| 摘要 |
PURPOSE:To form isolation regions regardless of depth of element forming regions enhancing integration, and to make high-frequency characteristic as favorable when a bipolar transistor is to be formed by a method wherein the element forming regions are provided in the concave parts formed in a semiconductor substrate. CONSTITUTION:An SiO2 film 5 and an Si3N4 film 6 are adhered being laminated on a p type Si substrate 1 having the face index of (100), etching is performed using a photo resist film as the mask to remove the element forming regions. Then anisotropic etching is performed using the mixed liquid of caustic potash and isopropyl alcohol to form the trapezoid concave parts having the bottom face of (100) face in the element forming regions. After then, SiO2 films 7 containing As or Sb are provided only on the bottom thereof, heat treatment is performed to make impurities in the films 7 to be diffused, and n<+> type layers 8 for reduction of collector resistance are formed. Then the films 7 are removed, n type layers 9 are made to grow epitaxially burying the upper parts of the layers 8 and pressing down the layers 8, and polycrystalline Si layers 10 generated at the same time on the films 6 are oxidized to convert into SiO2 layers. |
