A B S T R A C TA theory of the kinetics of vapor deposition and etching through small openings in an oxide layer on Si is developed and compared with experiments. A model that assumes equilibrium at the Si surface and purely diffusive transport through the gas phase is used to derive the concentrations and fluxes of the interesting gaseous species in the neighborhood of the window. The previously reported concave growth surfaces and convex etching surfaces are explained by the constriction of the flow near the edges of the windows. The measured etch rate is in quantitative agreement with theoretical estimates based on this model. Furthermore, the derived concentration profiles explain the appearance and relative size of the band of oxide free from Si overgrowth which surrounds each window in the growth experiments.) unless CC License in place (see abstract).
ABSTRACTThis report describes a method of growing CuCl single crystals of the zinc blende phase directly from a melt which contains a flux such as SrCI2 or BaCI2. The presence of the flux at 2 mole % depresses the temperature of the melt below 407~
The ability of silicon nitride layers deposited on silicon oxide‐passivated silicon to act as contamination barriers has been measured through the use of a radioisotope, sodium‐22. Transport studies at 500°C have shown that the concentration of sodium reaching the silicon oxide‐silicon interface Was reduced one thousandfold when a 1000Aå shield of silicon nitride was present. These nitride films which may be deposited by any one of several techniques act not only as mechanical barriers against sodium penetration, but also as sodium getters. The amount of sodium retained by the silicon nitride film depends mainly on the film deposition temperature. For example, silicon nitride films deposited at 850°C trap more sodium than those deposited at 1100°C. The presence of moisture in the ambient atmosphere during any annealing process of a silicon nitride shielded silicon oxide film will release some of the sodium trapped in the nitride layer and allow it to move to the silicon oxide‐silicon interface.
Nanometer-scale gratings have been fabricated in InP and InGaAs/InP heterostructures using electron-beam lithography and reactive-ion etching in methane-hydrogen plasmas. It is shown that the slight overcut obtained in the etch profiles during a single-step etch in CH4/H2 is due to polymer formation on inert mask surfaces and edges. Intermittent removal of the deposited polymer film is shown to be effective in obtaining anisotropic profiles. Highly anisotropic 35-nm-wide InP lines at 70-nm pitch demonstrate the potential of this fabrication process. The formation of 100-nm-wide free-standing InP wires is also presented.
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