Fabrication method to approach the conducting structure of a DRAM cell with straightforward bit line

摘要

A conducting structure of a COB cell of DRAM includes an piecewise straight active area and substantially straight bitline formed over a semiconductor substrate upon which a first dielectric layer existed. Contact holes are formed over the piecewise straight active area for electrically exposing both nodes (source and drain), of the active area of the access device. An offset landing plug pattern is defined by a photoresist-clear pattern beside, say, the source node of the primary contact pattern and recess-etched into the first dielectric layer and electrically connected to the source node of the primary contact structure finally. The contact structure is then formed by a deposition-etched process, which performs as a landing plug for contact of the upper contact structures. The top area of the landing plug is defined through the additive pattern of the primary contact as well as the offset landing plug pattern. Thereafter, a second dielectric layer is deposited on the first dielectric layer and the contact structure. A bit line contact is then formed in the second dielectric layer and defined at the offset position of the source node of the landing plug contact structure and electrically connected with it, so as to provide a capability of forming a substantially straight bit line lies on an off-axis site to the piecewise straight active area and the primary substrate contact plug.