At&t Bell Laboratories

Bell Telephone Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Lee E Trimble

George K Celler

Pradip Kumar Roy

Harry John Leamy

Rudolf J Voorhoeve

Donald G Schimmel

A membrane is supported at its edge by an annular, tapered skirt structure. The skirt strengthens the attachment of the membrane to the support ring and reinforces the edge region where the membrane would otherwise tend to fail. Stress concentrations are reduced by providing a skirt or featheredge, on the interior side of the skirt, that meets the membrane at a relatively small effective contact angle. In a preferred embodiment, the membrane is made by depositing a polysilicon layer on the surface of a substrate of silica-based glass. A portion of the substrate is removed by an isotropic, selective etchant, such that a portion of the polysilicon layer remains as a free-standing, tensile film supported by a remaining portion of the substrate.

Lithographic mask, comprising a membrane having improved strength

A mask for X-ray lithography is produced by initially forming a thin layer of polycrystalline silicon on a silicon oxide containing substrate. A portion of the substrate at the periphery of the major surface opposite the silicon layer is masked. The exposed portion of the substrate is removed by an etchant that is selective for silicon oxide containing composition relative to silicon, e.g. aqueous HF. The resulting membrane of silicon on a peripheral region of silicon oxide containing compositions is in tensile stress as required for lithography, but is robust. Metal, X-ray absorbing patterns are formed on the silicon by standard lithographic procedures.

X-Ray lithography mask and devices made therewith

In dielectrically isolated devices a buried conducting layer adjacent to the dielectric layer is produced by a drift effect. In particular, if arsenic antimony and/or phosphorus is present in the silicon dioxide layer, it is caused to drift from this layer and enter the adjacent isolated silicon region while maintaining a relatively narrow spatial configuration. Thus, a discrete buried highly conductive layer is formed. This configuration is particularly useful for transistor configurations such as utilized in switching applications.

Fabrication of dielectrically isolated devices with buried conductive

The efficacy of dielectrically isolated device formation on a substrate is substantially enhanced through a specific set of processing steps. In particular, before silicon oxide regions, e.g., gate oxide regions, are produced, bulk polycrystalline areas are heat treated to substantially increase their polycrystalline silicon grain size.

Process for fabricating dielectrically isolated devices utilizing

Crystal grain size in a material is increased by scanning the material with an appropriately directed energy beam. Short-term oscillation in the scan, and a particular temperature gradient configuration in the wake of the scan, results in growth of large-grain crystallites.

Method of increasing the grain size of polycrystalline materials by

The use of a reaction mixture of carbon monoxide, an oxide of nitrogen such as nitric oxide, and a source of hydrogen when passed over a hydrogenation catalyst produces cyanate compounds, e.g., ammonium cyanate and isocyanic acid. The reaction conditions chosen determine the relative amounts of the various cyanate compounds to be formed. When the formation of ammonium cyanate is desired, the addition of ammonia to the reaction mixture reduces the amount of nitric oxide reactant necessary, while enhancing the efficiency of ammonium cyanate production. When a palladium or iridium catalyst is used, the production of isocyanic acid is favored.

Growing community of inventors

Hillsborough, NJ, United States of America

Lee E Trimble