Showing papers on "Atomic layer deposition published in 1999"
Patent•
IBM1
TL;DR: In this paper, metal nitrate-containing precursor compounds are employed in atomic layer deposition processes to form metal-containing films, eg metal, metal oxide, and metal nitride, which films exhibit an atomically abrupt interface and an excellent uniformity.
Abstract: Metal nitrate-containing precursor compounds are employed in atomic layer deposition processes to form metal-containing films, eg metal, metal oxide, and metal nitride, which films exhibit an atomically abrupt interface and an excellent uniformity
677 citations
426 citations
Patent•
07 Sep 1999
TL;DR: An atomic layer deposition (ALD) apparatus capable of depositing a thin film on a plurality of substrates is described in this paper, where a vacuum chamber, a reactor, and a gas supply lines installed in the modules, for injecting the gases from the gas supply portion into the stages.
Abstract: An atomic layer deposition (ALD) apparatus capable of depositing a thin film on a plurality of substrates. The atomic layer deposition apparatus includes: a vacuum chamber, a reactor installed in the vacuum chamber, having a plurality of modules which can be assembled and disassembled as desired, a plurality of stages as spaces partitioned by assembling the plurality of modules, and openings which allow each stage to receive one substrate; a gas supply portion installed in the reactor, for supplying reaction gases and a purging gas to the reactor; and a plurality of gas supply lines installed in the modules, for injecting the gases from the gas supply portion into the stages.
347 citations
TL;DR: TaN, Ta3N5, and TaOxNy films were obtained by the atomic layer deposition technique as discussed by the authors with a resistivity of 9 × 10-4 Ω cm.
Abstract: TaN, Ta3N5, and TaOxNy films were deposited by the atomic layer deposition technique. The alternate surface reactions between TaCl5 and NH3 resulted in Ta3N5 films, but when elemental zinc, serving as an additional reducing agent, was supplied on the substrates between the TaCl5 and NH3 pulses, TaN with a resistivity of 9 × 10-4 Ω cm was obtained. TaOxNy films were grown by depositing first thin Ta3N5 layers which were then partially oxidized by single water pulses. By varying the number of the Ta3N5 deposition cycles between the water pulses, the oxygen-to-nitrogen ratio of the films was controlled. The permittivity of the TaOxNy films was around 30 which is somewhat higher than that of Ta2O5.
213 citations
TL;DR: In this paper, the conformal resistivities of thin and conformal copper films were examined using atomic layer deposition as possible seed layers for subsequent electrodeposition, and they were shown to be highly conformal over high aspect ratio trenches.
Abstract: Deposition of thin and conformal copper films has been examined using atomic layer deposition as possible seed layers for subsequent electrodeposition. For this investigation, the copper films were deposited on glass plates as well as on , , and films on silicon wafers. Typical resistivities of these films ranged from for thick copper films to for thick films. The adhesion of the copper films deposited on and at was excellent. These films were highly conformal over high aspect ratio trenches. ©2000 The Electrochemical Society
203 citations
TL;DR: In this article, thin films were deposited by atomic layer deposition making use of a novel class of strontium and barium precursors, i.e., their cyclopentadienyl compounds, together with titanium tetraisopropoxide and water.
Abstract: and thin films were deposited by atomic layer deposition making use of a novel class of strontium and barium precursors, i.e., their cyclopentadienyl compounds, together with titanium tetraisopropoxide and water. films were grown at from strontium bis(triisopropylcyclopentadienyl) and at from barium bis(pentamethylcyclopentadienyl). After annealing in air at , permittivities of 180 and 165 were measured for and , respectively. The films showed excellent conformality and complete filling of test trench structures. ©1999 The Electrochemical Society
202 citations
TL;DR: SiO2 thin films were deposited with atomic layer control using self-limiting surface reactions as discussed by the authors, which was achieved by separating the binary reaction SiCl4+2H2O→ SiO2+4HCl into two half-re...
