: (1) The solid-solid interaction parameters were based on InAs-GaAs miscibility gap data, and (2) liquid-bulk solid, as well as liquid-epitaxial solid, tie-lines were used. Comparison of tie- lines from epitaxial systems and bulk systems demonstrated that strain energy is not the dominant factor in equilibrium growth of epitaxial solid films of In1-xGaxAs on any Ill-V binary substrate. Both the “lattice- pulling” effect and the “substrate-orientation” effect were shown to be caused by different quaternary equilibria at the In1-xGaxAs/InP interface, and not by film-substrate strain.
Properties of Mbe Grown Heterostructures of GaAs/InSb and InP/InSb.
Authors: Asom M. T. , Fitzgerald E. A. , Thiel F. A. , People R. , Eaglesham D. , Luther L. , Sputz S. K. , Kimerling L.C.
Published: March 2011

We have employed molecular beam epitaxy in the growth of InSb on GaAs and InP. The transport, optical and structural properties of the films were investigated by in-situ reflection high energy electron diffraction, Hall effect and temperature dependent Hall effect, photoluminescence, transmission electron microscopy and X-ray diffractometry techniques. We report mobilities of up to 32,000 cm2/volt-sec and free electron concentrations of 3x1016/cm3at room temperature. We have discovered a new defect state in InSb with an energy position of Ec -0.05± 0.006eV. Optical and structural measurements reveal that the differences in thermal expansion and lattice mismatch between the substrates and films results in the broadening of the X-ray diffraction peaks and the near gap photoluminescence linewidths. Furthermore, we observe band gap shifts to higher energies of 10meV and 20meV for growth on GaAs and InP, respectively.
Low Interface State Density at Pseudomorphic ZnSe/Epitaxial GaAs Interface
Authors: Qian Q.-D. , Qiu J. , Kobayashi M. , Gunshor R.L. , Kolodziejski L.A. , Melloch M.R. , Cooper J.A. , Gonsalves J.M. , Otsuka N.
Published: March 2011

The electrical properties of pseudomorphic ZnSe/epilayer GaAs heterointerfaces, grown by MBE, have been investigated by capacitance versus voltage (C-V) and current versus voltage (I- V) measurements. Hole accumulation and inversion were observed in ZnSe/p-GaAs interfaces and ZnSe/n-GaAs interfaces, respectively. The C-V characteristics of the Au/ZnSe/p-GaAs capacitors are nearly ideal, exhibiting an interface state density (2.5x1011cm-2) which compares favorably with the densities reported at AlGaAs/GaAs interfaces.
Study of MBE ZnSe Growth Using Rheed Oscillations
Authors: Turco Francoise S. , Tamargo M.C.
Published: March 2011

Reflection high energy electron diffraction (RHEED) intensity oscillations are often used to investigate in situ the growth of III-V materials by molecular beam epitaxy (MBE). In this work, we have used RHEED oscillations to perform a quantitative study of the growth mechanisms of ZnSe, a II-VI semiconductor.

Our experiments illustrate that the RHEED pattern of ZnSe is far less intense than that of III-V materials grown by MBE, and no specular spot is observed over a wide range of growth conditions. We have, however, been able to record up to 25 oscillations allowing a quantitative study of the growth of ZnSe by MBE. Thus we have used RHEED oscillations to make an in situ systematic study of the influence of the three main growth parameters (substrate temperature and Zn or Se impinging fluxes) on the ZnSe growth rate. We observed that the variation of the ZnSe growth rate is due to a non unity sticking coefficient of both Zn and Se species at the interface in the standard growth conditions used. Our observations can be described using a thermodynamic model and enable us to control the desired growth conditions. Our work demonstrates the utility of RHEED oscillations to understand the MBE growth mechanisms of II-VI compounds.
Charge Carrier Recombination in AlGaAs Studied by Time-Resolved Microwave Conductivity Experiments
Authors: Werner A. , Agarwal A. M. , Moustakas T. D. , Kunst M.
Published: March 2011

