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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures

Issue 5 • Date Sep 1994

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Displaying Results 1 - 25 of 34
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • Fabrication and characterization of an array of gated avalanche p+–n++ junction as a micro‐vacuum triode

    Page(s): 2875 - 2879
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    An array of 3×4 ultrashallow p+–n++ silicon junctions with gate (grid) structure has been developed for application as a micro‐vacuum triode. The device is fabricated by low energy ion implantation in conjunction with a new anode oxidation technique. The final junction depth is estimated to be 150 Å. Device structure and fabrication processes, especially on the formation and monitoring of the ultrashallow junction, are described. The current emission characteristics of the triode are investigated as a function of anode voltage, gate (grid) voltage, anode–emitter distance, and reverse bias current. The typical emission efficiency measured on bare silicon is 7.6×10-5. View full abstract»

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  • Investigation of optical and electrical properties of ZnO ultrafine particle films prepared by direct current gas discharge activated reactive method

    Page(s): 2880 - 2883
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    The electrical and optical properties of ZnO ultrafine particle (UFP) films prepared by a new dc gas discharge activated reactive deposition technique were investigated. IR spectra and work function were used to study the samples. The results show that ln σ vs 1000/T accords with the Arrhenius equation at 227–300 °C, the absorption edge is near 480 nm, IR eigen absorption peaks of ZnO (UFP) films shift to high energy (short wavelength) with decreasing particle size. The work function changes with gas pressure was discussed. View full abstract»

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  • Scanning tunneling microscope tip‐induced anodization of titanium: Characterization of the modified surface and application to the metal resist process for nanolithography

    Page(s): 2884 - 2888
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    Nanometer scale oxide patterns were fabricated on titanium (Ti) surfaces on the basis of scanning tunneling microscope (STM) tip‐induced anodization. The spatial resolution of the method was limited to approximately 20 nm, owing to the surface roughness of the Ti film used. Chemical analyses of fabricated patterns by Auger electron spectroscopy proved that the surface chemical composition of the pattern was titanium dioxide (TiO2), and the oxide thickness on the pattern was certainly thicker than that of the native oxide on the unmodified area. A novel Ti‐metal resist process for nanolithography based on STM tip‐induced anodization was proposed. The Ti film on which anodized patterns were formed could be etched by hydrofluoric acid using the anodic oxide patterns as an etching mask. Ti lines of ∼60 nm in width were successfully fabricated by the present method. View full abstract»

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  • Electrostatic removal of lithium fluoride from field‐emitter tips at elevated temperatures

    Page(s): 2889 - 2893
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    The electrostatic removal of lithium fluoride (LiF) from field‐emitter tips has been visualized at elevated temperatures in the transmission electron microscope (TEM). The apex of a field‐emitter tip coated with ∼1500 Å of LiF provides a unique substrate for observing the removal process in the TEM in real time, and its curvature generates the required electrostatic field strength. The influence of the imaging electron beam on coating morphology has been visually assessed. A LiF coating can tolerate an electron dose of ∼2000 e-2 at room temperature without visible damage (at a resolution of 5 Å). At elevated temperatures a higher dose can be tolerated before visible damage is observed. Removal of LiF coatings at room temperature occurs at 18 MV/cm. At 800 °C piecewise removal of the coating occurs at 9 MV/cm. Synergistic effects of the electron beam and the electrostatic field on the removal of the coating were not observed. The removal of LiF at any temperature is attributed to field‐induced fatigue stress of the coating. Field desorption does not appear to play a significant role in the removal process. Implications for the production of ions from lithium fluoride thin films exposed to high electric fields (in laboratory experiments and in particle beam fusion accelerators such as PBFA II) are discussed. View full abstract»

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  • Scanning tunneling microscopy of Cl2‐gas etched GaAs (001) surfaces using an ultrahigh vacuum sample transfer system

