Semiconductor device and method for fabricating the same

A method for fabricating a semiconductor device comprising the steps of:

• forming a silicon film on an insulation film;
• forming a rugged polycrystalline silicon film having concavities on a surface;
• etching the rugged polycrystalline silicon film and the silicon film under an etching condition having a relatively high etching selectivity between a material forming the insulation film and silicon which make a deposition of an etching gas and/or an etching product relatively strong with respect to an etching of silicon, so that the rugged polycrystalline silicon film and the silicon film in a region where the concavities are formed are etched to thereby form a more rugged surface than before etching to form a surface rugged first electrode of the rugged polycrystalline silicon film and the silicon film;
• forming a dielectric film on the first electrode;
• and
• forming a second electrode on the dielectric film.

A method for fabricating a semiconductor device comprising the steps of:

• forming a silicon film on an insulation film;
• forming on the silicon film a rugged polycrystalline silicon film having a convex region and a concavity region on a surface;
• and
• selectively etching the rugged polycrystalline silicon film and the silicon film in the concave region of the rugged polycrystalline silicon film with respect to the convex region of the rugged polycrystalline silicon film by a micro loading effect which makes an etching rate at the concave region higher than that at the convex region to thereby form a more rugged surface than before etching.

A method for fabricating a semiconductor device comprising the steps of:

• forming a silicon film on an insulation film;
• forming on the silicon film a rugged polycrystalline silicon film having a convex region and a concavity region on a surface;
• and
• selectively etching the rugged polycrystalline silicon film and the silicon film in the concave region of the rugged polycrystalline silicon film with respect to the convex region of the rugged polycrystalline silicon film without using an etching mask to thereby form a more rugged surface than before etching.