Interconnect Structure and Method for Forming Interconnect Structure

Abstract

An improved interconnect structure and a method for forming the interconnect structure is disclosed that allows the interconnect structure to achieve a lower Rc. To lower the Rc of the interconnect structure, an α-phase inducing metal layer is introduced on a first Ta barrier layer of β phase to induce the subsequent deposition of Ta thereon into the formation of an α-phase Ta barrier layer. The subsequently deposited Ta barrier layer with a primary crystallographic structure of α phase has a lower Rc than that of the β-phase Ta barrier layer.

1 . An interconnect structure, comprising:
 a substrate;   a dielectric material layer on the substrate; and   a conductive feature in the dielectric layer, the conductive feature having:
 a copper (Cu)-containing metal; 
 an alpha (α)-phase tantalum (Ta) barrier layer at least partially, peripherally surrounding the Cu-containing metal; 
   an α-phase inducing metal layer peripherally surrounding the α-phase Ta barrier layer; and   a beta (β)-phase Ta barrier layer peripherally surrounding the α-phase inducing metal layer.   
     
     
         2 . The interconnect structure of  claim 1 , wherein the α-phase inducing metal layer has a thickness of between about 5 and about 60 angstroms. 
     
     
         3 . The interconnect structure of  claim 1 , wherein the α-phase Ta barrier layer has a thickness of between about 5 and about 60 angstroms. 
     
     
         4 . The interconnect structure of  claim 1 , wherein the β-phase Ta barrier layer has a thickness of between about 10 and about 100 angstroms. 
     
     
         5 . The interconnect structure of  claim 1 , wherein the Cu-containing metal is selected from the group consisting of Cu, copper magnesium (CuMg), copper aluminum (CuAl), copper manganese (CuMn), copper titanium (CuTi), copper silicon (CuSi), copper tungsten (CuW), copper tantalum (CuTa), copper zirconium (CuZr), copper molybdenum (CuMo), and combinations thereof. 
     
     
         6 . The interconnect structure of  claim 1 , wherein the α-phase inducing metal layer is at least over the β-phase Ta barrier layer at a bottom of an opening. 
     
     
         7 . The interconnect structure of  claim 1 , further comprising another conductive feature overlying or underlying the conductive feature. 
     
     
         8 . The interconnect structure of  claim 1 , wherein the α-phase inducing metal layer is made of a metal selected from the group consisting of Cu, Cobalt (Co), Titanium (Ti), and Ruthenium (Ru). 
     
     
         9 . An integrated circuit device, comprising:
 a substrate;   a plurality of inter-layer dielectric layer on the substrate; and   a plurality of conductive features, the respective conductive features correspondingly in the respective dielectric layers, each the conductive feature having:
 a β-phase Ta barrier layer; 
 an α-phase inducing metal layer on the β-phase Ta barrier layer; 
 an α-phase Ta barrier layer on the α-phase inducing metal layer; and 
 a Cu-containing metal on the α-phase Ta barrier layer. 
   
     
     
         10 - 20 . (canceled) 
     
     
         21 . The interconnect structure of  claim 1 , wherein the Cu-containing metal comprises a second copper-containing metal and a seed layer peripherally surrounding the second copper-containing metal. 
     
     
         22 . The interconnect structure of  claim 21 , wherein the seed layer is different from or same as the second copper-containing metal in composition. 
     
     
         23 . The integrated circuit device of  claim 9 , wherein the α-phase inducing metal layer has a thickness of between about 5 and about 60 angstroms. 
     
     
         24 . The integrated circuit device of  claim 9 , wherein the α-phase Ta barrier layer has a thickness of between about 5 and about 60 angstroms. 
     
     
         25 . The integrated circuit device of  claim 9 , wherein the β-phase Ta barrier layer has a thickness of between about 10 and about 100 angstroms. 
     
     
         26 . The integrated circuit device of  claim 9 , wherein the Cu-containing metal is selected from the group consisting of Cu, copper magnesium (CuMg), copper aluminum (CuAl), copper manganese (CuMn), copper titanium (CuTi), copper silicon (CuSi), copper tungsten (CuW), copper tantalum (CuTa), copper zirconium (CuZr), copper molybdenum (CuMo), and combinations thereof. 
     
     
         27 . The integrated circuit device of  claim 9 , wherein the α-phase inducing metal layer is at least over the β-phase Ta barrier layer at a bottom of an opening. 
     
     
         28 . The integrated circuit device of  claim 9 , wherein other conductive features are overlying or underlying the conductive feature. 
     
     
         29 . The integrated circuit device of  claim 9 , wherein the α-phase inducing metal layer is made of a metal selected from the group consisting of Cu, Cobalt (Co), Titanium (Ti), and Ruthenium (Ru). 
     
     
         30 . The integrated circuit device of  claim 9 , wherein the Cu-containing metal comprises a seed layer and a second copper-containing metal on the seed layer. 
     
     
         31 . The integrated circuit device of  claim 30 , wherein the seed layer is different from or same as the second copper-containing metal in composition.