| 摘要 |
PURPOSE:To obtain high gains with excellent reproducibility while enabling operation at high speed, and to improve load driving capability by forming a first conduction type third region diffused from the surface of an epitaxial layer to the side surface of a second region and demarcating the side surface and base of an epitaxial layer in an island region by the second region and the third region. CONSTITUTION:An N<+> type buried diffusion layer 2 is shaped to a P<-> type silicon substrate 1, an silicon oxide film 10 is formed, and boron ions are implanted while using a resist 11 as a mask, and annealed in an inactive atmosphere. An N-type epitaxial layer 4 is shaped, and isolated by an element isolation silicon oxide film 3. Boron is buried into the N<+> type buried layer 2 in high concentration as a rule at that time, and an active P-type layer is not formed yet. An inactive P-type layer 51 is diffused and shaped to the N-type epitaxial layer 4, boron made to be contained in the buried diffusion layer 2 is diffused upward through the heat treatment of the layer 4 to form an active P-type layer 52, and an N-type layer 6 is isolated from the epitaxial layer 4. A P<+> type layer 7 is diffused and shaped, and the opening of an N<+> layer for the ohmic contact of the N-type layer 6 is bored. The current gains of a PNP transistor are controlled by the diffusion depth of the P<+> type layer 7. |
