bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternate Titanium Source Compounds for CVD of Ti/TiC Coatings
Authors: Groshens Thomas J. , Lowe-Ma Charlotte K. , Scheri Richard C. , Dalbey Robert Z. 
Published: March 2011

ABSTRACTCVD experiments were conducted using (Me3SiCH2)4Ti, Bis(2,4-dimethylpentadienyl) titanium, Cl3TiMe, (Me3SiCH2TiCl3 to evaluate their potential as Ti precursor compounds. Only Me3SiCH2TiCl3 was suitable for atmospheric CVD applications. Uniform thin films of polycrystalline TiC were deposited using Me3SiCH2TiCl3 in an argon ambient between 700 °C and 800 °C. A mechanism involving initial loss of Me3SiCl to generate a titanium carbene intermediate is proposed. Thin films of TiC deposited on Si[111] were characterized using XRD and AES. Depth profile line shape analysis showed only TiC and elemental Si in the interfacial region. XRD indicates some titanium silicide is formed at 800 °C. In a hydrogen ambient, hydrogenolysis of the alkyl group occurs and very poor film growth results were obtained.
Aluminum Particle Formation in the GaS Phase of a Low Pressure Chemical Vapor Deposition Reactor Using Dimethylethylamine Alane (AlH3) as a Precursor
Authors: Simmonds Michael G. , Gladfelter Wayne L. , Li Haojiang , McMurry Peter H. 
Published: March 2011

ABSTRACTParticle formation in the gas phase during the chemical vapor deposition of Al using dimethylethylamine alane was studied. Typical sizes of the crystalline Al particles monitoredwere in the range 20 nm to 1000 nm. Introducing trace amounts of H2O, CO and O2 into the reactor during the flow of the precursor caused an increase in the number of particles. Our results suggested that Al particle formation was induced by impurities in the gas phase although competing mechanisms could not be ruled out.
Metal Organic Chemical Vapor Deposition of Al and CuAl Alloy Films in a Vertical, High-Speed, Rotating Disk Reactor
Authors: Tompa G. S. , Wolak E. , Stall R. A. , George M. A. , Lippitt M. , Norman John A.T. 
Published: March 2011

ABSTRACTA vertical high-speed, rotating disk reactor has been used to produce Al and CuAl alloy films on 125 mm diameter Si (100) wafers. Trimethylamine-alane and Cu (hexafluoroacetylacetonate) trimethylvinylsilane (CupraSelect™) were used as metal precursors. Aluminum films were deposited over the temperature range from ∼100 C to 700 C. Aluminum sheet resistance measurements showed the films to have resistance 2 to 3 times that of bulk Al films. CuAl alloy films were deposited sequentially and by codeposition. At 30 Torr, deposition rates as high as 3.7 um/hr, 0.024 um/hr, and 1 um/hr for Al, Cu, and CuAl films, respectively, were demonstrated. Auger analysis showed the deposited films to be free of contaminants.
Low Temperature Selective Area Chemical Vapor Deposition of Gold Films: Growth and Characterization
Authors: Seidler Paul F. , Kowalczyk Steven P. , Holl Mark M. Banaszak , Yurkas John J. , Norcott Maurice H. , Read F. 
Published: March 2011

ABSTRACTSubstrate-selective, low-temperature chemical vapor deposition of high quality gold filmswas obtained with the new precursor ethyl(trimethylphosphine)gold(I) in an ultrahigh vacuum reactor designed to handle wafers up to 3 inches in diameter. Growth behavior at temperatures as low as room temperature as well as substrate pre-cleaning procedures are presented. Activation energies of 35.1 ± 0.4 kcal mol−1 and 18.3 ± 0.7 kcal mol−1 were found for growth of gold films on gold and copper substrates, respectively.
Copper CVD Reactions of Cu(I)(hfae)(vtms) Adsorbed on TiN
Authors: Guinn K. V. , Donnelly V. M. , Gross M. E. , Baiocchi F. A. , Petrov I. , Greene J. E. 
Published: March 2011

