[en] The cleaning of Si_0.85Ge_0.15 surfaces using HCl and HF solutions is studied using synchrotron radiation photoelectron spectroscopy. The HF solution is found to be effective in removing both the Si oxide and the Ge oxide while the HCl solution can only remove part of the Ge oxide. For samples treated with HF, four spectral components are needed to fit the Ge 3d photoemission spectra. One is the bulk component and the other three are attributed to the surface Ge atoms with mono-hydride, di-hydride and tri-hydride terminations, respectively

[en] Synchrotron-based EUV exposure tools continue to play a crucial roll in the development of EUV lithography. Utilizing a programmable-pupil-fill illuminator, the 0.3-NA microexposure tool at Lawrence Berkeley National Laboratory's Advanced Light Source synchrotron radiation facility provides the highest resolution EUV projection printing capabilities available today. This makes it ideal for the characterization of advanced resist and mask processes. The Berkeley tool also serves as a good benchmarking platform for commercial implementations of 0.3-NA EUV microsteppers because its illuminator can be programmed to emulate the coherence conditions of the commercial tools. Here we present the latest resist and tool characterization results from the Berkeley EUV exposure station

[en] One important issue for integrating atomic-layer-deposited (ALD) TaN barrier metal into Cu interconnects is a low thickness margin due to high electrical resistivity (∼50 mΩ cm) of ALD-TaN. In investigating this issue, the median via resistance (0.16 μm diameter vias) was found to increase from 0.5 to 26 Ω/via as the ALD-TaN thickness was increased from 1 to 2 nm. To reduce the resistivity of ALD-TaN, its atomic concentration on various substrates was investigated. The N/Ta ratio of ALD-TaN was found to be about 4/5 on a SiO₂ substrate but about 1/2 on a Ta substrate. We also confirmed that the Ta-rich ALD-TaN film on the Ta substrate had low electrical resistivity (∼2 mΩ cm). We could thus successfully obtain low via resistance (5.4 Ω/via) with thick ALD-TaN (5 nm) by using a PVD-Ta/ALD-TaN/PVD-Ta multilayer structure

[en] Gas and surface phase chemistries of CF₄ plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO₂ and Si were measured during plasma processing as functions of the pressure, CF₄ gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF₄, CF₃, CF₂, SiF₄, and COF₂, among which CF₄ and SiF₄ were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF₄ and COF₂ was about 2:1 with no bias on the substrate and increased up to ∼8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF₂ density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF₄ increased. Comparisons between the gas phase data and etch rate results of Si and SiO₂ indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate

[en] Radio frequency magnetron sputtering from oxide targets has been used to synthesize crystalline alumina-zirconia nanocomposites at a relatively low temperature of 450 deg.C. Films of different compositions have been deposited ranging from pure zirconia to pure alumina, the compositions being measured with Rutherford backscattering and elastic recoil detection analysis. X-ray diffraction studies show the presence of the monoclinic zirconia phase in pure zirconia films. Addition of alumina into the film results in the growth of the cubic zirconia phase and amorphous alumina. No crystalline alumina was detected in either the composite or the pure alumina film. The microstructure of the films as studied by high resolution electron microscopy and scanning transmission electron microscopy shows a columnar growth mode in both the pure zirconia and nanocomposite films, but reveals differences in the intracolumnar structure. For the nanocomposite small equiaxed grains, ∼5 nm in size, are found at the base of the columns at the interface with the substrate. An amorphous tissue of alumina was present between the small crystallites in the case of the nanocomposite

