Patent ID: 6908831

Claim:
A method for fabricating a semiconductor structure, which comprises the steps of: providing a semiconductor substrate having a trench formed therein; providing a first barrier layer in the trench of the semiconductor substrate; providing a second barrier layer above the first barrier layer; filling the trench with a filling; etching-back the filling in an upper trench section, resulting in a formation of a hole in the upper trench section and a filling residue remaining in a lower trench section; providing a non-conformal cover layer in the upper trench section, the cover layer having a bottom region with a first thickness greater than a second thickness of a wall region of the cover layer; and isotropic etching-back of the cover layer and of the second barrier layer in the upper trench section, so that, in the wall region, the cover layer and also the second barrier layer are removed and the first barrier layer remains and the bottom region remains covered by a residual cover layer, as a result of which the filling residue is encapsulated by the first barrier layer and the residual cover layer in a capsule.