S. Habermehl

Low-temperature preparation of SiO2/Si(100) interfaces using a two-step remote plasma-assisted oxidation-deposition process

SiO2/Si(100) interfaces have been prepared by a low‐temperature, 200–300 °C, remote plasma‐assisted oxidation‐deposition process. The oxidation: (i) creates ∼0.5 nm of SiO2; (ii) removes residual C from an otherwise H‐terminated Si surface; and (iii) produces a SiO2/Si interface with a midgap trap density of ∼1×1010 cm−2 eV−1, and when combined with remote plasma‐enhanced chemical vapor deposition (RPECVD) of SiO2, (iv) forms a SiO2/Si structure with properties comparable to those prepared by thermal oxidation of Si at 850–1050 °C.

HETEROEPITAXIAL GROWTH OF SI ON GAP AND GAAS SURFACES BY REMOTE, PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION

Heteroepitaxial thin films of Si have been deposited onto GaP and GaAs substrates at low temperatures, <400 °C, by remote plasma‐enhanced chemical vapor deposition. Cleaning and passivation of the GaP and GaAs surfaces, by ex situ wet chemistry, and in situ exposure to atomic‐H at temperatures from 400 to 530 °C, were found to be critical in promoting epitaxial growth. The exposure to atomic‐H was effective in removing surface oxides and hydrocarbon contamination. After the H‐exposure, low energy electron diffraction (LEED) measurements revealed an ordered 1×1 structure for the GaP(111) surface, and a c(8×2)Ga structure for the GaAs(100) surface. Heteroepitaxial films of Si have been deposited at temperatures from 300 to 400 °C and pressures between 50 and 500 mTorr, with the highest quality epitaxial growth proceeding on vicinal GaP(100) surfaces. In contrast, for the growth of Si on GaP(111) and GaAs(100) surfaces, LEED measurements indicate the onset of strain‐induced disorder within the first few mono...

Low temperature plasma-assisted oxidation and thin-film deposition processes for forming device-quality SiO2/Si and composite dielectric-SiO2/Si heterostructures

In the high-temperature thermal oxidation of Si, the SiO2/Si interface is continuously regenerated as the bulk oxide grows. This paper describes an alternative low temperature, 200–300 °C, plasma-assisted process that optimizes electrical properties of SiO2/Si interfaces and bulk SiO2 layers by separately controlling interface formation and bulk oxide deposition. Composite dielectrics, oxide/nitride (ON) and oxide (ONO), have been fabricated by extending the low temperature plasma-assisted processes to include deposition of Si3N4 films. The electrical properties of SiO2/Si structures formed by the two-step, low temperature oxidation-deposition process are essentially the same as those of SiO2/Si structures formed by high temperature, 850–1050 °C, thermal oxidation. The electrical properties of devices incorporating ON and ONO composite dielectrics are degraded with respect to the SiO2/Si structures, but are similar to those of composite dielectrics formed by combinations of high temperature processing.

Quasi-Stoichiometric Silicon Nitride Thin Films Deposited by Remote Plasma-Enhanced Chemical-Vapor Deposition

Conditions for depositing quasi-stoichiometric silicon nitride films by low-temperature, remote plasma-enhanced chemical-vapor deposition, RPECVD, have been identified using on-line Auger electron spectroscopy, AES, and off-line optical and infrared, IR, spectroscopies. Quasi-stoichiometric films, by the definition propose in this paper, do not display spectroscopic evidence for Si-Si bonds, but contain bonded-H in Si-H and Si-NH arrangements. Incorporation of RPECVD nitrides into transistor devices has demonstrated that electrical performance is optimized when the films are quasi-stoichiometric with relatively low Si-NH concentrations.

