Patent ID: 7759190

Claim:
A method for forming a memory device, the method comprising the steps of: providing a substrate having a trench, wherein a trench capacitor is disposed in a lower portion of the trench, a conductive column is disposed in the trench and electrically connects the trench capacitor, a collar dielectric layer covers a portion of a sidewall of the trench overlying the trench capacitor, a top dielectric layer is disposed in the trench and on the conductive column, a gate structure is disposed on the substrate; etching the substrate to form an opening between the collar dielectric layer and the gate structure; implanting the substrate through the opening to form a doped region in a portion of the substrate below the opening for increasing partial threshold voltage of a parasitical transistor; and forming a transmissive strap by selective deposition, electrically connecting a drain of the gate structure and the conductive column.