Enhanced copper growth with ultrathin barrier layer for high performance interconnects

Abstract

A method for depositing a refractory metal nitride barrier layer having a thickness of about 20 angstroms or less is provided. In one aspect, the refractory metal nitride layer is formed by introducing a pulse of a metal-containing compound followed by a pulse of a nitrogen-containing compound. The refractory metal nitride barrier layer provides adequate barrier properties and allows the grain growth of the first metal layer to continue across the barrier layer into the second metal layer thereby enhancing the electrical performance of the interconnect.

1 . A method for forming a refractory metal nitride layer, comprising: 
 alternately pulsing a metal-containing compound and a nitrogen-containing compound until a refractory metal nitride layer having a thickness that exhibits a crystalline like structure and is sufficient to inhibit atomic migration is deposited over at least a portion of a substrate surface.    
     
     
         2 . The method of  claim 1 , wherein the refractory metal nitride layer comprises tantalum nitride.  
     
     
         3 . The method of  claim 1 , wherein the pulsing occurs at a pressure between about 1 and about 5 Torr at a temperature between about 200° C. and about 300° C.  
     
     
         4 . The method of  claim 1 , wherein each pulse is repeated until the refractory metal nitride layer has a thickness less than about 20 angstroms.  
     
     
         5 . The method of  claim 1 , wherein each pulse is repeated until the refractory metal nitride layer has a thickness of about 10 angstroms.  
     
     
         6 . The method of  claim 1 , wherein the refractory metal nitride layer has a thickness of about 10 angstroms.  
     
     
         7 . The method of  claim 1 , wherein the alternately pulsing is repeated between about 10 and about 70 times to form the refractory metal nitride layer.  
     
     
         8 . The method of  claim 1 , further comprising flowing a non-reactive gas continuously during each pulse of the metal-containing compound and each pulse of the nitrogen-containing compound.  
     
     
         9 . The method of  claim 8 , wherein the non-reactive gas comprises argon, nitrogen, helium, or a combination thereof.  
     
     
         10 . The method of  claim 8 , wherein the non-reactive gas has a flowrate of about 200 sccm to about 1,000 sccm.  
     
     
         11 . The method of  claim 1 , wherein each pulse of the metal-containing compound has a flow rate of about 100 sccm to about 1,000 sccm.  
     
     
         12 . The method of  claim 1 , wherein each pulse of the nitrogen-containing compound has a flow rate of about 100 sccm to about 1,000 sccm.  
     
     
         13 . The method of  claim 1 , wherein each pulse of the metal-containing compound and the nitrogen-containing is separated by a time delay.  
     
     
         14 . The method of  claim 13 , wherein each time delay is sufficient for a volume of the metal-containing compound or a volume of the nitrogen-containing compound to adsorb onto the substrate surface.  
     
     
         15  The method of  claim 14 , wherein the time delay is sufficient to remove any non-adsorbed molecules from the substrate surface.  
     
     
         16 . The method of  claim 1 , wherein the nitrogen-containing compound is selected from a group consisting of nitrogen gas, ammonia, hydrazine, methylhydrazine, dimethlyhydrazine, t-butylhydrazine, phenylhydrazine, azoisobutane, ethylazide, and derivatives thereof, and combinations thereof.  
     
     
         17 . The method of  claim 1 , wherein the metal-containing compound is selected from a group consisting of pentaethyl methylamino-tantalum (PEMAT), pentadiethylamino-tantalum (PDEAT), pentadimethylamino-tantalum (PDMAT), t-butylimino tris(diethylamino) tantalum (TBTDET), t-butylimino tris(dimethylamino) tantalum (TBTDMT), bis(cyclopentadienyl) tantalum trihydride, bis (methylcyclopentadienyl) tantalum trihydride, tantalum fluoride, tantalum bromide, tantalum chloride, derivatives thereof, and combinations thereof.  
     
     
         18 . A method for forming a refractory metal nitride layer, comprising: 
 alternately pulsing a metal-containing compound, a silicon-containing compound, and a nitrogen-containing compound until a refractory metal silicon nitride layer having a thickness less than about 20 angstroms is deposited over at least a portion of a substrate surface.    
     
     
         19 . The method of  claim 18 , wherein the refractory metal silicon nitride layer comprises titanium silicon nitride.  
     
     
         20 . The method of  claim 18 , wherein the pulsing occurs at a pressure of about 2 Torr and a temperature of about 250° C.  
     
     
         21 . The method of  claim 18 , wherein each pulse is repeated until the refractory metal silicon nitride layer has a maximum thickness that still exhibits a crystalline like structure.  
     
     
         22 . The method of  claim 18 , wherein each pulse is repeated until the refractory metal nitride layer has a thickness of about 10 angstroms.  
     
