Kohji Inoue

Low Temperature Growth of SiO2 Thin Film by Double-Excitation Photo-CVD

A new technique for the low-temperature growth of SiO2 films has been developed by double-excitation photo-CVD. SiO2 films can be grown at 30~240°C from a mixture of Si2H6 and O2 by photo-CVD using a D2 lamp as a VUV light source, or by double-excitation using an additional Xe lamp or a low-pressure Hg lamp as a UV light source. The growth rate is 90 A/min in a photo-CVD at 30°C, while deposition does not occur in thermal CVD at 30°C. Concentrations of Si–OH and Si–H bonds can be considerably reduced by the use of photo-excitation. Particularly, double-excitation reduces the oxide-charge density to a large extent and also brings the dielectric constants close to those of thermally-grown SiO2. The minimum charge density is 5×1010 cm-2 in a film deposited at 240°C. The interface state density of a Si MOS diode is also reduced by double-excitation using a Hg lamp in an O2-excess atmosphere and annealing at 280°C. Its minimum density is 8×1010 cm-2eV-1.

Metalorganic molecular beam epitaxy and etching of GaAs and GaSb using trisdimethylaminoarsenic and trisdimethylaminoantimony

Abstract Metalorganic molecular beam epitaxy and etching of GaAs and GaSb using trisdimethylaminoarsenic (TDMAAs) and trisdimethylaminoantimony (TDMASb) are studied. The GaAs growth rate (GR) variation with substrate temperature ( T sub ) is similar to that in the GaAs growth with TEGa (triethylgallium) and elemental As (As 4 ). However, the GR shows about 15% reduced values at T sub of 500–600°C and a rapid decrease above 600°C. Furthermore, the etching of GaAs is observed when only the TDMAAs is supplied to the (001) GaAs surface at T sub above 500°C. On the other hand, in the case of (001) GaSb the etching of GaSb is only observed when TDMASb is supplied to the GaSb surface without precracking in spite of the simultaneous supply of TEGa, although the GaSb layers can be grown when the TDMASb is precracked at high temperatures (i.e. 620°C) in the gas cracker cell. The etching effect is the common effect of both TDMAAs and TDMASb and is considered to be caused by the formation of the volatile Ga species due to the reaction of surface Ga atoms and the amine products from the TDMAAs and TDMASb.

Preparation of SiO2 Film by Photo-Induced Chemical Vapor Deposition Using a Deuterium Lamp and Its Annealing Effect

Silicon dioxide thin films have been prepared at low temperatures from SiH4 and O2 by direct photo-induced CVD using a deuterium lamp. The growth rate is 75 A/min at 84°C while no growth occurs below 180°C without deuterium lamp irradiation. UV and VUV light irradiation and an increase of the substrate temperature have effects of increasing the refractive index, and decreasing H incorporation and the amount of the oxide charge. The photo-CVD films deposited above 180°C show refractive indices of 1.45–1.46. Annealing in an O2 environment decreases the infrared absorptions due to Si–H stretching, Si–OH deformation and Si2O3 bondings as well as the oxide charge. The activation energies of the Si–H, the Si–OH deformation, the Si2O3 and the oxide charge obtained from the annealing characteristics are 0.18–0.19, 0.12, 0.19 and 0.12–0.13 eV, respectively. The reduction of Si–OH deformation absorption is considered to be closely related to the reduction of oxide charge.

SiO2 Thin Film Prepared from Si3H8 and O2 by Photo-CVD Using Double Excitation

Silicon dioxide thin films have been prepared at low temperatures from 25 to 390°C from Si3H8 and O2 gases by photo-CVD using the double excitation of VUV light from a D2 lamp and UV light from a Hg lamp. Growth rate is ~150 A/min at 25°C and decreases as the substrate temperature increases. The amount of Si-H and Si-OH, and the fixed-oxide-charge also decrease as the temperature increases. The film deposited at 260°C shows small interface state density and the minimum is 3.6 × 1010 cm-2eV-1 near the midgap.

Etching effect on metal‐organic molecular‐beam epitaxy growth of GaSb using triethylgallium and trisdimethylaminoantimony

Metal‐organic molecular‐beam epitaxy growth of GaSb is investigated for the first time by using the new precursor trisdimethylaminoantimony (TDMASb) together with triethylgallium (TEGa). An etching effect is observed when TDMASb is supplied to the (001) GaSb surface without precracking. The etching rate is dependent on the substrate temperature and TDMASb flow rate, while independent of the TEGa flow rate. GaSb layers can be grown when the TDMASb is precracked in the gas cracker cell. The etching mechanism is discussed in connection with the decomposition process of TDMASb on the surface.