Abstract: SiO2 thin films were deposited with atomic layer control using self-limiting surface reactions. The SiO2 growth was achieved by separating the binary reaction SiCl4+2H2O→ SiO2+4HCl into two half-re...
181 citations
TL;DR: Titanium-silicon-nitride films were grown by metal-organic atomic-layer deposition at 180 °C as mentioned in this paper, and the Si content in the deposited films and the deposition thickness per cycle remained almost constant at 18 at.
Abstract: Titanium–silicon–nitride films were grown by metal–organic atomic-layer deposition at 180 °C. When silane was supplied separately in the sequence of a tetrakis(dimethylamido) titanium pulse, silane pulse, and ammonia pulse, the Si content in the deposited films and the deposition thickness per cycle remained almost constant at 18 at. % and 0.22 nm/cycle, even though the silane partial pressure varied from 0.27 to 13.3 Pa. Especially, the Si content dependence is strikingly different from the conventional chemical-vapor deposition. The capacitance–voltage measurement revealed that the Ti–Si–N film prevents the diffusion of Cu up to 800 °C for 60 min. Step coverage was approximately 100% even on the 0.3 μm diam hole with slightly negative slope and 10:1 aspect ratio.
174 citations
TL;DR: The properties of titanium nitride deposited by atomic layer epitaxy (ALE) using three different deposition processes, i.e., TiI4+NH3, TiCl4+ NH3 and TiCl 4+Zn+NH 3, as a diffusion barrier between cop...
Abstract: The properties of titanium nitride deposited by atomic layer epitaxy (ALE) using three different deposition processes, i.e., TiI4+NH3, TiCl4+NH3 and TiCl4+Zn+NH3, as a diffusion barrier between cop ...
121 citations
TL;DR: In this paper, tetrakis(dimethylamido)titanium (TDMAT), silane, and ammonia were used for atomic layer deposition of Ti-Si-N films.
Abstract: Titanium-silicon-nitride films were grown by atomic layer deposition using an alternating supply of tetrakis(dimethylamido)titanium (TDMAT), silane. and ammonia, at substrate temperature of 180°C. The supply of a reactant was followed by a purge with inert gas before introducing another reactant onto the substrate in order to prevent gas-phase reactions. In one set of experiments the reactants were supplied separately in the sequence of TDMAT. silane. and ammonia. The Si content of the films remained constant at 18 at.%. and the film growth rate varied little from 0.24 nm per reactant-supply-cycle, even though silane partial pressure varied from 0.002 to 0.1 torr. In the other set of experiments silane and ammonia were simultaneously supplied in the sequence of TDMAT and silane/ammonia. The Si content varied from 3 to 23 at.% as the silane-to-ammonia ratio varied from 0.01 to 10. Atomic layer deposition of Ti-Si-N films allows the precise control of Si content as well as film thickness.
101 citations
TL;DR: The suitability of atomic layer deposition for making corrosion protection coatings was examined in this article, where thin films of Al 2 O 3, TiO 2, Ta 2 O 5 and Al 2O 3 -TiO 2 multilayers were deposited on stainless steel substrates.
Abstract: The suitability of Atomic Layer Deposition for making corrosion protection coatings was examined. Thin films of Al 2 O 3 , TiO 2 , Ta 2 O 5 and Al 2 O 3 -TiO 2 multilayers were deposited on stainless steel substrates. The films were deposited at 150-400°C. The corrosion behaviour of the samples was studied by Electrochemical Impedance Spectroscopy in 3.5 wt% NaCl and 0.1 and 1 mol/l HCl solutions. Al 2 O 3 was found to protect the substrate material against corrosion for a limited time in NaCl. TiO 2 alone does not give good protection, but when combined with Al 2 O 3 in a multilayer structure better protection is achieved. Ta 2 O 5 films were tested in HCl and were found to protect the base material to some extent.
TL;DR: The growth mechanism of vanadium oxide films has been studied in situ by quartz crystal microgravimetry allowing us to distinguish different growth regimes as discussed by the authors, ranging from near room temperature to higher temperatures.
