| 摘要 |
PURPOSE:To prevent the mask alignment from being displaced and to improve the high frequency characteristic, by opening diffusion layer forming holes and electrode forming holes at the same time by one photo mask. CONSTITUTION:A base region 3 is formed by diffusion, and oxide film 4 is adhered thereon, three holes 9 are opened at regular intervals, a thinner oxide film 4 is formed, and a photo resist 10 which is adhered thereon is etched only on the central hole 9 to open a little wide. Next, the oxide film 4 is etched at the section in which the photo resist 10 is being opened, the left photo resist 10 is removed, and impurities are diffused into the silicon wafer 1 from the central hole 9 having the silicon face exposed by vapor phase diffusion to form an emitter region 6. Thereafter, a photo resist 10 is adhered thereon and then is etched to be removed with being left only on the central hole 9, the silicon oxide film 4 is etched on the holes, and electrodes 11 are formed in the respective holes 9 to finish a high frequency transistor. |