AlxGa1-xAs films, doped with silicon in the 1 x 1018 cm-3 range, have been prepared in the composition range x = 0.20 - 0.46 by molecular beam epitaxy. The influence of defect states on excess carrier trapping and recombination processes is studied by a contactless transient photoconductivity technique in the microwave region. Effective electron life- times in the 1 x 10-5s range for the 20% Al film down to the 1 x 10-7s range for the 46% Al film were found, indicating a larger density of electron traps in more Al rich films. The decay kinetics in AlGaAs is compared with the decay kinetics in GaAs.
Rocking-Curve Peak Shift in Thin Heterojunction Single Layers
Authors: Wie C.R. , Choi Y-W. , Kim H.M. , Chen J.F. , Vreeland T. , Tsai C.-J.
Published: March 2011

A simple method for determining layer composition and mismatch of semiconductor hetero-epitaxial samples is by measuring the separation of peaks in x-ray rocking curve (XRC). This method fails if the peak separation is affected by other factors. For a small layer thickness, the layer peak position is affected by the x-ray amplitudes of the substrate or other thicker layers through the interference and overlap effects. In this case, a diffraction theory fitting process is necessary for a correct determination of layer parameters. We have used dynamical and kinematical x-ray diffraction theories to calculate the layer peak position as a function of its thickness for various layer/substrate combinations. These two theories yield substantially different results, indicating that the kinematical diffraction theory analysis is no longer valid for these thin layers. When a thick layer is present along with the thin layer, the thick layer is more influential than the substrate to the thin layer peak position, making the dynamical theory fitting necessary even from higher thickness.
Formation of Radiative Binding States for the Pairs Between Acceptors in Heavily Acceptor-Doped Gaas.
Authors: Ohnishi Nobukazu , Makita Nunosuke , Shibata Hajime , Beye Aboubaker.C. , Yamada Akimasa , Mori Masahiko
Published: March 2011

We carried out the photoluminescence measurements at low temperature for Be-doped GaAs. Samples were grown by molecular beam epitaxy and Be con- centration was varied by controlling the cell temperature of Be. Besides the well-defined emission, [g-g], which is observed for the acceptor con- centration [A] from ∼ 5x1016 cm-3 to ∼ 1x1018 cm-3 and which shows steep red shift with increasing [A], we observed two unusual emissions temporarily denoted by [g-g]α and [g-g]β. These emissions were commonly observed just below bound exciton emissions for heavily-doped region of [A]>1x1018 cm-3. [g-g]α indicated a strong blue shift with increasing [A] and its energy can become larger than the direct band-gap energy of undoped GaAs at 2K when [A] exceeds 5x1019 cm-3. On the other hand, [g-g]β was observed in the vicinity of the band-to-acceptor emission and showed red shift with increas- ing [A]. We here proposed a model that these two emissions are attributed to the binding states of acceptor-acceptor pair formed by the overlapping of the wave functions in the ground state of an isolated acceptor. This situation is principally different from that of [g-g] in which the formation of acceptor-acceptor pair was ascribed to the overlapping of the wave func- tions of 2P excited state. It was revealed that the theoretical estimation made through the simplified calculation agreed qualitatively well with the dependence of [g-g]β on [A]. However this calculation presented unsatisfac- tory agreement with the features of [g-g]α and it was suggested that another physical conjecture such as a formation of GaAs-Be alloy should be proposed.
Growth of Thin Epitaxial Silicon Layers on Heavily Doped Substrates by RTP-CVD
Authors: Lee S. K. , Ku Y. H. , Kwong D. L.
Published: March 2011

Silicon epitaxy plays an important role in improving the performance and reliability of semiconductor devices. The continuous scale-down in device feature size demands a low thermal budget epitaxial technique to maintain the structural integrity of processed devices. In this paper, rapid thermal processing chemical vapor deposition (RTP-CVD) has been used to deposit high quality, thin silicon epitaxial films with superior thickness control. Parameters affecting the quality and rate of epitaxial growth are discussed.
300° C Processing of Si Using Remote Plasma Techniques for In Situ Cleaning, Epitaxy, and Oxide/Nitride/Oxide Depositions
Authors: Fountain G.G. , Hattangady S.V. , Rudder R.A. , Posthill J.B. , Markunas R.J.
Published: March 2011

