Methods of forming integrated circuit capacitors using metal reflow

Abstract

Methods of forming integrated circuit capacitors include the steps of forming an electrically insulating layer on a face of a semiconductor substrate and then patterning the electrically insulating layer to define a contact hole therein. A barrier metal layer is then formed in at least a portion of the contact hole. A lower electrode metal layer is then formed on the barrier metal layer and then planarized by reflowing the lower electrode metal layer at a temperature greater than about 650.degree. C. in a nitrogen gas ambient, to define a lower capacitor electrode. A layer of material having a high dielectric constant is then formed on the lower capacitor electrode. An upper capacitor electrode is then formed on the dielectric layer, opposite the lower capacitor electrode. The dielectric layer may comprise Ba(Sr, Ti)O.sub.3, Pb(Zr, Ti)O.sub.3, Ta.sub.2 O.sub.5, SiO.sub.2, SiN.sub.3, SrTiO.sub.3, PZT, SrBi.sub.2 Ta.sub.2 O.sub.9, (Pb, La)(Zr, Ti)O.sub.3 and Bi.sub.4 Ti.sub.3 O.sub.12. According to one embodiment of the present invention, the step of patterning the electrically insulating layer comprises patterning the electrically insulating layer to define a contact hole therein that exposes the face of the semiconductor substrate. The step of forming a barrier metal layer also preferably comprises depositing a conformal barrier metal layer on sidewalls of the contact hole and on the exposed face of the substrate. The barrier metal layer may be selected from the group consisting of TiN, CoSi, TaSiN, TiSiN, TaSi, TiSi, Ta and TaN.