bluuebunny/crossref_metadata_2025 huggingface dataset:
Excimer Laser-Induced Shallow Diffusion of Boron
Authors: Kato S. , Nagahori T. , Matsumoto S. , Fujioka T.
Published: March 2011

The very shallow junction of boron has been formed by the irradiation of ArF excimer laser on silicon substrate set in BF3 ambient. The sheet resistance decreases with the increase of the number of pulses and saturates above 150 pulses. It also decreases with increasing both gas pressure and laser energy density. The junction depth increases with increasing the number of pulses, ranging from about 400 Å to 2000 Å. It is confirmed from SIMS and four-point probe measurements that boron atoms diffused are electrically activated up to the concentration of about 1020cm−3.
Oxygen Precipitation Studies for N-Type and Epitaxial Silicon Substrates During Simulated Cmos Cycles by Synchrotron Section Topography
Authors: Tuomi T. , Hahn S. , Tilli M. , Wong C.-C. D. , Borland O.
Published: March 2011

Synchrotron section topography is applied to the study of silicon wafers pulled out froma simulated advanced CMOS twin-tub process. Substrates are heavily doped with antimony and phosphorus. For comparison also high-resistivity samples are studied. Prior to epi deposition of arsenic doped layers some wafers are subjected to a three-step intrinsic gettering cycle.

Section topographs show that in the lightly doped samples a denuded zone is formed by the CMOS process itself in contrast with the heavily doped ones in which the intrinsic gettering is needed.
Infrared and Ion Beam Analysis of SIxN1−x Alloys Grown by Ion Beam Assisted Deposition
Authors: Donovan E.P. , Brighton D.R. , Vechten D. Van , Hubler G.K.
Published: March 2011

Thin films of amorphous SixNl-x alloys were produced by nitrogen ion beam assisted deposition of electron beam evaporated silicon. Infrared reflection spectra were measured in the range 600 to 10000 cm−1. Fringes were observed due to interference between light multiply-reflected from the front surface and film-substrate (single crystal silicon) interface. Similar measurements were performed on films crystallized by post-deposition furnace anneals. Analyses of the reflection spectra were used to obtain refractive index profiles. Profiles were correlated with nitrogen content as measured by Rutherford BackscatterLng Spectometry (RBS) and Auger Electron Spectroscopy (AES). Film adhesion, density, and purity were found to be improved for depositions assisted by nitrogen ion beams (1000 to 25,000 eV) relative to unassisted evaporation, and the index of refraction decreases monotonically with increasing nitrogen content.
Performance and Reliability of thin Gate Dielectrics for VLSI: Materials and Processing Perspective
Authors: Singh R.
Published: March 2011

Current trends are in the direction of submicron MOSFETs employing gate dielectrics in the thickness range of about 30 - 100A°. The performance and reliability of submicron MOSFETs can be improved by using high dielectric constant gate dielectric material. A new concept involving 2 or more dielectric material is proposed in this paper. In- situ rapid isothermal processing is proposed for the fabrication of thin gate dielectrics.
Lateral Extension of Dislocations in Nmos Ic.
Authors: Tseng W. F. , Wilkins B. R. , Mccarthy D.
Published: March 2011

Dislocations extending through channel regions of NMOSFETs with submicron gate lengths have been observed. Additionally, arrays of dislocations in the field regions of IC's have also been observed and found to be generating from the corners of the first n+ region during subsequent high temperature process.
Dolts of Polysilicon for Solar Cell Applications
Authors: Mclarty P.K. , Huang Y.I. , Ioannou D. E. , Johnson S.M.
Published: March 2011

DLTS was applied to p—type polycrystalline silicon, grown by a casting technique to form ingots with a nominal doping level of ∼1016 acceptors/cmg. Both Schottky diodes and n+p mesa structures were used for the measurements. Very complex DLTS spectra were obtained from diodes that contained electrically active grain boundaries, whereas no traps were detected in areas that did not contain electrically active grain boundaries. Several electron and hole traps were resolved.
Characterization of the Sol-Gel Transition of Alumina Sols Prepared from Aluminum Alcoxides via 27Al NMR
Authors: Olson William L. , Bauer Lorenz J.
Published: March 2011

27Al NMRsp ectra were obtained on a series of alumina sols prepared by the hydrolysis of aluminum sec-butoxide. Subtle but distinct differences were observed in the solution 27Al NMR spectra of sols which varied in appearance from being very milky to completely transparent. No changes were observed in the 27Al spectra of sols which had been aged. The adddition of sufficient quantities of acid or base to gel the sol precipitated dramatic changes in the Al spectra. Aluminum-27 NMR was found to be a highly useful tool for probing the sol-gel transformation of this system.
Raman Spectra of Rings in Silicate Materials
Authors: Tallant D. R. , Bunker B. C. , Brinker C. J. , Balfe C. A.
Published: March 2011

Raman spectroscopic studies on gel-derived silicates have confirmed that narrow bands near 607 cm-1 and 492 cm-1, first observed in the Raman spectrum of fused silica, are associated with three- and four-fold siloxane rings. Using these results, we have identified three- and four-fold siloxane rings in other high-surface-area silica materials, including leached glasses and Cab-OSil. This Raman spectroscopic evidence not only shows that small siloxane rings are a common characteristic of a number of silica materials but also suggests that they form preferentially at silica surfaces. This paper reviews the Raman spectroscopic evidence that led to the identification of the vibrational frequencies of the small siloxane rings and presents the results of Raman experiments on high-surface-area silica materials in which the concentration of small siloxane rings is enhanced compared to fused silica.
Chemical Route to Aluminosilicate Gels, Glasses and Ceramics
Authors: Pouxviel J. C. , Boilot J. P. , Dauger A. , Huber L.
Published: March 2011

