| 摘要 |
PURPOSE:To realize isolation of elements in flat surface by forming at first a thermal oxidation film through provision of a double-layer mask of SiO2 and Si3N4 on an Si substrate, forming a plasma anode oxide film on the exposed surface of substrate, and sequentially removing both oxide films from the surface. CONSTITUTION:A double-layer mask 12 of SiO2 13 and Si3N4 14 is provided and a Si substrate 11 is etched in the depth of about 1/2 of the desired isolation layer thickness. Then, when an isolation SiO2 16 is formed by wet oxidation, a bird's head 17 is formed. Then, a mask 12 is removed using H2PO3, HF and a SiO2 19 is formed up to a height almost equal to the height of bird's head 17 on the exposed surface of substrate by the plasma anode oxidation. Next, when a SiO2 is sequentially etched from the upper surface using the HF liquid, the element isolation layer 16 which is buried in the substrate and has a flat surface can be obtained. |