Abstract: Vanadium oxide films have been deposited by atomic layer epitaxy (ALE) at temperatures ranging from 50 to from vanadyl triisopropoxide and water precursors. The growth mechanism was studied in situ by quartz crystal microgravimetry allowing us to distinguish different growth regimes. ALE growth extends from near room temperature to . For higher temperatures there was a change in the ALE regime, followed by a different chemical vapor deposition regime involving the direct decomposition of the vanadium precursor at temperatures higher than ca. . As‐grown films were amorphous and crystallized easily during thermal post‐treatments. Films annealed at offered excellent electrochemical stability and cyclability for lithium ion insertion/deinsertion between 3 and . ©2000 The Electrochemical Society
TL;DR: In this article, the most important deposition and growth processes that influence the optoelectronic material properties of a-Si:H deposited by hot-wire chemical vapor deposition (HWCVD) are clarified.
Abstract: Device-quality a-Si:H films have been deposited by hot-wire chemical vapor deposition (HWCVD). We have investigated the influence of deposition parameters on the film growth and properties. The most important deposition and growth processes that influence the optoelectronic material properties of a-Si:H deposited by HWCVD are clarified. During the deposition process attention must be paid to accurately control the substrate temperature, which is a key parameter to obtain device-quality films. A heat transport model is presented to be able to correct for the heating of the substrate by the filaments. It is found that films deposited at high deposition temperatures are under a high compressive stress. We show how the hydrogen incorporation in the layer is influenced by hydrogenation of subsurface layers by the atomic hydrogen flux that is inherent to the HWCVD process. We further identify the fundamental differences between plasma enhanced CVD and HWCVD material.
TL;DR: In this paper, the performance of Cd-free ZnO/Cu(InGa)Se2 solar cells using a high-resistivity buffer layer was evaluated using an atomic layer deposition (ALD) method using diethylzinc and H2O as reactant gases.
Abstract: The aim of our experiments is to improve the performance of Cd-free ZnO/Cu(InGa)Se2 solar cells using a high-resistivity ZnO buffer layer. Buffer layers were deposited by atomic layer deposition (ALD) using diethylzinc (DEZn) and H2O as reactant gases. The structural and electrical properties of the ZnO films on glass substrates were characterized. A high resistivity of more than 103 Ωcm and a transmittance of above 80% in the visible range were obtained. We focused on determining the optimum deposition parameters for the ALD-ZnO buffer layer. Results indicate that the thickness and resistivity of the ALD-ZnO buffer layer, as well as the heat treatment prior to the deposition of the buffer layer, affect the device characteristics. The best efficiency obtained with an ALD-ZnO buffer layer of solar cells without an antireflective coating was 12.1%. The reversible light soaking effect was observed in these devices.
TL;DR: In this paper, the high-field leakage current in (Ta 1−xNbx)2O5 solid solution films with x = 0.02-0.07 decreases by two to three orders of magnitude when compared to that of the non-oped Ta 2O5.
Abstract: (Ta1−xNbx)2O5 solid solution films and Ta2O5–Nb2O5 nanolaminates have been grown in an atomic layer deposition process at 300 and 325 °C. TaCl5 or Ta(OC2H5)5 and Nb(OC2H5)5 have been used as metal precursors while H2O has been applied as the oxygen source. Application of Ta(OC2H5)5 resulted in amorphous films with considerably better thickness uniformity than that characteristic of TaCl5-based process. Application of TaCl5 resulted in crystallized films. The high-field leakage current in (Ta1−xNbx)2O5 solid solution films with x=0.02–0.07 decreases by two to three orders of magnitude when compared to that of the nondoped Ta2O5. The permittivity of Ta2O5 films was 25 while the permittivity of amorphous or partially crystallized solid solution films and nanolaminates increased up to 33.
TL;DR: In this article, the thickness and the doping level of the p-layer were optimized in order to increase the open-circuit voltage (Voc) of the fabricated a-Si solar cells.