Chemically ultra-homogeneous gels have been prepared, in the SiO2-Al2O3 system, using new metal-organic precursors with Al-O-Si linkages. By thermal treatment at 900°C, transparent monolithic gels lead to aluminosilicate glasses and above 1000°C, to optically transparent glass-ceramics (for instance by homogeneous crystallization of mullite in an amorphous silica matrix).
Precursors to Boron-Nitrogen Macromolecules and Ceramics
Authors: Narula C. K. , Paine R. T. , Schaeffer R.
Published: March 2011

Boron nitride has been prepared in the past from classical high temperature reactions and more recently by CVD methods. Few attempts have been made to prepare this important material from pyrolyses of preceramic oligomers or polymers. In the present study oligomerization reactions of substituted borazenes with silyamine crosslinking groups have been found to provide useful gel materials which upon pyrolysis form boron nitrogen materials. Selected aspects of this chemistry and some characterization of the materials is presented.
Structure and Properties of Ceramic Fibers Prepared From Polymeric Precursors [1]
Authors: Lipowitz J. , Freeman H. A. , Goldberg H. A. , Chen R. T. , Prack E. R.
Published: March 2011

Ceramics can be prepared by pyrolysis of organosilicon polymers. Advantages of this method of ceramics preparation are; the ability to prepare shapes difficult to achieve by other methods such as fibers and films; the ability to achieve high purity because reagents used to prepare the polymer can be purified by well established chemical methods; processing at lower temperature than conventional methods [2].
Solution Chemistry of Silicate and Borate Materials
Authors: Bunker B. C.
Published: March 2011

Reactions which create and destroy Si-O-Si, Si-O-B, and B-O-B bonds occur in leached layers on borosilicate glasses during glass dissolution. Solid state NMR, Raman, and TEM techniques have been used to determine the distribution of species formed in leached layers as a function of solution pH and the mechanisms of glass-water reactions. The chemical principles which govern the reactivity of silicate and borate bonds in leached layers appear to be similar to those which govern the formation of silicate and borate gels via sol-gel techniques.
Molecular Mimicry of Structure and Electron Density Distributions in Minerals
Authors: Gibbs G. V. , Boisen M. B.
Published: March 2011

Molecular orbital calculations on hydroxyacid molecules with first- and secondrow X-cations (X = Li through N and Na through S) yield bond lengths and angles that mimic those of chemically similar minerals. These bond lengths are used to find a formula giving bond length as a function of a bond-strength parameter that reproduces XO bond lengths in crystals with main-group X-cations from all six rows of the periodic table within 0.05Å on average. The molecular orbital calculations also provide insights into reaction energies, physical properties of crystals such as electron density distributions, and data not amenable to direct measurement. They also provide a basis from which computational models for mineral structures may be constructed.
Drying Behavior of Sol-Gel Derived A12O3 and Al2O3-Sic Composites
Authors: Krabill R. H. , Clark D. E.
Published: March 2011

Gel drying is a critical step in the sol-gel synthesis of Al2O3 and Al2O3-SiC composites. Problems exist during the drying stage that affect the monolithic properties of the sintered products. Classical drying theory was applied to the drying behavior of Al2O3 and Al2O3-SiC composites in an effort to optimize the drying process and understand the controlling mechanisms.
Sol-Gel Coatings on Carbon/Carbon Composites.
Authors: Sim S. M. , Krabill R. H. , Dalzell W. J. , Chu P-Y. , Clark D. E.
Published: March 2011

The need for structural materials that can withstand severe environments up to 4000°F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates.
The Effect Of Hydrolysis Conditions On The Characteristics Of PbTiO3 Gels And Thin Films
Authors: Budd K. D. , Dey S. K. , Payne D. A.
Published: March 2011

Sol-gel processing represents a promising method of fabrication for thin films of electronic ceramics which are useful in a number of packaging and device applications. In this study, the influence of acid and base catalysts on the structure of PbTiO3 gels and films (0.1–1.0 μm) was investigated, for the purpose of inducing and identifying gel structures which were the most suitable as precursors for thin dielectric layer. Continuous, crack-free films, with dielectric strengths in excess of 106 V/cm were developed. Basic solutions gelled rapidly, phase separated, and were probably more crosslinked than acidic gels. Acidic gels seemed more capable of polymeric rearrangement during drying, yielding denser amorphous structures with microcrystalline regions. High-field dielectric constants (1 MV/m ac) in the range K=30–40 and K=160–170, were determined for amorphous and crystalline films, respectively.
Chemistry And Applications Of Inorganic-Organic Polymers (Organically Modified Silicates)
Authors: Schmidt H. , Seiferling B.
Published: March 2011

The combination of inorganic polymeric networks with organic components leads to inorganic-organic polymers. A convenient method for the introduction of organic radials into an inorganic backbone is the use of organosubstituted silico esters in a polycondensation process. This leads to≡Si-O-Si≡ network containing materials, so-called organically modified silicates (ORMOSILs). For the synthesis of the inorganic backbone, in opposition to the high temperature preparation of non-metallic inorganic materials like ceramics, “soft chemistry” methods have to be applied in order to preserve organic groupings to be incorporated. Therefore, the sol-gel process is a suitable technique [1–5]. A review over basic synthesis principles and chemical methods, their effect on special material properties and the application potential will be given.
Crystallization and Melting of Amorphous Silicon on a Microsecond Time Scale
Authors: Olson G. L. , Roth J. A. , Nygren E. , Pogany A. P. , Williams J. S.
Published: March 2011