[en] This study investigated the deformation of ArF photoresist (PR) and the etch characteristics of ArF PR and SiO₂ layers in a dual frequency superimposed capacitively coupled plasma (DFS-CCP) etcher with multiple frequency sources under different frequency combinations in C₄F₈/CH₂F₂/O₂/Ar capacitively coupled plasma. In the DFS-CCP etcher, the high-frequency (f_HF) power (13.56, 27, and 60 MHz) was varied to control the plasma density while a fixed low frequency (f_LF) of 2 MHz was used to control the ion bombardment energy to the wafer. The morphology of the blanket ArF PR surfaces and line patterns of the ArF PR after etching showed a significant increase in the level of surface roughening and deformation with increasing HF source frequency (f_HF) from 13.56 to 60 MHz under the same V_dc and gas flow conditions. This was attributed to the increased F radical flux and possibly ion flux on the surface. The V_dc also played an important role in increasing the surface roughness and ArF PR deformation, which was presumably due to the increased ion flux and ion-bombardment energy, respectively. The etch rates of the ArF PR and silicon oxide layers increased significantly with increasing |V_dc| and f_HF possibly due to the increased ion energy and ion/radical flux density, respectively. The etch selectivity of the SiO₂ layer to the ArF PR was enhanced most significantly by the increase in CH₂F₂ flow rate due to the formation of a thicker and C-rich CF_x polymer on the oxide and PR surfaces

[en] In plasma etching processes, the reactor wall conditions can change over time due to a number of intentional and unintentional reasons, leading to a variability in the radical number densities in the plasma, caused by changes in the probabilities for reactions such as recombination at the walls. This leads to loss of reproducibility in the etching process. Here the authors isolated one such effect in which the feed gas was changed in the absence of a substrate. The transient surface composition of an anodized aluminum surface was determined for inductively coupled plasmas as the gas was switched from Cl₂ to O₂ and vice versa. The study was carried out with the spinning wall method and Auger electron spectroscopy. When the surface was first conditioned in an O₂ plasma and then exposed to Cl₂ plasmas, a rapid uptake of Cl was found in the first tens of seconds, followed by a slow approach to a steady-state value within ∼5 min of plasma exposure. Conversely, when the surface was exposed to a Cl₂ plasma for a long time and then switched to an O₂ plasma, the anodized aluminum surface underwent a rapid dechlorination in the first few seconds and then a slow approach to steady state over ∼3 min. Throughout these treatments, the coverages of Si (from erosion of the quartz discharge tube) and O were nearly constant.

[en] The substrate temperature effects on the amorphous carbon film growth were investigated, by using the deposition rates and in situ and ''real-time'' infrared spectroscopy in multiple internal reflection geometry. The deposition rates were decreased, in contrast with the increases of substrate temperature. The growth mode was also changed with substrate temperatures: the film growth depends on the gas phase reaction at low substrate temperature; on the other hand, at high temperature the film grows with the decomposition of the CH₃ species.

[en] The tungsten piperidylhydrazido complex Cl₄(CH₃CN)W(N-pip) (1) was used for film growth of tungsten carbonitride (WN_xC_y) by metal-organic chemical vapor deposition (CVD) in the absence and presence of ammonia (NH₃) in H₂ carrier. The microstructure of films deposited with NH₃ was x-ray amorphous between 300 and 450 deg. C. The chemical composition of films deposited with NH₃ exhibited increased N levels and decreased C levels over the entire deposition temperature range (300-700 deg. C) as compared to films deposited without NH₃. As determined by x-ray photoelectron spectroscopy, W is primarily bonded to N and C for films deposited at 400 deg. C, but at lower deposition temperature the binding energy of the W-O bond becomes more evident. The growth rates of films deposited with NH₃ varied from 0.6 A/min at 300 deg. C to 4.2 A/min at 600 deg. C. Over 600 deg. C, the growth rate decreased when using NH₃ presumably due to parasitic gas phase reactions that deplete the precursor. Diffusion barrier properties were investigated using Cu/WN_xC_y/Si stacks consisting of 100 nm Cu deposited at room temperature by reactive sputtering on a 20 nm WN_xC_y film deposited at 400 deg. C by CVD. X-ray diffraction and cross-sectional transmission electron microscopy were used to determine the performance of the diffusion barrier. Cu/WN_xC_y/Si stacks annealed under N₂ at 500 deg. C for 30 min maintained the integrity of both Cu/WN_xC_y and WN_xC_y/Si interfaces.

[en] While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd)₃), triethylsilane (HSi(C₂H₅)₃ or HSiEt₃), and titanium tetrakisdiethylamide (Ti(N(C₂H₅)₂)₄ or Ti(NEt₂)₄) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt₃ showed the formation of SiC phase but Al(hd)₃-derived films were amorphous. The Ti(NEt₂)₄ precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO₂ anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.