    Page(s): 2894 - 2900
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    A novel ultrahigh vacuum (UHV) sample transfer system was constructed for the purpose of transferring Cl2‐gas etched GaAs samples from an in situ processing UHV multichamber to a scanning tunneling microscopy (STM) chamber. First, the performance of the sample transfer system was confirmed by an UHV‐STM observation of an As‐stabilized (2×4) structure of a molecular‐beam epitaxially (MBE) grown GaAs (001) surface. Next, four kinds of Cl2‐gas etched samples were prepared in the UHV multichamber, and an UHV‐STM observation of these etched surfaces was carried out. A strong dependence of the surface roughness on the etching temperature was observed; a 200 °C Cl2‐gas etched GaAs (001) surface exhibited a corrugation amplitude of several nanometers, which was about 1.5‐times smaller than that of a 70 °C etched surface. Through annealing under an arsenic pressure at 600 °C which is a typical temperature for MBE growth, the smoothness of the etched surfaces remarkably improved; the corrugation amplitude of the 70 °C etched surface decreased by a factor of 2, and that of the 200 °C etched surface decreased by a factor of 3–4. As a result, the 200 °C etched surface has become very smooth, being only about 1.5‐times rougher than the MBE grown surface. This indicates the usefulness of the in situ fabrication processes, since an interface formed by Cl2‐gas etching and following MBE regrowth has been guaranteed to be nearly as smooth as an as‐grown surface. View full abstract»

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  • Combined scanning tunneling microscopy/spectroscopy study on the surface electronic structure of GaAs(100) with spatially resolved scanning tunneling spectroscopy spectra

    Page(s): 2901 - 2904
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    A combined scanning tunneling microscopy/scanning tunneling spectroscopy (STS) system has been developed by which the spatially resolved electronic structure of a surface can be measured step by step consecutively. With this system, etched GaAs(100) surfaces have been studied in ambient with experimental measurements of the (d ln I/d ln V) vs V curves along a line on the surfaces. The curves exhibit the basic band structure of GaAs. Specific band energies from the curves are plotted versus the surface position at which each of the corresponding STS spectra is measured. The plots show a correlative variation of the surface electronic structure with the surface corrugations. The results present the possibility of investigating the spatial variation of the surface electronic states with surface structures. Based on the correlative variation of the surface electronic structure, a way of imaging the surface corrugation more sensitively is proposed. View full abstract»

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  • Integration of vertical‐cavity surface‐emitting devices by molecular beam epitaxy regrowth

    Page(s): 2905 - 2909
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    We used two‐step molecular beam epitaxial (MBE) growth to integrate monolithically single and double vertical‐cavity structures on a wafer. This technique is useful for making a single vertical‐cavity surface‐emitting laser–thyristor with a low threshold and a double vertical‐cavity heterojunction phototransistor with both a high responsivity and a large spectral bandwidth. Regrowth on a patterned distributed Bragg reflector after thermal desorption of a passivating GaAs layer resulted in the laser in the single‐cavity section having a threshold current density of 1.0 kA/cm2, which is comparable to that of one grown by conventional one‐step MBE. Controlling thickness to within ±0.3% resulted in the regrown double‐cavity section having a bandwidth of 5 nm. View full abstract»

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  • Improved inverted AlInGa/GaInAs two‐dimensional electron gas structures for high quality pseudomorphic double heterojunction AlInAs/GaInAs high electron mobility transistor devices

    Page(s): 2910 - 2915
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    Molecular beam epitaxy grown AlInAs/GaInAs single quantum well high electron mobility transistor structures (SQW‐HEMT) on InP were developed for transistor applications with high current drive capability. Use of low growth temperatures for the layers below the GaInAs channel in case of the inverted interface proved to be essential to achieve simultaneously high electron concentrations in the channel region and mobilities equal to those of normal single heterojunction HEMT structures. The mobilities obtained in SQW‐HEMT structures which employed Si δ‐doping on both sides of the SQW channel were found to be only weakly dependent on the channel thickness down to 16 nm whereas below the mobility tended to degrade. Based on theoretical calculations an optimum spatial distribution of the carriers is deduced aiming at high channel electron density and low parallel concentration in the lower supply region by optimizing the thickness of the spacers and the asymmetric distribution of the donors above and below the channel. Further improvements of the SQW‐HEMT structures were obtained by incorporating elastically strained In‐rich channels. In this way, increased mobilities and concomitantly enhanced electron concentrations have been achieved. Unsurpassed 77 K mobilities amounting up to 55.000 cm2/V s in conjunction with a Hall carrier density of 6.0×1012 cm-2, which compares with a simulated channel density of 5.4×1012 cm-2, were attained. 0.6 μm gate length devices fabricated on the optimized SQW‐HEMT layer structures clearly demonstrate the superior performance of the SQW design in terms of saturation current without compromising the pinch‐off behavior. View full abstract»

