Verfahren zur Ausbildung einer integrierten Schaltung mit Grabenisolation

A process for fabricating integrated circuits is disclosed. In particular, the process includes rounding corners of the active regions. In one embodiment, a substrate prepared with a support region having an active area between first and second trench isolations. The top surfaces of the trench isolations extend above the surface of the substrate. First and second etch stop layers are deposited on the substrate, lining the substrate surface and trench isolations without filling the gap. The etch stop layers can be etched selective to each other and layers beneath and or above. The second etch stop layer includes horizontal and vertical portions. An etch selectively removes the vertical portions of the etch stop layer. An isotropic etch is then performed, removing exposed portions of the first etch stop layer. The second etch stop layer acts as an etch mask. The etch also creates an undercut beneath the second etch stop layer, exposing edge portions of the active area. The second etch stop layer is removed, following by oxidizing the edge portions of the active area unprotected by the first etch stop layer.