Step-controlled epitaxy

H Matsunami, T Ueda, H Nishino. Step-controlled epitaxial growth of SiC. In Diamond, Silicon Carbide and Related Wide Bandgap Semiconductors. JT Glass R Messier, N Fujimori, eds. Pittsburgh Materials Research Society, 1990, p 397. 

T Kimoto, H Nishino, WS Woo, H Matsunami. Growth mechanism of 6H-SiC in step-controlled epitaxy. J Appl Phys 73 726, 1993. 

In recent years, a lot of progress has been made in fabricating CMOS devices that use new high mobUity channel materials. Not all of these approaches need CMP steps, in some cases controlled epitaxial growth and etch steps can be sufficient. 

The two-step process of epitaxial polymerization has been applied to symmetrically substituted diacetylenes First, the monomers have been crystallized epitaxially on alkali halides substrates from solution and the vapor phase. The oriented monomer crystals are then polymerized under the substrate s influence by gamma-irradiation. The diacetylenes in this study are 2,4-hexadiyn-l,6-diol (HD) and the bis-phenylurethane of 5,7-dodecadiyn-l,12-diol (TCDU). The polydiacetylene crystal structures and morphologies have been examined with the electron microscope. Reactivity and polymorphism are found to be controlled by the substrate. 

The development of Atomic Layer Epitaxy was the first step in the simplification of the complex CVD process, in order to achieve a better understanding and thus a better control of the reaction mechanisms involved. 

It has been widely demonstrated that the preparation of oriented, and in some cases epitaxial films by CSD is possible, despite the relatively large thickness of the films that is deposited in a single step. Lange ° reviewed the various mechanisms that lead to oriented growth, and a variety of factors including reactions at the electrode interface, - organic content within the film," " and the use of seed layers" to promote homoepitaxy have been discussed. The ability to control film properties (remanent polarization, dielectric constant, etc.) through manipulation of film orientation has also been shown. 

Whatever the mode of growth (epitaxial or polycrystalline) the current diffusion control is effective a fraction of second after the potential has been stepped. At this moment it has been shown (2), thanks to AFM observations, that the film coalescence is not achieved. Stuctural observations are requisite to describe the phenomena associated with the formation of a continuous film. 

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