By Topic

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films

Issue 2 • Date Mar 1992

Filter Results

Displaying Results 1 - 25 of 29
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (250 KB)  
    Freely Available from IEEE
  • Polycrystalline TiN films deposited by reactive bias magnetron sputtering: Effects of ion bombardment on resputtering rates, film composition, and microstructure

    Page(s): 265 - 272
    Save to Project icon | PDF file iconPDF (8416 KB)  

    Transmission electron microscopy, x‐ray diffraction, and Rutherford backscattering have been used to investigate the effects of ion irradiation during growth on the deposition rate, composition, and microstructure of single‐phase polycrystalline NaCl‐structure TiNx films deposited by reactive magnetron sputtering with a negative substrate bias voltage Vs. The layers were deposited on thermally oxidized Si(001) substrates in mixed Ar+4% N2 discharges at a total pressure of 4.2 mTorr. Varying Vs between 0 and 1800 V resulted in incident ion‐to‐Ti atom flux ratios of 0.3 to 0.6 at the film growth surface and increases in the substrate temperature Ts (initially Ts=300 °C) of 40 to 200 °C. The Ti resputtering yield increased from ≤0.02 (Vs≤100 V) to 0.30 (Vs=1800 V) Ti atoms per incident ion (primarily Ar+), while the N/Ti ratio in as‐deposited films increased from 1.03 for Vs=0 V to 1.12 for 100 V≤Vs≤400 V and then decreased to ≂0.95 as Vs was raised to 1800 V. Trapped Ar concentrations ranged from ≤0.5 at.% (Vs=0) to ≂5.5 at.% (Vs=1800 V). However, the Ar was not randomly dispersed in films grown with Vs≳1000 V and gas bubbles were observed. Film lattice parameters a0 were found to vary from the bulk value of 0.4240 nm at Vs=0 to a maximum of 0.4295 nm at Vs=800 V and then decrease to 0.4265 nm at Vs=1800 V. Voided grain boundaries were observed in films grown with Vs≤120 V. The use of higher substrate biases initially resulted densification of grain boundaries with a corresponding decrease in average grain size. However, with Vs≥800 V, the films again became less dense and- - increased intragranular defect densities were observed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characterization of sputter deposited tungsten films for x‐ray multilayers

    Page(s): 273 - 280
    Save to Project icon | PDF file iconPDF (1020 KB)  

    The microstructural and optical properties of tungsten thin films prepared by dc magnetron sputtering were investigated as a function of the argon pressure. The films were characterized by x‐ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), x‐ray diffraction (XRD), grazing x‐ray reflectometry (GXR), and spectroscopic ellipsometry (SE). From the analysis of the XPS data, the films were found to consist of a base tungsten layer, a graded oxide transition layer, and a surface oxide layer. Also, the thickness of the oxide layers were determined. XRD indicated that the films were either amorphous or composed of crystallites with grain size ≪100 Å. STM and GXR have revealed that the films grown at low pressures were the smoothest. Finally, SE measurements allowed the determination of the dielectric function of a compact tungsten layer. Further SE analysis of the films indicated that with increasing argon pressure, the films developed into a more voided columnar structure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Molecular beam deposition of Dy1Ba2Cu3O7-δ(001) high‐temperature superconductor thin films

    Page(s): 281 - 283
    Save to Project icon | PDF file iconPDF (464 KB)  

    Epitaxial Dy1Ba2Cu3O7-δ(001) high‐temperature superconductor thin films on LaAlO3 substrates have been prepared by coevaporation of Dy, BaF2, and Cu and postannealing. The vapors in desired ratio were evaporated from effusion cells in a miniature molecular beam deposition system. The films show critical transition temperature (Tc,0) of 89.5±0.5 K. During process development it was found that single phase Dy1+xBa2-xCu3Oy(001) thin films can be grown (x=0 to 0.3). Their electrical properties were useful in calibration of quartz crystal thin film thickness monitor (FTM) for determination of relationships between the actual vapor arrival rate (flux) and FTM reading. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of the deposition gas mixture on the structure and failure modes of diamondlike carbon films

    Page(s): 284 - 289
    Save to Project icon | PDF file iconPDF (15513 KB)  

