METHOD FOR FABRICATING SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for fabricating a semiconductor device is provided to supplement the quantity of insufficient dopants by using a mask for patterning a thick gate oxide layer as an additional ion implantation mask, and to improve a channeling effect by easily controlling damage to a substrate and a range of projection. CONSTITUTION: The first gate insulation layer of the first thickness is formed on a semiconductor substrate(20) in which the first and second regions(R3,R4) are defined. A mask layer(23) covers the first region including the first gate insulation layer. An additional ion implantation for controlling a threshold voltage is performed regarding the surface of the substrate under the first gate insulation layer in the second region not protected by the mask layer to form an ion buried layer. The first gate insulation layer not protected by the mask layer is eliminated to expose the surface of the substrate in the second region. The mask layer is removed. The second gate insulation layer of the second thickness is formed on the exposed substrate in the second region.