ABSTRACTWe have studied the thermal decomposition of a Cu MOCVD precursor, hexafluoroacetylacetonate copper vinyl trim ethylsilane (CuI (hfac)(vtms)), on both air-oxidized and N2 ion beam sputter-annealed single crystal (100) and polycrystalline TiN surfaces. Dosing TiN with CuI(hfac)(vtms) at 25°C results in chemisorption of CuIhfac) and desorption of vtms. On oxidized surfaces, litle or no decomposition of CF3 groups is detected at room temperature, while on sputter-annealed polycrystalline and single crystal surfaces, a small amount of decomposition is indicated by a CF2 feature in the C(1s) X-ray photoelectron spectroscopy (XPS) spectrum, and a low-binding energy fluoride in the F(1s) spectrum. Between 100 and 250°C, CuI(hfac) decomposes to evolve gaseous products and leaves Cu, F, and C on the surface. Further heating leads to diffusion of Cu into the TiN, apparently enhanced by simultaneous diffusion of F. Decomposition of the hfac CF3 groups at elevated temperature is independent of the nature of the TiN surface (i.e. polycrystalline vs. (100), or clean vs. oxidized). However, Cu diffusion depends strongly on the surface preparation. The onset of Cu diffusion into oxidized polycrystalline, clean polycrystalline, and clean single crystal (100) TiN occurs at 250, 320, and 430°C, respectively.
Substrate Pretreatments and Strength Limiting Factors in Cu-AlN Direct Bonds
Authors: Chiang Wan-Lan , Greenhut Victor A. , Shanefield Daniel J. , Johnson Lois A. 
Published: March 2011

ABSTRACTCu-AlN direct bonds were made by the gas-metal eutectic method. Two kinds of AlN substrates from different suppliers were used for the research. The AlN surfaces were preoxidized in O2 at three different temperatures. An optional “anneal” in Ar was applied following the oxidation procedure. Two processes were used for the bonding.The bond strengths and the failure modes were found to depend on the substrate used, the pretreatment of the AlN and bonding conditions. There was an optimum thickness for the Al2O3 layer on the AlN surface. High temperature annealing in Ar was demonstrated to effectively promote bond strength. The highest peel strength measured was 50 N/cm.A thermal expansion mismatch between Al2O3 and AlN was considered to be the main factor which dominated the ultimate bond strength. This mismatch resulted in a residual stress in the Al2O3 layer. A measurement by XRD indicated a 300 MPa tensile stress existed in the surface Al2O3 after AlN oxidation. This made Al2O3/AlN the weakest interface and limited the bond strength rather than the eutectic bond.
Comparison of Trichlorosilane and Trichlorogermane Decomposition on Silicon Surfaces Using FTIR Spectroscopy
Authors: Dillon A. C. , Robinson M. B. , George S. M. 
Published: March 2011