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  • Fabrication of self‐aligned GaAs/AlGaAs and GaAs/InGaP microwave power heterojunction bipolar transistors

    Page(s): 2916 - 2928
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    Self‐aligned processing of high efficiency power heterojunction bipolar transistors (HBTs) using implant isolation, selective wet and dry etching for mesa formation, plasma‐enhanced chemical vapor deposited SiNx for sidewall spacers and through‐wafer via connections is reported. GaAs/AlGaAs and GaAs/InGaP HBTs grown by metalorganic molecular beam epitaxy utilizing carbon for high, well‐confined base doping produced power‐added efficiencies of 63%, power gain of 10 dB and output power of 1.7 W at 4 GHz for twelve 2×15 μm2 double‐emitter finger devices (GaAs/AlGaAs) and 57% power‐added efficiency, power gain of 11.3 dB and output power of 0.6 W at 4 GHz (GaAs/InGaP), respectively. View full abstract»

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  • Self‐aligned dry‐etching process for waveguide diode ring lasers

    Page(s): 2929 - 2932
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    A dry‐etching process that produces very smooth facets in the AlGaAs/GaAs material system is described. Chemically assisted ion beam etching (CAIBE) is used to fabricate the facets, with SiO2 as the etch‐mask. Reactive ion etching (RIE) is used to transfer the resist pattern to the underlying SiO2 layer. RIE operating conditions, including gas type, power density, and etching pressure were characterized to achieve smooth SiO2 sidewalls. It is found that CF4 etching at low power density of 0.10 W/cm2 and low pressure of 1 mTorr produces very smooth SiO2 sidewalls. As a result, excellent etched facets are obtained by CAIBE, using SiO2 as the etch‐mask. This dry‐etching process is being used to fabricate waveguide diode ring lasers. A self‐aligned etching process, which defines both the ridge and the facets for the ring lasers in the same lithography step, is also discussed. View full abstract»

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  • Reactive ion etching of GaAs through wafer via holes using Cl2 and SiCl4 gases: A comprehensive statistical approach

    Page(s): 2933 - 2940
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    The reactive ion etching behavior of GaAs in Cl2 and SiCl4 gases is investigated with regard to the suitability of this process for etching through wafer via holes using a photoresist mask. The criteria used are etch rate, profile (wall angle), selectivity, undercut, and smoothness of the etch. The experimental points were chosen using a D‐optimal statistical design. The experimental results have been evaluated by multiple stepwise regression, eliminating insignificant terms from a quadratic model of the controlled parameters (mask bake time, power, pressure, chlorine flow, and etch time). Empirical models of the dc bias and each etch criterion are obtained. The highest etch rates, at over 3 μm/min, are obtained in high chlorine concentrations at high dc bias values (high power and low pressure) for short etch times. This method yielded an optimized process for etching metallizable via holes. View full abstract»

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  • Dependence of contact resistivity and Schottky diode characteristics on dry etching induced damage of GaInAs

    Page(s): 2941 - 2946
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    GaInAs was etched in a Cl2 plasma generated with an electron cyclotron resonance source. The effects of changing etch parameters on etch rate, morphology, and surface damage were analyzed. Increased microwave power, rf power, and Cl2 percentage in Ar caused the etch rate to increase monotonically. The etch rate decreased with increasing distance and reached a maximum for a pressure of 1.0 mTorr. The etch conditions were chosen to maintain smooth morphology, which requires a balance between ion energy, ion flux, concentration of reactive species, and pressure. Ohmic contacts for transmission lines and Schottky contacts for diodes were deposited directly on the etched GaInAs surface for the evaluation of etch induced damage. It was found that the transmission line measurements were more sensitive to surface damage than the diode characteristics and the specific contact resistivity (ρc) was a more sensitive measure of the damage than sheet resistivity. Defects generated by dry etching typically caused a reduction in ρc. The contact resistivity decreased with increasing rf power and source distance. More damage was introduced when only rf power was applied, as indicated by the lower ρc compared to when both microwave and rf power were applied. Addition of 10% Cl2 in Ar dramatically reduced the damage when compared to etching only with Ar. Increasing the pressure from 0.5 to 5.0 mTorr caused an increase in ρc but a degradation in surface morphology. The damage depth was estimated to be ∼6 nm at 50 W rf power and increased to ∼18 nm at 200 W rf power. Minimal surface damage was obtained when low rf power was used. For a self‐induced dc bias of -68 V (25 W rf power), ρc was 8.3×10-5 Ω cm2, similar to the control sample. View full abstract»