Measurements of the competition beween solid phase epitaxy, solid phase random nucleation, and melting in amorphous Si on a microsecond time scale are reported. We find that the behavior of amorphous Si under microsecond pulsed dye laser irradiation depends strongly on film thickness and temperature. In “thin” (≲1000 Å) films solid phase epitaxy is observed at temperatures up to and exceeding 1300°C with random nucleation dominating at T>1330° C; however, melting of amorphous Si does not occur. In contrast, in “thick” (2600 Å) amorphous films melting is observed at T˜1190°C. These results are discussed with respect to measurements obtained previously in the nanosecond time regime using Q-switched laser heating and in the 0.1–1 millisecond regime using “chopped beam” cw laser heating.
Faster Quenching by Silicon Pulsed Laser Annealing Under Water
Authors: Polman A. , Roorda S. , Ogale S. B. , Saris F. W.
Published: March 2011

A novel method of pulsed laser processing of ion-implanted silicon is presented, in which samples are irradiated in water ambient. The water layer in contact with the silicon during irradiationh as a considerable influence on melting and solidificationd ynamics. Still, perfect epitaxy of a thin amorphous layer can be obtained using this method.

For epitaxy to occur on a sample irradiated under water, 40 % more absorbed energy is necessary than for a sample irradiated in air. This indicates the occurrence of a considerable heat-flow from the silicon into the water layer during the laser pulse. From impurity redistribution after irradiation it is found that by processing a sample under water liquid-phase diffusion is reduced. Diffusion theory arguments indicate that this can be due to a reduction in total melt duration by about afactor 2–3. This can be due to faster cooling of the liquid silicon layer after the laser pulse whereas the melt-in time might be influenced as well. As a consequence, shallower impurity profiles can be obtained in crystalline silicon. No oxygen incorporation is detected and the surface morphology is not disturbed using this new process.
Crystallization of Silicon on Electro-Optic Plzt by a Laser Beam Modulated in Shape and Intensity Profile
Authors: Lin T. H. , Burgener M. L. , Esener S. C. , Lee S. H.
Published: March 2011

PLZT, a ferroelectric material with a high quadratic electro-optic coefficient, is combined with silicon technology via chemical vapor deposition to enable the realization of Si/PLZT spatial light modulators. Laser crystallization is required to produce device quality silicon deposited on PLZT. The critical issues in the laser crystallization are (i) achieving crystallization in the absence of a good seed, and (ii) preventing damage to the PLZT. To prevent PLZT damage during the laser heating, a 3.5 μm silicon dioxide layer is used as a thermal buffer between the silicon and the PLZT and the effective scanning time is shortened to 100 μs. A double humped cw argon ion laser with a shaped beam is used to achieve successful crystallization with good surface smoothness and large grain size. This technology and devices fabricated on these samples will be discussed.
Melting Point Measurements for Quasicrystalline Phases
Authors: Knapp J. A. , Follstaedt D. M.
Published: March 2011

Melting transitions of metastable quasicrystalline phases of Al-Mn have been observed using rapid electron-beam heating of fine-grained icosahedral surface layers. The congruent melting-point for icosahedral Al80 Mn20 was directly measured to be 910±20°C. Heating to higher temperatures shows another transition which is inferred to correspond to the liquidus of the decagonal phase at 965±20°C for 20 at.% Mn. The microstructure and formation kinetics of the decagonal phase are discussed, and its electron diffraction is described.
Time-Resolved Picosecond Reflectivity Study of Laser-Excited Layered Compounds
Authors: Huang C. Y. , Malvezzi A. M. , Bloembergen N. , Di Salvo F.J.
Published: March 2011

We have employed the pump-and-probe technique to perform picosecond time resolved measurements of the reflectivity changes in two archetypal layered compounds, IT-TiS2 and lT-TiSe2 probed at 1.064 μm after pumping by 20 ps, .532 μm laser pulses. At the threshold fluence, ∼ 40 mJ/cm2, the reflectivity drops sharply, marking the occurrence of a phase transformation on the surface of the sample. Above threshold, the reflectivity reaches a value as low as ∼0.1 at high fluences, strongly suggesting that, like in graphite, the high temperature phase is not metallic.
Damage Production in B-Sic During Ion Implantation
Authors: Withrow S. P. , More K. , Edmond John A. , Kong H. S. , Maziasz P. J. , Davis R. F.
Published: March 2011

Damage in single crystal ß-SiC(100) as a result of ion bombardment has been studied using Rutherford backscattering (RBS) and cross-section transmission electron microscopy (X-TEM). Samples were implanted with 123 keV 27Al at liquid nitrogen temperature. RBS spectra for He channeling in the (110) axis at 45° were obtained as a function of implantation dose to determine damage accumulation. X-TEM was used to characterize damage structure for selected doses. The surface of the SiC becomes amorphous for doses greater than 1 x 1015 /cm 2. At lower doses, significant uniaxial lattice strain along the (100) direction is suggested by comparison of RBS channeling spectra obtained for several high index axes. High resolution TEM on a sample implanted at 4 x 1014 /cm2 shows no damage structure in the surface region; lattice damage in a broad layer centered roughly at the depth of highest energy deposition is characterized by small amorphous pockets in a crystalline matrix. Qualitatively similar backscattering results were obtained for other elements implanted at room and liquid nitrogen temperature.
The Effect of Damage Density Profile on Moving specles in Ion-Induced Reactions
Authors: Tao K. , Hewett C. A. , Lau S. S. , Buchal Ch. , Poker D. B.
Published: March 2011