ABSTRACTFourier transform infrared (FTIR) transmission spectroscopy was used to compare the decomposition of trichlorosilane (SiHCl3) and trichlorogermane (GeHCl3) on silicon surfaces. Chlorosilanes, such as SiHCl3 are employed in silicon chemical vapor deposition (CVD). Chlorosilanes and chlorogermanes are also possible molecular precursors for the controlled atomic layer growth of silicon and germanium. GeHCl3 may be useful for the deposition of germanium on silicon surfaces and the growth of Si1−xGex heterostructures. The FTIR studies were performed in-situ in an ultra-high vacuum chamber on high surface area, porous silicon samples. The FTIR spectra revealed that SiHCl3 dissociatively adsorbs at 200 K to form SiH, SiClx, ClSiH and Cl2SiH surface species. The presence of ClxSiH species is revealed by ClxSiH stretching (2196 cm−1) and bending (775, 744 cm−1) vibrations. The presence of these modes indicates that there is incomplete decomposition of SiHCl3 upon adsorption at 200 K. GeHCl3 also dissociatively adsorbs at 200 K to form SiH and SiClx species. An infrared absorption feature in the Ge-H stretching region (1970–1995 cm−1) was not detected in the FTIR spectrum. The absence of a Ge-H absorption feature argues that there is a complete transfer of hydrogen from germanium to surface silicon atoms at 200 K. The thermal stabilities of the surface species were studied with annealing experiments. The Clx SiH formed upon initial SiHCl3 exposures at 200 K were observed to decompose between 200–590 K and form additional surface SiH and SiCl species. For both GeHCl3 and SiHCl3 dissociative adsorption on porous silicon, the SiCL. (x = 2 or 3) surface species were converted to silicon monochloride surface species between 200–600 K. In addition, SiH surface species were lost upon annealing between 680–780 K as H2 desorbed from the surface. The adsorption kinetics of SiHCl3 and GeHCl3 were also monitored on porous silicon at various isothermal temperatures. These experiments provide insight into the surface chemistry of chlorosilanes and chlorogermanes during CVD and atomic layer controlled growth.
Germanium Deposition on Silicon: Surface Chemistry of (CH3CH2)2GeH2 and GeC14
Authors: Coon P. A. , Wise M. L. , Dillon A. C. , George S. M. 
Published: March 2011

ABSTRACTDiethylgermane, (CH3CH2)2GeH2, and germanium tetrachloride, GeCl4 may be useful precursors for chemical vapor deposition (CVD) or atomic layer controlled deposition of germanium. To explore the surface chemistry of these alternative precursors, the adsorption and desorption kinetics of (CH3CH2)2GeH2 (DEG) and GeCl4 on Si(111) 7×7 have been examined using laser-induced thermal desorption (LITD), and temperature programmed desorption (TPD) techniques. Fourier transform infrared (FTIR) spectroscopy has also been employed to monitor the decomposition of DEG on porous silicon surfaces. The FTIR spectra revealed that DEG dissociatively adsorbs on porous silicon surfaces at 200 K to form SiH, GeH, and SiCH2CH3 surface species. No spectral features were observed for GeCH2CH3 surface species. The TPD studies following DEG exposures on Si(111) 7×7 observed CH2=CH2 and H2 desorption products at 700 and 800 K, respectively. The production of CH2=CH2 (ethylene) was consistent with a βhydride elimination mechanism from surface ethyl species, i.e. SiCH2CH3(ad) → SiH(ad) + CH2=CH2 (g). Similar TPD experiments following GeCl4 exposures monitored the desorption of only SiCl2 at approximately 920 K. Desorption of SiCl2 indicates that the chlorine on GeCl4 has transferred to the silicon surface. Atomic Ge was also observed to desorb at 1200 K following both DEG and GeCl4 adsorption. LITD experiments measured initial reactive sticking coefficients of So ∼0.05 for DEG and So ∼1.0 for GeCl4 at 200 K. As expected from a precursor-mediated adsorption model, the sticking coefficients decreased versus increasing surface temperature. The sticking coefficients for these germanium containing precursors were higher than the corresponding sticking coefficients for (CH3CH2)2SiH2 and SiCl4. Possible recipes for the CVD or atomic layer controlled deposition of germanium on silicon can be proposed based on the surface chemistry and adsorption and desorption kinetics for DEG and GeCl4.
Investigation of the Hydrogen Content of Silicon in an Integrated Rapid Thermal Processing Reactor
Authors: George M. A. , Beck S. E. , Bohling D. A. , Hames G. A. , Wortman J. J. , Melzak J. A. 
Published: March 2011

