Two solid, air stable, volatile tungsten complexes, tris(methylvinylketone) tungsten, I, and tris(butadiene)tungsten, II, have been investigated as precursors for chemical vapor deposition (CVD) of tungsten containing films. Thermal gravimetic analysis, (TGA), of I and II under argon showed the onset of decomposition at 140°C and 150°C, respectively. A rapid weight decrease corresponding to loss of all three ligands, methylvinyl ketone or butadiene, was observed.

Tungsten film growth under hydrogen using I was investigated on Si, SiO2, Cu, TiN, Si, and Pt substrates. Selective tungsten film growth on platinum using a hydrogen carrier was observed at temperatures above 200°C. No appreciable tungsten deposition was observed on clean Si, SiO2. Cu or TiN surfaces below 400°C. No oxygen or carbon was detected in these films to the level of EDX analysis (∼1%) for depositions at 200°C. Increased growth temperatures resulted in increasing amounts of oxygen incorporation. The films grown at 200°C were smooth whereas cracking was observed in films grown at 300°C. The volatile products from the deposition were identified by a combination of gas chromatography and mass spectrometry. Small amounts of methylvinylketone. and methylethylketone were observed. Higher molecular weight species are as yet unidentified, but constituted the majority of the products.

Thin films of cobalt, rhenium, or cobalt silicide have been deposited down the pores of porous silicon layers, using HCo(CO)4, HRe(CO)5, and SiH3Co(CO)4 as precursors in a Chemical Vapour Infiltration and Decomposition (CVID) technique.

TiN films were grown by CVD from Ti(N M e2)4 and ammonia using a novel gas delivery system which allowed the sample to be kept in high vacuum while the reactants were mixed at elevated pressures. The object was to study fundamental chemistries and growth properties. We obtained clean (<5% carbon), near-stoichiometric (Ti:N = 1.15+/-0.1) TiN films. The gas phase chemistry was studied by mass spectrometry while the films were analyzed in situ by Auger electron spectroscopy (AES), and then removed for Rutherford backscattering (RBS) analysis. Film quality was studied as a functionof reactant ratio, substrate temperature, and reactant gas pressure. We obtained definitive information on the growth mechanism. Isotopic substituiton experiments establish that a rapid transami-nation reaction occurs in the gas phase. Mass spectrometry experiments indicate that the reactive intermediate is polymeric, consisting of Ti, N, H, arid perhapscarbon. Growth on patterned wafers shows that this intermediate has a high sticking coefficient and a low surface mobility at 300°C. These findings are considered in terms ofthe potential of this precursor system to be used in manufacturing.

The syntheses of the first single-source precursors to gold-colored titanium nitride films are reported. The precursors have the empirical formula [TiCl2(NHR)2(NH2R)0–2] and [TiCl4(NH3)2] and are obtained upon treatment of titanium tetrachloride with alkylamines or ammonia in nonpolar organic solvents. Both precursors sublime without decomposition between 80–120 °C and 0.01–0.1 mmHg. Deposition of titanium nitride films on glass and silicon substrates was achieved using either precursor at substrate temperatures of 475–600 °C. The films were characterized by x-ray diffraction, resistivity measurements, and X-ray photoelectron spectroscopy. In particular, low levels of carbon and chlorine contaminants were observed in the films.

CVD experiments were conducted using (Me3SiCH2)4Ti, Bis(2,4-dimethylpentadienyl) titanium, Cl3TiMe, (Me3SiCH2TiCl3 to evaluate their potential as Ti precursor compounds. Only Me3SiCH2TiCl3 was suitable for atmospheric CVD applications. Uniform thin films of polycrystalline TiC were deposited using Me3SiCH2TiCl3 in an argon ambient between 700 °C and 800 °C. A mechanism involving initial loss of Me3SiCl to generate a titanium carbene intermediate is proposed. Thin films of TiC deposited on Si[111] were characterized using XRD and AES. Depth profile line shape analysis showed only TiC and elemental Si in the interfacial region. XRD indicates some titanium silicide is formed at 800 °C. In a hydrogen ambient, hydrogenolysis of the alkyl group occurs and very poor film growth results were obtained.

Aluminum thin films were deposited by chemical vapor deposition on SiO2 substrates using trimethylamine alane (TMAA) in a standard low pressure CVD reactor system, with argon as a carrier gas. Film quality and morphology were found to be a sensitive function of reactor flow dynamics. High purity films were obtained with resistivities of ∼5.0 μΩ-cm and grain sizes of 1–2 μm in diameter, but many of these films also exhibited aluminum whiskers, which caused VLSI processing problems. The CVD aluminum films exhibited conformal deposition over 0.5μm topographies, and also demonstrated electromigration lifetimes comparable to those of sputtered aluminum films. Aluminum films deposited using TMAA were also found to be selective at 90°C for titanium oxide.

