摘要 |
A method for forming a well of a semiconductor device sequentially forms a buffer film, an oxidizable film, and an oxidation-blocking film on a periphery area of a semiconductor substrate. A predetermined part of the oxidation-blocking film is etched to partially expose a surface of the oxidizable film and a thermal oxidation is performed to form a field oxide film on a region of the periphery area where the oxidizable film is exposed and on a cell area where the substrate is exposed. The oxidation-blocking film, the oxidizable film, and the buffer film are removed. Impurity ions of a first conductivity type are implanted using high energy. Impurity ions of a second conductivity type are implanted using low energy by using the field oxide film as a mask. The field oxide film is removed and a diffusion is performed to form wells of the first and second conductivity types.
|