    Diamondlike carbon films have been deposited from binary mixtures of 1,3 butadiene and hydrogen or argon in a radio‐frequency parallel plate plasma reactor. An infrared spectroscopic analysis revealed some of the effects of the diluents (hydrogen and argon) on the bonding characteristics of the deposited films. The film properties are a strong function of the deposition gas mixture. Hydrogen and argon both increase the diamondlike behavior. However, there is a trade‐off between enhanced diamondlike characteristics and a tendency to delaminate or crack due to excessive stress and poor adhesion. The failure modes and stress relief forms have been imaged by the Nomarski interference contrast technique. Two new stress relief forms have been observed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • One GHz leaky SAW velocity of metal layers and bilayers evaporated onto fused quartz

    Page(s): 290 - 294
    Save to Project icon | PDF file iconPDF (641 KB)  

    An acoustic microscope operating at 1 GHz was used to determine the surface acoustic wave velocities v of thin film metal layers and metal bilayers deposited onto fused quartz. V(0)’s influence was reduced by gating. This produced a calibrated accuracy of 3%. A program was constructed from the explicitly solved 6×6 theoretical determinant. Single film thicknesses were decided upon by using this theory to produce a v equal to a standard. Since the single film v’s were linear with respect to their thickness, half the single film thicknesses were used for the bilayered films. The velocities for these bilayered films agreed with theory. This experimentally confirms the theoretical technique used here to examine bilayered systems, or a prototype composite interphase. No discrepancy was seen for gold films as others have reported. V(z) seemed insensitive to the formation of intermetallics or CuO. Some annealed and unannealed platinum films did not change the v from that of fused quartz. Two platinum films whose v’s were in agreement with theory peeled off with the tape test. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characterization of Cu–In–Se–Te system in thin films grown by thermal evaporation

    Page(s): 295 - 300
    Save to Project icon | PDF file iconPDF (2143 KB)  

    The growth conditions of thin films of Cu–In–Se–Te system fabricated by thermal evaporation and their composition, structural, optical, and electrical properties have been studied. When analyzing the optical absorption coefficient of the films, several energy gap discrete values appear: 0.86±0.04, 0.95±0.05, 1.26±0.06, 1.51±0.02, and 1.71±0.03 eV. Resistivities and mobilities varying in the ranges of 10-3 to 8 Ω cm and 0.2 to 28.6 cm2 V-1 s-1, respectively were found depending on growing conditions. The ‘‘as grown’’ samples were p type. The thermal treatments may change the type of conduction from p to n. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reactive ion etching (CF4+O2 plasma) induced deep levels in metal–oxide–semiconductor devices

    Page(s): 301 - 304
    Save to Project icon | PDF file iconPDF (571 KB)  

    A reduction in device dimensions requires more accurate etching procedures. Reactive ion etching (RIE) provides many of the needed improvements. The energetic ions and photons produced by the glow discharge plasma of RIE, individually or in combination, can create lattice damage thereby forming trapping centers for electrons and holes at the Si–SiO2 interface, as well as in the bulk silicon. In this work the capacitance–voltage (C–V) measurement techniques and deep level transient spectroscopy (DLTS) were used to investigate the interface trapping sites and the bulk defect centers at or near to the Si–SiO2 interface region, produced by the energetic ions and/or photons present in the reactive ion etching. An electron trap level, ascribed to a bulk defect, was detected using the DLTS technique. In this study two types of metal–oxide–semiconductor (MOS) test structures were used to investigate the origin of damage. It has been observed that a major source of RIE damage in MOS structures and to the underlying silicon substrate can be energetic photons. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of Ti–W target processing methods on defect generation during very large scale integrated device fabrication

    Page(s): 305 - 312
    Save to Project icon | PDF file iconPDF (3942 KB)  

    The relationship between Ti–W target manufacturing technique and deposited film quality is examined with an emphasis on film defect density. Three different target manufacturing methods are investigated; vacuum hot pressing (VHP), inert gas hot pressing, and hot isostatic pressing. The target composition in all cases is 18 wt % titanium, the configuration is seven inch diameter conical and two purity levels (99.95% and 99.995%) are evaluated. Target processing methods and microstructure results are discussed. Scanning electron microscopy micrographs show distinct differences in the amount of pure alpha titanium and the homogeneity of the titanium and tungsten rich beta Ti–W phases. The characteristics of films deposited from each of the three targets are investigated. Standard film properties are presented with an emphasis on film defect density as measured by several different methods. Transmission electron microscopy micrographs of the deposited film show distinct differences in film structure. Significant differences in defect density were also found with the VHP having the lowest overall defect density. A mechanism for defect generation due to pressure within target voids is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Borophosphosilicate glass crystal induction and suppression

    Page(s): 313 - 315
    Save to Project icon | PDF file iconPDF (2841 KB)  

