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Abstract

A contact structure for a semiconductor device having a first refractory metal layer formed only at the bottom of a contact hole. The first refractory metal is selected from a group comprising titanium (Ti), titanium alloys or compounds such as Ti/TiN, tungsten (W), titanium/tungsten (Ti/W) alloys, or chromium (Cr) or tantalum (Ta) and their alloys or some other suitable material. A low resistivity layer comprising a single, binary or ternary metalization is deposited over the first refractory metal layer in the contact hole by a method such as PVD using evaporation or collimated sputtering. The low resistivity layer has side walls which taper inwardly toward one another with increasing height of the layer and the low resistivity layer does not contact the side walls of the contact hole. The low resistivity layer may be Al.sub.x Cu.sub.y (x+y=1; x.gtoreq.0, y.gtoreq.0), ternary alloys such as Al-Pd-Cu or multicomponent alloys such as Al-Pd-Nb-Au. A second refractory metal layer is deposited over the low resistivity layer. The second refractory metal layer may be tungsten, cobalt, nickel, molybdenum or alloys/compounds such as Ti/TiN. The first and second refractory metal layers completely encapsulate the low resistivity layer. The first and second refractory metal layers can comprise an alloy containing silicon with a higher incorporated silicon content near the top of the contact hold present as a distinct or graded composition than at a location closer to the bottom of the contact hole.

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First Claim