| 摘要 |
<p>There are repeated the step of isotropically etching an oxide film (12) formed over the surface of a semiconductor substrate (11) through an opening (12a) to form a recess (11a), the step of anisotropically etching an oxide film (14) formed on the inner face of the recess to form an opening (14a), and the step of isotropically etching through the opening to form a recess (11b) succeeding to the recess (11a) through the opening (14a). A deep gate structure can be achieved within a short time while eliminating the overlapping errors of a mask, by using the overhangs of the openings formed in the oxide films (12, 14, 15 and 16) as the mask in all the following etching steps to repeat the isotropic and anisotropic etching steps through the same mask. The sectional shapes of the recesses are formed of a plurality of curved surfaces having different curvatures. It is possible to achieve a semiconductor device having recesses of a large aspect ratio (i.e., length/width ratio), i.e., of a larger depth than an opening width.</p> |