Low temperature Si processing techniques have been developed using remote plasma enhanced chemical vapor techniques. The 300° C in situ processes include indirectly excited hydrogen treatments for obtaining reconstructed Si(100) surfaces, Si/Si(100) homoepitaxy, and deposition of poly-Si/oxide/nitride/oxide/Si(100) structures with no capacitance-voltage hysteresis and low interface state density (4×1010cm−2eV−1). While all these processes have been accomplished with the same tool, the success of the in situ hydrogen treatment and the homoepitaxy are sensitive to the past history of the reactor. In particular, they are sensitive to by-products formed during the oxide deposition process. To eliminate these by-products, plasma conditioning of the chamber walls prior to introduction of the silicon wafer from the load lock has been necessary to obtain reproducible results.
Impact of Patterned Layers on Temperature Non-Uniformity during Rapid Thermal Processing for VLSI-Applications
Authors: Vandenabeele P. , Maex K. , De Keersmaecker R.
Published: March 2011

The influence of patterned oxide layers on temperature non-uniformity during RTP is studied. It is shown that large temperature non-uniformities (up to 80 °C) can occur during RTP as a consequence of large scale patterns of thick oxides. The dependence of oxide thickness and pattern geometry on temperature non-uniformity over a wafer is studied. A set of simulation programs is developed to calculate the optical characteristics of a wafer inside a chamber and to calculate the time dependent temperature non-uniformities on patterned wafers. The calculated results agree very well with the experimental results. The simulation program was used to define the optimal optical conditions for RTP systems for minimal temperature non-uniformity due to patterned overlayers on Si.
Implications of Rapid Thermal Processing for Step Coverage in Low Pressure Chemical Vapor Deposition
Authors: Shemansky Frank A. , Jain Manoj K. , Cale Timothy S. , Raupp Gregory B.
Published: March 2011

A multicomponent mathematical model incorporating simultaneous Knudsen diffusion and heterogeneous reaction in a feature of arbitrary geometry has been developed to quantitatively predict step coverage in LPCVD. The single component model reveals that for a given CVD chemistry and feature geometry, deposition uniformity is controlled by a single parameter called the step coverage modulus. In multicomponent systems, each additional reactant partial pressure dependence in the deposition rate expression introduces an additional parameter equal to the ratio of the initial reactant partial pressures. Manipulation of the instantaneous step coverage modulus, through time variations of temperature and/or pressure results in higher average film growth rates without incurring a penalty in step coverage over patterned regions of the wafer. For deposition of SiO2 from TEOS, the step coverage modulus is varied through a time dependent temperature path. The path is chosen by constraining the deposition rate in the feature such that it varies by less than a few percent from top to bottom. For deposition of SiO2 from SiH4/O2, silane partial pressure is varied since the reaction rate is relatively insensitive to temperature. In each case. time savings of approximately 50% are achieved.
Rapid Thermal Annealing of Double Polysilicon Bipolar Transistors
Authors: Patton Evan E. , Yamaguchi Tadanori , Lee June , Tang Alex , Yu Y.-C. S.
Published: March 2011

This paper reports on very shallow double rapid thermally diffused npn transistor junctions, emitter polysilicon sheet resistance, and titanium disilicide formation. A transistor with a 675Å base width fabricated using rapid thermal annealing is demonstrated.
Influence of Rapid Thermal Processing on Minority Carrier Diffusion Length in Silicon
Authors: Eichammer Wolfgang A. , Vu Thuong-QUat , Siffert P.
Published: March 2011

Minority carrier diffusion length measurements (SPV-method) are presented which illustrate the role of contamination, residual impurity content and surfaces in the formation of RTP-induced recombination centers.
Integrated Processinyg of Silicided Shallow Junctions using Rapid Thermal Annealing Prior to Dopant Activation
Authors: Rubin Leonard , Herbots Nicole , Gutierrez JoAnne , Hoffman David , Ma Di
Published: March 2011

A method for producing shallow silicided diodes for MOS devices (with junction depths of about 0.1 µm), by implanting after forming the silicide layer was investigated. The key to this integrated process is the use of rapid thermal annealing (RTA) to activate the dopants in the silicon, so that there is very little thermal broadening of the implant distribution. Self-aligned titanium silicide (TiSi2) films with thicknesses ranging from 40 to 80 nm were grown by RTA of sputter deposited titanium films on silicon substrates. After forming the TiSi2, arsenic and boron were implanted. A second RTA step was used after implantation to activate these dopants. It was found that implanting either dopant caused a sharp increase in the sheet resistivity of the TiSi2. The resistivity can be easily restored to its original value (about 18 µΩ-cm) by a post implant RTA anneal. RBS analysis showed that arsenic diffuses rapidly in the TiSi2 during RTA at temperatures as low as 600°C. SIMS data indicated that boron was not mobile up to temperatures of 900°C, possibly because it forms a compound with the titanium which precipitates in the TiSi 2. Coalescence of TiSi2 occurs during post implant furnace annealing, leading to an increase in the sheet resistivity. The amount of coalescence depends on the film thickness, but not on whether or not the film had been subject to implantation. Spreading resistance profiling data showed that both arsenic and boron diffused into the TiSi2 during furnace annealing, reducing the surface concentrations of dopant at the TiSi2/Si interface. Both N+/P and P+/N diodes formed by this technique exhibited low leakage currents after the second RTA anneal. This is attributed to removal of the implant damage by the RTA. In summary, the second RTA serves the dual purpose of removing implant damage in the TiSi2 and creating the shallow junction by dopant activation.
Rapid Thermal Process Integration
Authors: Calder I.D. , Naem A.A.
Published: March 2011