    Grapelike crystalline cluster defects with no specific shapes were induced in borophosphosilicate glass (BPSG) deposited in a low‐pressure chemical vapor deposition tube following cooling of the film to room temperature. The crystal defects were induced by exposing the film for about 3 min to high, controlled humidity (80%–90%) and a temperature of 30±2 °C. The film was then fused for 15 min in a 900 °C furnace at four different atmospheres: N2, O2, 1:1 O2/N2, or steam (3 min)/N2 (12 min). The steam/N2 treatment was the only effective ambient to eliminate BPSG crystal defects. A chemical mechanism is proposed to explain the crystal appearance in BPSG film. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A high resolution electron energy loss spectroscopy study of trimethylgallium decomposition on gallium rich GaAs(100)

    Page(s): 316 - 320
    Save to Project icon | PDF file iconPDF (834 KB)  

    The adsorption and decomposition of trimethylgallium (TMGa) on the gallium rich (4×6) and (1×6) GaAs(100) surfaces have been studied by high resolution electron energy loss spectroscopy (HREELS), in conjunction with temperature‐programmed desorption, x‐ray photoelectron spectroscopy, and low energy electron diffraction. TMGa adsorbs molecularly at 108 K and dissociates above 200 K to form monomethylgallium (MMGa) and, possibly, some dimethylgallium surface species. Above 400 K, MMGa dominates. Surface MMGa remains stable until 650 K, above which temperature methyl radicals desorb. HREELS results showed unambiguously that methyl groups remain intact throughout the thermal decomposition of TMGa on GaAs(100). The effect of UV photons on both surface TMGa and MMGa has also been investigated, but no photochemistry was observed at wavelengths longer than 230 nm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Heteroepitaxial growth of alkali halides on a GaAs(001) substrate

    Page(s): 321 - 323
    Save to Project icon | PDF file iconPDF (1448 KB)  

    Heteroepitaxial growth of alkali halides on GaAs(001) substrates was studied by use of reflection high‐energy electron diffraction and electron energy loss spectroscopy (EELS). In the case of NaCl growth on a GaAs(001) substrate (misfit 0.40%), epitaxial growth occurred when the substrate temperature was between 100 and 300 °C. EELS revealed that the NaCl film thicker than 3 nm completely covers the substrate and that the grown film is stoichiometric. This contrasts with the case of KBr growth on a GaAs(001) substrate, where epitaxial growth was not observed. The latter result seems to be due to the large misfit (16.8%). However, KBr was found to grow epitaxially on a NaCl‐on‐GaAs(001) substrate. The NaCl epilayer enables heteroepitaxial growth of another foreign alkali halide. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adsorption and desorption kinetics for SiH2Cl2 on Si(111) 7×7

    Page(s): 324 - 333
    Save to Project icon | PDF file iconPDF (1656 KB)  

    The adsorption and desorption kinetics for dichlorosilane (SiH2Cl2) on Si(111) 7×7 were studied using laser‐induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. The TPD experiments monitored H2, HCl, and SiCl2 desorption products at 810, 850, and 1000 K, respectively. H2, HCl, and SiCl2 desorption products were also observed in the LITD yield at all surface coverages. In agreement with the TPD studies, linear ramp LITD experiments monitored the disappearance of the H2, HCl, and SiCl2 LITD signals at 810, 850, and 1000 K. LITD measurements determined the initial reactive sticking coefficient (S0) of SiH2Cl2 on Si(111) 7×7 versus surface temperature. The sticking coefficient was S0≊0.36 at temperatures from 150 to 200 K. Above 200 K, the sticking coefficient decreased to S0≊0.10 at 350 K and S0≊0.0025 at 850 K. The temperature‐dependent sticking coefficient was consistent with a precursor‐mediated adsorption model. As a function of surface coverage following SiH2Cl2 exposure, TPD studies observed that the HCl desorption yield decreased relative to the H2 and SiCl2 desorption yields. These results indicated that when more hydrogen desorbs as H2 at higher coverages, the remaining chlorine is forced to desorb as SiCl2. TPD experiments also determined that the surface chlorine coverage saturated and was independent of surface temperature after large SiH2Cl2 exposures on Si(111) 7×7. Epitaxial growth of silicon by dichlorosilane chemical vapor deposition can be predicted using the measured adsorption and desorption kinetics for dichlorosilane on Si(111) 7×7. When these kinetics are employed together with incident SiH2- - Cl2 fluxes, very good agreement is observed between predicted and measured silicon growth rates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Phase transition of the Si(111)–Au surface from √3 ×√3 to 5×1 structure studied by means of the low‐energy electron diffraction, Auger electron spectroscopy, and Rutherford backscattering spectroscopy techniques

