DRAM cell having tunnel shaped structure and formation process thereof

摘要

A DRAM cell having a tunnel-shaped structure (in the form of buried bit line structure) and a formation process therefore are disclosed. A storage poly and a local connecting layer are interconnected in such a manner as to form a tunnel-shaped portion, and a bit line passes through the tunnel formed by the combination of the local connecting layer and the storage poly. A flattening insulating layer, a bit line capping-oxide-layer and a spacer are filled between the storage poly, the local connecting layer and the bit line. The storage poly is contacted through the local connecting layer to a first semiconductor region, while the bit line is directly contacted to a second semiconductor region.