Journal of the Electrochemical Society, Vol.147, No.5, 1854-1858, 2000
Selective area chemical vapor deposition of Si1-xGex thin film alloys by the alternating cyclic method: Experimental data II. Morphology and composition as a function of deposition parameters
Selective area deposition of Si1-xGex thin films, with x as large as 0.63, on oxide masked silicon wafers, was carried out in a hot wall, low pressure chemical vapor deposition system, using an alternating cyclic method described in the companion paper, Part I. In order to remove any Si1-xGex previously deposited on the walls of the system, an HCl clean of the system was performed prior to every deposition, thereby enabling good control over the composition of the deposited Si1-xGex films. The effect of various processing conditions, such as deposition temperature, input gas phase composition, and deposition time on the resulting Si1-xGex film composition, morphology, and crystalline perfection were studied. For a particular film composition, there exists a morpho logical thickness, t(m), at a particular deposition temperature, at which the Si1-xGex films make a transition from smooth to rough morphology. The rough films are in a relaxed state and exhibit three-dimensional growth. Below t(m), the films exhibit a smooth morphology. With lowering of deposition temperature while keeping all other conditions constant, the Si1-xGex films become richer in Ge. Thermodynamic calculations were found to be in agreement with this observation. Energy dispersive X-rap spectroscopy using an environmental scanning electron microscope technique was used fur composition determination purpose, and transmission electron microscopy was performed to study the crystalline quality of the selectively deposited Si1-xGex films.