| 摘要 |
PURPOSE:To improve the characterisitcs of an element while increasing the degree of integration by obtaining the desired distribution of an impurity by changing the depth of implantation and the quantity of douse during an ion implantation process. CONSTITUTION:The ions of the impurity having the same conduction type as a substrate 31 such as boron are implanted twice while using an Al film 33 as a mask by altering acceleration voltage and the quantity of douse, and an ion implanted layer 34 is formed. A concave section is shaped to a field section through etching while employing the same Al film 33 as a mask, and boron ions are implanted in the bottom. The concave section is buried with a silicon oxide through the burying of an oxide film at two stages the same as a conventional BOX method, and structure in which a field oxide film 35 is buried is obtained. A gate oxide film 36 and a polysilicon gate 37 are formed, As ions are implanted while using the polysilicon gate 37 as a mask and source and drain 38 are shaped in succession, and the MOS transistor is completed. |
