| 摘要 |
PURPOSE:To alleviate the hole accumulation effect attributable to hole injection from a p-n-p-n transistor emitter by a method wherein a trench is formed in a semiconductor substrate so deep as to penetrate through an n-type epitaxial layer but not an n-type buried layer. CONSTITUTION:A p-type silicon substrate 1, high concentration n-type buried layer 2, and low concentration n-type epitaxial layer 3 are provided for the constitution of a semiconductor substrate, wherein an element isolating trench 4 is provided and, therein, an insulating film 5 which is a silicon oxide film is buried. In an element forming region surrounded by the element isolating trench 4, a vertical n-p-n transistor is built of a high concentration n-type diffusion region 101, p-type diffusion region 104, and low concentration n-type epitaxial layer 3. Trenches 6A and 6B are provided, wherein boron-doped polycrystalline silicon layers 110A and 110B are buried. A lateral p-n-p transistor is arranged using the trenches 6A and 6B. |
