Showing papers on "Atomic layer deposition published in 1991"
TL;DR: In this paper, a capacitor fabrication technique is developed to obtain an extremely thin Ta/sub 2/O/sub 5/ film with an effective SiO/ sub 2/ film thickness of 2.8 nm (equivalent to 12 fF/ mu m/sup 2/) for use in low power 64-Mb DRAM.
Abstract: A capacitor fabrication technique is developed to obtain an extremely thin Ta/sub 2/O/sub 5/ film with an effective SiO/sub 2/ film thickness of 2.8 nm (equivalent to 12 fF/ mu m/sup 2/) for use in a low-power 64-Mb DRAM. A two-step annealing process is used after deposition of the Ta/sub 2/O/sub 5/ film by thermal chemical vapor deposition (CVD). The first step is ozone (O/sub 3/) annealing with ultraviolet light irradiation, which is the most effective means of reducing leakage current. A model for explaining the effectiveness of the UV-O/sub 3/ annealing treatment is proposed. Excited oxygen atoms in the singlet state (/sup 1/D), which are generated selectively in the ozone gas irradiated by a mercury lamp, repair the oxygen vacancies existing in the as-deposited CVD-Ta/sub 2/O/sub 5/ film, resulting in a marked reduction of the film's leakage current. The second step is dry-O/sub 2/ annealing, which reduces the defect density of initial breakdown. Sufficient capacitance can be obtained while maintaining a low leakage current and sufficient step coverage for a 1.5-V supply-voltage 64-Mb DRAM having a high-aspect three-dimensional memory cell. >
209 citations
60 citations
TL;DR: In this paper, a low-temperature (<300°C) process for selective deposition of silicon using time modulated flow of silane into a hydrogen plasma was reported. But the application of the selective deposition process to the fabrication of thin-film transistor structures is also presented.
Abstract: We report a new low‐temperature (<300 °C) process for selective deposition of silicon using time modulated flow of silane into a hydrogen plasma. Time modulated gas flow allows the chemical processes associated with deposition and surface modification or etching to occur sequentially, and be controlled independently, giving an additional degree of freedom to the deposition process. The observed selective deposition is consistent with substrate specific nucleation, and preferential etching of the nuclei during the hydrogen plasma exposure. The application of the selective deposition process to the fabrication of thin‐film transistor structures is also presented.
35 citations
TL;DR: In this paper, an atomic layer epitaxy of Ge using GeH 4 decomposition at a surface heated with a Xe flash lamp in an ultraclean low-pressure environment was investigated.
22 citations
TL;DR: A quasi-three-dimensional ballistic deposition model for thin film growth by physical vapor deposition is described, which incorporates three-dimensional incident flux distributions and shadowing effects, but simulates deposition through disc accretion in a two-dimensional plane.
Abstract: A quasi-three-dimensional ballistic deposition model for thin film growth by physical vapor deposition is described. This model incorporates three-dimensional incident flux distributions and shadowing effects, but simulates deposition through disc accretion in a two-dimensional plane. Results from the simulation of sputtered metal deposition over vias ranging from 0.5 to 3.0 mu m width are presented and compared with two-dimensional simulation results. Step coverages are calculated and plotted as a function of via size. The use of a ballistic deposition program enables a density analysis of the simulated films. The simulated films display a drop in density of 22-27% for the films deposited on the via sidewalls, and this density drop is plotted versus via size for both the two-dimensional and three-dimensional simulations. >
18 citations
11 Jun 1991
TL;DR: In this paper, the reaction mechanism of TEOS/O/sub 3/APCVD was studied for dependence of deposition rate on base material, and for step coverage, and the mechanism was discussed in terms of hydrophile of substrate surface and deposition gases.