Abstract: B-doped ZnO films deposited by the photo-induced metalorganic chemical vapor deposition (photo-MOCVD) method were applied to p-i-n single junction amorphous silicon (a-Si) solar cells as front contacts. The thickness and the doping level of the p-layer were optimized in order to increase the open-circuit voltage (Voc) of the fabricated a-Si solar cells. As a result, a stabilized conversion efficiency of 8.7% (Voc: 0.926 V, Jsc: 14.6 mA/cm2, FF: 0.646) was achieved under AM 1.5 (100 mW/cm2) illumination. Furthermore, the electrical properties of ZnO films were improved by employing an atomic layer deposition (ALD) technique instead of the conventional MOCVD method, and a lower resistivity of 5×10-4 Ωcm was achieved. It was also found that the stability of the electrical properties of ZnO films was improved by the ALD technique. The performance of the a-Si solar cells was further improved by applying the obtained high-quality ZnO films.
TL;DR: In this article, X-ray diffraction, NMR and mass spectroscopy, and thermal analysis were used to determine the crystal structures of compounds [Mg2(thd)4] (1) and [mg2[thd]2(EtOH)2] (2) with a rather constant growth rate of 0.10−0.14 A/cycle was observed at 325−425 °C.
Abstract: Complexes [Mg2(thd)4] (1) and [Mg(thd)2(EtOH)2] (2) (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) were prepared and characterized using various techniques, viz. X-ray diffraction, NMR and mass spectroscopy, and thermal analysis. Crystal structures of compounds 1 and 2 were determined. Complex 1 crystallizes as a dimer where three oxygen atoms from three different thd ligands join the Mg atoms together. Crystallization from ethanol results in a monomeric complex having solvent coordinated to Mg. Both complexes volatilize completely, but in 2, coordinated ethanol molecules do not stay intact in the gas phase. Complex 1 was used with H2O2 as precursors in the growth of MgO thin films by atomic layer deposition techniques. A rather constant growth rate of 0.10−0.14 A/cycle was observed at 325−425 °C.
Patent•
03 May 1999TL;DR: In this paper, a method for fabricating a thin-film field effect transistor (TFT) is described, where the active layer of the TFT is formed by a low-cost chemical bath deposition method.
Abstract: A method for fabricating a thin film field effect transistor is described in this invention. The active layer of the thin film transistor (TFT) is formed by a low cost chemical bath deposition method. The fabrication procedure includes deposition of a metal layer on an insulating substrate, patterning of the metal layer to form a metal gate, formation of the di-electric layer, deposition of the active layer and formation of source and drain contacts.
TL;DR: The mass thickness of thin titanium oxide and hafnium oxide films grown by the atomic layer deposition method on silicon substrates was determined using EPMA data and STRATA and FLA programs.
Abstract: The mass thickness of thin titanium oxide and hafnium oxide films grown by the atomic layer deposition method on silicon substrates was determined using EPMA data and STRATA and FLA programs. The results of the two programs coincided well if a set of relative intensities was measured at different energies of probe electrons. Comparative measurements by XRF gave higher values. Comparing the mass thicknesses of films measured by EPMA and absolute thicknesses determined by optical spectrophotometry, ellipsometry and profilometry, the densities of polycrystalline films were estimated. Values of 3.3±0.2 and 8.7±0.2 g cm
–3
were obtained for TiO
2
anatase grown at 300 °C and monoclinic HfO
2
grown at 600 °C, respectively. Titanium oxide films deposited at 100 °C contained significant amounts of chlorine and hydroxyl groups (7.2±0.7 and 6.9±0.9 mass-%, respectively).
TL;DR: In this paper, the electrical properties of metal/ferroelectric/insulator/semiconductor (MFIS) structures with various insulators were investigated, and the memory windows for MFIS structures with NO inter-dielectrics in the range of 0.75-1.2 V were maintained up to annealing temperatures of 900°C.
