Papers by Author: Fabrice Letertre

Abstract: QuaSiC TM substrates can be obtained by transferring a single crystal SiC layer onto a poly SiC substrate using the Smart Cut TM technology. In order to overcome the difficulty of limited thickness, an important improvement has been demonstrated, which consists in obtaining thick SiC structure by growing epitaxial SiC layers on top of transferred layers. The aim of this work is a structural analysis of such layers by Transmission Electron Microscopy and Photoluminescence.

Abstract: The transfer by wafer-bonding of single-crystalline SiC thin films to a polycrystalline SiC support to obtain a “quasi-wafer” is an attractive way for lowering the cost of silicon carbide wafers. Such a process needs high quality polycrystalline substrates, with controlled and high-level bulk properties (thermal conductivity, electrical resistivity) and with very low surface roughness and surface bowing. Currently, polycrystalline SiC wafers which are available are siliconized SiC or CVD processed SiC wafers. Siliconized ceramic wafers are very heterogeneous (mixture of 3C, 6H, 15R and silicon), while CVD ones are of better quality (homogeneous and textured 3C). However neither the siliconized SiC nor the CVD SiC can be CMP polished with low roughness over large dimension. In this paper, wafers with large and textured grains (> 1cm) are processed and characterized. The polishing of such structures is studied and optimized to obtain low surface roughness. To meet these requirements high temperature processes used for single crystal growth were selected. Structural investigations performed on the grown ingots showed an important influence of the used seed since no preferential crystallographic orientation was observed during the growth. The final polishing quality was of high level but step heights were observed between grains.

Abstract: QuaSiC TM substrates can be obtained by transferring a single crystal SiC layer onto a poly SiC substrate using the Smart Cut TM technology. The structure evolution of metal bonding (W-Si silicide) layer has been investigated by Transmission Electron Microscopy and X-ray diffraction. Results indicate that the metal bonding film is made of W5Si3. The film is discontinuous and strained. Annealing releases stress at least partially.