Thin copper films have been grown on a variety of substrates using Cu(nona-F)2, (bis[4-(2,2,2-trifluoroethyl)imino-1,1,1,5,5,5-hexafluoro-2-pentanonato] copper(II)), a new volatile organometallic copper precursor, and the results are compared with those obtained using copper(II) betadiketonates. Copper films were grown in a cold wall reactor at reduced pressure at temperatures between 270°C and 350°C. For Cu(nona-F)2, films which are pure as determined by Auger electron spectroscopy and have a resistivity of 2.1 micro-ohm cm were deposited at temperatures above 270°C, 40°C lower than was possible using Cu(hfac)2. At low deposition temperatures, Cu(nona-F)2 shows some selectivity towards silicon oxide surfaces in preference to metals. The effects of CVD process parameters on the deposition rate and microstructure of the films were studied with a designed experiment and were statistically modeled. Deposition rates up to 70 nm/min were measured. The standard enthalpy of vaporization of Cu(nona-F)2 was found to be 9.6 kcal/mol.

A series of (0β-diketonate) copper(l) trimethylphosphine compounds has been prepared. These species exist either as liquids or low-melting solids at room temperature. The utility of these compounds as precursors for Chemical Vapor Deposition (CVD) of copper has been examined under a variety of conditions. High purity films with low resistivities have been deposited under a variety of conditions. Selective copper deposition was observed as a function of the substrate, precursor and substrate temperature. Evidence consistent with thermallyinduced disproportionation of the title compounds to form copper metal and copper(II) (β-diketonate)2 during deposition was observed.

Self-induced repair (SIR) is a new concept in chemical microfabrication of microelectronic interconnections. It is based on local chemical processes (deposition or etching) induced by certain local electrical phenomena at defect sites (Joule heat, concentration of electrical field or current density, etc.). It has been demonstrated on four types of defects: near-opens, small opens, near-shorts, and thin shorts. The example of the SIR of near opens, or constrictions in interconnections, is discussed in detail.

We describe a two step method that uses thermally driven exchange plating to repair open copper circuits with local heating produced by ac Joule losses. The first step utilizes a non-acid copper sulfate solution to grow copper dendrites across the open circuit. This electrical “bridge” is then strengthened using additional plate-up in acid copper sulfate.

The deposition of high purity and controlled stoichiometry metal boride thin-film materials has recently received considerable interest. Borane clusters and their corresponding metal complexes are currently being investigated in our laboratories for their utility as unique source materials for the formation of metallic boride thin films by MOCVD. Variable composition nickel boride thin films ranging from 0.1 micron to several microns have been prepared. These new materials have been characterized by SEM, AES and XES. The magnetic properties of these new films have been investigated with torque magnetometry and magneto-optic Kerr effect magnetometry.

The ptanarization of metal interconnect Layers has recently been a subject of intensive development effort in semiconductor processing. Although layer thicknesses have not decreased In proportion, lateral dimensions have been reduced to the point that aspect ratios are too large for effective step coverage by conventional film deposition techniques. The most difficult structure to peanarize is submicron contact holes in thick dielectrics.

A dual-Layer CVD blanket tungsten film was shown to be viable for use as an interconnect material in submicron processes. A single-wafer reactor operating at a pressure of 80 Torr was used to deposit the film. The film exhibits superior properties in terms of its basic characteristics. The film completely fits submicron contacts to silicon, yet has a low surface roughness that would minimize concomitant photolithography and etching problems. Film adhesion is excellent, uniformity and reproducibility are >95%, depgsition rate is greater than 400 nm/mmn., stress is below 8×109 dynes/cm2, and resistivity is 11 μ-ohm-cm or less.

A thermodynamic and experimental study of in-situ chlorination of tungsten is presented. When gaseous tungsten chlorides are used as metal precursors for tungsten and tungsten silicide CVD, their direct synthesis provide a reproductible volatile chloride source.

The conditions leading to the best production of volatile tungsten chlorides have been optimized by means of thermodynamic calculations. The influence of the different production parameters (temperature, nature of reactant gas, …) have been determined.

During some chlorination experiments, volatile chlorides have been detected in-situ by a quadrupole mass spectrometer.

Good agreement between theoretical and experimental results is obtained.