Abstract: The electrical properties of metal/ferroelectric/insulator/semiconductor (MFIS) structures with various insulators were investigated. Layers of Si3N4/SiO2 (NO) formed by thermal oxidation and low pressure chemical vapor deposition (LPCVD) and Al2O3 layers deposited by atomic layer deposition (ALD) were used as inter-dielectric layers. SrBi2Ta2O9 (SBT) films used as ferroelectric layers were prepared by metal organic decomposition (MOD). The capacitance-voltage (C–V) curves including the memory window were affected by varying the annealing temperature for SBT films. Memory windows for MFIS structures with NO inter-dielectrics in the range of 0.75–1.2 V were maintained up to annealing temperatures of 900°C. The width of the memory window in C–V curves for MFISs using thin Al2O3 layers decreases with increasing annealing temperature. Therefore, the selection of a good insulator and parameter control are required for the use of MFIS-ferroelectric random access memories (FRAMs).
TL;DR: Tantalum oxide films were grown by chemical vapor deposition using an alternating supply of tantalum pentaethoxide and ammonia as mentioned in this paper, and they were crystallized after annealing at 800 °C in oxygen atmosphere by rapid thermal process.
Abstract: Tantalum oxide films were grown by chemical vapor deposition using an alternating supply of tantalum pentaethoxide and ammonia. The supply of one source was followed by a purge with argon gas before introducing the other source onto the substrate in order to prevent gas-phase reactions. At substrate temperature between 250-275 °C the film growth depended only on the number of source supply cycles (0.15 nm/cycle) and did not depend on the substrate temperature nor supply time of the sources. As-deposited films were amorphous, however, were crystallized after annealing at 800 °C in oxygen atmosphere by rapid thermal process. Annealed films showed increased dielectric constant and decreased leakage current density, which were 13.3 and 6.6 μA/cm 2 at 1 MV/cm, respectively, for a 15-nm-thick film after annealing at 800 °C for 10 minutes.
TL;DR: In this paper, an epitaxial PbTiOO3 (PTO) thin film was grown on (001) LaAlO3(LAO) substrates by a preseeded, two-step process via spin coating a Pb-Ti double alkoxide precursor solution.
Abstract: Epitaxial PbTiO3 (PTO) thin films were grown on (001) LaAlO3 (LAO) substrates by a preseeded, two-step process via spin coating a Pb–Ti double alkoxide precursor solution. In the first step, a substrate was preseeded with epitaxial islands of PTO by coating the substrate with a very thin layer of the precursor solution and heat treating to 800 °C for 1 h. The isolated islands had an epitaxial orientation relationship of [100] (001)PTO || [100] (001)LAO. In the second step, another PTO thin film was deposited by spin coating to produce an epitaxial film via grain growth from the seeded islands. The sequence of epitaxy during heating between 400 and 800 °C was characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM). This sequence was compared to the case where the LAO substrate was not seeded. Regardless of whether the substrate was seeded or not, perovskite PTO grains nucleated and grew within the pyrolyzed, amorphous film. Films grown on the unseeded substrates were, at best, only highly textured, polycrystalline films. TEM observations showed that only a low number of epitaxial nuclei formed at the substrate/film interface due, apparently, to the large strain energy associated with the large lattice mismatch (~4%) between PTO and LAO. Other, unoriented, PTO grains that nucleated within the amorphous film were not consumed as the epitaxial grains grew larger with increasing temperature. On the other hand, good epitaxial films could be produced when the number density of epitaxial nuclei was increased by first forming a seeded substrate.
Patent•
11 Sep 1999
TL;DR: In this paper, a method of chemically depositing a film in which a catalyst component is employed to enhance the deposition rate is described, and a deposition film having superior step coverage and high deposition rate can be obtained.
Abstract: A method of chemically depositing a film in which a catalyst component is employed to enhance the deposition rate. The present invention is characterized in that a catalyst component is not buried under the film to be deposited but moved onto the surface of the film during the deposition to facilitate the surface deposition reaction of gas phase deposition sources. According to the present invention, a deposition film having superior step coverage and high deposition rate can be obtained.
TL;DR: In this article, the surface structure of polycrystalline CaS thin films was studied by AFM and compared with respective SEM images, and a possible growth mechanism was presented, on studying the variation of morphological features (i.e., roughness and size of crystallites) with thickness and growth rate.