Aluminum films deposited on silicon with MOCVD methods generally exhibit a high surface roughness due to the hindered nucleation. To decrease the nucleation barrier a pretreat-ment of the wafer with TiCl4 vapor as a chemical activator is commonly suggested.

This work examines the influence of a rf hydrogen plasma on the nucleation of aluminum onSi and SiO2 using TMAA as precursor.

Atomic force microscopy (AFM) was used to determine the surface roughnesses and crystallite sizes of the aluminum deposits. Without plasma activation the nucleation barrier on Si(111) is substantially higher than on oxidized Si and therefore the pretreatment of the wafer plays an important role. The hydrogen plasma causes a substantial increase of the nucleus density leading to deposits with lower surface roughnesses compared to conventionalMOCVD aluminum. The influence of the substrate on the nucleation is almost “switched off” by the plasma activation and the grain sizes of Al on Si (111) and SiO2 differ only slightly. Relatively smooth films with a resistivity of 2.7 μΩcm are obtainable by employing a plasma activated nucleation step followed by a thermal MOCVD process. The increased nucleation rate is discussed in terms of kinetic effects of plasma activation.

Particle formation in the gas phase during the chemical vapor deposition of Al using dimethylethylamine alane was studied. Typical sizes of the crystalline Al particles monitoredwere in the range 20 nm to 1000 nm. Introducing trace amounts of H2O, CO and O2 into the reactor during the flow of the precursor caused an increase in the number of particles. Our results suggested that Al particle formation was induced by impurities in the gas phase although competing mechanisms could not be ruled out.

A vertical high-speed, rotating disk reactor has been used to produce Al and CuAl alloy films on 125 mm diameter Si (100) wafers. Trimethylamine-alane and Cu (hexafluoroacetylacetonate) trimethylvinylsilane (CupraSelect™) were used as metal precursors. Aluminum films were deposited over the temperature range from ∼100 C to 700 C. Aluminum sheet resistance measurements showed the films to have resistance 2 to 3 times that of bulk Al films. CuAl alloy films were deposited sequentially and by codeposition. At 30 Torr, deposition rates as high as 3.7 um/hr, 0.024 um/hr, and 1 um/hr for Al, Cu, and CuAl films, respectively, were demonstrated. Auger analysis showed the deposited films to be free of contaminants.

For the next generation of integrated microcircuits, there exists a need in the electronics industry for high conductivity, electromigration resistant metallization that can be deposited selectivity by chemical vapor deposition techniques. This paper describes a new process for depositing copper/aluminum metallization selectively onto diffusion barrier surfaces in two consecutive steps. First copper is selectively deposited by OMCVD ontoa patterned diffusion barrier surface using a Cu(I)(hfac)(olefin) precursor. Selective copper deposition onto tungsten or titanium nitride is achieved at 150°C and 100 mtorr. Aluminum is then selectively deposited onto copper using trimethylaminealane as the OMCVDprecursor. Trimethylaminealane gives good selectivity for aluminum deposition onto coppersurfaces over a temperature range of 100–120°C without the use of a surface activating agent. A small amount of copper diffuses into the as deposited aluminum layer atthe low deposition temperature. Complete diffusion of copper into aluminum is achieved by a rapid thermal anneal at a higher temperature. The selectivity of aluminum deposition onto copper surfaces is far superior to that observed for aluminum deposition onto other metal surfaces.

By using the strong reductive potential of copper acetylacetone (Cu(acac)2) when Cu(acac)2) was thermally decomposed, copper metal films were prepared by metal organic chemical vapor deposition (MOCVD) process using sublimed Cu(acac)2 vapor and water vapor as reactants, at one atmosphere pressure. According to thermodynamic calculations, Cu films could be prepared by MOCVD process with a high ratio of partial pressures for water vapor and Cu(acac)2 vapor (PH2O/Pcu(acac)2>30) In this paper, the impacts of MOCVD processing parameters such as watervapor partial pressure, total carrier gas flow rate, and precursor partial pressure on film composition and microstructure were investigated. Deposition temperature is the primary processing parameter affecting film stoichiometry. In a specific deposition temperature window, from 370°C to 400°C, polycrystalline Cu films with Cu [111] preferential orientation were deposited. ER and XRD results indicated that films deposited at temperature lower than 350°C contain copper oxide phase with poor crystal structure. By comparing the values of X-ray Auger Electron Spectroscopy (XAES) and Auger parameter (αAu) from photoelectrons of Cu films and standards from reference compounds, die principle oxidation state of copper in these films was determined as Cu(0). The deposition results indicated that a water vapor partial pressure above 10 torr is necessary to produce Cu films. As indicated by SEM, Increasing the carrier gas flow rate, above 600 sccm, can reduce the average temperature profile in the thermal boundary layer above the substrate surface, retard the gas phase reaction rate, presumably eliminate the homogeneous nucleation, and deposit smooth Cu films.