A new method for selective metal deposition on aluminum nitride (AIN) is presented. Excimer laser radiation is used for local decomposition of AIN in air. The degree of the surface modification depends on the fluence and number of pulses. A distinct wavelength dependence of the threshold fluence decomposition of AIN was found. The irradiated surface regions act as catalysts in conventional electroless metal plating baths. Structured metal coatings of various elements (Cu, Ni, Au, Pd, etc.) on AIN can thus be obtained in a simple way.

Highly localized metal deposits can be produced at low temperature by direct writing using a focused laser beam to induce photodissociation of gaseous organometallic precursors. The deposition rate and localization of the deposit are influenced by the kinetics of photochemical reaction and transport of reactants and products. Two-dimensional finite-element computations were performed to determine the effect of deposition parameters, such as laser power, precursor concentration, system pressure, and sticking coefficient, on deposition rates and deposit profiles resulting from single-photon gas-phase dissociation of organometallic precursors. The effect of various gas-phase transport regimes and the conditions and importance of reactant depletion have been investigated. Numerical results have also been compared to theoretical and experimental results from the literature.

The chemistry of SiO2 deposition from N20-SiH4 plasma was studied by line-ofsight mass spectrometry coupled with film analysis. If rf power and N2O flow are sufficient, more than enough O atoms are available to convert all of the SiH4 to SiO2, and good electrical characteristics (IV and breakdown) are then obtained with or without He dilution. Gas-phase SimHn(OH)p species make a minor contribution to the deposition and may be the source of the OH in the film. Both [OH] and electron trapping are much larger than for thermal oxide, with or without He dilution.

The interaction of SiO radicals from a SiCl4/O2 plasma with the surface of a depositing thin film is studied with the IRIS (Imaging of Radicals Interacting with Surfaces) technique, which combines spatially-resolved laser-induced fluorescence with molecular beam methods. In contrast to previous results for SiH, SiO appears not to react at the surface of the depositing film, but desorbs with a cosine spatial distribution for a wide range of substrate temperatures. No evidence is observed for specular scattering of the molecules.

Thin films of silicon dioxide were deposited on (100) Si at low temperatures (room temperature to 375 °C). Oxygen was introduced into the resonance chamber while a dilute silane gas mixture (2% in helium) was fed to a gas ring supported 10 cm above the wafer. Index of refraction, deposition rates, etch rates (for buffered HF), dielectric constant, and oxide breakdown strength were determined as a function of substrate temperature and RF substrate bias. Hydrogen content and Si-O bonding were measured by FTIR spectroscopy. All properties are reported in terms relative to thermally grown oxide.

Film properties improved with increasing substrate temperature and RF substrate bias, sometimes equaling that of thermal oxide. Film quality was the highest for samples deposited at 375 °C, with an applied RF substrate bias.

The deposition rate of silicon dioxide from TEOS/02 capacitively-coupled plasmas increases with increasing applied rf power, increasing total pressure and decreasing wafer temperature. These dependences can be explained by a mechanism in which deposition occurs through both an ionassisted and an oxygen atom initiated pathway. The ion-induced deposition rate increases with increasing rf power density and decreasing total pressure, and is independent of wafer temperature. Assuming a well-mixed plasma, and using literature values for reaction rate parameters and rate forms for oxygen plasma reactions, the rate of atom-induced deposition was found to be independent of temperature and TEOS concentration and directly proportional to oxygen atom concentration. The model suggests that the apparent negative activation energy for deposition results from competition between deposition and thermally-activated atomic oxygen surface recombination. The derived deposition rate form is consistent with an Eley-Rideal mechanism in which the rate determining step for film deposition is oxidative attack of adsorbed TEOS or TEOS fragments by a activated oxygen.

Photoreactions in polyalkylsilyne thin films induced by ArFlaser (193 nm) irradiation have been examined. Photoexcitation of the σ-conjugated Si-network at 193 nm (6.42 eV) results in Si-Si bond scission and alkyl-group desorption when irradiated in a vacuum. In addition to these processes, efficient (up to 7% quantum efficiency) insertion of oxygen into the Si backbone occurs when the irradiation is performed in air, resulting in the formation of a siloxane. Both infrared and X-ray photoelectron spectroscopies indicate a higher oxygen coordination about the Si atoms in the oxidized product than observed for linear polysilanes. This higher oxygen coordination indicates a siloxane network. The polysilynes have been demonstrated as deep UV photoresists and may have additional applications as precursors for thin film or binary optical components.