Reduction of interface‐state density by F2 treatment in a metal‐oxide‐semiconductor diode prepared from a photochemical vapor deposited SiO2 film

A new technique for the reduction of the interface‐state density Nss of a metal‐oxide‐semiconductor (MOS) diode has been developed. The SiO2 film was deposited on Si from Si2 H6 and O2 by direct photochemical vapor deposition (CVD) using vacuum ultraviolet (VUV) light of a D2 lamp. The new technique is a F2 treatment of the Si surface prior to the deposition of SiO2 film. Typically, 5% F2 gas diluted in He was introduced into the CVD chamber at 20 Pa for 5 min under UV light irradiation. The minimum value of the Nss was ∼5×109 cm−2 eV−1 at the Si midgap for the film deposited at 180 °C.

Growth of SiO2 thin film by double‐excitation photoinduced chemical vapor deposition incorporated with microwave excitation of oxygen

A new technology for low‐temperature growth of good‐quality silicon dioxide (SiO2) thin films has been developed. The film growth technology is a double‐excitation photoinduced chemical vapor deposition using vacuum ultraviolet and ultraviolet lights from source gases of Si2H6 and microwave‐excited O2 in the substrate temperature region of 25–300 °C. Growth rate is about 140 A/min at 25 °C and does not change with the substrate temperature. Infrared absorption peak of the Si  H bond completely disappears in the films deposited even at 25 °C. The interface state density is extremely low and its minimum density is 7×1010 cm−2 eV−1 for the film deposited at 100 °C. The reaction and deposition mechanisms are discussed from mass spectroscopic analysis. O3 molecules are increased by the microwave excitation of O2 and chemically active oxygen radicals are produced by the irradiation of the D2 and Hg lamps. Si2OH5, SiH2, and H2 molecules are also increased by either the photo‐ or microwave excitation, but H2O and...

METALORGANIC MOLECULAR BEAM EPITAXY GROWTH CHARACTERISTICS OF GAAS USING TRIETHYLGALLIUM AND TRISDIMETHYLAMINOARSENIC

Metalorganic molecular beam epitaxy (MOMBE) growth characteristics of GaAs using triethylgallium (TEGa) and trisdimethylaminoarsenic (TDMAAs) are studied in detail by using reflection high energy electron diffraction intensity oscillations. It is found that the GaAs growth rate variation with substrate temperature (Tsub) is similar to that in the MOMBE growth of GaAs with TEGa and elemental As (As4) except in the high Tsub region, despite the use of uncracked TDMAAs instead of As4. GaAs growth starts at about 350 °C and shows a maximum growth rate at about 500 °C. However, the absolute growth rate is about 15% lower than that using As4 with the same TEGa flow rate in the mass‐transport limited growth region. Above 600 °C the growth rate shows a rapid decrease with increasing Tsub. Further, it is found that etching of GaAs occurs when only TDMAAs is supplied to the GaAs surface at Tsub above 500 °C. Unintentionally doped GaAs films show n‐type conduction in the whole Tsub range investigated with the highes...

Growth of SiO2 Thin Film by Selective Excitation Photo-CVD Using 123.6 nm VUV Light

A new technology for low-temperature growth of high-quality silicon dioxide (SiO2) film on silicon has been developed. The technology is photo-CVD using 123.6 nm light of a Kr resonance lamp from Si2H6 and O2, in which only Si2H6 can be selectively excited but not O2. The amounts of Si-OH bondings in the SiO2 films deposited by the 123.6 nm light are much lower than those by the other VUV lamps. The interface state density of the Si-MOS diode is extremely low, and its minimum value is 2×1010 cm-2 eV-1 near the Si midgap for the SiO2 film deposited at a substrate temperature of 145°C.

Highly Oriented Polycrystalline Si Film on Quartz Grown from Si3H8 by Thermal and Photo-CVD

Si films deposited on quartz plates grown from Si3H8 by thermal and photo-CVD have shown a strong crystalline orientation and are preferentially grown as (110) planes at substrate temperatures below 560?C, but turn to (100) above 575?C. In the transition region, an enhancement of -orientation occurs with increasing H2 partial pressure and Si3H8 flow rate, but -orientation occurs at extremely high H2 pressure and Si3H8 flow rates. Surface morphologies have also been investigated, and pyramidal texture, dome like structure and random roughness are found in - and -oriented films and non oriented crystalline film, respectively. The mechanism of the preferred orientation is discussed, taking into consideration the bonding structure of the crystal plane and that of decomposed species in the vicinity of the surface.