Dimethylethylamine alane (DMEAA) has been used to deposit thin films of aluminum selectively on gold in the presence of silicon oxide. This paper presents studies of the effect of temperature, pressure, and substrate pattern on the selectivity. A specially designed reactor allowed us to probe the structure of the species on the silica surface using infraed spectroscopy. At room temperature two absorptions in the Al-H stretching region were assigned to two species; weakly bound molecules of the intact precursor and a strongly bound dihydride formed from the reaction of DMEAA with surface bound (and H-bonded) hydroxyls (from H2O or silanol groups). At higher temperatures the CH vibrations of the amine disappeared, and the Al-H stretch shifted to higher energy. A weak absorption at 2250 cm−1 attributable to a Si-H also appeared. The impact of these observations on the loss of selectivity is discussed.

Aluminum thin films were deposited by chemical vapor deposition on SiO2 substrates using trimethylamine alane (TMAA) in a low pressure CVD reactor system. A high TMAA flow rate during deposition, combined with an initial burst of added argon during the nucleation of the substrate surface resulted in the growth of aluminum thin films with excellent purity and surface morphologies. Film resistivities averaged 3.4 μΩ-cm, and the average surface peak-to-valley height for each film was found to be <4% of the film thickness. The surfaces of films with thicknesses of ≤ 1 μm were extremely smooth and reflective. In contrast, the use of a high alane flow rate in the absence of any added argon resulted in the growth of films with extremely textured surface morphologies. Furthermore, films grown using an argon carrier gas, but with a slow alane flow rate, exhibited both textured surface morphologies and whisker growth.

The deposition of Aluminum on Si(100) surface has been investigated using density functional methods. This has been accomplished by adoption of a Si9H16 cluster to model the H terminated Si(100) 1XI surface and Si9H15 cluster to model the surface with an unpaired electron. The predicted NLSD dissociation energy for the Si9H16 → Si9H15 + H is 86.3 ± 2.0 Kcal/Mol. This is in agreement with previous theoretical calculations on similar systems.

Dimethyl(1,1,1,5,5,5-hexafluoroaminopenten-2-onato)Au(III), DMAu(hfap) was found to be very promising compound for CVD Au wiring. It is liquid at r.t. and has high vapor pressure (0.5 Torr at r.t.) and high thermal stability (dec.t. 171°C, δE=25.4Kcal/mol) and can be used as a precursor for MOCVD. CVD gold films were grown on Si(100) from DMAu(hfap) in a quartz vacuum chamber, using thermal activation by an electric heater or photo activation through quartz windows by excimer lasers(XeC1 308nm). A growth rate of 10 nm/min was achieved by thermal activation at 250 °C, (evaporation temperature of 30 °C, H2 flow rate at 100 sccm and chamber pressure of 30 Torr). Resistivities ranged between 2.8 and 5.lμΩ-cm, depending on the film morphology. The growth rate of laser CVD gold films had the tendency of increasing with decreasing the substrate temperature. This phenomenon indicates that photolysis of adsorbed species on the substrate plays an important role in film growth by laser CVD.

Low temperature deposition of W on Semiconductor substrates is vital for microelectronics technology. Laser ablation technique using KrF (248 nm) excimer laser has been employed to deposit W films from W(CO)6. The substrates used are Si(100) and SiO2. The influence of substrate temperature on the film growth rate was investigated in a broad temperature range (20 - 500 °C), keeping the laser fluence fixed at 0.4 Jcm−2. The substrate temperature is found to have a strong influence on the resistivity of the deposited films. Film resistivities within a factor of 3 of the value for pure bulk W have been observed in the substrate temperature range of 300 - 500 °C. X-ray diffraction data were also obtained. These revealed that the crystal structure of the film deposited in this temperature range corresponds specifically to the m-phase. Optical emissions from the plasma generated during the pulsed excimer laser ablation of W(CO)6 are also examined by an optical Multichannel Analyser (OMA).

In the context of “chemistry and its effects on film quality,” we and a number of other research groups have developed spectroscopic and modeling approaches to better define the pulsed laser deposition process. An overview of these approaches is given here, using the results of recent work performed in our laboratory on the oxide dielectric systems of BaTiO3 and PbZr0.53Ti0.47O3(PZT).

The adsorption and reaction of titanium tetrachloride (TiC14) on W(100) was investigated using temperature programmed desorption mass spectrometry (TPRS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). TiC14 adsorbs molecularly on W(100) at 100 K. Desorption from the molecularly bound state occurs near 220 K. Competing with desorption is dissociation to adsorbed TiCl3, which reacts to form gaseous TiCl4 near 450 K. TiC13 also decomposes into atomically adsorbed Ti and Cl on the surface upon heating to 700 K.

