Plug structure having low contact resistance and manufacturing method thereof

Abstract

A manufacturing method of a plug structure having low contact resistance includes the following steps. First, a silicon substrate and a BPSG layer covering thereon are provided. The silicon substrate has a dopant area. Next, the BPSG layer is etched to form a contact window to be contiguous with the dopant area. If the dopant area is doped with Boron, a silicon-germanium layer is formed upon the dopant area as a barrier layer. Then, a barrier layer is formed next to the contact window, and a metal plug surrounded by the barrier layer is formed. After conductive interconnecting lines are formed upon the BPSG layer, a rapid thermal annealing is adopted to reactivate the dopant area. In the case that the Boron is doped in dopant area, the silicon-germanium layer keeps the Boron from migrating to the barrier layer to lower the contact resistance of the plug structure.

Dependencies are inferred from the claim text.