| 摘要 |
PURPOSE:To attempt high speed and high frequency operation by forming an N type buried layer by two steps and making higher concentration on the side of the region where elements are formed and lower that on the side of the substrate. CONSTITUTION:An oxide layer 11 is formed on a P type semiconductor substrate 1. Next, resist is coated on the layer 11, which is removed by etching. Next, an N type impurity is deposited and diffused to form an N type buried layer 3. In this time, concentration of the impurity is selected as low as possible. Next, an N type impurity 4 is deposited by ion implantation or the like. In this time, concentration of the impurity 4 is selected as high as possible. Next, the layer 11 is wholly removed to grow an N type epitaxial layer 5. Next, an insulating oxide layer 6, a P type base region 8, an N type emitter region 9 and aluminum wiring 10 are formed. |
