Reduction of bonding constraints by self-organization in gate dielectrics for a-Si:H thin film transistors (TFTs) and crystalline Si field effect transistors (FETs)

Studies of binary chalcogenide alloys have established that the onset of mean-field rigidity is generally delayed by a chemical self-organization, resulting in an intermediate phase with deviations from mean-field bonding. In GexSe1−x, the onset of rigidity occurs for a mean field coordination, rc, = 2.4 at x = 0.2, but percolation of stress is delayed until rc = 2.52. For SixNyHz plasma-deposited thin films, self-organization occurs during deposition at 300 °C, and for (SiO2)x(Si3N4)y(ZrO2)z thin films, it occurs during annealing at about 900 °C. Thin films in the respective self-organized intermediate phase have low defect densities, and also display low defect densities at semiconductor interfaces. The hydrogenated silicon nitride films are used as gate dielectrics in a-Si:H thin film transistors, and the Zr Si oxynitride films are used in crystalline Si field effect transistors.