A manufacturable process must be designed with device integrity and reliability in mind. The optimum cumulative thermal budget should be chosen to achieve a shallow junction (for performance optimization) while minimizing junction leakage. At the same time the processing must satisfy reliability requirements such as good metal step coverage and oxide integrity. Interactions between thermal processes create problems such as repeated anneals, chemical reactions, pattern shifts, and non-equilibrium conditions, as well as opportunities for process simplification, such as greater flexibility in anneal and silicidation processes. In general RTP integration requires a redesign of the complete process sequence.
Epitaxial Growth of NiSi2 and CoSi2 on Laterally Confined Silicon by Rapid Thermal Annealing
Authors: Hsu H.F. , Chu J.J. , Chen L.J.
Published: March 2011

Epitaxial growth of NiSi2 and CoSi2 on silicon inside miniature oxide openings by rapid thermal annealing has been studied. Effects of lateral confinement, including two-dimensional and linear oxide openings, as well as deposition methods on the growth of NiSi2 and CoSi2 on silicon were investigated. Vast difference found in the behaviors of the growth of epitaxy inside oxide openings between samples with the metal films deposited by electron beam evaporation and sputtering are attributed to the differences in the geometrical configuration of the films and stress levels as well as surface cleanliness.
A Self-Aligned Silicide Technology using Ion-Beam Mixing, Doped Silicide, and Rapid Thermal Processing
Authors: Ku Y. H. , Lee S. K. , Kwong D. L. , Chu P.
Published: March 2011

A SALICIDE process is described in this paper, in which ion-beam mixing is used for silicide formation, and doped silicide in conjunction with RTA drive-in are used for shallow silicided junction formation. Fundamental issues related to this process have been investigated, including (i) effects of ion-beam mixing and RTA on the properties of Ti SALICIDE and the interaction between Ti and SiO2; (ii) the self-aligned TiNxOy TiSi2 contact barrier formation and phase transformation; (iii) the mechanism of impurity rediWstrbution and segregation, and junction formation during RTA drive-in; and (iv) the performances and reliability of fabricated SALICIDE devices. Results show that this process may have a great impact on future VLSI technology.
Nucleation Phenomena during Titanium Silicon Reaction
Authors: Raaijmakers Ivo J.M.M. , Ijzendoorn Leo J. van , Theunissen Anton M.L. , Kim Ki-Bum
Published: March 2011

It is known that thermal annealing of Ti and amorphous (α) Si first results in an amorphous silicide, after which the crystalline disilicide grows under diffusion control. The situation with respect to the reaction of Ti with crystalline (x) Si is much less clear. We have investigated the reaction of Ti with xSi with (high resolution) cross-section transmission electron microscopy and in-situ Rutherford backscattering spectroscopy. It is shown that an amorphous silicide can also be formed on crystalline Si. The presence of this amorphous silicide as a precursor to the C49TiSi2 phase is suggested to be an important issue in the nucleation and growth of the disilicide.
Process Uniformity and Electrical Characteristics of Thin Gate Dielectrics Grown by Ramped-Temperature Transient Rapid Thermal Oxidation of Silicon
Authors: Moslehit Mehrdad M. , Kermani Ahmad
Published: March 2011

Rapid thermal oxidation (RTO) of Si using transient linearly-ramped-temperature saw-toothed (LRT-ST) and triangular (LRT-TA) thermal cycles has been examined through evaluations of the process uniformity, slip dislocation patterns, and electrical characteristics of MOS devices. The strong effects of the thermal cycle parameters on process uniformity and slips indicate that the overall performance of an RTP tool must be specified both under the steady-state and transient thermal cycles. The electrical characteristics of MOS devices with LRT-grown gate oxides are comparable to those for devices with oxides grown by the trapezoidal thermal cycles.
Kinetics of Rapid Thermal Oxidation : Critical Analysis of Experimental Results
Authors: Dilhac J-M.
Published: March 2011

