| 摘要 |
1,147,014. Silicon carbide diffusion masking. WESTINGHOUSE ELECTRIC CORP. 12 Jan., 1968 [27 Jan., 1967], No. 1879/68. Heading H1K. A silicon carbide layer is formed on, for example, a silicon body by pyrolytic decomposition of methyl silane or halogenated methyl silanes mixed with an inert gas, and the layer selectively removed to provide a diffusion mask. The masking pattern is produced by oxidizing the entire surface of the carbide layer and providing a photoresist pattern thereon; the exposed oxide is then etched away to leave a thin carbide layer in the window areas, and the system again exposed to an oxidizing atmosphere (e.g. steam/oxygen) to convert the exposed carbide to oxide which is etched away with buffered hydrofluoric acid. It may be necessary to repeat the oxidation and etching steps to penetrate the carbide completely. Boron or phosphorus may be diffused through the mask produced. Phosphorus sources identified are phosphorus oxychloride carried by oxygen and ammonium phosphate carried by oxygen or nitrogen. The mask is effective when formed upon a lapped but unpolished semiconductor surface. |
