Method of forming thin metal and semi-metal layers by thermal remote oxygen scavenging

Abstract

Methods for forming thin metal and semi-metal layers by thermal remote oxygen scavenging are described. In one embodiment, the method includes forming an oxide layer containing a metal or a semi-metal on a substrate, where the semi-metal excludes silicon, forming a diffusion layer on the oxide layer, forming an oxygen scavenging layer on the diffusion layer, and performing an anneal that reduces the oxide layer to a corresponding metal or semi-metal layer by oxygen diffusion from the oxide layer to the oxygen scavenging layer.

What is claimed is: 
     
         1 . A method of processing a substrate, comprising:
 forming an oxide layer containing a metal or a semi-metal on the substrate, where the semi-metal excludes silicon;   forming a diffusion layer on the oxide layer;   forming an oxygen scavenging layer on the diffusion layer; and   performing an anneal that reduces the oxide layer to a corresponding metal or semi-metal layer by oxygen diffusion from the oxide layer to the oxygen scavenging layer.   
     
     
         2 . The method of  claim 1 , wherein the oxygen-scavenging layer contains a chemical element with higher reducing capability than the metal or semi-metal of the oxide layer. 
     
     
         3 . The method of  claim 1 , wherein the diffusion layer contains a buffer layer, a cap layer, or a laminate containing a buffer layer and a cap layer. 
     
     
         4 . The method of  claim 3 , wherein the buffer layer contains a high-k oxide, a high-k nitride, a high-k oxynitride, or a high-k silicate, or a combination thereof. 
     
     
         5 . The method of  claim 4 , wherein the high-k oxide contains HfO 2 , ZrO 2 , or a combination thereof. 
     
     
         6 . The method of  claim 5 , wherein the high-k oxide is doped with a rare earth metal element or an alkali earth metal element. 
     
     
         7 . The method of  claim 4 , wherein the buffer layer contains an oxide, nitride, oxynitride, or titanate layer containing one or more elements selected from alkali earth metals and rare earth metals. 
     
     
         8 . The method of  claim 3 , wherein the cap layer contains a metal nitride layer, a metal carbide layer, or a metal carbonitride layer, or a combination thereof. 
     
     
         9 . The method of  claim 1 , wherein the diffusion layer contains a buffer layer that abuts the oxide layer, and a cap layer that abuts the buffer layer. 
     
     
         10 . The method of  claim 1 , wherein the oxide layer contains Ti, Ta, Nb, Ni, Pd, Pt, Fe, Ru, Os, Co, Rh, or Ir, or a combination thereof. 
     
     
         11 . The method of  claim 1 , wherein the oxygen-scavenging layer contains Sc, Zr, Hf, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, or a combination thereof. 
     
     
         12 . The method of  claim 1 , wherein the oxide layer contains a non-stoichiometric metal oxide or semi-metal oxide layer. 
     
     
         13 . The method of  claim 1 , wherein the oxide layer contains TiO 2  and the diffusion layer contains 1) at least one of HfO 2  and ZrO 2  that abut the oxide layer and 2) a TiN layer that abuts the oxygen scavenging layer. 
     
     
         14 . The method of  claim 1 , further comprising:
 following the performing an anneal that reduces the oxide layer, removing the diffusion layer and the oxygen scavenging layer from the substrate.   
     
     
         15 . A method of processing a substrate, comprising:
 forming a TiO 2  layer on the substrate;   forming a diffusion layer on the TiO 2  layer, the diffusion layer containing a high-k layer abutting the TiO 2  layer and a TiN layer abutting the high-k layer;   forming an oxygen scavenging layer on the diffusion layer; and   performing an anneal that reduces the TiO 2  layer to a Ti layer by oxygen diffusion from the TiO 2  layer to the oxygen scavenging layer.   
     
     
         16 . The method of  claim 15 , wherein the oxygen-scavenging layer contains a chemical element with higher reducing capability than Ti. 
     
     
         17 . The method of  claim 15 , further comprising:
 following the performing an anneal that reduces the TiO 2  layer, removing the diffusion layer and the oxygen scavenging layer.   
     
     
         18 . The method of  claim 15 , wherein the oxygen-scavenging layer contains Zr, Hf, Al, or Li, or a combination thereof. 
     
     
         19 . The method of  claim 15 , wherein the diffusion layer includes a high-k layer containing at least one of HfO 2  and ZrO 2  that abuts the oxide layer and a crystalline or a polycrystalline TiN layer that abuts the high-k layer. 
     
     
         20 . A method of processing a substrate, comprising:
 forming an oxide layer containing a metal or a semimetal on the substrate, where the semi-metal excludes silicon;   forming a diffusion layer on the oxide layer;   forming an oxygen scavenging layer on the diffusion layer; and   performing an anneal that partially reduces the oxide layer by oxygen diffusion from the oxide layer to the oxygen scavenging layer.