A purified diethylsilane (DES), LTO-410TM, has been studied as a silicon precursor for the deposition of silicon nitride and silicon oxynitride films by LPCVD. In the temperature range from 650 to 725°C mixtures of DES and NH3 produce uniform, oxidation resistant silicon nitride layers. Auger and RBS analyses show that the carbon concentrations in the films are correlated with the DES partial pressures. The film refractive indices also correlate with the carbon levels in the films for a fixed deposition temperature. Mixtures of DES, NH3, and N2O deposit silicon oxynitride films in the temperature range from 650 to 700°C with compositions controlled by the NH3:N2O ratio for a fixed DES flow. These films have carbon levels below the minimum detectable limit of Auger and RBS analyses.

The series of azidosilanes, SiEtn(N3)4-n where n = 1,2,3 and Si(t-butyl)(N3)3 were evaluated for the LPCVD of silicon nitride thin films. Both SiEt(N3)3 and Si(t-butyl)(N3)3 gave deposition rates of approximately 100 Å/min at temperatures of 450–500°C but films appear to be porous and air sensitive. Film properties improved as deposition temperatures were increased to 600°C. The polyazides must be handled with extreme caution. An unexplained detonation of one sample of SiEt(N3)3 occurred during the course of this study.

Synchrotron photoemission measurements of the Si(2p) and N(ls) levels have been made on Si3N4 thin films grown in-situ by high temperature reaction of Si(100) with NH3. The tunability of the excitation photons allowed the mean-free-path of the emitted photoelectrons to be varied, thereby providing the capability to determine not only the types of chemical species present, but their location within the film as well. The structure of these films consists of an outer monolayer (ML) of Si atoms on top of stoichiometric Si3N4. In addition, there are a smaller number (1/2 ML) of Si atoms with intermediate oxidation states at the Si3N4/Si interface.

A study has been made of basic mechanisms involved in a new process for the rapid synthesis of preceramic nanoparticle powders. In this process an aerosol, formed from an ultrasonically atomized liquid organosilazane monomer, (CH3SiHNH)n with n = 3 or 4, is injected into the beam of an industrial cw CO2 laser. One critical feature examined is the rapid condensation of molecular species from the laser plume, in a process involving 3-dimensional cross-linking. In accompanying studies, a model has been formulated to determine the laser plume temperature, the cooling rate of condensing species, and the particle diameter. These are obtained by analytical solution of heat conduction, momentum and mass conservation equations that consider heat loss, by gas conduction, radiation, evaporation, and convection.

Borophosphosilicate glass (BPSG) films used in integrated circuit processing are grown from combinations of toxic and pyrophoric silane, diborane, and phosphine at atmospheric and reduced pressures. A safe, alternative chemical system has been developed with liquid source replacements for each dangerous gas. 2,4,6,8 tetramethylcyclotetrasiloxane (TMCTS) and oxygen are used as the silicon oxide sources, and trimethylphosphite (TMP) and trimethylborate (TMB) are the phosphorous and boron sources, respectively. Films grown in a hot wall LPCVD reactor with standard diffusion boats have thickness uniformities of ± 2 % and doping uniformities < ± 5 %.

The curing of a commercial ethoxymethyl-phosphosiloxane at different temperatures and under various gas ambients was characterised using NMR, thermoanalytical techniques, and FTIR spectroscopy. DSC (Differential Scanning Calorimetry) and DTG (Differential Thermo Gravimetry) were employed to characterize the reactions that occur during thermal treatments in O2 or N2 atmospheres. FTIR spectroscopy and CP (Cross Polarization) 133C - NMR were used to detect the presence of the hydroxyl and organic groups in the cured samples. The experimental results identified three different temperatures (400,580,700°C) that define important stages of the curing reaction. In particular, for annealing at temperatuires up to 580°C in 02, DSC, DTG and FTIR spectra showed the elimination of the organic groups. However, when the annealing was carried out in N2 up to 700°C, these groups are retained.