Fujitsu Corporation

Akira Tabata

Motoshu Miyajima

Hiroshi Goto

Hirokazu Tanaka

Kazushi Kawaguchi

Yoshifumi Kikuchi

Tamotsu Ishikawa

A bipolar transistor having self-aligned base and emitter regions is fabricated in a silicon layer which is epitaxially grown on a substrate so as to fill up a cavity formed through a polysilicon layer deposited on the substrate. The polysilicon layer is doped with impurities for creating an extrinsic base region in the epitaxially grown silicon layer and is insulated from the emitter electrode by a dielectric layer formed thereon. The dielectric layer can be provided by selectively oxidizing the polysilicon layer. Thus, the step formed at the emitter electrode is small and equal to the thickness of the dielectric layer, about 3000 .ANG., for example, thereby eliminating the faulty step coverage in the prior art self-aligned bipolar transistor usually having the step as large as 1 micron.

Method for fabricating a bipolar transistor having self aligned base and

A method of producing a complementary semiconductor device having p-type islands and n-type islands in a dielectric isolation structure, including removing a projecting portion of a polycrystalline silicon layer, which is formed at the same time as the formation of an epitaxial silicon layer for one of two types of islands, so as to obtain an almost smooth exposed surface. The smooth surface contributes to the formation of a good masking pattern on the epitaxial silicon layer by a photoetching method, so that mesa portions for islands having exact dimensions are formed at predetermined positions.

Method of producing a complementary semiconductor device with a

A method for fabricating a wafer for a dielectric isolation (DI) integrated circuit device is provided, wherein the substrate of the wafer, comprises portions of polycrystalline silicon positioned beneath regions for electrical elements, namely, 'islands', and portions of single crystal silicon are positioned in other areas of the wafer such as scribing regions, peripheral regions and contact regions. The single crystal portions of the substrate are grown during its fabricating steps by exposing surfaces of an original substrate of single crystal silicon, before the deposition of silicon onto the original substrate, by removing a dielectric isolation layer over the predetermined regions to be exposed. The single crystal silicon portions of the wafer provide various advantages for subsequent mechanical processing of the wafer such as shaping and rounding of the peripheral region and the scribing of the wafer into dice.

Method for fabricating a dielectric isolated integrated circuit device

A method for fabricating an isolation region in a semiconductor substrate that produces neither a 'bird's beak' nor a 'bird's head'. A smooth substrate surface is provided, which is preferable for multi-layered wiring. The packing density of devices in a bipolar IC circuit can be increased. A sharp-edged isolation groove having a U-shaped cross-section is made by reactive ion etching. The inner surface of the isolation groove is coated by an insulating film. Then the groove is buried with polycrystalline semiconductor material. The polycrystalline material which is deposited on the surface of the substrate is etched off. At the same time the polycrystalline material in the groove is also etched to a specific depth from the surface. An insulating film is then deposited so as to again fill the groove. Then the substrate surface is polished or etched to provide a flat surface.

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Zama, Japan

Akira Tabata