ABSTRACTThe effects of H2 and H atoms on electronic properties of crystalline silicon is of great interest to many scientists and technologists involved in developing and manufacturing of microelectronic devices. Hydrogen is of interest because of its ability to interact with defects and impurities in single crystal silicon, its abundance in many processing steps, and its effect on electronic structure of the interface between Si and SiO2. Here we present results of experiments examining the gas phase concentration of impurities during thermal oxidation and annealing of p(100) silicon. These experiments reveal that a significant quantity of hydrogen is contained in virgin wafers, which may have significant impact on thermal processing. A brief review of studies done on hydrogen diffusion in p-type silicon is provided with a perspective to the process investigated here.
Chemical Vapor Cleaning of Sodium from SiO2
Authors: Bohling David A. , Felker Brian S. , George Mark A. 
Published: March 2011

ABSTRACTChemical vapor cleaning (CVC) is an emerging technology which has been used to remove transition metal contamination from wafer surfaces. CVC is a gas phase/surface reaction which does not incorporate any wet steps nor condensation of reagents onto the wafer surface. In previous work, we reported the effective removal of trace iron and copper from native oxide surfaces using 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC) and other chelating or coordination compounds. In general, surface metal contaminants form volatile reaction products with these CVC reagents at relatively low temperatures (<300°C). In this paper, we report the extension of that work to include the facile removal of sodium from silicon oxide surfaces. Wafers doped with sodium from aqueous sodium hydroxide can be cleaned in a fully gas phase process at temperatures below 225°C.We will describe our preliminary process results, which have led to a surface sodium concentration reduction of roughly one order of magnitude. Current understanding related to the mechanisms controlling mobile ion removal will also be described.
Divinylmercury as a Precursor in the Metalorganic Molecular Beam Epitaxy of Hg Containing II-VI Materials
Authors: Zinck J. J. , Rajavel D. 
Published: March 2011

ABSTRACTWe have used x-ray photoelectron spectroscopy, temperature programmed desorption, and epitaxial growth experiments to study the feasibility of using divinylmercury (DVHg) as a precursor for metalorganic molecular beam epitaxial (MOMBE) growth of Hg-containing II-VI materials. The surface chemistry associated with the interaction of DVHg and Te was investigated using polycrystalline Te (poly-Te) films as the substrates for DVHg adsorption. nDVHg dissociatively adsorbed on a poly-Te surface at temperatures as low as -118°C. However, the DVHg dissociation probability was temperature dependent and substantially less than unity when extrapolated to typical Hg1−xCdx Te growth temperatures of 150–200°C. Preliminary results from MOMBE growth experiments showed that successful MOMBE growth of HgTe on CdTe//ZnTe//GaAs using DVHg and thermally precracked diethyltellurium was only possible when the DVHg was also thermally precracked. Simultaneous exposure of atomic H and DVHg to a poly-Te surface significantly enhanced the dissociative adsorption of DVHg, indicating that the presence of atomic H in the growth environment may be an effective alternative to precracking DVHg for MOMBE growth.
IR Diagnostics of MOCVD Reaction Chemistry
Authors: Weiller Bruce H. 
Published: March 2011

ABSTRACTThe gas-phase chemical reactions in the Metallorganic Chemical Vapor Deposition (MOCVD) of A1N and TiN have been studied using IR spectroscopy. The products formed from the reaction of trimethyl aluminum (TMA) and NH3 were compared to those from the reaction of TMAwith NF3 using a static gas-phase IR cell. Reaction with NH3 is rapid at 25 °C, and the IR spectrum of the product is consistent with the acid-base adduct (CH3)3Al-NH3. At 25 °C, no reaction between TMA and NF3 was observed. However, at 58 °C a slow reaction occurredto give (CH3)2AlF. The reaction of Ti(N(CH3)2)4 with NH3 was also studied using a flow-tube reactor with a sliding injector port that provides control over the reaction time between two reactive flows. By monitoring the disappearance of Ti(N(CH3)2)4 as a function of NH3 partial pressure and reaction time, we have obtained a preliminary estimate of the rate constant as ∼ 10−16 cm3 molecule−1 s−1 at 25 °C. This result confirms that the reaction is rapid even at room temperature and demonstrates the utility of the flow-tube reactor and FTIR spectrometer for studies of MOCVD chemistry.
Formation of TiO2 Thin Films by Oxidation of TiN
Authors: Truman J. K. , Ballentine P. H. , Terzioglu E. , Kadin A. M. 
Published: March 2011

