Fabrication method for semiconductor memory device

Abstract

A fabrication method for a semiconductor memory device, which forms a capacitor over a bit line, includes the steps of forming an active region pattern on a semiconductor substrate, forming a field oxide region for electrically isolating single devices in the semiconductor substrate, forming a gate insulating film on the semiconductor substrate, forming a first conductive film to serve as a gate electrode on the gate insulating film, forming a first insulating film having a first etching characteristic on the first conductive film, and patterning the first insulating film and the first conductive film to form a plurality of word line patterns. Next a second insulating film, having the first etching characteristic, is formed over the semiconductor substrate, and is etched to form sidewall spacers at lateral walls of each word line pattern. A third insulating film is then formed over the semiconductor substrate, and removed from regions where a bit line is to be formed. This exposes the active region and forms a bit line trench pattern. A bit line is then formed with portions thereof disposed in the bit line trench pattern, and a capacitor is formed over the bit line. The different etching characteristics of the insulating films allows for a larger contact hole to be formed thereby improving the contact hole aspect ratio.