Growth and processing of heteroepitaxial 3C-SiC films for electronic devices applications (original) (raw)
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Structural characterization of heteroepitaxial 3C-SiC
In this work, we focus our attention on the characterization of 3C-SiC films, grown within a CVD reactor, on Si substrates. It will be shown how the growth procedures influence the SiC film structure and quality with the growth rate used during the growth used as example. Evaluation of crystal structure has been conducted by X-Ray Diffraction (XRD), Raman microscopy and Transmission Electron Microscopy (TEM). Overall film quality increases if films are grown under low growth rate conditions, thanks also to an important reduction in the density of micro-twins. The trend of the full widths at half maximum (FWHMs) of SiC rocking curves, considered good 'quality indicator' as their broadenings are affected by crystallographic defects, as a function of 3C-SiC thickness shows a saturated regime for very thick films, due to the saturation of stacking fault density after 50 µm of growth. This work wants to suggest a reasonable path for the characterization of the material structure that can be useful, anywhere and in any time, to assess if the morphology and microstructure of our films are satisfactory and to drive towards the desired improvement.
CVD growth and characterization of 3C-SiC thin films
Bulletin of Materials Science, 2004
Cubic silicon carbide (3C-SiC) thin films were grown on (100) and (111) Si substrates by CVD technique using hexamethyldisilane (HMDS) as the source material in a resistance heated furnace. HMDS was used as the single source for both Si and C though propane was available for the preliminary carbonization. For selective epitaxial growth, patterned Si (100) substrates were used. The effect of different growth parameters such as substrate orientation, growth temperature, precursor concentration, etc on growth was examined to improve the film quality. The surface morphology, microstructure and crystallinity of grown films were studied using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS).
Heteroepitaxial growth of 3C–SiC using HMDS by atmospheric CVD
Materials Science and Engineering B-advanced Functional Solid-state Materials, 1999
Single crystal cubic silicon carbide (3C-SiC) films have been deposited on carbonized Si(100) substrate using HMDS{Si 2 (CH 3 ) 6 } by atmospheric CVD at 1350°C. The HMDS flow rate was 0.5 sccm and the carrier gas flow rate was 2.5 slm. The growth rate of the 3C-SiC films was 4.3 mm h − 1 . The HMDS flow rate was important to get a mirror-like surface. The 3C-SiC epilayers on Si(100) were characterized by XRD, Raman scattering, and PL measurement as well as AFM. The 3C-SiC distinct phonons of TO(G) near 796 cm − 1 and LO(G) near 973 9 l cm − 1 were recorded by Raman scattering measurement. The PL spectra of CVD 3C-SiC/Si at 11 K from 3.6 to 9.1 mm included the nitrogen-bound excitor (N-BE) lines, the defect-related W band near 2.15 and 2.13 eV peak corresponding to D -A pair recombination as well as the divacancy-related D1 line at 1.97 eV. The results indicated that the crystallinity of the 3C -SiC films became better with increase of the film thickness.
MRS Proceedings, 2004
Single crystal 3C-SiC epitaxial layers have been grown on SOI substrates using low-pressure chemical vapour deposition (LPCVD). The SOI substrates consist of nominally 150 Å Si layers bonded to 100 mm poly 3C-SiC substrates using direct wafer bonding and SOI film transfer techniques. Miscut Si(100) films were incorporated into the wafer bonding process for the first time in an effort to further reduce anti-phase domain formation in the 3C-SiC films. The Si films were transferred from Si(100) wafers miscut 4° toward the (110) direction. For growth of 3C-SiC layers, a two-step process is needed. First the Si is carbonized using propane mixed in a hydrogen carrier gas to convert the surface to SiC at atmospheric pressure. Next SiC growth is conducted by the addition of silane into the gas mix and a reduction of the process to 150 Torr. Previous characterization of these films via SEM and XRD indicated that the films were single crystal and oriented with respect to the starting Si bonde...
3C-SiC epitaxial growth on large area silicon: thin films
Cubic Silicon Carbide (3C-SiC) heteroepitaxy with Silicon (Si) substrates is desirable in order to sensibly reduce the manufacturing costs and increase the crystal area. Mismatches in lattice parameters and thermal expansion coefficients limits the development of such a technology, leading to formation of devicedegrading crystallographic defects and significant wafer bowing. In this chapter, a survey on chemical vapor deposition (CVD) of 3C-SiC on Si substrates is presented since the nucleation of the buffer layer. A comparison of experimental data extracted from the available literature indicates that thin epitaxial 3C-SiC films of better quality are grown when slower growth rate processes are used. The improvement of the crystal quality is also commonly observed as the epitaxial layers grow in thickness. Notwithstanding the quality improvement of nowadays available 3C-SiC epitaxial layers, stacking faults (SFs) reduction is still an open issue as SFs linear density commonly tend to a saturation value of about 5 × 10 3 cm -1 in 50 m thick films. Chapter ends with considerations on another issue involved in the 3C-SiC/Si heteroepitaxy, i.e. the wafer bow.