The ability to deposit high purity TiN by a CVD process that can provide improved conformality over current sputter deposition processes is critical for multilevel Si ULSI device applications. Low temperature deposition of high quality TiN films has been achieved by an ECR plasma enhanced CVD process using the metal-organic precursor, tetrakis(dimethylamido) titanium, Ti(N(CH3)2)4 (TDMAT). TDMAT is introduced into the downstream region of either a N2 or NH3 ECR plasma to deposit highly conducting films at deposition temperatures of as low as 100°C. The electrical resistivity of the TiN films decreases from 100-150μΩ-cm at a deposition temperature of 100°C to 45μΩ-cm at 600°C. The choice of plasma gas, N2 or NH3, affects the composition as well as the crystallographic texture of the films, which exhibit preferred (200) and (111) orientations, respectively. Pretreatment of the Si substrate with N2 or NH3 plasmas also affects the film morphologies, as demonstrated by switching the plasma gas between pretreatment and deposition.

Sequential Ti and TiN thin film deposition by CVD is highly desirable for advanced Si integrated circuit applications. To date, most CVD TiN work has been performed using Ti(IV) compounds. We have investigated plasma assisted CVD using a lower oxidation state precursor, cyclopentadienyl cycloheptatrienyl titanium, (C5H5)Ti(C7H7) (CPCHT), which might provide a more facile pathway to both Ti and TiN film formation. CPCHT was introduced with H2 carrier gas into the downstream region of an NH3, N2 or H2 plasma. Low resistivity (100-250 μΩ-cm), nitrogen rich TiN films with little C or O incorporation were deposited at 300 to 600°C, inclusive with either activated N2 or NH3. Although the film texture was influenced by the chosen plasma gas, the average grain size of the N2 and NH3 plasma deposits was similar. Annealing studies showed that the CVD TiN was an effective diffusion barrier between aluminum and silicon to at least 575°C. TEM micrographs revealed that, in contrast to many CVD metal films, the growth of this TiN was not columnar. Film conformality was investigated by scanning electron microscopy (SEM). Experiments performed with activated H2 resulted in deposits of Ti contaminated with C. No depositions were observed in the absence of plasma excitation.

We have used the technique of molecular beam mass spectrometry, with time of flight measurement, to study the vaporization of two organoaluminum precursors to AIN. The compounds studied were the isomers (CH3)3Al·NH3 (I) and (CH3)3N·AIH3 (II). Compound I was synthesized in house by reaction of (CH3)3Al with NH3. Compound II was obtained commercially. Mass spectrometric measurements of Compound I indicated a room temperature vapor pressure below 1 Torr, and slow decomposition at room temperature to yield CH4 and a solid product, identified as the trimer, [(CH3)2AlNH2]3, as well as possible concentrations of the corresponding monomer and dimer. Similar measurements on Compound II indicated partial decomposition to metallic aluminum and gaseous trimethylamine and hydrogen.

We have characterized RPECVD formation of Si-nitride films by relating the chemical bonding in the deposited films to the growth conditions. Gas flow rates for different N- and Si-atom source gases have been correlated with (i) the film stoichiometry, i.e., the Si/N ratio, and the (ii) the growth rate. N2 and NH3 were used as N-atom source gases, and were either delivered (i) up-stream through the plasmageneration tube, or (ii) down-stream. Different flow-rate ratios of NH3/SiH4 were found for deposition of stoichiometric Si-nitride films using up-stream or down-stream introduction of NH3. This is explained in terms of competition between excitation and recombination processes for the N-atom precursor species. Stoichiometric nitride films could not be obtained using the N2 source gas for (i) either up-stream or down-stream delivery, and (ii) for plasma powers up to 50 W. This is attributed to the higher relative binding energy of N-atoms in N2 compared to NH3, and to significant N-atom recombination at high N2 flow rates through the plasma generation region.

Laser produced plumes from a GeO2 target were investigated using both optical emission spectroscopy and laser induced fluorescence. Elemental neutral and ionic Ge and diatomic GeO were monitored as a function of O2 pressure at 4 cm from the target surface. Data obtained from laser fluorescence experiments showed no indication of chemical production of GeO in these plumes under any conditions studied; however, the atomic emission intensities of several ionic and neutral Ge lines appeared to increase with O2 pressure. This signified plume interactions with the background gas. The trends in the species concentrations were determined and the results are interpreted with respect to mechanisms for thin film growth.

The electrical and optical properties of room temperature laser deposited indium tin oxide films were studied. It was found that the resistivity of the film was quite sensitive to the deposition conditions. At the optimized conditions, films with a bulk resistivity value of 2.8×10−4 Ω-cm and optical transmission of greater than 90% could be obtained. By using an in situ resistance measurement, it was shown that the initial growth mode was via island formation. Additionally, a classic transition from two- to three-dimensional behavior for the resistance was observed.

Recently, thin films of polytetrafluroethylene (PTFE) have been grown using pulsed laser ablation of TeflonTM at 266 nm.1,2 To provide further insight into the growth mechanisms we have examined the neutral and charged particle emissions generated in vacuum by 0 - 3 J/cm2 pulses of 248 nm radiation incident on solid PTFE. Measurements include quadrupole and time-of-flight mass spectroscopy. We find in addition to the neutral monomer (C2F4), copious emissions of highly reactive neutral and charged radicals, e.g., CF2, CF3, CF, F, and Cx. A careful analysis of the fluence dependence of these products provides definitive evidence that their precursors are generated by a thermally driven unzipping reaction. Models for the production of the radical species with the observed energies (several eV) involving gas phase processes are presented. Implications for improving PTFE thin film growth will be discussed.