In this paper, we present experimental kinetics data from the literature, and the large discrepancies between them is discussed. An analytical equation for oxide thickness vs. oxidation time and temperature, adequatly describing thin film growth, is used to estimate the temperature error likely to explain the discrepancy between the above data. We also assess this error by considering the temperature sensors.
Contactless Measurements of the Surface Recombination Velocity of P—N and High—Low (P—P+, N—N+) Junctions Fabricated by Rapid Thermal Processing
Authors: Usami A. , Yamada N. , Matsuki K. , Takeuchi T. , Wada T.
Published: March 2011

A photoconductive decay curve is analyzed theoretically to determine the surface recombination velocity and the bulk lifetime separately. And it can be applied to experimental photoconductive decay curves using the reflectance microwave probe method. Then it is verified numerically and experimentally to lower the effective surface recombination velocity at p—n and high—low junctions. The high—low junctions used in this study were fabricated from the ionimplanted wafer by rapid thermal annealing or furnace annealing. Then it is shown that the measurement system in relation to surface recombination can apply to evaluations in the ion implantation and its annealing process.
The Correlation between Quantitative Surface Metallic Contamination and RTP-Induced Surface Defects
Authors: Hockett R. S.
Published: March 2011

Recent studies have shown that surface metals, introduced by scraping metals either on the silicon wafer front or back surface, can contribute to surface crystalline defects during rapid thermal processing (RTP). These studies have been qualitative in the sense that the quantitative amount of surface metallic contamination was unknown. The work involved here uses Total reflection X-Ray Fluorescence (TXRF) analysis to quantitate the surface metallic contamination on silicon wafers from cleaning (rather than scraping) both before and after RTP. In this study there was no correlation found between surface copper (ranging from 2 to 200 ×1012 atoms/cm2) and surface defects after a RTP of 600°C for 30 seconds in argon, nor was there a correlation between temperature (ranging from 600°C to 1150°C) of the RTP (120 seconds in argon) and surface defects for constant surface copper of about 30×1012 atoms/cm2. The data also revealed the introduction of cross contamination of tungsten to the frontside surface of silicon wafers when air was used as the ambient with an activation energy of 0.8 eV for RTP of 120 seconds in air with temperatures ranging from 500°C to 1000°C. This cross contamination is presumed to come from prior tungsten silicide RTP, even though the quartz tube was etched before this study. Furthermore, the cross contamination of Ga and As occurred to the wafer backsides with no apparent activation energy, and this contamination is presumed to come from prior GaAs annealing several months before.
Anomalous Transient Diffusion of Ion Implanted Boron during Rapid Thermal Annealing
Authors: Kim Y. M. , Lo G. Q. , Kwong D. L. , Tseng H. H. , Hance R.
Published: March 2011

Effects of defect evolution during rapid thermal annealing (RTA) on the anomalous diffusion of ion implanted boron have been studied by implanting silicon ions prior to boron implantation with doses ranging from 1 × 1014cm−2 to 1 × 1016cm−2 at energies ranging from 20 to 150 KeV into silicon wafers. Diffusion of boron atoms implanted into a Si preamorphized layer during RTA is found to be anomalous in nature, and the magnitude of boron displacement depends on the RTA temperature. While RTA of preamorphized samples at 1150°C shows an enhanced boron displacement compared to that in crystalline samples, a reduced displacement is observed in preamorphized samples annealed by RTA at 1000°C. In addition, low dose pre-silicon implantation enhances the anomalous displacement significantly, especially at high RTA temperatures (1 150°C). Finally, the anomalous diffusion is found to depend strongly on the defect evolution during RTA.
Thermal Stability of Zinc and Selenium Implanted GaAs
Authors: Tang A C T , Sealy B J , Rezazadeh A A
Published: March 2011

