Semiconductor device and manufacturing method thereof

Abstract

A method of manufacturing a semiconductor device includes forming a buffer layer on a substrate including active regions and word lines, sequentially stacking a first conductive layer and a first insulating layer, forming bit line structure main parts such that each bit line main part is in contact with one or more of the active regions through a plurality of first contacts, by etching the first insulating layer and the first conductive layer, stacking first spacers, forming bit line structure expansions by etching the first spacers, the first insulating layer, and the first conductive layer, and forming second contacts such that the second contacts are in contact with the active regions, respectively. The bit line structure expansions are connected to the bit line structure main parts, respectively, and are wider than the bit line structure main parts as viewed in a plan view.