     
         23 . The method of  claim 18 , wherein the refractory metal silicon nitride layer has a thickness of about 10 angstroms.  
     
     
         24 . The method of  claim 18 , wherein the alternately pulsing is repeated between about 10 and about 70 times to form the 20 angstrom refractory metal silicon nitride layer.  
     
     
         25 . The method of  claim 18 , further comprising flowing a non-reactive gas continuously during each pulse of the metal-containing compound, each pulse of the silicon-containing compound, and each pulse of the nitrogen-containing compound.  
     
     
         26 . The method of  claim 25 , wherein the non-reactive gas comprises argon.  
     
     
         27 . The method of  claim 25 , wherein the non-reactive gas has a flowrate of about 100 sccm to about 1,000 sccm.  
     
     
         28 . The method of  claim 1 , wherein each pulse of the metal-containing compound, each pulse of the silicon-containing compound, and each pulse of the nitrogen-containing is separated by a time delay.  
     
     
         29 . The method of  claim 28 , wherein each time delay is sufficient for a volume of the metal-containing compound, a volume of the silicon-containing compound, or a volume of the nitrogen-containing compound to adsorb onto the substrate surface.  
     
     
         30  The method of  claim 29 , wherein the time delay is sufficient to remove any non-adsorbed molecules from the substrate surface.  
     
     
         31 . The method of  claim 18 , wherein the nitrogen-containing compound is selected from a group consisting of nitrogen gas, ammonia, hydrazine, methylhydrazine, dimethlyhydrazine, t-butylhydrazine, phenylhydrazine, azoisobutane, ethylazide, and derivatives thereof, and combinations thereof.  
     
     
         32 . The method of  claim 18 , wherein the metal-containing compound is selected from a group consisting of tetrakis (dimethylamino) titanium (TDMAT), tetrakis (ethylmethylamino) titanium (TEMAT), tetrakis (diethylamino) titanium (TDEAT), titanium tetrachloride (TiCl 4 ), titanium iodide (Til 4 ), titanium bromide (TiBr 4 ), and combinations thereof.  
     
     
         33 . The method of  claim 18 , wherein the silicon-containing compound is selected from a group consisting of silane, disilane, methylsilane, dimethylsilane, chlorosilane (SiH 3 Cl), dichlorosilane (SiH 2 Cl 2 ), trichlorosilane (SiHCl 3 ), and combinations thereof.  
     
     
         34 . A method for forming a metal interconnect on a substrate, comprising: 
 depositing a first metal layer on a substrate surface;    depositing a refractory metal nitride layer having a thickness less than about 20 angstroms over at least a portion of the first metal layer by alternately introducing one or more pulses of a metal-containing compound and one or more pulses of a nitrogen-containing compound; and    depositing a second metal layer over the refractory metal nitride layer.    
     
     
         35 . The method of  claim 34 , wherein the refractory metal nitride layer comprises tantalum nitride.  
     
     
         36 . The method of  claim 34 , wherein a grain growth of the first metal layer continues across the barrier layer into the second metal layer.  
     
     
         37 . The method of  claim 34 , wherein each pulse is repeated until the refractory metal nitride layer has a maximum thickness that still exhibits a crystalline like structure.  
     
     
         38 . The method of  claim 34 , wherein each pulse is repeated until the refractory metal nitride layer has a thickness of about 10 angstroms.  
     
     
         39 . The method of  claim 34 , wherein the refractory metal nitride layer has a thickness of about 10 angstroms.  
     
     
         40 . The method of  claim 34 , wherein the metal layers comprise copper, a copper alloy, or combinations thereof.  
     
     
         41 . The method of  claim 40 , wherein depositing the metal layers comprises first depositing a copper seed layer and then an electrochemical plating copper layer.  
     
     
         42 . The method of  claim 34 , further comprising chemical mechanical polishing the substrate surface after depositing each metal layer.  
     
     
         43 . The method of  claim 34 , further comprising reactively cleaning the substrate surface prior to depositing the barrier layer.  
     
     
         44 . The method of  claim 34 , further comprising flowing a carrier gas continuously during each pulse of the metal-containing compound and each pulse of the nitrogen-containing compound.  
     
     
         45 . The method of  claim 34 , wherein each pulse is separated by a time delay.  
     
     
         46 . The method of  claim 45 , wherein the time delay is sufficient to remove any non-adsorbed molecules from the substrate surface.  
     
     
         47 . The method of  claim 34 , further comprising sequentially introducing a silane-containing compound to deposit a ternary metal containing barrier layer.  
     
     
         48 . The method of  claim 47 , wherein the ternary metal containing barrier layer comprises titanium silicon nitride.