We present evidence in this study that the moving species under ion mixing conditions are affected by the implantation damage distribution in the sample. This observation holds for metal-semiconductor, metal-metal and semiconductorsemiconductor systems. The direction of thermal annealing and atomic transport appears to play a role in ion-mixing as well. When these two factors are in the same direction, only one dominant moving species is observed. When these two factors are in opposite directions, both constituents can contribute to the atomic transport in ion mixing.
Temperature Dependence of Ion Mixing Of Markers in Zr
Authors: Kim S. -J. , Nicolet M. -A. , Averback R. S.
Published: March 2011

Ion mixing of thin markers in Zr was investigated by irradiating with 660 keV Kr++ ions at temperatures between 300 to 423 K. Very thin films of vacuum evaporated Ti, Cr, Fe, Co, Ni, Cu+ Hf, W, and Au served as markers. The samples were analyzed by 2 MeV He backscattering spectrometry. The marker elements that are likely to dissolve interstitially in Zr have higher mixing efficiencies at elevated irradiation temperature than the markers that are likely to dissolve substitutionally. The results are explained by radiation-enhanced diffusion theory.
Amorphisation Tendency of Intermetallic Compounds Under Electron Irradiation
Authors: Luzzi D. E. , Meshii M.
Published: March 2011

The chemical disordering model for the electron irradiation induced crystalline to amorphous (C-A) transition was previously developed using in-situ experiments in the intermetallic compounds of the Cu-Ti binary alloy system. In the context of this model, a rule was developed which predicts the amorphisation tendency of these and other binary intertransition metal compounds with an accuracy of 92% in the 38 compounds studied to date. Two aspects of this rule, the composition of the compound and the crystal structure are examined through a first approximation computer comparison of ordered, partially ordered, and disordered crystal structures. It is found that in bcc based compounds and in complex crystal structure compounds, the ability of the chemical disordering to raise the energy of the crystal is severely inhibited at compound compositions away from 50:50. During the disordering process, the greatest increase of the crystal energy occurs during the early stages of chemical disordering. These results mesh well with the concept of an amorphous transition driven by the energy increase due to chemical disordering.
Formation of Submicron Metastable Phase Structures in Alloys with Focused Electron or Proton Beams
Authors: Lam N. Q. , Okamoto P. R. , Leaf G. K.
Published: March 2011

Recent theoretical and experimental studies of radiation-induced segregation in alloys under irradiation with focused charged-particle beams have shown that point-defect currents generated by axial and radial displacement-rate gradients can cause significant redistribution of the alloying elements within the irradiated zone. In the case of irradiation of thin films with highly-focused electron beams, two important features have been established experimentally: (i) the diameter of the local region in which the alloy composition and phase are modified is practically equal to the beam diameter, and (ii) the time required to produce a given change in the alloy composition in the center of the irradiated zone decreases rapidly with beam diameter. Our theoretical modeling indicates that these features will also be observed in semi-infinite alloys bombarded with focused proton beams. However, in this case, the spatially-nonuniform defect production in both the axial and radial directions renders the compositional redistribution more complex. The present work shows that the ability to locally modify the alloy composition by focused electron or proton beams may offer a new method for producing local regions of controlled composition and microstructure on a submicron scale. The results of our model calculations and experimental studies will be presented to demonstrate the feasibility of this novel technique.
Elimination of Subboundaries in 0.5-µm-Thick Si-on-Insulator Films Produced by ZMR
Authors: Geis M. W. , Chen C. K. , Smith Henry I.
Published: March 2011

When Si-on-insulator films 0.3 to 0.5 µm thick are recrystallized by zone melting under the usual conditions, the defect trails within grains are subboundaries. We report that the use of an entrainment pattern, consisting of a grating of carbonized photoresist on top of the SiO2 encapsulating layer, can lead to the replacement of subboundaries by defect trails that are spaced dislocation clusters or discrete threading dislocations. Such defects are expected to be less detrimental to submicrometer MOSFET circuits than subboundaries.
Limited Reaction Processing
Authors: Gibbons James F. , Gronet C. M. , Sturm J. C. , King C. , Williams K. , Wilson S. , Reynolds S. , Vook D. , Scott M. , Hull R. , Nauka C. , Turner J. , Laderman S. , Reid G.
Published: March 2011

Limited reaction processing (LRP), a new technique which provides precise control of thermally driven surface reactions, was used to grow multilayer structures composed of semiconductors and insulators. Results are presented for group IV-based materials including epitaxial Si, SiGe alloys, SiO2, and polysilicon. III–V materials such as GaAs, AlGaAs, and InGaAs have also been successfully grown. A number of diagnostic techniques were used to define the advantages and capabilities of LRP, including TEM, SIMS and AES. In addition, some preliminary device results are presented.
Rapid Thermal Oxidation of Polysilicon and Silicon
Authors: Nulman Jaim
Published: March 2011

