We have developed a low temperature process for the deposition of thin films of silicon dioxide and silicon nitride. The process consists of four steps: (a) excitation of an oxygen or nitrogen-containing molecule in an RF plasma; (b) transport of the excited oxygen or nitrogen species out of the plasma region; (c) mixing of the transported excited species with silane (or disilane) out of the plasma region to form precursor species; and (d) a CVD reaction at a heated substrate to form the desired thin film. We call this process remote plasma enhanced CVD (RPECVD). Silicon rich oxide films have been grown at substrate temperatures (Ts) between 100 and 350 °C using an excited O2/He mixture. Two different ‘‘silicon nitrides’’ have been deposited depending on the excited gas, NH3 or an N2/He mixture, and Ts. Using either nitrogen source and Ts greater than 450 °C, we obtain near stoichiometric films of Si3N4. On the other hand, films grown from NH3 and deposited with Ts of about 50 to 100 °C are silicon diimide [Si(NH)2], which is isostructural with respect to SiO2 with bridging NH groups substituted for the bridging oxygen atoms. Films grown from the NH3 source and at Ts between 150 and 450 °C are solid solutions of silicon nitride and silicon diimide. We discuss the application of these dielectric films in device structures.
The crystal structure of ekanite (Thl,76, Ce0,0s, Pb0.01,) (K1.21, ['-]0,79) (Nal,80, Cal,46, Mn0.as, Mg0.07, I-]0,29)Sit6(O38.08, OHi,92 ) was determined by the symbolic addition method with data collected on a single-crystal diffractometer using Mo K~ radiation. The crystals are tetragonal, space group P4/mcc, with a= 7.58, c= 14.77/~. The structure was refined by least-squares methods to an R value of 0.058 for 1602 reflexions of measurable intensity. Eight SiO4 tetrahedra are grouped together in a tetragonal double-ring (with mirror symmetry in the plane of the ring), the rings being linked together by cations of K, Th and Na, distributed on the vertices, the edges and the faces of the tetragonal cell. The structure is very porous.
We have deposited silicon nitride (Si3N4) and silicon oxide (SiO2) thin films using remote plasma enhanced chemical vapor deposition (RPECVD). We have characterized the chemical composition of the films by infrared absorption (IR), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Rutherford backscattering (RBS), and have studied the electrical properties in metal insulator semiconductor (MIS) device configurations. We have configured the deposition system and adjusted gas flow rates in order to minimize: (a) O contamination in the Si3N4 films; and (b) OH groups in the SiO2 films. This paper describes the deposition apparatus and the process, and presents a phenomenological model for the plasma phase and surface reactions involved. We have combined both types of insulators in a trilayer dielectric that has been used as a gate insulator for (In,Ga)As insulated gate field effect transistors (IGFET’s). We have found that the electrical properties of these devices are superior to devices utilizing single layer SiO2 or Si3N4 gate insulators.
The growth of diamond films on (001) Si substrates by bias-controlled chemical vapor deposition is described. The film quality as judged by Raman spectroscopy and scanning electron microscopy depends strongly on the biasing conditions. Under low current reverse bias conditions, highly facetted cubo-octahedral diamond growth exhibiting a single sharp Raman line at 1332 cm−1 was obtained, while biasing in high current conditions which created a plasma resulted in multiply twinned, microcrystalline growth incorporating sp2-bonded carbon into the diamond film.
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