| 摘要 |
PROBLEM TO BE SOLVED: To roughen the surface of a lower electrode and enlarge the surface area thereof, by performing cluster ion implantation on the surface of a conductor film which is to be a lower electrode of a capacitor, and then selectively etching a local part where cluster ions have been implanted. SOLUTION: Accelerated P-cluster ions 11 are implanted onto the surface of a lower electrode 10 made of a polycrystal silicon film. The P-cluster ions 11 have a very large mass number and therefore reach only a shallow part of the lower electrode 10, thus forming a large damaged region. A crystal defect is generated in this region by the damage and makes this region amorphous. Then, the region is impregnated with a heated phosphoric acid solution and etching is performed. With the heated phosphoric acid solution, the etching rate is dependent on the impurity density, and such a characteristic is observed that a portion having a high impurity density is selectively etched. Therefore, only the portion of P-cluster is selectively etched and a number of recess portions 15 are formed.
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