Patent ID: 6849529

Claim:
A method for manufacturing a trench capacitor, comprising: providing a semiconductor substrate; forming a trench in the substrate; forming a thin sacrificial layer on a surface of the trench; forming a hemispherical silicon grain layer over the thin sacrificial layer; depositing a doped silicate glass layer on the hemispherical silicon grain layer, providing a photoresist inside the trench; removing exposed portions of the doped silicate glass layer; removing exposed portions of the hemispherical silicon grain layer; removing the photoresist provided in the trench; depositing a cap layer over the thin sacrificial layer and on a surface of the trench; annealing the doped silicate glass layer to form buried plates; removing at least the cap layer and the remaining doped silicate glass layer, and exposed thin sacrificial layer; providing a layer of dielectric over the trench and hemispherical silicon grain surfaces; depositing polysilicon inside the trench; and etching the dielectric layer, wherein the sacrificial layer has a thickness to act as an etch stop during the step of removing exposed portions of the hemispherical silicon grain layer, and is electrically conductive.