An epoxy-compatible layer was produced in the near-surface region of a fluorocarbon resin by irradiating with an ArF excimer laser in a gaseous B(CH3)3 or a B(OH)3 water solution atmosphere. The pure photochemical reaction was employed in the modification process, the defluorination of the surface was performed with boron atoms which were photo-dissociated from B(CH3)3 or B(OH)3. The CH3 or OH radicals, also photo-dissociated, replaced the fluorine atoms of the surface. As a result, chemical bonding of the surface with the epoxy was performed. The adhesive strength was evaluated by the shearing tensile test, and the epoxy break value of 130 kgf/cm2 was sucessfully achieved.

Electronic and physical properties of SiO2 films deposited by microwave ECR plasmas of the mixtures of SiH4 and N2O have been measured as functions of the pressure and the gas-flow ratio of N2O to SiH4 gases in the processing chamber. Experimental results show that the film deposition rate increases with increasing SiH4 concentration, that is, with decreasing gas-flow ratio. The films deposited at N2O/SiH4 gas-flow ratios smaller than 10 tend to have a refractive index higher than the thermally grown oxide. However, for the N2O/SiH4 gas-flow ratios between 10 and 20, the films have the refractive index close to that of thermally grown oxide, which is about 1.45-1.46. The film deposition rate increases linearly with increasing pressure. In general, the films deposited at high pressures (>100 mTorr) have a higher refractive index as compared with the thermally grown oxide; also films deposited at high pressures have more electron traps. Good quality SiO2 films can be deposited at pressures with the range of 20 -50 mTorr and the N2O/SiH4 gas-flow ratio of 10.

This paper explores the use of a flow-tube reactor coupled to an FTIR spectrometer to study gas-phase chemical reactions in CVD systems. We show that our apparatus can generate reliable kinetics data by reproducing the literature rate constant for the reaction between O3 and isobutene. We present data from this apparatus on two technologically important systems: TiN from Ti(NMe2)4 (TDMAT) and NH3 and SiO2 from tetraethoxysilane (TEOS) and O3. The results presented include kinetics data for the reaction of Ti(NMe2)4 with NH3 and ND3 at room temperature and the IR spectra of the products from the reaction of TEOS with O3 at 175°C.

The deposition of SiO2 by remote PECVD using microwave activated oxygen species and SiH4 were examined. The deposition rate has been found to be greatly enhanced by reducing the distance between the substrate surface and the end of the supplying nozzle for the plasma excited oxygen species.

The deposition rate decreased with increasing substrate temperature under the condition that the activated oxygen species and SiH4 molecules collide with each other many times. Its activation energy was -0.27 eV.

It has been found that the gas phase reaction caused by the collision is important to obtain high quality films. A SiO2 film with a resistivity larger than 1×1016 Ω·cm was able be obtained with high deposition rates beyond 200 nm/min, at low temperatures below 400°C. The minimum interface state density was 4.3×1010 cm−2eV−1 for a film deposited at 230 nm/min, and 2.0×1010 cm−2eV−1 for a film deposited at 30 nm/min.

Carboxyl groups were photochemically substituted for hydrogen atoms at a polyphenylenesulfide surface by using an KrF excimer laser light and vaporized formic acid. In the process, the polyphenylenesulfide film was placed in the formic acid vapor, and the surface was irradiated with the KrF excimer laser light. Irradiating with the laser, the surface was dehydrogenated by the hydrogen atoms which were photodissociated from the formic acid; the dangling bonds on the surface combined with the COOH radicals which were also photodissociated. The hydrophilic property of the photomodified surface was evaluated by the measurement of the contact angle with water. The dehydrogenation reaction and the substitution reaction of the COOH radicals were inspected by XPS analysis. Surface morphology of the sample was observed by SEM photograph.

For some dry etching applications in III-V semiconductors, such as via hole formation in InP substrates, the currently used plasma chemistries have etch rates that are up to a factor of 30 too slow. We report on the development of 3 new classes of discharge chemistries, namely C12/CH4 /H2/Ar at 150°C (yielding InP etch rates of >1 μm · min−1 at 1 mTorr and –80V dc), HBr/H2 for selective etching of InGaAs over AlInAs, and iodine-based plasmas (HI/H2, CH3 I/H2) that offer rapid anisotropic etching of all III-V materials at room temperature. In all cases, Electron Cyclotron Resonance sources (either multipolar or magnetic mirror) with additional rf biasing of the sample position are utilized to obtain low damage pattern transfer processes that generally use metal contacts on device structures as self-aligned etch masks. The temperature dependence of etch rates with these new chemistries display non-Arrhenius behavior in the range 50-250°C and a detailed study of the phenomenon are reported. Electrical, optical and chemical analysis of the etched surfaces show that it is possible to achieve essentially damage-free pattern transfer.