Electrical coupling stack and processes for making same

Abstract

A process of making an electrical coupling stack is disclosed. A conductive structure is coupled to a substrate. The coupling includes a crystalline salicide first structure above the conductive structure, a nitrogen-containing amorphous salicide second structure above the crystalline salicide first structure, and a refractory metal third film above the nitrogen-containing amorphous salicide second structure. Processing includes depositing a refractory metal silicide first film over the conductive structure, depositing a refractory metal nitride second film over the refractory metal silicide first film, and depositing the refractory metal third film over the refractory metal nitride second film. Thermal processing is carried out to achieve the electrical coupling stack.

1 . An electrical coupling stack comprising: 
 a conductive structure coupled to a substrate, wherein the conductive structure includes a characteristic dimension;    a crystalline salicide first structure above the conductive structure;    an amorphous salicide second structure above the crystalline salicide first structure; and    a refractory metal third film above the amorphous salicide second structure, wherein the refractory metal third film includes an average grain size that is in a range from about one-twentieth the conductive structure characteristic dimension to larger than the conductive plug characteristic dimension.    
   
   
       2 . The electrical coupling stack according to  claim 1 , wherein the conductive structure characteristic dimension is in a range from about a 0.25 micron geometry to about a 0.01 micron geometry.  
   
   
       3 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a source/drain (S/D) structure of a substrate active area, wherein the S/D structure has a depth from about 200 Å to about 2,000 Å, wherein the crystalline salicide first structure has a thickness from about 30 Å to about 300 Å, wherein the amorphous salicide second structure has a thickness from about 50 Å to about 500 Å, and wherein the refractory metal third film has a thickness from about 50 Å to about 3,000 Å.  
   
   
       4 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a source/drain (S/D) structure of a substrate active area, wherein the S/D structure has a depth of about 1,200 Å wherein the crystalline salicide first structure has a thickness of about 80 Å, wherein the amorphous salicide second structure has a thickness of about 130 Å, and wherein the refractory metal third film has a thickness of about 450 Å.  
   
   
       5 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a source/drain (S/D) structure of a substrate active area wherein the refractory metal third film includes a resistivity in a range from about 0.1 Ω/sq to about 300 Ω/sq.  
   
   
       6 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a polysilicon plug over a substrate active area, wherein the crystalline salicide first structure has a thickness from about 30 Å to about 300 Å, wherein the amorphous salicide second structure has a thickness from about 50 Å to about 500 Å, and wherein the refractory metal third film has a thickness from about 50 Å to about 3,000 Å.  
   
   
       7 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a polysilicon plug over a substrate active area, wherein the crystalline salicide first structure has a thickness of about 80 Å, wherein the amorphous salicide second structure has a thickness of about 130 Å, and wherein the refractory metal third film has a thickness of about 450 Å.  
   
   
       8 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a polysilicon plug over a substrate active area, wherein the crystalline salicide first structure has a thickness of about 215 Å, wherein the amorphous salicide second structure has a thickness of about 90 Å, and wherein the refractory metal third film has a thickness of about 380 Å.  
   
   
       9 . The electrical coupling stack according to  claim 1 , wherein the conductive structure includes a polysilicon plug over a substrate active area wherein the refractory metal third film includes a resistivity in a range from about 0.1 Ω/sq to about 300 Ω/sq.  
   
   
       10 . The electrical coupling stack structure according to  claim 1 , wherein the crystalline salicide first structure is MSi 2 , wherein M is selected from Ta, W, Mo, Hf, Ti, TaTi z , WTi z , MoTi z , HfTi z , Ta x W, Ta y Ti z W, Ta x Mo, Ta y Ti z Mo, Ta x Hf, Ta y Ti z Hf, WTi x , W x Mo, W y Ti z Mo, W x Hf, W y Ti z Hf, Mo x Hf, Mo y Ti z Hf, and HfTi z , wherein 0.2≦x≦0.99, wherein 0.2≦y≦0.9, and wherein 0.01≦z≦0.8.  
   
   
       11 . The electrical coupling stack structure according to  claim 1 , wherein the crystalline salicide first structure is approximately TaSi 2 , wherein the amorphous salicide second structure is nitrogen-containing TaSi x , wherein 0.1≦x≦2.  
   
   
       12 . A computer system, comprising: 
 a processor;    a memory system coupled to the processor;    an input/output (I/O) circuit coupled to the processor and the memory system; and    at least one of a buried digit line structure or a source/drain contact stack structure, disposed in the processor or the memory system, including: 
 a conductive structure coupled to a substrate, wherein the conductive structure includes a characteristic dimension;  
 a crystalline salicide first structure above the conductive structure;  
 a nitrogen-containing amorphous salicide second structure above the crystalline salicide first structure; and  
 a refractory metal third film above the nitrogen-containing amorphous salicide second structure, wherein the refractory metal third film includes an average grain size that is in a range from about one-twentieth the conductive plug characteristic dimension to larger than the conductive plug characteristic dimension.  
   