Growth kinetics of silicon dioxide films grown by rapid thermal processing on polysilicon and single crystal silicon films is described. Oxides were grown in pure oxygen and oxygen with up to 4% HCI. For process time in the 1 to 120 s, oxide films thicknesses in the 2 to 36 nm are obtained with a uniformity of ±2% across 100 mm wafers. These oxides show an interface density of states of 5×109 eV−1cm−2 after a 30 s post-oxidation anneal in nitrogen ambient at 1050 C.
Effects of Indium Preamorphization on Boron Implanted Silicon Annealed by RTA
Authors: Ganin E. , Scilla G. , Sedgwick T. O. , Sai-Halasz G. A.
Published: March 2011

Preamorphization by indium of boron implanted silicon layers has been studied as a means of reducing defects in the annealed and activated shallow junctions. The In preamorphized samples after RTP annealing at 950 to 1150°C show an absence of spanning dislocations. A 5 sec. anneal at 1100 °C results in the complete annihilation of residual dislocation loops at the original crystalline/amorphous (c/a) interface. The minimum dose to preamorphize Si with 200keV In was 5×1013/cm2. During annealing the In was found to localize at two peaks, one at the original c/a interface and the other closer to the surface, where In precipitation was observed.
Recrystallization of Implanted LPCVD Amorphous Si Films Using Rapid Thermal Annealing
Authors: Kwor R. , Tang S. M. , Alvi N. S.
Published: March 2011

The effect of rapid thermal annealing on the crystallization of arsenic and boron implanted amorphous silicon films is studied. Amorphous Si films of 4000 Å were deposited using LPCVD and implanted with arsenic or boron to doses of 5 × 1013, 5 × 1014, and 5 × 1015 cm−2. These films were then annealed using an Eaton Nova-400 RTA system (with temperature ranging from 900 to 1200 °C and dwell time ranging from 1 to 30 sec). The annealed films were studied using transmission electron microscopy, Hall effect measurement and temperature coefficient of resistance measurement. The optimal annealing conditions for the films were found.
Chemically-Enhanced GaAs Maskless Etching Using a Novel Focused Ion Beam Etching System with a Chlorine Molecular and Radical Beam
Authors: Takado N. , Asakawa K. , Arimoto H. , Morita T. , Sugata S. , Miyauchi E. , Hashimoto H.
Published: March 2011

Chlorine-enhanced GaAs maskless etching using a novel focused-ion-beametching (FIBE) system has been examined for establishing high-rate and smooth FIBE. The system is composed of an air-locked ultrahigh-vacuum chamber, a 30 KeV Ga+ FIB column and two kinds of chlorine-irradiation nozzles. A fine nozzle enabled us to irradiate a high-density Cl2 flux on a desired, small area of the sample while retaining a sufficiently low surrounding-gas pressure for stable Ga+ FIB emission. Highly chemically-enhanced sputtering yields (up to 50 GaAs molecules per incident ion) were obtained. At the maximum yield, line-scanned deep-groove (6.5 um) etching with a smooth surface, capable of fabricating a laser-cavity optical mirror, was demonstrated. The chemical-enhancement effect showed high FIB-scanning-time dependence. This effect was also observed by irradiating with a plasma-dissociated Cl radicals using a novel radical beam gun. An analytical model, based on the Ga+-ion bombardment on the chlorine-adsorbed substrate surface, suggested that the maximum chemical enhancement is obtained when the Ga+-FIB scanning time is adjusted to the chlorine-coverage time, given by the Cl2-molecule or Cl-radical flux density.
Surface Photochemically Activated Chemical Vapor Deposition of Patterned Aluminum Thin Films
Authors: Higashi G. S. , Blonder G. E. , Fleming C. G.
Published: March 2011

KrF excimer laser (248 nm) images of mask patterns have been Iused to photochemically activate tihe surface catalytic decomposition of triisobutylaluminum (TIBA). The activation step is shown to involve the photolysis of organoaluminum surface adlayers leading to the formation of reactive Al sites. These sites serve to selectively nucleate the thermal decomposition of TIBA which results in the growth of high quality Al filns (resistivities ∼5 μΩ-cm). The growth on the chemically inert surfaces of SiO2 and Al2O3 is extremely selective and results in patterns with resolutions ∼2 μm. To evaluate the utility of this process for real circuit applications, the laser activated deposition technique has been used in conjunction with standard photolithographic processing to fabricate metal-oxide field effect transistors and Al interconnects. The successful fabrication of working devices indicates that the laser activated deposition technique is compatible with standard photolithographic patterning schemes and may provide a means for simplifying integrated circuit fabrication.
Direct Writing of Al on Si by UV Exposure Prior to Laser-Assisted CVD
Authors: Bouree J. E. , Flicstein J. , Nissim Y. I.
Published: March 2011

Photodissociation of trimethylaluminum molecules with a UV lamp is shown to be an effective technique for predisposing the irradiated silicon surface prior to subsequent aluminum film growth via visible laser induced pyrolysis. The Al deposits thus obtained are carbon contamination free. The UV exposure time needed for the onset of Al nucleation and growth is deduced from an in situ laser reflectometry technique. Direct laser writing is obtained using this two-step process and a microscopic analysis of the lines is made in correlation with the experimental procedure.
UV Multiphoton Dissociation of Group VIB Hexacarbonyls and Derivatives
Authors: Tyndall George W. , Jackson Robert L.
Published: March 2011