Abstract: The reaction mechanism of TEOS/O/sub 3/ atmospheric pressure CVD was studied for dependence of deposition rate on base material, and for step coverage. Base material dependence of TEOS/USG, PSG, BSG and BPSG (on silicon and thermal oxide) was studied. Lower deposition rates and poorer quality of TEOS/USG films have been obtained on more hydrophilic substrate surface with high ozone concentration. The mechanism was discussed in terms of hydrophile of substrate surface and deposition gases. To eliminate surface effects of thermal oxide, plasma treatment in nitrogen at 350 degrees C for 1 min was effective. So the substrate surface plays very important role for TEOS/O/sub 3/ APCVD. In OMCTS and HMDS/USG depositions there was strong base material dependence compared with TEOS. TEOS/USG and BSG films showed base material dependence but PSG and BPSG films did not. The former showed superior step coverage, but PSG showed some overhang step coverage and BPSG showed good step coverage. TEOS is hydrophobic, TMOP is hydrophilic and TMB is not hydrophilic, so USG and BSG films showed low deposition rates on hydrophilic thermal oxide surface. Overhang step coverage in PSG deposition can be attributed to partial gas phase reaction, which is also a cause of zero base material dependence. >
11 citations
TL;DR: In this article, the V2O5/SiO2 catalysts were prepared by a chemical vapour deposition (CVD) method and showed the formation of thin thin films.
Abstract: V K-edge EXAFS studies of V2O5/SiO2 catalysts prepared by a chemical vapour deposition (CVD) method demonstrate the formation of V2O5 thin films, while the V2O5 of V2O5/SiO2 prepared by an impregnation method is mainly in the form of microcrystallites.
10 citations
TL;DR: In this article, the authors compared Si and SiNx thin films from addition of SiH4 to the afterglow of N2 and H2 microwave plasmas.
Abstract: Deposition of Si and SiNx thin films from addition of SiH4 to the afterglow of N2 and H2 microwave plasmas has been compared. Deposition of Si films requires SiH4 concentrations several orders higher than SiH4 for SiNx deposition. It is concluded that for Si film deposition, luminescence from the H2 plasma induces SiH4 dissociation and reactions between silane species are necessary for Si film formation. The proposed mechanism supports a deposition model based on the SiH2 radical.
7 citations
TL;DR: In this paper, the growth and fabrication of a nonalloyed delta-doped FET entirely grown by atomic layer epitaxy was reported, and the DC and RF performances were shown to be comparable to similar devices fabricated on materials grown by other techniques.
Abstract: The growth and fabrication of a nonalloyed delta-doped FET entirely grown by atomic layer epitaxy are reported. The DC and RF performances are shown to be comparable to similar devices fabricated on materials grown by other techniques. FETs having a gate length of 1.5 mu m show transconductances as high as 144 mS/mm at a current density of 460 mA/mm. The breakdown voltage for these devices is between 20 and 25 V for a gate-to-drain spacing of 1.6 mu m. An f/sub T/ and f/sub max/ of 13 and 19 GHz were obtained respectively. These values are among the highest values reported for MESFETs with similar geometry. >
7 citations
TL;DR: In this article, an evidence of self-limiting adsorption of Cu-s-diketonate complex on sapphire substrates is presented, for the first time, by employing mass spectroscopy in the thermal desorption process.
Abstract: An evidence of self-limiting adsorption of Cu-s-diketonate complex on sapphire substrates is presented, for the first time, by employing mass spectroscopy in the thermal desorption process This fact provides an very important step towards atomic layer epitaxy of oxide superconductor films by chemical vapor deposition
3 citations
TL;DR: The dependence of the magnetic properties of multilayer CoNbZr/AlN films on the conditions of film preparation was investigated in this article, where the soft magnetic properties were found to be strongly related to the rf input power during AlN deposition.
Abstract: The dependence of the magnetic properties of multilayer CoNbZr/AlN films on the conditions of film preparation was investigated. AlN films were prepared by N 2 reactive sputtering deposition on CoNbZr films. The soft magnetic properties of the as-deposited films were found to be strongly related to the rf input power during AlN deposition. The anisotropy field decreases drastically at an input power of greater than 2 W/cm2, and a high permeability of around 10,000 (at 5 MHz) was obtained for as-deposited films prepared at an rf input power during A1N deposition of 4.4 W/cm2. SEM observations revealed that CoNbZr films in as-deposited multilayer form have nearly the same morphology as amorphous alloy films annealed at the optimum temperature for reduction of the anisotropy field. The annealing process during film preparation (self-annealing effect) is attributed to the heat generated during AlN deposition, originating mainly in the heat of formation in AlN reactive sputtering.
