Semiconductor structure and manufacturing method thereof

The invention discloses a semiconductor structure and a manufacturing method thereof. The semiconductor structure comprises a substrate, an active region, an element insulating region surrounding theactive region, first and second bit line structures on the substrate, a conductive diffusion region which is in the active region and is between the first and second bit line structures, a contact hole which is located between the first and second bit line structures and exposes a portion of the conductive diffusion region, a buried plug layer which is disposed in the contact hole and is in directcontact with the conductive diffusion region, and a storage node contact layer which is disposed on the buried plug layer in the contact hole, wherein the storage node contact layer includes a downward protruding portion surrounded by the buried plug layer, and the buried plug layer has a U-shaped cross-sectional profile. 本发明公开一种半导体结构及其制作方法，其中该半导体结构包含基底；主动区域；元件绝缘区域，围绕主动区域；第一、第二位线结构，位于基底上；导电扩散区域，位于主动区域内，且介于第一、第二位线结构间；接触洞，位