| 摘要 |
This disclosure relates to a method of forming a polycrystalline silicon contact to a buried collector region of a transistor or the like. This is accomplished by providing a monocrystalline silicon substrate body having a collector region exposed at its top surface. A layer of refractory metal is subsequently formed over the entire top surface of the body. Using conventional photomasking and etching techniques a refractory metal pad is formed over a portion of the exposed surface of the collector region, and an insulating layer is formed over the top surface of the body and pad. The insulated covered body is then heated to a temperature sufficient to completely convert the refractory metal to a refractory metal silicide while simultaneously causing the metal silicide to diffuse into the collector region. The insulating layer is next completely removed using a suitable etchant. A silicon layer is subsequently epitaxially deposited onto the top surface of the entire silicon substrate body. This layer forms as a column of polycrystalline silicon material above the refractory metal silicide region, and as an epitaxial layer of monocrystalline silicon material above the rest of the top surface of the substrate body. The column of polycrystalline silicon, is subsequently treated, so that, it has the same conductivity as the collector region and together with the refractory silicide region, constitutes a vertically extending low resistance conductive path from the top surface of the completed composite body down to the collector region buried beneath the epitaxial layer, and the epitaxial layer provides a site in which are formed other functional portions of the transistor or the like, such as base and emitter portions.
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