| 摘要 |
PURPOSE:To form a permeable base transistor (PBI) in which parasitic capacitance is reduced, by a method wherein, after a WSix layer of narrow width is formed on the side-wall of a groove, the WSix layer is buried in an epitaxial layer by epitaxial growth. CONSTITUTION:After an N-GaAs layer 2 is formed on an N<+> GaAs layer 1, a groove 10 is formed in the above layer 2 by using a mask G, and then a WSix layer 4 is formed on the whole surface. By etching, the above WSix layer 4 is left only on the side-wall of a lower protruding part. By epitaxial growth of the N-GaAs layer 2, a groove 10 is buried. After the mask 3 is eliminated, the N-GaAs layer 2 is again grown by epitaxy, and thereon an N<+> GaAs layer 5 is formed in succession. Thereby, a narrow side-wall 4A composed of WSix formed on the groove 10 can be made a base electrode, so that a depletion layer 10 around the base electrode 4A takes more roles in PBT operation. Therefore, the parasitic capacitance can be reduced. |