We have observed for the first time reversible changes in the sheet carrier concentration of the rapid thermally annealed Se and Zn implanted GaAs samples during subsequent heat treatments. The electrical profiles of the implanted samples have also been modified during the annealing processes. By observing the initial rate of change in the carrier concentration, an activation energy of about 2 eV is obtained which is thought to correspond to the diffusion of gallium atoms/vacancies.
Electrical Properties of Si/SiGe Structures Grown by Low Temperature Epitaxy
Authors: Temkin H. , Green M. L. , Brasena D. , Bean J. C.
Published: March 2011

Si/SiGe heterostructures offer improved performance for many electronic and optoelectronic Si devices. The expected improvement in device characteristics depends critically on the structural perfection and precise compositional control of the epitaxial layers. This implies a combination of abrupt interfaces, on the order of 10 Å, capability of maintaining high doping levels, in the 1019 cm−3 range, with a similar spatial resolution, and low density of electrically active defects. These requirements are particularly stringent in the case of Ge-rich alloys for which the critical layer thicknesses are below ∼100 Å. The desired characteristics can be obtained by low temperature techniques such as molecular beam epitaxy (MBE) and rapid thermal chemical vapor deposition (RTCVD).
Amorphization and Annealing of 6H SiC Implanted with N-Type, P-Type or Isovalent Dopants
Authors: Spitznagel J. A. , Wood Susan , Choyke W. J. , Devaty R. P. , Ruan J.
Published: March 2011

lons of boron, phosphorous, titanium and neon were implanted into (0001) oriented 6H SiC crystals at 300 K. Implantation energies and fluences were chosen to produce equal (calculated) displacements per atom at similar peak damage depths and a randomized (metaminct or amorphous) zone extending to the front surface. RBS/channeling was used to test the amorphization criteria. Dopant effects on regrowth kinetics and microhardness have been determined by isochronal annealing.
In-Situ Measurement of Ion Beam Induced Deposition of Gold
Authors: Dubner A. D. , Wagner A.
Published: March 2011

mechanistic model of the ion beam induced deposition (IBID) process is proposed, and an experimental system for measuring IBID is described. In IBID, the kinetic energy of the incident ion is deposited in the substrate surface resulting in the ejection of atoms (sputtering), and the decomposition of adsorbed molecules. Net deposition occurs when the number of atoms added through decomposition exceeds the number removed by sputtering.

Gold films were deposited by decomposing dimethyl gold hexafluoroacetylacetonate (C7H7F6O2Au) molecules with a 5 keV argon ion beam. The beam current density was 5 μA/cm2. These films were deposited on quartz crystal microbalances (QCM). The QCM's provide an in-situ measurement of the deposition rate as a function of ion dose, dose rate, gas pressure, and substrate temperature. The mass of the depositing film increases with increasing ion dose. The deposition yield, or mass deposited per incident ion, is independent of the power input of the ion beam and therefore, the decomposition is not due to macroscopic heating. The deposition yield is shown to depend on the sputter yield of the substrate. The yield increases with increasing gas pressure and decreasing substrate temperature. This increase is proportional to the adsorption of the organometallic gas.
Lateral Confinement of Silicide Layers Synthesized with High Dose Implantation and Annealing
Authors: White Alice E. , Short K. T. , Berger S. D. , Huggins H. A. , Loretto D.
Published: March 2011

Using mesotaxy, a technique which involves high dose implantation followed by high temperature annealing, we have created narrow wires of CoSi2 buried beneath the surface of a silicon wafer. The implantation masks are fabricated directly on the silicon substrate using high resolution electron beam lithography in combination with reactive ion etching. TEM analysis shows that the wires are single-crystal and oriented with the substrate with very abrupt interfaces. The electrical continuity of the wires has been confirmed with electron-beam-induced current measurements.
Back Channel Degradation and Device Material Improvement by Ge Implantation
Authors: Namavar F. , Buchanan B. , Cortesi E. , Sioshansi P.
Published: March 2011

Because of potential “back channel” leakage problems in silicon-oninsulator (SOI) metal-oxide-semiconductor (MOS) devices, especially n-channel MOS devices which must operate in an ionizing radiation environment, it is desirable to produce Separation by IMplantation of OXygen (SIMOX) wafers which have a layer of poor quality silicon near the Si/buried SiO2 interface. At the same time, these wafers must have low defect, high quality silicon near the wafer surface for device fabrication.