11 Jun 1991
TL;DR: In this paper, the oxide deposition in a biased ECR CVD reactor using TEOS (tetraethylorthosilicate) and TMCTS(tetramethylcyclotetrasiloxane) as Si sources was studied.
Abstract: The authors have studied oxide deposition in a biased ECR CVD reactor using TEOS (tetraethylorthosilicate) and TMCTS (tetramethylcyclotetrasiloxane) as Si sources. Oxide films with good material quality are deposited as long as O/sub 2//TEOS and O/sub 2//TMCTS flow rate ratios are greater than 2 and 3 respectively. The deposition rate using TMCTS is about four times higher than using TEOS under similar condition. The step coverage of oxide is found to be excellent when additional RF bias is applied on the substrate during the deposition. They have demonstrated that trenches with high aspect ratios (>1.5) can be filled without voids. >
TL;DR: Pd/Co multilayer films were prepared by rf sputtering, with a buffer layer of Pt, Pd, Cu or SiAlON between the multillayer film and the glass substrate.
Abstract: Pd/Co multilayer films were prepared by rf sputtering, with a buffer layer of Pt, Pd, Cu or SiAlON between the multilayer film and the glass substrate. The type of buffer layer was found to have an effect on the structure as well as the perpendicular magnetic anisotropy and coercive force of the multilayer film. A Pt buffer layer improves the layer structure and ≪111≫ orientation, as well as increasing the anisotropy, while SiAlON and Cu do not improve the layer structure but do increase the coercivity.
01 Jan 1991
TL;DR: In this article, a self-limiting mechanism in the processing procedure at one monolayer is involved in each cycle of digital processing, which provides not only atomic ordered controllability, but also process characteristics which are independent of the particular feature of the apparatus.
Abstract: In recent years, digital processing for ultra-microfabrication with atomic scale controllability has been interested by many researchers for realizing new quantum materials and devices controlled in atomic scale. In digital processing, pulsed operation of gas feeding and/or energetic beam irradiation is repeated in contrast to the simultaneous operation in analog processing. Moreover, it should be emphasized that a self-limiting mechanism in the processing procedure at one monolayer is involved in each cycle of digital processing. Therefore, digital processing provides not only atomic ordered controllability, but also process characteristics which are independent of the particular feature of the apparatus. There have been many reports on the use of digital processing in thin-film growth. Recently Aoyagi et have firstly realized digital etching of GaAs with saturation characteristics at one atomiclayer per cycle.
Proceedings Article•
01 Jan 1991
01 Jan 1991
TL;DR: In this paper, the effect of the UV irradiation (using the KrF(248nm) and XeC1(308nm) excimer laser) on the single source system (Y(thd)3, Y-Ba, Ba-Cu, and Y-Cu) and the triple source system(YBCO) was investigated.
Abstract: The effect of the UV irradiation (using the KrF(248nm) and XeC1(308nm) excimer laser) on the single source system (Y(thd)3, Ba(thd)2, and Cu(thd)2), the double source system (Y-Ba, Ba-Cu, and Y-Cu) and the triple source system (YBCO) were investigated. The KrF laser irradiation has improved the crystallization in the single source system and also improved both the crystallization and the reactivity of the Ba-Cu and Y-Cu systems in the double source system. These results indicate that the laser irradiation promotes the reactivity of sources, the crystallization and oxidation of films during the deposition.
01 Jan 1991
TL;DR: In this paper, a single phase as-grown Bi2Sr2Can−1CunOy (n = 2, 3, 4) thin films with layer-by-layer deposition using shutter control was successfully prepared.
Abstract: We have successfully prepared selectively a single phase as-grown Bi2Sr2Can−1CunOy (n = 2, 3, 4) thin films with layer-by-layer deposition using shutter control. The deposition was carried out by reactive evaporation.
07 Oct 1991
TL;DR: In this article, a feasibility study of producing thin polycrystalline GaAs-films on neutral substrates in a cost-efficient medium-quality vacuum of around 10/sup -7/mbar is presented.