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  • CH4/H2/Ar/Cl2 electron cyclotron resonance plasma etching of via holes for InP‐based microwave devices

    Page(s): 2947 - 2951
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    We report on a dry etch process for backside through‐wafer via hole fabrication in InP‐based transistors which addresses many manufacturing issues including wafer mounting schemes, degradation of the frontside ohmic metal pads, yield across two‐inch wafers, and reliability issues. Low pressure electron cyclotron resonance plasma etching using a CH4/H2/Ar/Cl2 gas chemistry is investigated and compared to other InP via etching techniques. A photoresist mask was used to define 54 μm×54 μm backside vias in substrates thinned to ∼50 μm. Post‐baking the resist served both to strengthen the mask against the plasma, and to control the profile of the through‐via. The etching was performed at a temperature of 130 °C to enhance etch product volatility while allowing a reliable wax‐mounting scheme for the thinned wafers. Etch rates of ∼1 μm/min were obtained for 950 W microwave power and 250 W rf power (-260 V). After ∼95% of the etched depth was achieved, the rf bias was reduced to minimize sputtering of the frontside metal pad on which the etch terminates. After the residual resist mask was removed, the samples were metalized, de‐mounted, and tested for electrical connection, resulting in high yield via etching across the wafer. View full abstract»

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  • Study of silicon etching in CF4/O2 plasmas to establish surface re‐emission as the dominant transport mechanism

    Page(s): 2952 - 2962
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    This article describes an investigation of the etching of polysilicon in a CF4/O2 plasma. The ‘‘undercut’’ observed in etch profiles is related to the surface transport of reaction precursors. The possible mechanisms for this transport include surface re‐emission and surface diffusion of the precursors. Simulations of profile evolution, conducted with both mechanisms, are compared with experimental results. The surface reemission simulations are found to predict experimental profile evolution accurately, whereas surface diffusion simulations require unphysical values for the surface diffusion length. Novel test structures have been fabricated and etched under the same conditions as used for trench etching. Surface re‐emission simulations accurately predict the etch rate deep inside the shadowed cavity of different structures. On the other hand, simulations assuming surface diffusion to be dominant do not capture even the qualitative trends in test structure etching. This is strong evidence that surface re‐emission is the dominant mechanism for transport of etch precursors in CF4/O2 plasmas. View full abstract»

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  • Linewidth uniformity versus etch rate uniformity in refractory metal plasma etching

    Page(s): 2963 - 2969
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    Etch rate, etch rate uniformity, linewidth uniformity, and microloading in tungsten, molybdenum, and niobium plasma etching have been studied. Electrical linewidth data with typically 100–300 measured lines/wafer have been used. Relation between linewidth uniformity and etched depth uniformity (as measured by profilometer) has been explored. Effects of tungsten film deposition processes (oxygen contamination) have been studied. Tungsten etch rate maximum in SF6/O2 is at 85/15 ratio for the oxygen contaminated films, but higher oxygen percentage in SF6/O2 is required for maximum etch rate of pure films. Oxygen impurities in the tungsten film affect the etch rate but neither linewidth nor linewidth uniformity. In molybdenum etching in Cl2/O2 plasma the etched depth uniformity gives an overly pessimistic uniformity value even though linewidth uniformity is acceptable 12% (3σ). Addition of 3%–6% of CHF3 to Cl2/O2 is shown to change microloading characteristics and to improve linewidth uniformity. On 100 mm wafers, 6%–12% (3σ) linewidth uniformities were obtained for the different metals. Linewidth differences between isolated and array lines were 4%–8%. View full abstract»

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  • Tungsten etching in pulsed SF6 plasmas

    Page(s): 2970 - 2975
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    Tungsten etching in pulsed plasmas has been investigated in a helicon plasma source reactor. The time dependence of the fluorine atom concentration has been measured using the time‐resolved actinometry technique and related to the etch rate. According to our observations, it appears that fluorine adsorption on the tungsten substrate surface continues in the post‐discharge period until the surface saturates. Moreover, it appears that two etching regimes exist. For short discharge off periods, the etching is limited by the fluorine adsorption ability of the surface, whereas for long periods, the etching is limited by the desorption rate of the etch products. Experiments were performed at different substrate temperatures and plasma gas pressures. An empirical model has been developed, in good agreement with the experimental data. View full abstract»

