Patent ID: 6376873
Filing Date: 2002-04-23
Classification: H01L

Abstract:
A dynamic random access memory device comprising:a substrate having a trench formed therein, the trench having a lower portion, a top, a circumference and a side wall; a signal storage node including a storage node conductor formed in the lower portion of the trench, a node dielectric, and a collar oxide disposed above the node dielectric, the storage node conductor isolated from the side wall by the node dielectric and by the collar oxide; a buried strap coupled to the storage node conductor and contacting a portion of the side wall of the trench along a fragment of the trench circumference above the collar oxide; a trench-top dielectric having a trench-top dielectric thickness formed upon the buried strap; a signal transfer device including: a first diffusion region extending into the substrate adjacent the portion of the trench side wall contacted by the buried strap, a gate insulator having a gate insulator thickness formed on the trench side wall above the buried strap, wherein the gate insulator thickness is less than the trench-top dielectric thickness, and a gate conductor formed within the trench upon the trench-top dielectric and adjacent the gate insulator; and a trench insulator formed in the trench extending from the top of the trench down through a portion of the collar oxide and extending around the circumference of the trench exclusive of the fragment of the trench contacted by the buried strap.