Ultra-Low Resistivity Contacts

Abstract

Contacts for semiconductor devices and methods of making thereof are disclosed. A method comprises forming a first layer on a semiconductor, the first layer comprising one or more metals; forming a second layer on the first layer, the second layer comprising the one or more metals, nitrogen and oxygen; and heating the first and second layer such that oxygen migrates from the second layer into the first layer and the first layer comprises a sub-stoichiometric metal oxide after heating. Exemplary embodiments use transition metals such as Ti in the first layer. After heating there is a sub-stoichiometric oxide layer of about 2.5 nm thickness between a metal nitride conductor and the semiconductor. The specific contact resistivity is less than about 7×10 −9 Ω·cm 2 .

What is claimed is: 
     
         1 . A method of fabricating a contact test structure, the method comprising
 designating a plurality of site-isolated regions on a substrate,
 each of the plurality of site-isolated regions comprising a semiconductor; 
   forming a first layer on the semiconductor in each of the plurality of site-isolated regions, the first layer comprising one or more metals;   forming a second layer on the first layer in each of the plurality of site-isolated regions,
 the second layer comprising the one or more metals and at least one of nitrogen or oxygen; and 
   heating the first layer and the second layer in each of the plurality of site-isolated regions,
 wherein at least one of forming the first layer, forming the second layer, or 
   heating the first layer and the second layer is varied in a combinatorial manner among the plurality of site-isolated regions.   
     
     
         2 . The method of  claim 1 , wherein the at least one of forming the first layer, forming the second layer, or heating the first layer and the second layer is varied in the combinatorial manner by varying one of sputtering target composition, sputtering power, sputtering pressure, sputtering atmosphere composition, sputtering time, precursor composition, precursor gas flow rates, substrate temperature, substrate bias, chamber pressure, processing time per cycle, number of deposition cycles, or precursor gas. 
     
     
         3 . The method of  claim 2 , further comprising characterizing the first layer and the second layer by measuring one or more parameters of the first layer and the second layer in each of the plurality of site-isolated regions and determining an effect of varying in the combinatorial manner the one of sputtering target composition, sputtering power, sputtering pressure, sputtering atmosphere composition, sputtering time, precursor composition, precursor gas flow rates, substrate temperature, substrate bias, chamber pressure, processing time per cycle, number of deposition cycles, or precursor gas. 
     
     
         4 . The method of  claim 3 , wherein the one or more parameters comprises one or more of crystallinity, grain size (distribution), lattice parameter, crystal orientation (distribution), matrix and minority composition, bandgap, carrier concentration, mobility, minority carrier lifetime, surface roughness, adhesion, thermal expansion coefficient, elemental composition, or thickness. 
     
     
         5 . The method of  claim 1 , further comprising measuring a specific contact resistivity for the contact test structure in each of the plurality of site-isolated regions. 
     
     
         6 . The method of  claim 1 , wherein the semiconductor comprises one of Si, SiC, Ge, or SiGe. 
     
     
         7 . The method of  claim 1 , wherein the semiconductor comprises n-doped silicon. 
     
     
         8 . The method of  claim 1 , wherein the semiconductor comprises a III-V semiconductor. 
     
     
         9 . The method of  claim 1 , wherein the one or more metals comprise one of titanium or zinc. 
     
     
         10 . The method of  claim 1 , wherein heating the first layer and the second layer is performed in an oxygen-free atmosphere. 
     
     
         11 . The method of  claim 1 , wherein a ratio of oxygen atoms to nitrogen atoms in the second layer is about 1:10 prior to heating. 
     
     
         12 . The method of  claim 1 , wherein a thickness of the first layer is between about 1 nm and about 3 nm prior to heating. 
     
     
         13 . The method of  claim 1 , wherein a thickness of the first layer is about 2.5 nm prior to heating. 
     
     
         14 . The method of  claim 1 , wherein a thickness of the second layer is between about 2 nm and about 5 nm prior to heating. 
     
     
         15 . The method of  claim 1 , wherein the first layer and the second layer are formed using one of physical vapor deposition, atomic layer deposition, chemical vapor deposition, or plasma enhanced variations thereof. 
     
     
         16 . The method of  claim 1 , wherein at least forming the first layer is varied in the combinatorial manner among the plurality of site-isolated regions. 
     
     
         17 . The method of  claim 1 , wherein at least forming the second layer is varied in the combinatorial manner among the plurality of site-isolated regions. 
     
     
         18 . The method of  claim 1 , wherein at least heating the first layer and the second layer is varied in the combinatorial manner among the plurality of site-isolated regions. 
     
     
         19 . The method of  claim 1 , wherein forming the first layer, forming the second layer, and heating the first layer and the second layer are all varied in the combinatorial manner among the plurality of site-isolated regions. 
     
     
         20 . The method of  claim 1 , wherein the first layer comprises a sub-stoichiometric oxide of a metal, and wherein the second layer comprises a nitride of the metal.