Formation of electronically excited metal atoms via excimer laser multiphoton dissociation of Cr(CO)6, C6H6Cr(CO)3, and Mo(CO)6 has been examined in the gas phase. The dissociation mechanism was studied by determining the laserfluence- dependence and buffer-gas-pressure dependence of the metal atom emission intensity. Each of these species was found to form metal atoms via two-photon and three-photon dissociation processes. The data suggest that dissociation occurs by both direct and sequential processes.
Rapid Formation of Beryllium Nitride and Beryllium Oxide by Excimer Laser Irradiation of Samples Immersed in Liquids
Authors: Dijkkamp D. , Wu X. D. , Chan Siu-Wai , Venkatesan T.
Published: March 2011

Excimer laser induced rapid formation of nitride and oxide layers on beryllium samples immersed in liquid nitrogen and water, resp., has been studied. From Rutherford backscattering spectra the amounts of incorporated nitrogen and oxygen were determined. In addition, scanning electron microscopy was used to study the morphology of the irradiated surface and compound formation was confirmed by X-ray diffraction. Our results show that extremely rapid reaction takes place when the laser energy is sufficient to melt the beryllium surface. The amount of reaction is found to be proportional to both the energy density and the number of laser shots, until a nearly stoichiometric layer of Be3N2 or BeO is formed at the surface, at which point the reaction saturates. Growth rates on the order 20 nm per shot are deduced from the data, which is orders of magnitude higher than those achieved by conventional means.
Room Temperature Growth of Silicon Dioxide Using a Low Energy Ion Beam
Authors: Todorov S. S. , Fossum E. R.
Published: March 2011

Ultra-thin films of silicon dioxide are formed on silicon surfaces at room temperature by direct bombardment with an oxygen-containing ion beam at energies of 150 eV or less. The process of film growth is studied.through ellipsometric measurements of their properties as a function of ion energy and dose, oxygen partial pressure and substrate temperature. Typical oxide thicknesses of the order of 50 Å are obtained by three minute or longer exposures to beams of current density 135 μA/cm2. Ion-beam grown oxides are compared to conventional thin oxide films grown at elevated temperatures and show the same stoichiometry. The growth rate decreases rapidly after a continuous oxide film has been formed. Performing the ion bombardment at elevated substrate temperatures leads to only small enhancement of the oxide growth indicating non-thermally driven reaction kinetics.
Photochemical Dry Etching of Semiconductors and its Relationship to Semiconductor Electronic Properties
Authors: Ashby Carol I. H.
Published: March 2011

The general utility and selectivity of photochemical dry etching processes which require direct participation of photogenerated carriers is largely determined by the electronic properties of the semiconductor. The laser which is used to produce the carriers responsible for etching can also provide in situ measurement of some of the important electronic properties which influence the etching process.
Laser-Assisted Selective Chemical Etching of GaAs/AlGaAs Layered Structures
Authors: Brown R. T. , Black J. F. , Sacks R. N. , Peterson G. G. , Leonberger F. J.
Published: March 2011

Laser-assisted etching techniques have been developed for alloyselective patterning of GaAs/AlGaAs layered structures. Such techniques are potentially very important for the fabrication of a large variety of heterostructure devices. Studies have been carried out with several liquid etchants and have utilized a CW dye laser tuned to a wavelength above the band edge of GaAs, but below that of the AlGaAs layer (e.g., λ = 0.85 μm) to etch GaAs. Using the laser focal spot to spatially define the etched area, features exhibiting very smooth interface surfaces were produced in MBE-grown epitaxial layers. A high degree of selectivity for GaAs over A1(0.4)Ga(0.6)As, low background etch rates, and high feature etch rates (> 2 μm/min) were demonstrated. Patterned etching with AZ 1350J photoresist exhibited good pattern resolution and nearly vertical sidewall profiles. Etchant mixtures of dilute H2S04:H202:H20 and HNO3:H20 produced qualitatively different results, with the HNO3:H20 mixture exhibiting a tendency to leave a residual GaAs layer at the interface, even for long etch times. Surface analysis techniques, including Auger spectroscopy, profilometry, and interference contrast microscopy have been used to characterize the etched structures, and a simplified analytical model has been used to predict the qualitative dependence of etch rate on layer thickness.
Etching of LiNbO3 by Laser-Driven Fusion of Salts
Authors: Ashby C. I. H. , Brannon P. J.
Published: March 2011

Lithium niobate exhibits low reactivity with most chemical etchants. Consequently, etching a LiNbO3 surface to produce optical structures such as ridge waveguides or grooves for fiber coupling normally requires relatively slow processes such as ion milling. We have developed a laser-driven chemical etching process for etching highly unreactive ionic solids based on the fusion of salts In the molten phase and show that the etch rate can be more than 100 times faster than ion milling rates. This process involves spatially localized melting of LiNbO3 by high-power density laser pulses with photon energies in excess of the band gap of LiNbO3. While molten, LiNbO3 undergoes reaction with a surface coating of KF to form niobium oxyfluoride anions by fusion of the salts. The resulting solid is highly water soluble. The insolubility of LiNbO3 permits subsequent removal of only the irradiated area by rinsing in water. Surface morphology is determined by laser power density. The process exhibits a wavelength dependence.
Surface Fluorination of Polyimide Thin Films by CF4 + O2 Reactive Ion Beam Etching
Authors: Vanderlinde William E. , Ruoff Arthur L.
Published: March 2011

Surface fluorination of polyimide thin films during CF4 + O2 reactive ion beam etching (RIBE) was investigated. The removal of the fluorinated layer by a subsequent oxygen ion beam etch was also studied. Electron spectroscopy for chemical analysis (ESCA) and Rutherford backscattering spectrometry (RBS) detected a fluorinated surface layer on the order of 100 A thick. Fluorine atom concentration in the surface of the film (as measured by RBS) and the etch rate of the film were measured as a function of several experimental parameters: ion energy, ion current density, etch time, and gas composition. The results are compared with theoretical predictions of the total number of fluorine atoms retained in the film after etching.
Control of the Surface Reactivity of the Si(100) Surface
Authors: Yates John T. , Bozack M. J. , Muehlhoff L. , Choyke W. J.
Published: March 2011

