Microstructure modification in copper interconnect structures

Abstract

A metal interconnect structure and a method of manufacturing the metal interconnect structure. Manganese (Mn) is incorporated into a copper (Cu) interconnect structure in order to modify the microstructure to achieve bamboo-style grain boundaries in sub- 90 nm technologies. Preferably, bamboo grains are separated at distances less than the “Blech” length so that copper (Cu) diffusion through grain boundaries is avoided. The added Mn also triggers the growth of Cu grains down to the bottom surface of the metal line so that a true bamboo microstructure reaching to the bottom surface is formed and the Cu diffusion mechanism along grain boundaries oriented along the length of the metal line is eliminated.

1 - 22 . (canceled) 
     
     
         23 . A method of forming a metal interconnect structure comprising:
 forming a dielectric material layer comprising a recessed line pattern;   forming a metallic barrier layer on the dielectric material layer within the recessed line pattern;   forming a copper-containing seed layer on the metallic barrier layer within the recessed line pattern;   forming a copper-containing layer on the copper-containing seed layer, wherein at least one of the copper-containing seed layer and the copper-containing layer comprises a copper-manganese alloy comprising a manganese concentration ranging from about 1 ppm to about 10 atomic percent, and   wherein the copper-containing seed layer and the copper-containing layer constitute a copper-manganese alloy line; and   forming a bamboo microstructure within the copper-manganese alloy line, the bamboo microstructure comprising one or more grain boundaries extending across a width and a height of the copper-manganese alloy line.   
     
     
         24 . The method of  claim 23 , wherein forming the bamboo microstructure within the copper-manganese alloy line comprises:
 annealing the copper-manganese alloy line at a temperature ranging from about 20° C. to about 400° C. for a time period ranging from about 1 second to about 1 week, wherein grain size within the copper-manganese alloy line increases during the annealing.   
     
     
         25 . The method of  claim 23 , wherein forming the bamboo microstructure within the copper-manganese alloy line comprises:
 increasing grain size within the copper-manganese alloy line such that a width of a grain is equal to the width of the copper-manganese alloy line.   
     
     
         26 . The method of  claim 23 , wherein forming the bamboo microstructure within the copper-manganese alloy line comprises:
 increasing grain size within the copper-manganese alloy line such that a width and a height of a grain are equal to the width and the height of the copper-manganese alloy line, respectively.   
     
     
         27 . The method of  claim 23 , wherein forming the bamboo microstructure within the copper-manganese alloy line comprises:
 increasing grain size within the copper-manganese alloy line such that each grain boundary is separated from any other grain boundary by a distance equal to or greater than the width of the copper-manganese alloy line.   
     
     
         28 . A method of forming a metal interconnect structure comprising:
 forming a dielectric material layer comprising a recessed line pattern;   forming a metallic barrier layer on the dielectric material layer within the recessed line pattern;   forming a copper-containing seed layer on the metallic barrier layer within the recessed line pattern;   forming a copper-containing layer on the copper-containing seed layer, wherein the copper-containing seed layer and the copper-containing layer constitutes a metal line;   forming a copper-manganese alloy cap layer above the metal line, wherein the copper-manganese alloy cap layer comprises a manganese concentration ranging from about 1 ppm to about 50 atomic percent;   diffusing manganese from the copper-manganese alloy cap layer to the metal line; and   increasing the grain size within the metal line such that one or more grain boundaries extend across a width and a height of the metal line.   
     
     
         29 . The method of  claim 28 , wherein diffusing manganese from the copper-manganese alloy cap layer to the metal line comprises:
 annealing the metal line and the copper-manganese alloy cap layer at a temperature ranging from about 20° C. to about 400° C. for a time period from about 1 second to about 1 week, wherein grain size within the metal line increases during the annealing.   
     
     
         30 . The method of  claim 28 , wherein increasing the grain size within the metal line such that one or more grain boundaries extend across the width and the height of the metal line comprises:
 increasing grain size within the metal line such that a width of a grain is equal to the width of the metal line.   
     
     
         31 . The method of  claim 28 , wherein increasing the grain size within the metal line such that one or more grain boundaries extend across the width and the height of the metal line comprises:
 increasing grain size within the metal line such that a width and a height of a grain are equal to the width and the height of the metal line, respectively.   
     
     
         32 . The method of  claim 28 , wherein increasing the grain size within the metal line such that one or more grain boundaries extend across the width and the height of the metal line comprises:
 increasing grain size within the metal line such that each grain boundary is separated from any other grain boundary by a distance equal to or greater than the width of the metal line.   
     
     
         33 . The method of  claim 28 , wherein increasing the grain size within the metal line such that one or more grain boundaries extend across the width and the height of the metal line comprises:
 forming a bamboo microstructure.   
     
     
         34 . The method of  claim 28 , wherein diffusing manganese from the copper-manganese alloy cap layer to the metal line comprises:
 forming a high concentration of manganese along one or more interfaces as compared to the entire metal line, the interfaces being between the metal line and the cap layer, and between the metal line and the metallic barrier layer.   
     
     
         35 . A structure comprising:
 a dielectric material layer containing a recessed line pattern;   a metallic barrier layer abutting the dielectric material layer within the recessed line pattern; and   a copper-manganese alloy line abutting the metallic barrier layer within the recessed line pattern and having an atomic concentration of manganese ranging from about 1 ppm to about 10 atomic percent, the copper-manganese alloy line comprising one or more grain boundaries extending across a width and a height of the copper-manganese alloy line.   
     
     
         36 . The structure of  claim 35 , wherein the copper-manganese alloy line has a bamboo microstructure, wherein the one or more grain boundaries extends from a top surface of the copper-manganese alloy line to a bottom surface of the copper-manganese alloy line, and is separated from any other grain boundary by a distance greater than the width of the copper-manganese alloy line. 
     
     
         37 . The structure of  claim 35 , wherein a width of a grain is equal to the width of the copper-manganese alloy line. 
     
     
         38 . The structure of  claim 35 , wherein a width and a height of a grain is equal to the width and the height of the copper-manganese alloy line. 
     
     
         39 . The structure of  claim 35 , wherein the copper-manganese alloy line comprises oxygen (O), nitrogen (N), carbon (C), chlorine (Cl) , and sulfur (S), a sum of concentrations of which ranges from about 1 ppm to about 200 ppm. 
     
     
         40 . The structure of  claim 35 , wherein the copper-manganese alloy line comprises a manganese concentration ranging from about 10 ppm to about 2 atomic percent. 
     
     
         41 . The structure of  claim 35 , wherein a top surface of the copper-manganese alloy line is substantially coplanar with a top surface of the dielectric material layer. 
     
     
         42 . The structure of  claim 35 , further comprising:
 a copper-manganese alloy via of integral construction with the copper-manganese alloy line, and free of any grain boundary perpendicular to a substrate.   
     
     
         43 . The structure of  claim 42 , wherein the metallic barrier layer is of unitary construction and abuts and lines the copper-manganese alloy via. 
     
     
         44 . The structure of  claim 35 , further comprising:
 a copper-manganese alloy cap containing a manganese concentration ranging from about 1 ppm to about 50 atomic percent and abutting the copper-containing layer.   
     
     
         45 . The structure of  claim 35 , wherein the copper-manganese alloy line comprises a higher concentration of manganese along one or more interfaces, the interfaces being between the copper-manganese alloy line and a cap layer, and between the copper-manganese alloy line and the metallic barrier layer.