3C-SiC Heteroepitaxial Layers Grown on Silicon Substrates with Various Orientations
Materials Science Forum
This work investigates the 3C-SiC heteroepitaxial growth on silicon substrates having a wide variety of orientations, i.e. (100) on axis and 2°off, (111), (110), (211), (311), (331), (510), (553) and (995). All the 3C-SiC layers were grown using the same two-step CVD process with a growth rate of 2 μm/h. According to X-ray diffraction characterizations, direct heteroepitaxy (layer having exactly the same orientation as the substrate) was successful on most of the Si substrates except for (110) one which was the only orientation leading to obvious polycrystalline deposit. Each layer led to a specific surface morphology, the smoothest being the ones grown on Si (100)2°off, and (995) substrates. None of these layers cracked upon cooling though those grown on Si (111), (211) and (553) substrates were highly bowed.
Polycrystalline SiC growth and characterization
Applied Surface Science, 2004
Growth of 3C-SiC on (1 0 0) Si wafers has been carried out by low pressure chemical vapor deposition (LPCVD), using a H 2 þ SiH 4 þ C 3 H 8 gas mixture at about 1000 8C. No carbonization layer was performed. Micro-Raman measurements yield the presence of microcrystalline SiC matrix, while neither carbon nor silicon clusterization in amorphous phase was detected with optimized deposition conditions. Transmission electron microscopy has been used to analyze the orientation of the films and the surface growth: the presence of voids and edge dislocations at the interface was revealed. #
CVD Growth of 3C-SiC on 4H/6H Mesas
Chemical Vapor Deposition, 2006
This article describes growth and characterization of the highest quality reproducible 3C-SiC heteroepitaxial films ever reported. By properly nucleating 3C-SiC growth on top of perfectly on-axis (0001) 4H-SiC mesa surfaces completely free of atomic scale steps and extended defects, growth of 3C-SiC mesa heterofilms completely free of extended crystal defects can be achieved. In contrast, nucleation and growth of 3C-SiC mesa heterofilms on top of 4H-SiC mesas with atomic-scale steps always results in numerous observable dislocations threading through the 3C-SiC epilayer. High-resolution X-ray diffraction and transmission electron microscopy measurements indicate non-trivial in-plane lattice mismatch between the 3C and 4H layers. This mismatch is somewhat relieved in the step-free mesa case via misfit dislocations confined to the 3C/4H interfacial region without dislocations threading into the overlying 3C-SiC layer. These results indicate that the presence or absence of steps at the 3C/4H heteroepitaxial interface critically impacts the quality, defect structure, and relaxation mechanisms of single-crystal heteroepitaxial 3C-SiC films. Table of Contents Text By properly nucleating 3C-SiC on top of a patterned array of (0001) 4H-SiC mesas with surfaces completely free of atomic scale steps, growth of 3C-SiC mesa heterofilms free of extended crystal defects can be achieved. Detailed characterization, including AFM, TEM, and X-ray, indicates that the presence or absence of steps at the 3C/4H interface critically impacts the quality, defect structure, and relaxation mechanisms of single-crystal heteroepitaxial films.
Journal of Crystal Growth, 2001
The growth of SiC layers on hexagonal (or a-) SiC(0001) has been performed by solid-source MBE between 1300 and 1600 K. The a-SiC layers have been grown homoepitaxial via step-flow on off-axis substrates, whereas pseudomorphic cubic (or 3C-) SiC layers were obtained on a-SiC via nucleation and subsequent step-flow. Under more equilibrium-like conditions, 3C-layers nearly free of twin-boundaries were obtained. The SiC layers were of high quality and without unintentional doping, as revealed by photoluminescence investigations The controlled growth of SiC heteropolytypic structures consisting of hexagonal and cubic polytypes, such as 4H/3C/4H-SiC(0 0 0 1) and 6H/3C/6H-SiC(0 0 0 1), has also been demonstrated. Such structures were obtained by changing the growth conditions from lower temperatures (1550 K) and Si-rich Si/C ratio (3C-SiC) to higher temperatures (1600 K) and more C-rich Si/C ratio. On off-axis substrates, such heterostructures were also obtained by first nucleating selectively wire-like 3C-SiC nuclei on the terraces of well-prepared a-SiC(0 0 0 1) substrates at low T (51500 K) and a subsequent step-flow of both the 3C wires and the surrounding a-SiC material. #