Methods of Fabricating a Barrier Layer Over Interconnect Structures in Atomic Deposition Environments

Abstract

Methods of depositing a barrier layer on an interconnect structure in an atomic deposition environment are provided. One method includes depositing a barrier layer on the interconnect structure with a first nitrogen concentration during a first phase of deposition in the atomic deposition environment, The interconnect structure is formed in a dielectric layer. Then, continuing the deposition of the barrier layer on the interconnect structure with a second nitrogen concentration during a second phase deposition in the atomic deposition environment. The nitrogen concentration step-wisely decreases from the first nitrogen concentration in the first phase of the barrier layer to the second nitrogen concentration in the second phase of the barrier layer, and the first nitrogen concentration is highest where the barrier layer is in contact with the dielectric layer. A copper layer is then formed over the barrier layer, such that a nitrogen concentration in the barrier layer is lowest where the barrier layer is in contact with the copper layer.

What is claimed is: 
     
         1 . A method of depositing a barrier layer on an interconnect structure in an atomic deposition environment, comprising:
 (a) depositing a barrier layer on the interconnect structure with a first nitrogen concentration during a first phase of deposition in the atomic deposition environment, the interconnect structure being formed in a dielectric layer; and   (b) continuing the deposition of the barrier layer on the interconnect structure with a second nitrogen concentration during a second phase deposition in the atomic deposition environment, wherein the nitrogen concentration step-wisely decreases from the first nitrogen concentration in the first phase of the barrier layer to the second nitrogen concentration in the second phase of the barrier layer, and the first nitrogen concentration is highest where the barrier layer is in contact with the dielectric layer; and   (c) forming copper layer over the barrier layer, such that a nitrogen concentration in the barrier layer is lowest where the barrier layer is in contact with the copper layer.   
     
     
         2 . The method of  claim 1 , wherein step (b) continues until a target thickness for the barrier layer is reached, and then step (c) is performed. 
     
     
         3 . The method of  claim 1 , wherein the copper layer defines at least part of an interconnect structure formed over the barrier layer. 
     
     
         4 . The method of  claim 1 , wherein the barrier layer is formed by sequentially pulsing a barrier metal precursor and a nitrogen precursor on the interconnect structure. 
     
     
         5 . The method of  claim 4 , wherein after each pulse of barrier metal precursor and after each nitrogen precursor there is a pulse of a purging gas. 
     
     
         6 . The method of  claim 4 , wherein the nitrogen precursor is plasmarized. 
     
     
         7 . The method of  claim 5 , wherein the purging gas is plasmarized. 
     
     
         8 . The method of  claim 1 , wherein the thickness of the barrier layer is between about 10 angstroms to about 50 angstroms. 
     
     
         9 . The method of  claim 1 , wherein the deposition process temperature is between about 100° C. to about 400° C. 
     
     
         10 . The method of  claim 1 , wherein the barrier metal in the barrier layer is selected from the group consisting of tantalum (Ta), titanium (Ti), tungsten (W), zirconium (Zr), hafnium (Hf), molybdenum (Mo), niobium (Nb), vanadium (V), ruthenium (Ru) and chromium (Cr). 
     
     
         11 . The method of  claim 10 , wherein the barrier metal precursor is one of pentaethylmethylamino-tantalum (PEMAT), pentadiethylamino-tantalum (PDEAT), pentadimethylamino-tantalum (PDMAT), tertbutylimido-tris(diethylamido)-tantalum (TBTDET), tertbutylimido-tris(dimethylamido)-tantalum (TBTDMT), tertbutylimido-tris(ethylmethylamido)-tantalum (TBTEMT), and tantalum halides TaX 5 , wherein X is fluorine (F), bromine (Br) or chlorine (Cl), and any and all derivatives thereof. 
     
     
         12 . The method of  claim 5 , wherein purging gas is one of helium (He), neon (Ne), argon (Ar), hydrogen (H 2 ), nitrogen (N 2 ), and combinations thereof. 
     
     
         13 . The method of  claim 5 , wherein the nitrogen precursor is one of ammonia (NH 3 ), N 2 , NO, and N x H y , wherein x and y are integers. 
     
     
         14 . A method of depositing a barrier layer in an atomic deposition environment, comprising
 (a) providing a first interconnect structure defined in a first dielectric layer;   (b) forming a second dielectric layer over the first interconnect structure;   (c) forming a trench and a via hole in the second dielectric layer, the via providing an exposed region through the second dielectric layer and to a surface of the first interconnect structure;   (d) depositing a barrier layer in the trench and via and in the exposed region of the first interconnect structure, the depositing being with a first nitrogen concentration during a first phase of deposition in the atomic deposition environment; and   (e) continuing the deposition of the barrier layer with a second nitrogen concentration during a second phase deposition in the atomic deposition environment, wherein the nitrogen concentration step-wisely decreases from the first nitrogen concentration in the first phase to the second nitrogen concentration in the second phase, and the first nitrogen concentration is highest where the barrier layer is in contact with the second dielectric layer; and   (f) forming copper layer over the barrier layer, such that a nitrogen concentration in the barrier layer is lowest where the barrier layer is in contact with the copper layer.   
     
     
         15 . A method of depositing a barrier layer as recited in  claim 14 , wherein the copper layer substantially fills the trench and the via. 
     
     
         16 . A method of depositing a barrier layer as recited in  claim 14 , wherein the barrier layer defines a coating over the second dielectric layer, in walls of the trench and in the via. 
     
     
         17 . A method of depositing a barrier layer as recited in  claim 14 , wherein step (e) continues until a target thickness for the barrier layer is reached, and then step (f) is performed. 
     
     
         18 . A method of depositing a barrier layer as recited in  claim 14 , wherein the barrier layer is formed by sequentially pulsing a barrier metal precursor and a nitrogen precursor on the interconnect structure. 
     
     
         19 . A method of depositing a barrier layer as recited in  claim 14 , wherein the thickness of the barrier layer is between about 10 angstroms to about 50 angstroms, and a deposition process temperature is between about 100° C. to about 400° C. 
     
     
         20 . A method of depositing a barrier layer as recited in  claim 18 , wherein
 the barrier metal in the barrier layer is selected from the group consisting of tantalum (Ta), titanium (Ti), tungsten (W), zirconium (Zr), hafnium (Hf), molybdenum (Mo), niobium (Nb), vanadium (V), ruthenium (Ru) and chromium (Cr);   the barrier metal precursor is one of pentaethylmethylamino-tantalum (PEMAT), pentadiethylamino-tantalum (PDEAT), pentadimethylamino-tantalum (PDMAT), tertbutylimido-tris(diethylamido)-tantalum (TBTDET), tertbutylimido-tris(dimethylamido)-tantalum (TBTDMT), tertbutylimido-tris(ethylmethylamido)-tantalum (TBTEMT), and tantalum halides TaX 5 , wherein X is fluorine (F), bromine (Br) or chlorine (Cl), and any and all derivatives thereof;   the purging gas is one of helium (He), neon (Ne), argon (Ar), hydrogen (H 2 ), nitrogen (N 2 ), and combinations thereof; and   the nitrogen precursor is one of ammonia (NH 3 ), N 2 , NO, and N x H y , wherein x and y are integers.