Semiconductor device having fine contacts

Abstract

A semiconductor device has a structure of contacts whose size and pitch are finer that those that can be produced under the resolution provided by conventional photolithography. The contact structure includes a semiconductor substrate, an interlayer insulating layer disposed on the substrate, annular spacers situated in the interlayer insulating layer, first contacts surrounded by the spacers, and a second contact buried in the interlayer insulating layer between each adjacent pair of the first spacers. The contact structure is formed by forming first contact holes in the interlayer insulating layer, forming the spacers over the sides of the first contact holes to leave second contact holes within the first contact holes, etching the interlayer insulating layer from between the spacers using the first spacers as an etch mask to form third contact holes, and filling the first and second contact holes with conductive material. In this way, the pitch of the contacts can be half that of the first contact holes.