    Page(s): 334 - 338
    Save to Project icon | PDF file iconPDF (721 KB)  

    The changes of the Au coverage and the structure of the Si(111)–√3×√3‐Au surface induced by isothermal annealing in the temperature range of 500–575 °C have been studied by means of low‐energy electron diffraction (LEED), Auger electron spectroscopy, and Rutherford backscattering spectroscopy techniques. It is found that the Au coverages by RBS and AES at each temperature decay exponentially down to 0.75 ML, above which only the LEED pattern of √3×√3 spots is observed, and decay biexponentially from 0.75 ML and a mix of √3×√3 + 5×1 spots is observed down to 0.54 ML at 575 °C, 0.52 ML at 550 °C, and 0.61 ML at 530 °C, below which only the LEED pattern of 5×1 spots is observed. From analysis of the decay curves of Au coverages, it is determined that the activation energies for Au atoms to be dissolved from the √3×√3 structure and the 5×1 structure into the bulk and for phase transition of the Au/Si(111) surface from the √3×√3 to the 5×1 structure are 2.5±0.5, 2.8±1.0, and 1.6±0.4 eV, respectively. The process for the phase transition is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Photoemission study of the SiO2/Si interface structure of thin oxide film on vicinal Si(100) surface

    Page(s): 339 - 343
    Save to Project icon | PDF file iconPDF (728 KB)  

    The SiO2/Si interface structure of thin oxide films thermally grown on vicinal Si(100) surfaces with the surface normal inclined at small angles with respect to [100] toward [001], has been investigated using high‐resolution core‐level photoemission spectroscopy with synchrotron radiation. Photoemission data suggest that as a result of the thermal oxidation Si(111) and (110) facets are favorably generated at the SiO2/Si interface on the vicinal Si(100) surfaces. It is also suggested that an ordered phase of SiO2 is present on the interfacial Si(111) facets. The generation of this phase is found to strongly depend on the inclination angle of the substrate surface to the (100) plane. This dependence is interpreted in terms of the variation in the density of interfacial Si(111) facets with the inclination angle. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnitude and effects of adsorbent temperature nonuniformities in temperature‐programmed desorption

    Page(s): 344 - 352
    Save to Project icon | PDF file iconPDF (1414 KB)  

    In a typical apparatus for temperature‐programmed desorption (TPD) measurements, heat is not added uniformly to the entire adsorbent volume, but rather is generated in support wires and conducts in at the contact points, forming a temperature gradient in the adsorbent during heating. Based on a simplified, one‐dimensional treatment, we determine the approximate magnitude of the temperature profile and investigate its deleterious effects in TPD simulations for first‐order kinetics. Analysis of the coupled equations governing surface temperature and coverage leads to a dimensionless group of parameters involving the heating rate, the desorption rate parameters, and the size and physical properties of the adsorbent that determines the magnitudes of systematic errors introduced by the temperature nonuniformity. The simulations allow a general expression to be developed for the maximum heating rate in TPD that will give estimates of E and ln(ν) reliable to within a few percent. The predictions of the model are verified by comparison to TPD data for CO/Ni(110). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermally stimulated exoelectron emission from graphite surfaces exposed to oxygen, tetrafluoromethane, and argon plasmas

    Page(s): 353 - 361
    Save to Project icon | PDF file iconPDF (1063 KB)  

    We have investigated the thermally stimulated exoelectron emission (TSEE) from graphite surfaces exposed to O2, CF4, and Ar plasmas in combination with the measurements of surface potential (SP) and x‐ray photoelectron spectroscopy (XPS). The surfaces exposed to the plasmas were left in the ambient air prior to the measurements. The TSEE glow curves, the change in SP, and the XPS spectra were examined as a function of plasma exposure time and pressure. The TSEE glow curves for each plasma gas exhibited one sharp emission peak (peak I) at ∼98 °C, the intensity of peak I decreasing in the order, O2≳CF4≳Ar. Furthermore, for CF4 plasma a broad peak (peak II) was also observed at ∼250 °C. The SP for the surfaces exposed to the plasmas became highly negative, decreasing in the order, Ar≳O2≳CF4. This can be attributed to an increase in the O and F contents on the surface. The change in SP after the plasma treatment was nearly reversed to the original value in each case after the TSEE measurement. The origins for the TSEE peaks I and II are discussed based on the change in SP and the atomic ratios of O1s/C1s and F1s/C1s measured by XPS. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Quantitative analysis of ionic solids by secondary neutral mass spectrometry

