| 摘要 |
PURPOSE:To prevent the shortcircuit between the emitter E and the base B of a transistor of miniature size by forming an electrode window in a mask layer made of an oxidized film and a nitrided film, forming a doped polysilicon layer over the emitter window, and then removing a nitrided film. CONSTITUTION:An oxidized film 13 and a nitrided film 30 are formed on a substrate formed with a base layer 12 in a step of formig a transistor of DOPOS type, and holes are opened at an emitter window 14 and a base contact window 15. Then, an As-doped polysilicon layer 16 and an oxidized film 17 are, for example, accumulated, and are photoetched to cover the window 14 and to pattern it. Then, the film 30 is removed in thermal phosphoric acid, is treated by supersonic wave, and the layer 16 and the oxidized film are retained only in the window 14. Subsequently, with the polysilicon 16 as a diffusion source, an emitter diffused layer is formed, the oxidized film 16 is removed, and a metallic electrode is formed. Thus, the structure in which the interval of the electrodes formed on the base contact and the polysilicon layer is reduce can be readily formed, and the shortcircuit between the electrodes can be prevented, and the characteristics and the yield can be improved. |