   
   
       13 . The computer system according to  claim 12 , wherein the processor is disposed in a host selected from a clock, a television, a cell phone, a personal computer, an automobile, an industrial control system, an aircraft, and a hand-held.  
   
   
       14 . The computer system according to  claim 12 , wherein the memory system is disposed in a host selected from a clock, a television, a cell phone, a personal computer, an automobile, an industrial control system, an aircraft, and a hand-held.  
   
   
       15 . The computer system according to  claim 12 , wherein the refractory metal third film includes a resistivity in a range from about 0.1 Ω/sq to about 300 Ω/sq.  
   
   
       16 . An electrical coupling stack comprising: 
 a semiconductor substrate having a first conductivity type and at least two diffused regions having a second conductivity type;    a conductive structure electrically coupled to at least one of the at least two diffused regions and the semiconductor substrate, the conductive structure including silicon;    a self aligned crystalline structure disposed above and in electrical contact with the conductive structure, the crystalline structure including a metal;    a self aligned amorphous structure disposed above and in electrical contact with the self aligned crystalline structure, the self aligned amorphous structure including nitrogen;    an amorphous refractory metal nitride layer disposed above and in electrical contact with the self aligned amorphous structure, the amorphous refractory metal nitride layer including portions annexed to the self aligned amorphous structure;    a transition layer disposed above and in electrical contact with the amorphous refractory metal nitride layer, the transition layer including at least one of a metal-eutectic transition layer, a metal-alloy transition layer, a graded nitrogen-metal transition layer and a metal-metal transition layer;    a refractory metal layer disposed above and in electrical contact with the transition layer; and    a dielectric layer disposed above the refractory metal layer, the dielectric layer including at least one electrical contact opening extending from a top surface of the dielectric layer to the refractory metal layer.    
   
   
       17 . The electrical coupling stack of  claim 16 , further comprising a titanium layer disposed on a sidewall of the at least one electrical contact opening, and on a portion of a top surface of the refractory metal layer exposed by the at least one electrical contact opening.  
   
   
       18 . The electrical coupling stack of  claim 16 , further comprising a titanium nitride layer disposed on a sidewall of the at least one electrical contact opening, and on a portion of a top surface of the refractory metal layer exposed by the at least one electrical contact opening.  
   
   
       19 . The electrical coupling stack of  claim 16 , further the conductive structure comprising polysilicon.  
   
   
       20 . The electrical coupling stack of  claim 16 , further the semiconductor substrate comprising single crystal silicon.  
   
   
       21 . The electrical coupling stack of  claim 16 , further the refractory metal layer comprising one or more materials selected from the list including W, Ta, Ti, Mo, TaW, TaWTi, TaMo, TaMoTi, TaHfTi, WTi, WMo, WMoTi, WHfTi, MoTi, MoHf, MoHfTi, and HfTi.  
   
   
       22 . The electrical coupling stack of  claim 21 , further the refractory metal layer comprising an average grain size that is in a range from about one-twentieth of a size of the conductive structure to about the size of the conductive structure.  
   
   
       23 . The electrical coupling stack of  claim 16 , further the self aligned crystalline structure comprising a metal silicide.  
   
   
       24 . The electrical coupling stack of  claim 23 , further the metal silicide comprising one or more metals selected from the list including Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, Rh, Ir, Ni, Pd, and Pt.  
   
   
       25 . The electrical coupling stack of  claim 23 , further the metal silicide comprising a formula MSi2, where M comprises one or more metals selected from the list including Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, Rh, r, Ni, Pd, and Pt.  
   
   
       26 . The electrical coupling stack of  claim 16 , further the self aligned amorphous structure comprising a nitrogen containing metal silicide having a formula MSixNy, where M comprises one or more metals selected from the list including Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, Rh, Ir, Ni, Pd, and Pt, where 0.2≦x≦2.0, and 0.01≦y≦1.0.  
   
   
       27 . The electrical coupling stack of  claim 26 , further the self aligned amorphous structure comprising TaSixNy, where 0.2≦x≦2.0, and 0.01≦y≦1.0.  
   
   
       28 . The electrical coupling stack of  claim 16 , further the amorphous refractory metal nitride layer is substantially consumed by the self aligned amorphous structure and the transition layer, and is substantially a discontinuous layer forming isolated islands.