    Page(s): 362 - 367
    Save to Project icon | PDF file iconPDF (870 KB)  

    Using an argon high frequency plasma for excitation and postionization, secondary neutral mass spectrometry was performed to examine the ability of the technique for depth‐resolved quantitative analysis of ionic solids. An argon energy Ep=300–500 eV was applied to bombard all alkali halides, some sulfates, Li2SiO3, Li4SiO4, NaNO3, and Na2CO3. The mass spectra obtained were found to be dominated by atomic signals including all elements of the measured salt. Averaged relative sensitivity factors for 20 elements calculated from these signals show close conformity to atomic ionization probabilities. Thus, the majority of sputtered neutrals from salts consists of atoms and these dominate also the whole sputter flux. All measured sensitivity factors lie within a range of 400 being the sensitivity ratio of cesium to fluorine. A moderate matrix dependence of mostly less than 40% is probably due to coemitted thermal and/or nonatomic species. A minor fraction of the neutral sputter flux (≪1% total signal intensity) consists of binary molecular clusters, of which the heteroelemental could be useful for compound identification. Erosion rates were determined to be 0.3±0.1 nm/s for five different salts under 0.6 mA/cm2 primary current. The corresponding sputter yields are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Quantitative analysis of deuterium implanted in crystalline silicon and pyrolytic graphite by pulsed XeCl laser desorption

    Page(s): 368 - 373
    Save to Project icon | PDF file iconPDF (897 KB)  

    We have investigated the pulsed XeCl laser induced thermal desorption of deuterium implanted in crystalline silicon (c‐Si) and highly oriented pyrolytic graphite (HOPG). Calibrations and experimental procedures for the quantitative analysis of deuterium are described. The desorption thresholds are 0.55±0.09 and 0.43±0.07 J/cm2 for c‐Si and c‐axis HOPG, respectively. However, for a‐axis HOPG, deuterium is difficult to desorb because of the higher thermal conductivity. As a desorption product from HOPG, CD4 has also been observed. The deuterium evolution in both c‐Si and c‐axis HOPG has been modeled with the code dtrlas. It appears to be mainly limited by the detrapping processes with the effective activation energies, EB= 1.2 ± 0.3 eV and EB = 2.35 ± 0.55 eV for c‐Si and c‐axis HOPG, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Au/Si interface: Experiments on substrate influence

    Page(s): 374 - 380
    Save to Project icon | PDF file iconPDF (2285 KB)  

    We have studied the influence of amorphous and crystalline substrate materials, such as a‐Si and a‐Si:H, as well as c‐Si(111), (100), and hydrogen implanted c‐Si(111) on the outdiffusion of Si through an evaporated Au thin film, and its subsequent oxidation in atmosphere. Using Auger electron spectroscopy depth profiling we observed that the SiO2 layer thickness d formed on top of the Au film strongly depends on the type of substrate material giving most enhanced Si outdiffusion from amorphous ones. The metastable phase AuxSi is detected on both interfaces between the Au/Si and the SiO2/Au layers. A temperature independent ratio, dH/d ≊ 2, is observed for the oxide layer thickness of substrates with and without hydrogen. This is a surprising result, which indicates the influence of nonthermodynamic effects, probably related to the surface structure of the semiconductor substrates and a strong influence of hydrogen. A model of the layer structure is developed, which permits the calculation of diffusion activation energies resulting in qHD ≂ qD ≂ 1.0 (eV) for the diffusing species on substrates with and without hydrogen, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cu/PI and Cu/PET adhesion: Influence of Si+ ion mixing

    Page(s): 381 - 387
    Save to Project icon | PDF file iconPDF (2824 KB)  