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  • Electron beam‐induced deposition of tungsten

    Page(s): 2976 - 2979
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    Tungsten films were deposited by decomposing films of frozen tungsten hexafluoride (WF6) with an electron beam and then warming the substrate to remove unreacted WF6. Deposition rates increase with increasing beam intensity. View full abstract»

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  • Compositional variation in sputtered Ti–W films due to re‐emission

    Page(s): 2980 - 2984
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    To test for re‐emission of titanium and/or tungsten during sputter deposition (PVD) of Ti and Ti–W, films were deposited on wafers with test structures which have large interior areas which are not in line of sight to the source volume. Auger electron spectroscopy (AES), scanning electron microscopy, and transmission electron microscopy results show that very little Ti is re‐emitted during Ti PVD, but a significant fraction of incoming Ti is re‐emitted during Ti–W PVD. AES spectra along the perimeter of a cross section show that Ti–W films become Ti rich in areas of the test structures without line of sight to the source volume. We also considered Ti–W deposited into trench structures. Physically based, three dimensional deposition process simulations, assuming either diffuse or specular re‐emission of Ti, qualitatively explain the experimental results for these trenches. The available information is not sufficient to decide whether the Ti sticking factor is lower on Ti–W films or if Ti is resputtered by incoming W. View full abstract»

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  • Long‐term reliability of Pt and Mo diffusion barriers in Ti–Pt–Au and Ti–Mo–Au metallization systems for GaAs digital integrated circuits

    Page(s): 2985 - 2991
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    Reliability of Ti–Pt–Au and Ti–Mo–Au systems has been investigated for GaAs integrated circuit first‐level metallizations on semi‐insulating GaAs substrates and second‐level metallizations on interlayer SiO2 films using Auger depth profile analysis, residual resistance examination and temperature storage step‐stress testing. Auger analysis and residual resistance examination showed significant reaction between first‐level Ti–Pt–Au and GaAs substrates during metallization processes, while Ti–Mo–Au system with the electron‐beam evaporated Mo film showed higher thermal stability because the Mo film acted as a good diffusion barrier between GaAs and Au. The second‐level Ti–Pt–Au on SiO2 was found to be free from the reaction with GaAs substrates, and its degradation was ascribed to interdiffusion of composite metals. The resistance increase in step‐stress testing for the second Ti–Pt–Au was analyzed on the basis of a new diffusion‐controlled model, and long‐term reliability was estimated. A mean time to failure value of 3×105 h at 150 °C was obtained for a failure defined as 10% increase in resistance. Much higher reliability was estimated for Ti–Mo–Au, because the resistance continued to decrease as long as 3000 h at 250 °C. The decrease in resistance clearly indicates defect annealing with reduced defect scattering in Au layers. This also shows that foreign metal diffusion into Au, acting as impurity scattering centers, is perfectly eliminated by Mo diffusion barriers. View full abstract»

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  • Electromigration in AlSiCu/TiN/Ti interconnects with Ti and TiN additional layers

    Page(s): 2992 - 2996
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    AlSiCu/Ti(TiN)//TiN/Ti interconnect structures, which have been fabricated by depositing a Ti or TiN additional layer on the TiN/Ti barrier exposed in atmospheric ambient and then by depositing AlSiCu on the additional layer without breaking vacuum, have shown improved electromigration lifetimes. These were 1.9 and 6.5 times longer than that of the conventional AlSiCu//TiN/Ti structure, for the TiN and Ti additional layer, respectively. From an analysis of these results, it has been assumed that elongated lifetimes were caused by an enhancement of the Al(111) crystallographic orientation in the AlSiCu/TiN//TiN/Ti structure, and caused by both a reduction of the Si nodule concentration in AlSiCu due to Al–Si–Ti ternary alloy formation and Al(111) texture further enhanced by the additional Ti underlayer in the AlSiCu/Ti//TiN/Ti structure. View full abstract»

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  • Reaction between diamond and titanium for ohmic contact and metallization adhesion layers

