The chemical vapor deposition of semiconductor silicon by pyrolysis of Sill4 and SiH.2CI~ often produces undesirable silicon powder in the reactor, owing to homogeneous nucleation in the gas phase. Experiments reported herein show the temperature:composition dependence of powdered silicon formation from SiH~C12-H~ mixtures. Classical nucleation theory has been applied to the St-H-C1 system to calculate nucleation rates for liquid or solid silicon from each silicon containing homolog. In general, these rates are dual valued, there being both a higher and a lower temperature associated with each. The lower temperature values compared favorably with literature values reported by Eversteijn and with experimental measurements reported here.

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Gold surfaces were investigated as promoters of dropwise condensation (DWC) of steam at atmospheric pressure. Very high heat fluxes at low ΔT’s may be achieved in this manner. Seven gold electroplating baths, one electroless immersion gold bath, and vacuum vapor deposition of gold were used. Five surface preparations for pure gold were tested. Gold deposits ranged in thickness up to 20,000 A.U. Auger electron spectroscopy and scanning electron microscopy were used to describe the surfaces chemically and physically. Deposits from the bright pure gold plating baths and the “acid, hard” baths promoted DWC. Deposits from alloyed baths, the ultrapure bath, and vapor deposition gave mixed or filmwise condensation. Two surface preparations on solid gold gave DWC, one gave mixed, and two gave filmwise condensation. The results indicate that gold provides an oxide-free surface which adsorbs trace organics from the surroundings. These promote DWC.

The vias between two levels of metal interconnect in a multilevel metal system are filled using either selective or nonselective chemical vapor deposited (CVD) tungsten. Excess tungsten is then removed from the surface of the interlayer dielectric using planarization and etch back which leaves the vias filled with tungsten plugs. The uniformity of the etch‐back process can be effected by “micro‐loading” which causes local accelerated etching of the tungsten in the vias. Other nonuniformities in etch rate, resulting in trenching around the periphery of the tungsten vias, can be caused by contaminants in the CVD reactor chamber which are incorporated in the deposited film. Methods for eliminating such problems and optimizing coverage of the plugs by the overlying metal are described.

Thermodynamic studies of the Si‐H‐Cl system are widely available. The results of these studies vary due to differences in the number of gas‐phase components used and differences in the basic thermodynamic data employed. This work describes the first experimental study to determine the equilibrium Si/Cl ratio as a function of Cl/H and temperature. The experimental results fall near those which are calculated, though they do not uniquely support any one of the theoretical studies. Computational studies make the assumption that the Cl/H ratio is constant for the silicon CVD reaction. It is shown in this study that this is not always the case, particularly when there is substantial condensation of polychlorosilanes.