Materials Science Forum Vols. 740-742

Abstract: Epitaxial growth of about 200 µm thick, low doped 4H-SiC layers grown on n-type 8° off-axis Si-face substrates at growth rates around 100 µm/h has been done in order to realize thick epitaxial layers with excellent morphology suitable for high power devices. The study was done in a hot wall chemical vapor deposition reactor without rotation. The growth of such thick layers required favorable pre-growth conditions and in-situ etch. The growth of 190 µm thick, low doped epitaxial layers with excellent morphology was possible when the C/Si ratio was below 0.9. A low C/Si ratio and a favorable in-situ etch are shown to be the key parameters to achieve 190 µm thick epitaxial layers with excellent morphology.

Abstract: The growth of 3C-SiC on hexagonal polytype is addressed and a brief review is given for various growth techniques. The Chemical Vapor Deposition is shown as a suitable technique to grow single domain 3C epilayers on 4H-SiC substrate and a 12.5 µm thick layer is demonstrated; even thicker layers have been obtained. Various characterization techniques including optical microscopy, X-ray techniques and photoluminescence are compared for the evaluation of the crystal quality and purity of the layers.

Abstract: 3C-SiC shows encouraging physical properties for the development of low cost high power compatible silicon based technology. The fundamental capability of grown 3C-SiC on silicon substrates leads to the possibility of a full integration of Si based process technologies. This is the driving force for the efforts for development a high quality heteroepitaxial film. The fundamental issue is the reduction of defects and stress due to the lattice mismatch between the 3C-SiC epilayer and the Silicon substrate. In this paper we show a way to reduce macroscopic structural features and to enhance the material quality and the surface quality by simply using a process based on a multilayer (ML) buffer structure with n++ and n doping alternation. This process leads to an evident improvement of both surface roughness, morphology and crystal quality.

Abstract: Abstract Results of an epitaxial growth of 3C-SiC epilayers on Si (0001) and C(000¯1) faces of hexagonal 6H-SiC substrates are described. TEM study of grown layers as well as interface between cubic and hexagonal polytypes is presented. Difference between the layers on the Si and C faces are discussed.

Abstract: In this paper, we report on a novel direct wafer bonding technique; Si (111) wafers to polycrystalline silicon carbide carrier wafers. The purpose of this work is to provide a platform for 3C-SiC epitaxial growth above the wafer bonded Si (111) wafers. We have demonstrated reduced wafer bow, confirmed by optical microscopy together with a digital camera. 3C-SiC epitaxial layers have been grown by conventional chemical vapor deposition techniques above Si/SiC structures. All of these 3C-SiC epitaxial layers are highly crystalline in nature. In the future, the realization of thick, bow-free 3C-SiC layers suitable for power device fabrication is achievable.

Abstract: Bulk-like 3C-SiC was grown on 1.2 degrees low off-axis 6H-SiC substrates using a sublimation epitaxy technique. The effects of temperature ramp-up and increase in layer thickness on the 3C-SiC domain formation were explored. The temperature ramp-up had no significant effect on the domain size. The domain size was considerably increased and the crystal quality was significantly improved by increasing the thickness of the layer towards bulk-like material. Average full width at half maximum values of 149 arcsec and 65 arcsec were measured in samples with thicknesses of 305 µm and 1080 µm, respectively, at a footprint of 1x3 mm2. This result implies that heteropeitaxial growth of 3C-SiC on low off-axis 6H-SiC substrates by a sublimation method can be used to prepare 3C-SiC seeds or can be further developed for growth of bulk 3C-SiC material.

Abstract: In this paper, a color chart was defined for thin SiC films grown on Si substrates. For SiC films thinner than 500 nm, the surface color was observed using an optical microscope with the incident light normally illuminated on the SiC surface. An image of the surface was then taken by a camera attached to the optical microscope and the surface color was defined using RGB code. For SiC films thicker than 500 nm, the image taken by the camera did not represent the real color of the SiC film. Therefore, for these thicker SiC films, the colors were defined by observing the films under daylight fluorescent lighting by naked eyes. It was found that the colors of the SiC films vary periodically as the thickness increased. No color saturation was found for SiC films up to 1185 nm thick.

Abstract: In this paper we present a concept on the defect generation and annihilation during the homoepitaxial growth step of cubic silicon carbide by sublimation epitaxy on templates grown by chemical vapor deposition on silicon substrates. Several structural defects like stacking faults, twins and star defects show opposite evolution from the template layer into the sublimation grown material. While single planar defects tend to annihilate with increasing layer thickness, the defect clusters assigned to the star defects are enlarging. These issues contribute to a balance of how to achieve the best possible quality on thick layers.

Abstract: Surfaces of cubic silicon carbide (3C-SiC), grown by vapour phase epitaxy with silane and propane as precursors, were treated with plasma to remove residual species deposited during the growth procedure and the sample cooling down, or due to atmospherical contamination. The impurity traces were investigated with optical absorption spectroscopy. No morphology changes due to the plasma exposure were observed.

Abstract: 3C-SiC layers were grown on Si substrates using standard precursors (SiH₄ and C3H₈) and by adding methyl trichloro silane (MTS) to the gas phase, with growth temperatures between 1200 and 1300 °C. Characterization of the 3C-SiC layers shows that 3C-SiC grown with MTS has higher polycrystalline and amorphous content as well as lower residual stress.