We have used molecular beam methods and temperature programmed desorption to probe the reaction of several hydrocarbons with the Si(100) surface at cryogenic temperatures. It has been found that the kinetics of the surface reaction with the C=C bond can be strongly influenced by the production of active surface sites using prebombardment with Ar ions. The chemistry of the adsorbate is also influenced by electron bombardment of the adsorbed layer. Conversely, capping of active sites with atomic hydrogen retards the kinetics of the surface reaction. This work forms a first step in using the methods of surface kinetics and spectroscopy to probe the details of the elementary steps at work in chemical vapor deposition and plasma vapor deposition, leading to the production of SiC films.
Production of Electronically Excited P2 and in from ArF Excimer Laser Irradiation of InP
Authors: Donnelly V. M. , McCrary V. R. , Brasen D.
Published: March 2011

We have investigated the decomposition of single-crystal InP surfaces irradiated by a 193 nm ArF excimer laser. These studies provide insight into mechanisms of thermal decomposition, surface diffusion and epitaxy. Pulsed laser exposure leads to evolution of P2 from the surface which is detected by resonance fluorescence resulting from a fortuitous overlap of the v″ = 0 with the laser frequency. P2-evolution occurs above a threshold fluence of 0.12 J/cm2 and lags the peak laser intensity by ∼20 nsec. These observations are explained by a thermally activated decomposition mechanism, as opposed to any direct, photochemical ejection process. Peak surface temperatures have been calculated and are used to predict P2 yields as a function of fluence and time which are in good agreement with experiments. These findings are also discussed in relation to previous studies of excimer laser stimulated growth of InP.
Crystallographic Effects on the Photoelectrochemical Etching of Gratings in Compound Semiconductors
Authors: Carrabba Michael M. , Nguyen Nguyet M. , Rauh R. David
Published: March 2011

Grooves have been etched photoelectrochemically into a (100) n-GaAs surface using a 100 cycle/mm grating mask to define the illuminated area. The degree of mask undercutting and the shape of the groove bottom are shown to be functions of doping density and crystallographic orientation. High doping density gives rise to reduced undercutting, presumably due to a lesser extent of surface diffusion of photogenerated holes.
Laser-Induced Thermal Decomposition of Platinum Metallo-Organic Films
Authors: Gupta A. , Sausa R. C. , White J. R.
Published: March 2011

The focused output from an argon ion laser (514 nm) has been used to pattern micron-size platinum features by decomposition of spun-on metallo-organic film on quartz substrate. The role of laser power and energy density on the thermal decomposition of the film is studied using pulsed and cw laser irradiation. Transient reflectivity has been used as a probe to study the reaction steps involved in the decomposition of the metallo-organic containing film. Preliminary results on the use of the platinum features as seed layer for electroless copper plating is presented.
Mechanical Property Determination for Supported Polymer Films using Double Bending Beams
Authors: Han B. J. , Tong H. M. , Saenger K. , Gryte Carl C.
Published: March 2011

A double-bending-beam technique has been developed to determine the mechanical properties (e.g., the elastic stiffness parameter and the in-plane coefficient of thermal expansion) of thin polymer films during thermal cycling. The mechanical properties of poly(methyl methacrylate) and a polyimide have been determined from the combined stress-temperature relationships of identical polymer films coated on two rigid beams (each with a distinctly different Young's modulus and coefficient of thermal expansion). The measured mechanical properties were found to agree with data obtained using conventional techniques. The double-bending-beam technique can be applied to a wide variety of dry and wet processing situations involving thin polymer films.
Evidence for Polycrystalline Si Surface Layer Formation by Argon Implantation and its Passivation by Atomic Hydrogen
Authors: Chien H.-C. , Ashok S. , Slowik J. H.
Published: March 2011

Al/p-Si Schottky barriers formed on wafers implanted with 10–20 keV Ar exhibit low-temperature electrical properties characteristic of grain boun1dary transport Subsequent low-energy (0.4 keV), high fluence ( ∼ IOE18 cm−2) H implant is found to passivate the grain boundaries of the Ar implant-induced microcrystals. Extremely high Al/p-Si Schottky barrier heights are obtained following the dual implants, and deep level transient spectroscopy (DLTS) measurements reveal that H also alters the properties of traps introduced by the Ar implant, thus improving the diode characteristics.
A Theoretical Study of the Etchback Planarization Process
Authors: Kuo Yue
Published: March 2011

A computer modeling method was used to study various factors such as the etch time, the degree of planarization of the sacrificial layer, the original surface shape of the sacrificial layer, the etch ratio, and the original oxide step shape, that directly affect the topography of an etchback planarized surface.
Nitride, Nitrided Oxide and Oxidized Nitride for Thin Dielectrics
Authors: Tay S. P. , Kalnitsky A. , Ellul J. P.
Published: March 2011

