| 摘要 |
PURPOSE:To enable the composition of this semiconductor device which is completely isolated both lengthwise and widthwise from a substrate and does not require an epitaxial layer, by equipping an element isolation region which is formed at a connection part between two crystal planes and the substrate and is made of a substrate oxidizing film. CONSTITUTION:After a silicon oxide film 14 and a silicon nitride film 15 are formed over the whole surface of a silicon substrate 11, a posi-resist 16 is used to perform selective etching of a bottom part on a <110> crystal plane of projected silicon 13. In succession, selective oxidation of the <110> silicon crystal plane is performed until it attains to a <-1-10> crystal plane on a back side of the substrate 11, so that an element isolation region 17 is formed to perform dielectric isolation of the projected silicon 13 from the silicon substrate 11. An element which is completely dielectrically isolated both lengthwise and widthwise from the substrate is thus formed on the crystal plane dissimilar to the substrate plane in this semiconductor device. Accordingly this device does not require an epitaxial layer of conventional structure or the like at all and is equipped with the element region which is completely isolated from the substrate, so that a bipolar transistor which is made very high-speed can be composed.
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