    The adhesion and interfacial chemistry of 50 nm Cu films on poly[N,N‐ (p,p’‐oxydiphenylene) pyromellitimide] (PI) and poly(ethylene terephthalate) (PET) substrates were examined as a function of 28Si+ implantation through the interfaces. The implantation was performed with 70 keV 28Si+ to doses between 1 and 10×1016 Si/cm2, while the substrate temperature was kept between 50 and 80 °C. The implantation induced extensive interfacial mixing and interfacial chemistry changes in both the Cu/PI and Cu/PET specimens. X‐ray photoelectron spectroscopy analysis of the ion‐induced Cu/PI interfacial chemistry indicated that the implanted 28Si+ had reacted with both the film substrate species to form Cu–Si, Si–O, and Si–C bonding, which suggested the formation of interfacial complexes, such as Cu–Si–C and Cu–Si–O–C. Similar interfacial chemistry was produced in the Cu/PET specimens by the implantation. However, additional Cu 2p3/2 and O 1s peaks associated with Cu–O–Si bonding were observed, suggesting the formation of Cu–O–Si–C interfacial complexes. Despite these changes in interfacial chemistry, only small (factor of 2) changes in adhesion were observed upon scratch testing. The absence of larger adhesion increases was attributed to the rather weak bonding between Cu and Si. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of hydrogen adsorption on the performance of the W(001) spin‐polarized low‐energy electron diffraction electron polarimeter

    Page(s): 388 - 393
    Save to Project icon | PDF file iconPDF (787 KB)  

    Since hydrogen is the main residual gas in a metal ultrahigh vacuum chamber, the effect of hydrogen adsorption on the performance of an electron polarimeter based on spin‐polarized low‐energy electron diffraction (SPLEED) from the W(001) surface, has been investigated experimentally. The experiments involved both dosing the analyzer crystal to calibrated coverages of hydrogen, and allowing residual gas in the vacuum chamber to adsorb on the analyzer crystal surface. The sensitivity (Sherman function, S) and efficiency (figure of merit, F) were monitored using SPLEED rotation curves. The W(001) SPLEED polarimeter is found to be resiliant to hydrogen adsorption. The sensitivity and efficiency require only a small scaling, which is linear in hydrogen coverage up to about 0.5 of saturation coverage. In a residual hydrogen partial pressure of 1 × 10-10 Torr, the analyzer crystal need be cleaned only every 2 h. The polarimeter may also be operated with a saturation coverage of hydrogen on the analyzer crystal. Under these conditions, the sensitivity falls to S=-0.19±0.02 and the efficiency to F = 4 × 10-5. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of two filtered cathodic arc sources

    Page(s): 394 - 397
    Save to Project icon | PDF file iconPDF (575 KB)  

    Cathodic arcs produce a highly ionized metal vapor which has proven useful in the production of dense, adherent coatings. For many applications, the macroparticles normally produced by the cathodic arc are unacceptable and must be filtered out. We have developed two filtered cathodic arc sources which have distinctly different operational characteristics. One of these makes use of so‐called ‘‘steered arc’’ magnetic control of the arc trajectory, while the other employs a different form of arc control. The ion transmission efficiencies of these sources were improved by carrying a portion of the arc electron current through the filter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measurement and modeling of ion energy distribution functions in a low pressure argon plasma diffusing from a 13.56 MHz helicon source

    Page(s): 398 - 403
    Save to Project icon | PDF file iconPDF (596 KB)  

    Helicon sources coupled to diffusion chambers provide a new method for better controlling plasma processing. It is, however, important to understand the effect of diffusion on the plasma evolving from the source to the wafer situated in the chamber. The diffusion of a 300 W argon plasma from a 13.56 MHz (6 cm diam, 20 cm long) cylindrical magnetic field free source into a 30 cm diam, 20 cm long chamber has been experimentally and theoretically investigated. A mobile electrostatic energy analyzer was used to measure the electron temperature, plasma potential, plasma density, and ion energy distribution functions (EDFs) along the common axis of the source and chamber. An analytical model based on experimental results has been developed. Although there is a potential difference of around 40 V between the source and the substrate table, charge exchange collisions associated with the plasma expansion reduce the average energy of the ions impinging on a grounded probe at the bottom of the chamber to about 3 eV. At 1 μbar the number of collisions is too low to cool all of the ions accelerated in the field and a tail remains in the ion distribution function. Although not measured, hot neutrals should also be generated as a consequence of charge exchange collisions and will impinge on the substrate. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the activation energy for the dissociation of the carbon–iodine bond in methyl iodide adsorbed on Ni(100) surfaces

    Page(s): 404 - 405
    Save to Project icon | PDF file iconPDF (228 KB)  

    The chemistry of methyl iodide on Ni(100) surfaces has been studied by using x‐ray photoelectron spectroscopy (XPS). Methyl iodide adsorption is molecular below 100 K, but the C–I bond begins to cleave around 120 K and is completely broken by 160 K. The activation energy for the C–I bond scission was estimated to be about 3.5 kcal/mol based on results from isothermal XPS experiments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles.

Full Aims & Scope

Meet Our Editors

Editor
G. Lucovsky
North Carolina State University