Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy



Major Professor

Ziling (Ben) Xue


This dissertation describes studies of the chemistry of siliconcontaining compounds and molecular approaches to silicon-based microelectronic materials. The preparation of new silyl dianions and transition metal silyl complexes, our studies of the mechanism of reactions between alkylidenes and silanes, and the fabrication of Ti02 thin films on Si as microelectronic gate materials are presented. Chapter 1 provides a brief overview of the field of early transition metal silyl chemistry and experimental techniques used in the research, and a summary of the research conducted in each subsequent chapter. In Chapter 2 are described the synthesis and characterization of new complexes [K(18-crown-6)]2[(Me3Si)2Si-(CH2)n-Si(SiMe3)2] (n = 1, 4; 2, 5; 3, 6) containing silyl dianions. These compounds represent some of the few known disilyl dianion complexes. In addition, the crystal structures of the starting materials to 5 and 6, (Me3Si)3Si-(CH2)n-Si(SiMe3)3, (n = 2, 2; 3, 3) were determined by single-crystal X-ray diffraction studies. The preparation and characterization of novel Zr and Zn silyl complexes from the reactions of 5 with (Me2N)3ZrCI and ZnCl2, respectively, are presented in Chapter 3. Both complexes are anionic with K(18-crown-6t as the counterion. {(Me2N)3Zr[n2-(Me3Si)2Si-(CH2)2-Si(SiMe3)2)} (7) consists of a fivecoordinate Zr center with a distorted trigonal bipyramidal geometry. [K(18-crown-6)]2{[n2 -(Me3Si)2Si-(CH2)2-Si(SiMe3)2]Zn2[µ-(Me3Si)2Si-(CH2)2- Si(SiMe3)2]} (8) is, to our knowledge, the first trisilyl Zn complex. 8 is a dimer with each Zn metal center coordinated by a chelating disilyl ligand and a disilyl ligand bridging each Zn center. Chapter 4 presents some new mechanistic insights into the reactions of a Ta alkylidene complex (Me3SiCH2)3 Ta(PMe3)(=CHSiMe3) (9) with silane H2SiMePh. Such reactions yielded new silyl-substituted alkylidene complexes. Experiments conducted in the presence of 20-fold PMe3 were found to be 19 times slower than those conducted with no added phosphine. Mass spectral analysis of the gaseous products from the reaction conducted in the presence of H2 suggested hydrogen scrambling. Finally, in Chapter 5 are discussed the preparation and characterization of TiO2 thin films on a Si wafer from the reaction of Ti(NMe2)4 with 02 by chemical vapor deposition (CVD) processes. These films were characterized by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), infrared spectroscopy (IR), ellipsometry and scanning electron microscopy (SEM), and found to be amorphous before annealing but crystalline anatase after annealing at 600 °C for 1 h in air. Importantly, analyses by XPS, XRD and IR suggested that the films were C-free and contained no TiN or TiOxNy species.

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