In this paper, comparisons of material and electrical parameters between qate and interpoly dielectrics consistinq of thermal oxides, nitrides, nitrided oxides and oxidized nitrides are reported. A range of dielectrics, 5 nm to 30 nm thick, are thermally grown using a matrix of oxidation cycles, ammonia concentration and nitridation temperatures and pressures. Fabrication of polysilicon gate and interpoly capacitors is typical of industry standards. AES, RBS and ellipsometric analysis of dielectric material properties are discussed and electrical characterization results are presented.
Process-Induced Point Defects in Oxidized Silicon Structures
Authors: Caplan P. J. , Poindexter E. H. , Vasudev P. K. , Henderson R. C.
Published: March 2011

Point defects caused by common fabrication methods may increase device susceptibility to radiation or hot carriers. In this study, defects induced by dry and wet oxidation, ion implantation, and rapid thermal annealing are examined by electron paramagnetic resonance. A brief 02 anneal at 900°C is found to be more effective than N2 in transformation of a steam-grown oxide interface to that of a dry oxide. A N2 anneal at 450 °C has little effect, and must be extended to about 2 hr to dessicate the interface. Implants of B, P, and BF2 have no direct effect on the interface, but activation anneal in N2 at 900°C produced large Pb concentration. Implant generates E′ centers in the oxide, which are eliminated by the activation. Rapid thermal annealing below 600°C reduces interface traps, but increases them above 700°C, with severe oxide and interface damage at 1100 °C. Electron-beam lithography and plasma- or ion-beam etching are discussed briefly.
Characterization of W/WSIx/Si Contact Structures under Thermal Annealing for Some X Values
Authors: Ogawa S. , Yamazaki K. , Akiyama S. , Terui Y.
Published: March 2011

Thermal stability of W/WSix/Si (X=1.4, 2.1, 2.5) contact structures has been characterized at annealing temperature up to 900°C. Thermal reaction in these contact structures was strongly affected by the X values of deposited WSix films. The X values were presicely controlled by a novel co-sputter deposition apparatus. After annealing at 900°C, in the samples of X=1.4 and 2.1, the W films were stably maintained. On the other hand, in the sample of X=2.5, the structure changed into the WSi2. 2/Si resulting in the disappearance of the W film. The silicidation of the W film in the sample of X=2.5 was likely due to a diffusion of Si into the W film through the precipitated region of the excess Si in the tungsten silicide film. The W/WSi2.2/Si structure can provide the electrically stable W-Si contact at annealing temperature up to 800°C.
Characterization of Bias Sputtered Aluminum Film
Authors: Homma Y. , Hinode K. , Terada T.
Published: March 2011

The characteristics of RF bias-sputtered Al films are clarified. A negative substrate bias voltage, VDC, produced by RF biasing, strongly influences not only the planarization effect but also film characteristics such as hillock and void growth, and Ar content.

Films deposited at VDc lower than -150 V. are significantly degraded due to the formation of two kinds of voids grown during annealing. One type is a blister-like voids, while the others are large and irregular. These are produced when Ar is released from the films during heat treatment. as evidenced by the fact that the amount of Ar released from the films rapidly increases when VDC is lower than -150 V.

Although biasing strongly effects Al films resulting in the formation of an almost complete (111) texture. the effect degrades as VDC exceeds -200 V. Thus, Al bias sputtering requires a high resputtering rate and a VDC higher than -150 V to achieve appropriate planarization with suitable film characteristics.
Simulation of Microposit 2400-17 Resist Profiles for 0.5μm Photolithography at 248 nm
Authors: Watts R. K. , Wolf T. M. , Stillwagon L. E. , Hellman M. Y.
Published: March 2011

Model parameters have been measured to characterize the exposure and development of Microposit 2400 resist exposed by a new deep UV wafer stepper at 248 nm. Resist profiles are obtained from the model for equal line/space patterns. The observed non-vertical wall profiles are correctly predicted by the simulation. These profiles result from the strong absorption of the resist and lack of photobleaching at 248 nm.
30-nm-Scale Device Fabrication for Electron Transport Studies
Authors: Rooks M. J. , Mceuen P. , Wind S. , Prober D. E.
Published: March 2011

The study of quantum interference effects in metallic structures requires the lithographic resolution of electron-beam lithography. Resolution and reproducibility can be greatly enhanced by the use of a multilayer resist. We have implemented a polymethylmethacrylate (PMMA) bilayer resist which avoids the typical problem of intermixing of the layers. This is accomplished by an expedient choice of the solvent, xylene, for the upper resist layer. Metal lines 30 nm wide have been fabricated. We also describe an additional deep ultraviolet (DUV) exposure method which facilitates making electrical contact to these ultrasmall structures. Quantum interference, localization effects, and the electron phase-coherence time have been studied.
Application of Scanning Tunneling Microscopy to the Study of Metals: Spectroscopy and Topography
Authors: Jaklevic R. C. , Kaiser W. J.
Published: March 2011

The design and performance of a scanning tunneling microscope for use in the study of metal surfaces is described. The system was designed for ultra high vacuum together with standard sample cleaning and characterization techniques. The STM provides both topographic and spectroscopie information. Topographic images of well annealed Au(lll) show very smooth planes with single atomic steps. Corrugation on the (111) planes, which is expected from reconstruction models for this surface, is not seen. Other areas show monatomic steps in the form of an ordered array with a period corresponding to that derived from previous studies. A possible alternative reconstruction mechanism is suggested by these STM data. On the same surface are steeper sloped regions with multiple steps of equal height with wide facets. Spectroscopie first derivative data for Au and Pd show peaks which correspond to surface and bulk electronic states, for both filled and unfilled cases. The energy values of these states are compared directly with the results of other experimental methods. The use of combined topographic and spectroscopie mode for metals is anticipated.