| 摘要 |
PURPOSE:To make a device fine and to improve the high frequency characteristic, by forming a polysilicon coating on a hole having a diffusion layer formed therein, and then forming electrodes. CONSTITUTION:A silicon oxide film 4 through which three holes 9 are opened at regular intervals is formed. A photo resist 10 coating thereon is etched only on the central hole 9 to open a little wide, the oxide film 4 existing therein is etched, the photo resist 10 is removed, and then a polysilicon coating 11 is formed. Moreover, after a photo resist 10 coating thereon is etched only on the central hole 9 to open a little wide, ion implantation and thermal diffusion forms an emitter region 6. After an electrode film 12 is formed, photo etching removes the polysilicon coating 11 and electrode film 12 with being left only on the central hole 9. Next, the polysilicon coating 11 and electrode film 12 are etched using the oxide film 4 as a mask, and electrodes 13 are formed in both the side holes 9 by a lift-off process to finish a high frequency transistor. |