We have demonstrated that with Ge ion implantation and solid phase epitaxy regrowth, the surface region of the silicon top layer of the SIMOX wafer is improved and the region adjacent to the buried SiO2 is degraded. These results have been observed by RBS/channeling, XTEM, and plane view TEM.
Effects of Helium Ion Implantation on the Optical and Crystal Properties of GaAs
Authors: Bowman R. C. , Adams P. M. , Knudsen J. F. , Moss S. C. , Dafesh P. A. , Smith D. D. , Herman M. H. , Ward I. D.
Published: March 2011

The damage to GaAs crystals caused by helium ion implants has been monitored by changes in the Raman scattering phonon modes, double-crystal x-ray diffraction rocking curves, photoreflectance (PR), and electron beam electroreflectance (EBER) band edge transitions. As the implanted helium ion dose was increased, the various techniques revealed threshold damage behavior at very different levels. Although PR and EBER were the most sensitive to the defects created at the lowest ion doses, all techniques indicated substantial disorder for implants greater than 1014 ions/cm2.
Ion Implantation into Inp/InGaAs Heterostructures Grown by Movpe
Authors: Häussler Wulf , Walter J. W. , Müller J.
Published: March 2011

Annealing of Beryllium implantations into epitaxial InP/InGaAs hetero-structures was investigated. Different ion energies were used to position the profile maximum in the InP cap, at the hetero-interface, or in the underlying InGaAs layer. By measuring the Be atom and carrier profiles, it is shown that annealing conditions necessary for optimum Be activation in the InP cap layer are compatible with good profile control for Be in InGaAs. There is a slight transfer of Be across the interface during annealing, which is important, if the pn-juntion is intended to be close to the hetero-interface.
The Study of Boron Implantation in 1:7 Nd/Fe Multilayers
Authors: Cheng Guoan , Peng Yingguo
Published: March 2011

The structures and magnetic characteristics of multilayered samples with alternatively deposited metal layers (Nd and Fe) were studied for 80 keV boron ion implantation to various doses. Boron ion implantation induced amorphization in Nd/Fe multilayers gradually with increasing irradiation dose. The hysteresis loops of magnetization of the samples showed that a sunken curve appear-ed in the second and fourth quadrants of the loops for the depo-sited Nd/Fe films and disappeared when implantation dose was more than 4*1016 B+/cm2. During ion irradiation, the coercive forces of the films were decreased. The saturation magnetization and the residual magnetization decreared first and then increased with increasing ion dose, the squareness ratio S. R increased first and then decreased. Discussion was carried out in this paper.
The Ion Implanted Arsenic Tail in Silicon
Authors: Beck S. E. , Jaccodine R. J. , Clark C.
Published: March 2011

Rapid thermal annealed tail regions of shallow junction arsenic implants into silicon have been investigated. Tail profiles have been roduced by an anodic oxidation and stripping technique after implantation to fluences of 1014 to 1016 cm−2 and by implanting through a layer of silicon dioxide. Electrical activation and diffusion have been achieved by rapid thermal annealing in the temperature range of 800 to 1100 °C. Electrically active defects remain after annealing. Spreading resistance and deep level transient spectroscopy results are presented. The diffusion of the arsenic tail is discussed and compared with currently accepted models.
Impurity Gettering by Implanted Carbon in Silicon
Authors: Wong H. , Cheung N. W. , Yu K. M. , Chu P. K , Liu J.
Published: March 2011

We have observed strong gold gettering by implanted carbon in silicon. It was found that the gettering agents in carbon implanted layers are point defects associated with singular carbon atoms. The positions of the gettered Au atoms were found to be distorted substitutional sites. A pointdefect gettering model is proposed to explain our findings.
New Electronic Properties of Metal / III-V Compound Semiconductor Interfaces
Authors: Brillson L. J. , Viturro R. E. , Chang S. , Shaw J. L. , Mailhiot C. , Zanoni R. , Hwu Y. , Margaritondo G. , Kirchner P. , Woodall J. M.
Published: March 2011

Recent studies of interface states and band bending at metal / III-V compound semiconductor interfaces reveal that these junctions are much more controllable and predictable than commonly believed. Soft x-ray photoemission spectroscopy studies demonstrate a wide range of band bending for metals on many III-V compounds, including GaAs. Cathodoluminescence spectroscopy measurements show that discrete states form at the microscopic junction which can have a dominant effect on the band bending properties. Internal photoemission measurements confirm the bulk barrier heights inferred by photoemission methods. After separating out surface chemical and bulk crystal quality effects, one finds simple, predictive barrier height variations which follow classical Schottky behavior.