| 摘要 |
PURPOSE:To prevent various kind of bad influences due to the thermal stress and thus improve the performance of a device by a method wherein a high impurity concentration region is used as at least a part of a control electrode region. CONSTITUTION:An N<+> buried layer, an N type Si semiconductor layer 11, an Si3N4 film 12 and windows 12A for isolation layer formation are formed on an Si semiconductor substrate. Next, porous Si layers 13 reaching the N<+> buried layer are selectively formed in the layer 11, and then boron is added. The boron diffuses also into the single crystal region adjacent to the layer 13, and accordingly a P<+> type gate region is formed. When the layer 13 is formed, the film 12 used as a mask is removed. Then, a field oxide film is formed by thermal oxidation treatment. In this thermal oxidation treatment, the porous Si layer 13 is rapidly converted into a porous Si dioxide layer 13', and therefore comes to have the effect as an element isolation layer constituted of an insulator. |