The gas phase chemistry of CuI(hexafluroacetylacetonateXvinyltrimethylsilane),Cu(hfac)(vtms), was investigated using molecular beam techniques. Mass spectrometric and infrared spectroscopic data clearly show that Cu(hfac)2 is produced at nozzle temperatures in excess of 500 K. This result suggests that Cu(hfac)(vtms) undergoes a thermally induced disproportionation reaction in the gas phase to yield CuII (hfac)2, vtms, and atomic copper. As a consequence, copper CVD from CuIβdiketonates is deprived of its inherent selectivity.

The selectivity of OMCVD copper films grown at 160°C/500 mTorr from the volatile liquid precursor Cu(hfac)tmvs was evaluated for various commercial 6” wafers patterned with either TiN/SiO2 or TiN/Si3N4. By processing wafers “as received”, only thermal grown SiO2 consistently resisted metallization, allowing copper films up to 1.5μ thick to be grown on TiN. For SiO2, films containing H2O, especially from PECVD, only blanket deposition was observed. However, by a utilizing simple thermal predeposition dehydration some of these SiO2 films were conditioned to give selective deposition.

Palladium acetylacctonate has received much consideration as a possible precursor for chemical vapor deposition of metallic palladium films for a variety of microelectronic applications. We have studied the adsorption and decomposition of palladium acetylacetonate ongold, polyimide, silicon and silver surfaces to understand the initial mechanisms of metallic palladium film formation. In situ x-ray photoelcctron spectroscopy was used to characterized the films after adsorption and their decomposition after thermal treatment or laser irradiation.

Substrate-selective, low-temperature chemical vapor deposition of high quality gold filmswas obtained with the new precursor ethyl(trimethylphosphine)gold(I) in an ultrahigh vacuum reactor designed to handle wafers up to 3 inches in diameter. Growth behavior at temperatures as low as room temperature as well as substrate pre-cleaning procedures are presented. Activation energies of 35.1 ± 0.4 kcal mol−1 and 18.3 ± 0.7 kcal mol−1 were found for growth of gold films on gold and copper substrates, respectively.

In this work, a hydrogen (H2) reduction process has been developed which gives tungsten (W) nucleation on titanium nitride (TiN) adhesion layers with a very short incubation time, eliminating the need for a silane (SiH4reduced seed layer. The nucleation was found to be strongly dependent on the following factors: temperature of the substrate, total pressure in chamber, and gas introduction sequence into the reactor. Theenhanced nucleation rate has been explained based on two competing reactions: dissociation of H2, and formation of titanium subfluorides on the TiN surface.

We have analyzed a single-wafer chemical vapor deposition (CVD) reactor used for the selective deposition of tungsten (W) by the silanc (SiH4) reduction of tungsten hcxafluoride (WF6). Results from a reactor model, which incorporates simplified heterogeneous reaction chemistry, arc compared to experimental data obtained from the same reactor to provide insight and understanding into reactor performance and define some of the trade-offs in the design of the reactor. A reactor for this process must provide: acold-wall temperature to suppress homogeneous reactions, a uniform wafer temperature to ensure uniform stress and resistivity in deposited films, and a uniform flux of SiH4 to the wafer surface to ensure uniform thickness of films. Maintaining a small internal volume in the reaction chamber was found to be beneficial for reducing both the quantity of rcactant gas at elevated temperatures and the residence time of the gas in the reactor, both of which lead to improved selectivity.

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

Cu-AlN direct bonds were made by the gas-metal eutectic method. Two kinds of AlN substrates from different suppliers were used for the research. The AlN surfaces were preoxidized in O2 at three different temperatures. An optional “anneal” in Ar was applied following the oxidation procedure. Two processes were used for the bonding.

The bond strengths and the failure modes were found to depend on the substrate used, the pretreatment of the AlN and bonding conditions. There was an optimum thickness for the Al2O3 layer on the AlN surface. High temperature annealing in Ar was demonstrated to effectively promote bond strength. The highest peel strength measured was 50 N/cm.

A thermal expansion mismatch between Al2O3 and AlN was considered to be the main factor which dominated the ultimate bond strength. This mismatch resulted in a residual stress in the Al2O3 layer. A measurement by XRD indicated a 300 MPa tensile stress existed in the surface Al2O3 after AlN oxidation. This made Al2O3/AlN the weakest interface and limited the bond strength rather than the eutectic bond.

Erbium-doped silicon has been prepared using Ultra High Vacuum/Chemical Vapor Deposition (UHV/CVD). An erbium mctalorganic compound, tris-1,1,1,5,5,5-hexafluoro-2,4-pentanedionato erbium (111) (Er(HFAC)3), was used as the erbium source and silane was used as the silicon source. Films were deposited at 650 °C at a total pressure of 1 mtorr. Erbium concentrations between 8×1019 and 1×1018 Er atoms/cm3 were prepared by varying the Er source reservoir temperature. Low temperature photoluminescence measurements showed strong emission at 1.54μm. The films are single crystal, but with a high concentration of threading defects.