Interrupted cycle chemical beam epitaxy of gallium phosphide on silicon with or without photon assistance

Abstract The low temperature epitaxial growth of Si-GaP heterostructures by chemical beam epitaxy (CBE) and interrupted cycle chemical beam epitaxy (ICCBE) on patterned partially SiO2 masked silicon substrates is investigated to achieve dielectric isolation layers for Si circuits as well as for optical interconnections. Excellent selectivity of the growth on exposed Si windows versus SiO2 covered surface areas is observed and verified by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Low temperature processing is essential to minimize interdiffusion and strain due to substantial mismatch of the thermal expansion coefficients of GaP and Si. We describe the deposition of GaP by CBE and ICCBE using sources of tertiarybutylphosphine (TBP) and triethylgallium (TEG) on (100) silicon at 310°C and the influence of photon assistance on the growth temperature and surface morphology. Secondary ion mass spectroscopy (SIMS) studies reveal that no measurable interdiffusion occurs under these conditions, including subsequent processing steps that require rapid thermal annealing for 30 s at 900°C. The GaP/Si interface is examined by high resolution cross-sectional transmission electron microscopy (HRTEM) before and after the 900°C anneal.

Bonding of Hydrogen and Deuterium in Silicon Nitride Films Prepared by Remote Plasma Enhanced Chemical Vapor Deposition

We have deposited Si-nitride thin films by remote plasma-enhanced chemical-vapor deposition using different combinations of hydrogen and deuterium source gases. In one set of experiments, NH 3 and SiH 4 were injected downstream from a He plasma and the ratio of NH 3 to SiH 4 was adjusted so that deposited films contained IR-detectable bonded-H in SiN-H arrangements, but not in Si-H arrangements. Similar results were obtained using the same ND 3 to SiD 4 flow ratio; these films contained only SiN-D groups. However, films prepared from ND 3 and SiH 4 displayed both SiN-D and SiN-H groups in essentially equal concentrations establishing that H and D atoms bonded to N are derived from both source gases SiH (D) 4 and NH (D) 3 , and further that inter-mixing of H and/or D atoms occurs at the growth surface. This reaction pathway is supported by additional studies in which films were grown from SD4 and ND3 with either i) He or ii) He/H 2 mixtures being plasma excited. The films grown from the deuterated source gases without H 2 , displayed only SiN-D bands, whereas the films grown using the He/H 2 mixture displayed both SiN-H and SiN-D bands. The total concentration of N-H and N-D bonds in the films grown from the He/H 2 excitation was the same as the concentration of N-D, supporting the surface reaction model. In-situ mass spectrometry provides additional insights in the film deposition reactions.

Microstructure of Si Films Deposited on Si(100) Surfaces by Remote Plasma-Enhanced Chemicalvapor Deposition, Rpecvd: Dependence on Process Pressure and Substrate Temperature

The microstructure of Si thin films, deposited on in-situ cleaned Si(100) surfaces by remote plasma-enhanced chemical-vapor deposition (RPECVD), is dependent on the process pressure, substrate temperature and H 2 flow rate. Surface characterization by on-line low energy electron diffraction, LEED, has been used to detect changes in the character of the deposited films which can either be amorphous, microcrystalline or crystalline, hereafter designated as a-Si, Sμc-Si, and c-Si, respectively. We have used these results to generate phase diagrams for the Si microstructure as a function of the process pressure and substrate temperature, including the flow rate of H 2 as an additional deposition parameter.

Si-N Bonding at The SiO 2 /Si Interfaces During Deposition of SiO 2 by the Remote Pecvd Process

Thin films of SiO 2 were deposited on Si substrates by remote PECVD following an in-situ cleaning/surface passivation with atomic-H. Si-N bonds were found in the immediate vicinity of the SiO 2 /Si interface when nitrous oxide, N 2 O, was used as O-atom source gas in the remote PECVD process. Si-N bonds, as well as Si-surface roughening produced by H-atom etching, contribute to the formation of high densities of midgap trapping states, D it ∼10 11 cm −2 eV −1 , at the SiO 2 /Si interface. Eliminating the H-atom processing step, and exposing the Si surface to plasma-generated O-atoms prior to the SiO 2 deposition: i) eliminated Si-N bonding at the Si/SiO 2 interface; ii) reduced midgap D it to ∼ 1–3×10 10 cm −2 eV −1 iii) eliminated surface roughening; and iv) improved process latitude and reproducibility.