Abstract: A feasibility study of producing thin polycrystalline GaAs-films on neutral substrates in a cost-efficient medium-quality vacuum of around 10/sup -7/ mbar is presented. To improve morphology and crystal structure of these films at the lowest possible temperature, the effectiveness of ion assistance during the process is examined. By adjusting the energy and intensity of the bombardment, well-defined energy can be brought to impact, which will be equivalent to an increased substrate temperature, levitating the actual thermal stress imposed on the substrate. This temperature is referred to as virtual temperature. If successful, this process will allow commercially attractive substrates to be used under deposition conditions corresponding to significantly higher temperatures. The ion-bombardment will continuously sputter-away loosely bound impurity atoms, so that a less ideal and therefore more cost-efficient vacuum in the 10/sup -7/ mbar range might be used. Experimental results demonstrate that GaAs epitaxial and polycrystalline films with good photovoltaic properties can be deposited in a common high vacuum using ion assistance. >
CNET1
TL;DR: In this article, a new chemical vapor deposition (CVD) process controlled by light irradiation is studied and applied to 111-V semiconductor device technology, where the interactions between the incident photons of and the gas-substrate system are either photolytic (UV lamps) or pyrolytic(JR lamps).
Abstract: New chemical vapor deposition (CVD) processes controlled by light irradiation are studied and applied to 111-V semiconductor device technology. The interactions between the incident photons of and the gas-substrate system are either photolytic (UV lamps) or pyrolytic (JR lamps). In the first case the process is cold and in the second one it produces fast thermal ramping. The technique is thus compatible in both cases with the fragile semiconductor substrate and it allows in-situ processing. We report here a set ofresults involving surface and interface studies in order to prepare the deposition of thin film materials and thin dielectric film deposition using " flash" CVD or UVCVD. The aim of this work is to propose alternative technologies for Ill-V semiconductors. 1 .
TL;DR: Zirconium fluoride (ZrF4 ) thin films were formed by plasma CVD and evaporation for thin-film optical wave guide as mentioned in this paper, and the optical transmission loss was measured by scattering detection method, and the loss was calculated to be 9.5 dB/cm.
Abstract: Zirconium fluoride (ZrF4 ) thin films were formed by plasma CVD and evaporation for thin-film optical wave guide. In the case of plasma CVD, ZrF4 compound was actually observed to be synthesized from the vapour of Zr and CF4 gas according to. ESCA measurement, even if the film contained impurities. As for evaporation, transparent and amorphous film was obtained and optical transmission loss was measured by scattering detection method, and the loss was calculated to be 9.5 dB/cm. But when only ZrF4 was deposited, thin film was tarnished to be white because of adsorption of moisture. Therefore, simultaneous evaporation of ZrF4 and BaF2 was performed and the charastaristic was stabilized.
01 Jan 1991
TL;DR: In this paper, electrical and structural measurements have been performed on novel test structures incorporatingp-type GaAs epilayers grown by organometallic vapor phase atomic layer epitaxy on the vertical sidewalls of semi-insulating GaAs rods formed by ion-beam-assisted etching.
Abstract: Electrical and structural measurements have been performed on novel test structures incorporatingp-type GaAs epilayers grown by organometallic vapor phase atomic layer epitaxy on the vertical sidewalls of semi-insulating GaAs rods formed by ion-beam-assisted etching. Preliminary results indicate that the vertical-sidewall epilayers have excellent crystal quality and sufficient electrical quality to support a sidewall-epitaxy device technology. Some examples of candidate electronic, electrooptic, and photonic devices for vertical-sidewall fabrication are FETs, resistors, waveguides, modulators, and quantum-wire and quantum-dot lasers.
08 Apr 1991
TL;DR: In this article, the preparation of high quality silicon nitride films by direct photolysis of NH/sub 3/SiH/sub 4/ at low temperature and their deposition onto InP substrates are discussed.
Abstract: The preparation of high quality silicon nitride films by direct photolysis of NH/sub 3/-SiH/sub 4/ at low temperature and their deposition onto InP substrates are discussed. The atomic composition of the films is determined by nuclear analysis. In order to optimise bulk and interface properties quasi-static I(V) and C(V) characteristics measurements were performed on MIS diodes at 1 MHz. At 250 degrees C, a critical field of 4 MV/cm and a resistivity of 6*10/sup 15/ Omega -cm are observed. For annealed samples. a density of states of 4*10/sup 11/ cm/sup -2/ eV/sup -1/ is determined by Terman analysis. The fabrication of a preliminary InP depletion mode MISFET without a recess and N/sup +/ contact layer is described. >