ABSTRACTTiN thin films were deposited by reactive sputtering onto Si substrates. TiO2 films were formed by subsequent oxidation of the TiN films, using either conventional furnace heating or rapid thermalprocessing (RTP). The materials properties of the resulting films were characterized by x-ray diffraction and Rutherford backscattering, and indicate conversion of the TiN to fully-oxidized rutile TiO2 by a diffusion-limited process. Electrical measurements of the insulating properties of the TiO2 films indicated a relative dielectric constant greater than 100, although the leakage current was greater than optimum. A fully in-situ process for the fabrication of microcapacitors is proposed, which involves the sputter deposition of TiN, the formation of TiO2 by RTP, and the deposition of a top TiN counterelectrode. This can be carried out under conditions that are compatible with Si microelectronic device processing.
Some Theoretical Aspects of Carbon Incorporation into III-V“s
Authors: Weyers Markus 
Published: March 2011

ABSTRACTCarbon as a constituent of some of the source molecules is always present in the metalorganic growth techniques and can potentially be incorporated into the grown layers. Unintentional carbon incorporation as well as intentional carbon doping of III-V compounds has been studied intensely, especially in the case of GaAs. However, a number of experimental findings still is not well understood. Besides the different electrical behavior of carbon in different host materials (acceptor in GaAs, donor in InAs) also the different probability of incorporation into, for example, GaAs compared to InAs is currently not well explained. Model calculations may provide useful hints to enhance the understanding of the experimentally observed trends. In this paper, two different approaches will be reviewed and their results will be discussed.The first approach is dealing with the expected incorporation site of carbon in III-V“s. The change in total energy associated with substitutional carbon incorporation onto group III or group V lattice sites has been calculated. From this change the conduction type of carbon doped arsenides and phosphides (except for InAs) can correctly be predicted. While this method is dealing with the bulk semiconductor, the second approach attempts to model the binding energy of methyl to atoms on the growing surface. By using appropriate molecules the methyl bond strength can be estimated. Both approaches together provide a basis for a more complete understanding of carbon incorporation behavior in III-V compounds.
Pyrolysis Studies of Single-Source Precursors to Gallium Phosphide
Authors: Lee Kenneth E. , Lowe-Ma Charlotte K. , Higa Kelvin T. 
Published: March 2011

ABSTRACTNew dialkylgallium dialkylphosphide compounds having the formula [(t- Bu)(R)GaPR'2]n (R = t-Bu, Me3SiC=C; R' = t-Bu, i-Pr, Et; n = 1, 2) were recently prepared and characterized. When R = R' = t-Bu, the compound is a low melting, monomeric solid. The other compounds are dimeric solids with the unsym-metrical acetylides occurring as cis and trans isomers. Polycrystalline gallium phosphide was deposited from these sources on silicon atlow pressure (0.05–0.1 Torr) and low temperature (350–600 °C) in a horizontal OMVPE reactor. The film growth was monitored by a residual gas analyzer and the by-products were trapped (N2(1)) to be later analyzed by 1H and 13C NMR. The deposited films were characterized by Raman spectroscopy, X-ray powder diffraction, and Auger emission spectroscopy.
Alternative Group V Precursors for the Growth of Al-Based III-V Epitaxial Layers by OMVPE
Authors: Hobson W. S. , Geva M. 
Published: March 2011

