Methods for fabricating integrated circuit capacitor electrodes using first and second insulating layers and a buffer layer

Abstract

Integrated circuit capacitor lower electrodes are fabricated by forming a plurality of spaced-apart contact pads on an integrated circuit substrate. A first insulating layer is formed on the integrated circuit substrate including on the contact pads. A plurality of spaced-apart conductive lines is formed on the first insulating layer that are laterally offset from the plurality of spaced-apart contact pads. A second insulating layer is formed on the first insulating layer including on the conductive lines. A buffer layer comprising material that is different from the second insulating layer, is formed on the second insulating layer. Openings are formed that extend through the buffer layer, through the second insulating layer and into the first insulating layer between the conductive lines to expose the contact pads. A conductive layer is formed in the openings and on the buffer layer. The conductive layer is etched between the openings to form the capacitor lower electrodes. The buffer layer preferably comprises material that has lower reflectivity than that of the second insulating layer and also preferably comprises material that has an etch rate for a predetermined etchant, that is intermediate that of the second insulating layer and the conductive layer. The first and second insulating layers preferably comprise silicon dioxide, the buffer layer preferably comprises at least one of silicon nitride and silicon oxynitride and the conductive layer preferably comprises polysilicon. During etching, a polymer preferably is formed on the capacitor lower electrode sidewalls adjacent the buffer layer. The etchant preferably is a plasma etchant including sulfur hexafluoride, chlorine and/or nitrogen gases.