in III, where it can be seen that because of the large phenyl substituents it is understandably disfavored here. IllIn conclusion, then, the introduction of the "stiffened backbone" in dppee, as contrasted with the flexible backbone in dppe, leads to certain changes in the conformational characteristics of these molecules. These conformational changes then have consequences with respect to the way in which the molecules are assembled in the complete crystal structure.Acknowledgment. Support from the National Science Foundation (Grant No. CHE85-14588 to F.A.C. and Grant No. 85-06702 to R.A.W.) is gratefully acknowledged.Registry No. a-Re2Cl4(dppee)2-«-PrOH, 114720-22-8; /3-Re2Cl4-(dppee)2, 110329-68-5; a-Re2Cl4(dppe)2, 114720-23-9; (n-Bu4N)2Re2Cls, 14023-10-0; [ReCl2(dppe)2]Cl, 15628-22-5; (zi-Bu4N)2Re2Br8, 14049-60-6; a-Re2Br4(dppe)2, 114720-24-0; a-[Re2Cl4(dppee)2]PF6, 114720-26-2; (Cp2Fe)PF6, 11077-24-0; a-[Re2Cl4(dppp)2]PF6, 114720-28-4; a-Re2Cl4(dppp)2, 86436-61-5; Re, 7440-15-5; a-Re2Cl4(dppee)2, 1 10329-67-4. Supplementary Material Available: Full tables of bond distances and bond angles and tables of anisotropic displacement parameters for a-Re2Cl4(dppee)2.«-PrOH and 0-Re2Cl4(dppee)2 and a table of torsional angles for the ß isomer (14 pages); listings of observed and calculated structure factors for both compounds (45 pages). Ordering information is given on any current masthead page.

This paper presents new insights into the mechanisms of gate depletion and boron penetration in deep submicron CMOS technologies. MOSFET matching measurements show that these effects are stochastic in nature, and are associated with the gate poly-Si grain size distribution. Moreover, this work demonstrates that these effects can strongly degrade transistor matching performance of future CMOS generations.

In this study, computer modeling of the contact fill process with chemical vapor deposition, (CVD) of tungsten is used to show the importance of several details on the quality of the fill process. The effect of surface curvature on the step coverage of CVD-W has been investigated. It is shown that for contacts with an aspect ratio smaller than one, the effect of surface curvature is substantial and actually improves step coverage. Therefore, surface curvature for features with aspect ratios smaller than one, should be accounted for in computer simulations of the fill process. For contacts with aspect ratios larger than one the effect of surface curvature is negligible. It is shown that the size of the void (which will be formed in cases of step coverage less than 100%) is a better way to describe the quality of the deposition and the repercussions of the void on subsequent process steps such as tungsten etch back. In addition, the size of the void depends for a given set of deposition conditions solely on the depth of the contact rather than the contact diameter (for aspect ratios larger than 1.0).

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A model is formulated to understand and predict wafer temperatures in a tungsten low pressure chemical-vapor-deposition (LPCVD) single-wafer cold-wall reactor equipped with hot plate heating. The temperature control is usually carried out on the hot plate temperature. Large differences can occur between the susceptor and the wafer temperature, especially at the typically low pressures for LPCVD systems. Verification of the model was done by measurements of the true wafer temperatures as a function of total pressure, gas composition, gas flow, and coatings of wafer and susceptor. A good agreement between model and measurements was found by considering the heat transport by radiation and gas conduction.