TL;DR: In this paper, a quadrupole mass spectrometer has been integrated to an ALD reactor and its performance is demonstrated by studies on ALD oxide processes employing Al(CH 3 ) 3, Ti(OC 2 H 5 ) 4, Ta (OC 2H 5 ) 5 and Nb(OC 3 ) 5 as metal precursors and water as the oxygen source.
Abstract: In situ characterization of the chemical reactions in atomic layer deposition (ALD) processes in flow-type reactors is an important and challenging task. For this purpose, a quadrupole mass spectrometer has been integrated to an ALD reactor The special features of this setup are described and its performance is demonstrated by studies on ALD oxide processes employing Al(CH 3 ) 3 , Ti(OC 2 H 5 ) 4 , Ta(OC 2 H 5 ) 5 and Nb(OC 2 H 5 ) 5 as metal precursors and water as the oxygen source.
03 Oct 1999
TL;DR: In this article, an electrostatic atomization technique has been developed to generate ultrafine spray droplets of ZrO/sub 2/ and SiC ceramic suspensions in a range of a few micrometers with a narrow size distribution.
Abstract: An electrostatic atomization technique has been developed to generate ultrafine spray droplets of ZrO/sub 2/ and SiC ceramic suspensions in a range of a few micrometers with a narrow size distribution. The aim of this paper is to deposit uniform thin films (from a few micrometers to a few tens of micrometers) of these ceramic materials on alloy substrates. Compared to some other thin-film deposition techniques, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and plasma spray (PS), etc., the thin-film deposition process using electrostatic atomization is not only cheap but also capable of depositing a very thin multilayer with abrupt interfaces. CVD and PVD are expensive techniques. They require either a high vacuum, even an ultrahigh vacuum environment or complex gas handling system. Their deposition rate is also low. PS is normally used to grow thermal barrier coatings which usually have a thickness of a few tens to a few hundreds micrometers. Its application is limited by the quality of the coatings (high porosity, coarse and nonuniform microstructure). Preliminary results in this work have shown that, for low through-put atomization, the cone-jet is the most suitable method to produce a fine charged aerosol with a narrow size distribution, which is crucial to produce uniform thin films. It was found that the size of ceramic particles in ZrO/sub 2/ and SiC thin films is less than 10 /spl mu/m. Microstructures of these thin films show very homogenous morphologies. These results indicate that ceramic thin films with high homogeneity can be deposited using electrostatic atomization. It was also observed that the morphology of the underlayer has some influence on the morphology of the top layer.
TL;DR: In this paper, a chemical solution deposition (CSD) procedure was used to prepare epitaxial lanthanum calcium manganese oxide (LCMO) thin films on (100) SrTiO3 single-crystal substrates.
Abstract: A chemical solution deposition (CSD) procedure was used to prepare epitaxial lanthanum calcium manganese oxide (LCMO) thin films on (100) SrTiO3 single-crystal substrates. The colossal magnetoresistance (CMR) properties of the films were found to be comparable to those processed with vacuum deposition techniques and to bulk samples. The (200) LCMO d-spacing and insulator-metal transition temperature (TIM) were measured for films heat-treated at different temperatures, partial pressures of O2, and different times. The variations observed suggest a direct link between lattice parameter and TIM, as can be understood through their mutual dependence on the Mn4+/Mn3+ ratio. The measurements also suggest that film and powder samples crystallize Mn41-rich with respect to the Ca-substitution level, consistent with the larger lattice parameter and higher TIM observed following short heat treatments at high temperatures or long treatments at lower temperatures. Films refired in reducing conditions had the largest (200) d-spacing and slightly lower TIM, as expected from the 30% Ca-substitution level and consistent with the LCMO electronic/magnetic phase diagram constructed for bulk samples.
TL;DR: In this article, the authors show that the measuring of the reflectance changes in transparent systems allows one to optically characterize the surface of films growing under the conditions of atomic partial-monolayer deposition.