    Page(s): 2997 - 3005
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    The reaction of sputter deposited layers of Ti on the (001) surface of a synthetically grown single crystal type IIb boron doped diamond has been investigated using Auger electron spectroscopy with depth profiling, Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. Electrical characteristics of the contacts were measured using I–V data and separated from substrate electrical effects using Hall measurements of the carrier concentration and mobility. Heat treatments above 425 °C were found necessary to cause the transition from a rectifying to an ohmic contact. Without a protective 150 nm layer of Au, oxidation of the Ti layer was observed at T≥425 °C, even for annealing in forming gas. This was detrimental to the adhesion of the layer and the long term stability of the ohmic contact resistance. With a protective Au film, low resistance, adherent ohmic contacts were observed even after 1 h at 750 °C, even though Ti diffused along Au grain boundaries to form nodules of TiO2 at the Au/ambient interface. Interfacial carbides were detected by both Auger peak shape changes and RBS measurements for annealing temperatures as low as 500 °C, and their appearance correlated with the transition to ohmic contacts. The carbides increased in thickness to about 50 nm after 1 h at 750 °C. View full abstract»

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  • Fabrication of n‐metal–oxide semiconductor field effect transistor with Ta2O5 gate oxide prepared by plasma enhanced metalorganic chemical vapor deposition

    Page(s): 3006 - 3009
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    n‐metal–oxide semiconductor field effect transistors (MOSFETs) were fabricated with plasma enhanced metalorganic chemical vapor deposited Ta2O5 gate oxide on Czochralski grown Si wafers using localized oxidation of silicon isolation technology by the conventional Si‐based process. The Ta2O5 gate oxide n‐MOSFETs showed excellent electrical characteristics such as subthreshold swing of 68–74 mV/dec, transconductance of 4 μS/μm for 4 μm gate length, and carrier mobility of 400 cm2/V s at the saturation region. The large Cox of the gate oxide with the high dielectric constant, ϵr=20–25, allowed the higher drain current of the device. During the whole process of n‐MOSFET fabrication, the cross sectional transmission electron microscopy analysis of the Ta2O5/Si interface showed SiO2 interfacial oxide formation of about 35 Å thick. The Ta2O5 gate oxide n‐MOSFET showed good performance compared to the high‐temperature silicon oxide gate devices and thus has great potential for applications in the electronic devices. View full abstract»

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  • Silicon surface electrical properties after low‐temperature in situ cleaning using an electron cyclotron resonance plasma

    Page(s): 3010 - 3015
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    Electron cyclotron resonance hydrogen plasma and argon plasma was used to clean Si surface without additional heating within 4 min and 30 s, respectively. Changes in the electrical properties after plasma treatment with different exposure times have been studied and compared using a Schottky diode structure. The reverse saturation current of the Schottky diodes changes less in the case of the hydrogen plasma cleaned samples than the argon plasma cleaned samples. After hydrogen plasma exposure, residual hydrogen introduced into the Si was found to enhance greatly the formation of thermal donors which induces considerable changes in the defect states after annealing. After annealing at ∼450 °C in N2, new defects, caused by thermal donors, appear and these defects decrease significantly at 750 °C. Defects in the argon plasma treated samples annihilate after annealing at 1000 °C for 1 h. View full abstract»

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  • Thermal stability of highly Sb‐doped molecular beam epitaxy silicon grown at low temperatures: Structural and electrical characterization

    Page(s): 3016 - 3022
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    The structural and electrical properties of highly Sb‐doped molecular beam epitaxy grown silicon have been investigated as function of rapid thermal annealing (RTA) temperature. Doping levels of 3×1020 cm-3 were obtained using low temperature epitaxy (LTE) performed at a growth temperature of 300 °C. Ion channeling and transmission electron microscopy (TEM) measurements showed that the as‐grown samples were of very high quality. The combination of Hall‐effect profiling and Rutherford backscattering spectroscopy revealed an electrically active Sb fraction of 0.8. Short time RTA processing improved the electron mobility and the activation: RTA at 600 °C for 10 s yielded unity activation and RTA at 800 °C gave mobilities matching phosphorus doped bulk values, thus significantly exceeding previously reported values for highly doped LTE material. A degradation of the crystalline quality was observed for higher RTA temperatures: RTA at 1000 °C for 10 s reduced both the Sb‐substitutional fraction and electrical activation to 0.6 due to precipitation of Sb, and lead to the formation of a high density of dislocation loops as observed by TEM. A large fraction of the precipitates decorated these dislocation loops. Mesa isolated diodes were fabricated to evaluate the use of LTE material for device production. Current–voltage measurements on these diodes revealed high quality junctions with low reverse currents and near‐ideal forward characteristic. View full abstract»

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

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Gary E. McGuire
International Technology Center