ABSTRACTTertiarybutylarsine (TBAs), tris-dimethylaminoarsenic (DMAA), and tertiarybutylphosphine (TBP) were investigated as alternatives to arsine and phosphine for the growth of AlGaAs, AlInAs, and AlInP by organometallic vapor phase epitaxy. The use of TBAs led to a significant reduction in carbon and oxygen incorporation compared to ASH3 for AlGaAs. Increasing the TBAs molar flow rate reduced the oxygen (and carbon) concentration. Lower oxygen concentration was observed in AllnP grown with TBP compared to PH3. Increasing the PH3 molar flow rate decreased the oxygen incorporation in AllnP. The morphology of AllnP improved considerably as the growth temperature was increased from 650°C to 750°C, similar to the case of PH3. AlInAs and AlGaAs layers grown with DMAA exhibited rough morphology, presumably due to oxygen-containing impurities in the DMAA source.
Reaction and Transport Models of the MOVPE of Ternary III-V Semiconductors
Authors: Ingle N. K. , Mountziaris T. J. 
Published: March 2011

ABSTRACTReaction and transport models describing the deposition of thin films of ternary compoundsemiconductors by Metalorganic Vapor Phase Epitaxy (MOVPE) are being developed. The growth of AlxGa1−x As (0≤x≤1) films from trimethyl-aluminum (TMA1), trimethyl-gallium (TMG) and arsine has been used as a typical example. A kinetic model of the process including both gas phase and surface reactions has been coupled to a two-dimensional transport model of a horizontal reactor with a flat susceptor. The model predicts reported experimental observations on growth rates and film compositions [1] using a single adjustable parameter, the activation energy of the the AlAs growth reaction. A parametric study was performed to identify operating conditions maximizing the thickness andcompositional uniformity of the deposited films. All inlet flow rates considered in this work were higher than the ones required to suppress transverse buoyancy-driven recirculations in the reactor [2,3]. Such conditions permit the growth of abrupt heterojunctions byrapidly switching various precursors on and off. Our results indicate that the most promising operating conditions coincide with the transition from kinetic limited to diffusion limited growth, which occurs at temperatures between 800 K and 850 K for typical experiments [1]. The optimal inlet mole fraction of the limiting group-III species was found to be about 6×10−4 for such cases.
PL and FTIR Absorption Study on Porous Silicon in Situ During Etching, in Oxygen Ambient, and After Chemical Oxidation
Authors: Mauckner G. , Walter T. , Baier T. , Thonke K. , Sauer Abteilung R. 
Published: March 2011

ABSTRACTSteady state and time-resolved photoluminescence (PL) and Fourier-transform infrared (FTIR) spectroscopy have been performed in situ during etching, on “as prepared” porous Si in air under laser exposure and on chemically oxidized porous Si. We suppose that PLdegradation of “as prepared” porous Si is caused by creating non-radiative defect centers during photooxidation. Chemically oxidized porous Si shows increased PL intensity and longer recombination lifetimes as compared to non-oxidized samples. We conclude, that an oxide layer with low defect density on the inner surface of chemically oxidized porous Si reduces the non-radiative recombination rate.
Radiative and Non-Radiative Processes for the light Emission from Porous Silicon
Authors: Vial J. C. , Bsiesy A. , Fishman G. , Gaspard F. , Herino R. , Ligeon M. , Muller F. , Romestain R. , Macfarlane R. M. 
Published: March 2011

ABSTRACTHighly porous silicon, well passivated via an anodic oxidation process, is a stable and efficient visible light emitter showing a 3% photoluminescence efficiency at room temperature. Luminescence decay times are on the order of 100 μs at room temperature and 10 ms at low temperature. Above room temperature the de-excitation is dominated by non-radiative processes well describe by a tunnelling escape of carriers from confined regions. The “anomalous” luminescence behaviour showing a dramatic increase of the lifetimes upon cooling associated with a decrease of the intensity is explained by the temperature dependence of the effective radiative recombination rates due to a population redistribution among two excited states with very different radiative relaxation rates.