Metal gate structure and manufacturing method thereof

Abstract

A method for manufacturing a metal gate structure includes providing a substrate having a high-K gate dielectric layer and a bottom barrier layer sequentially formed thereon, forming a work function metal layer on the substrate, and performing an anneal treatment to the work function metal layer in-situ.

What is claimed is: 
     
         1 . A metal gate structure comprising:
 a high-K gate dielectric layer;   a bottom barrier layer formed on the high-K gate dielectric layer;   a titanium tri-aluminide (TiAl 3 ) work function metal layer formed on the bottom barrier layer;   a top barrier layer formed on the TiAl 3  layer; and   a low-resistance metal layer formed on the top barrier layer.   
     
     
         2 . The metal gate structure according to  claim 1 , wherein the bottom barrier layer comprises titanium nitride (TiN). 
     
     
         3 . The metal gate structure according to  claim 1 , wherein the bottom barrier layer comprises titanium nitride or tantalum nitride (TaN). 
     
     
         4 . The metal gate structure according to  claim 1 , wherein the top barrier layer comprises titanium nitride or titanium oxynitride (TiON). 
     
     
         5 . The metal gate structure according to  claim 1 , wherein the high-K gate dielectric layer comprises materials selected from the group consisting of hafnium oxide (HfO 2 ), hafnium silicon oxide (HfSiO 4 ), hafnium silicon oxynitride (HfSiON), aluminum oxide (Al 2 O 3 ), lanthanum oxide (La 2 O 3 ), tantalum oxide (Ta 2 O 5 ), yttrium oxide (Y 2 O 3 ), zirconium oxide (ZrO 2 ), strontium titanate oxide (SrTiO 3 ), zirconium silicon oxide (ZrSiO 4 ), and hafnium zirconium oxide (HfZrO 4 ). 
     
     
         6 . The metal gate structure according to  claim 1 , wherein the low-resistance metal layer comprises aluminum (Al). 
     
     
         7 . The metal gate structure according to  claim 1 , wherein cross-sectional views of the high-K gate dielectric layer, the bottom barrier layer, the TiAl 3  layer, and the top barrier layer comprise a U-shape. 
     
     
         8 . The metal gate structure according to  claim 1 , wherein cross-sectional views of the TiAl 3  layer and the top barrier layer comprise a U-shape.