| 摘要 |
PURPOSE:To prevent a stress from affecting a single crystal silicon and to prevent a leakage current from increasing by forming a cavity on the lower surface of a mask when forming a polycrystalline silicon by forming a groove on the surface, and subjecting the polycrystalline silicon to anodic reaction and oxidation to fill the groove with silicon oxide. CONSTITUTION:When a single crystal silicon substrate 11 formed with a mask 12 is dipped in an etchant, V-shaped grooves 13 are formed, and when a P-type polycrystalline silicon 14 is accumulated, cavities 15 remains in the grooves of the portion coated with the mask 12. When the surface of the substrate is polished to remove the polycrystalline silicon on the surface of the substrate, the mask 12 of the nitride silicon is exposed. When the single crystal substrate buried with the P-type polycrystalline silicon in the grooves is subjected to an anodic reaction in hydrogen fluoride solution, the silicon 14 becomes porous silicon 16. When this is treated in oxidative atmosphere, the silicon 16 is oxidized to become silicon dioxide 17. Since the cavities 15 are formed in this manner, a volume expansion can be absorbed to reduce a stress affecting the silicon layer 11. |
