Method for fabricating a metal gate structure

Abstract

A metal gate structure is disclosed. The metal gate structure includes: a semiconductor substrate having an active region and an isolation region; an isolation structure disposed in the isolation region; a first gate structure disposed on the active region; and a second gate structure disposed on the isolation structure, wherein the height of the second gate structure is different from the height of the first gate structure.

1 . A metal gate structure, comprising:
 a semiconductor substrate having an active region and an isolation region;   an isolation structure disposed in the isolation region;   a first gate structure disposed in the active region; and   a second gate structure disposed on the isolation structure, wherein the height of the second gate structure is different from the height of the first gate structure.   
     
     
         2 . The metal gate structure of  claim 1 , wherein the isolation structure comprises a shallow trench isolation (STI) or a field oxide (FOX). 
     
     
         3 . The metal gate structure of  claim 1 , further comprising a first spacer around the first gate structure. 
     
     
         4 . The metal gate structure of  claim 1 , further comprising a second spacer around the second gate structure and above the isolation structure. 
     
     
         5 . The metal gate structure of  claim 1 , wherein the first gate structure comprises a first gate dielectric layer and a first metal layer. 
     
     
         6 . The metal gate structure of  claim 5 , wherein the first gate dielectric layer comprises a first dielectric material and a high-k dielectric material. 
     
     
         7 . The metal gate structure of  claim 5 , wherein the first metal layer comprises an N-type metal material or a P-type metal material. 
     
     
         8 . The metal gate structure of  claim 7 , wherein the N-type metal material comprises titanium aluminum nitride (TiAlN), tantalum carbide (TaC), tantalum nitride (TaN), or an arbitrary combination of titanium aluminum nitride (TiAlN), tantalum carbide (TaC), and tantalum nitride (TaN). 
     
     
         9 . The metal gate structure of  claim 7 , wherein the P-type metal material comprises titanium nitride (TiN), tungsten (W), tungsten nitride (WN), molybdenum nitride (MoN), molybdenum aluminum nitride (MoAlN), or an arbitrary combination of titanium nitride (TiN), tungsten (W), tungsten nitride (WN), molybdenum nitride (MoN), and molybdenum aluminum nitride (MoAlN). 
     
     
         10 . The metal gate structure of  claim 1 , wherein the second gate structure comprises a second gate dielectric layer and a second metal layer. 
     
     
         11 . The metal gate structure of  claim 10 , wherein the second gate dielectric layer comprises a dielectric material and a high-k dielectric material. 
     
     
         12 . The metal gate structure of  claim 10 , wherein the second metal layer comprises an N-type metal material or a P-type metal material. 
     
     
         13 . The metal gate structure of  claim 12 , wherein the N-type metal material comprises titanium aluminum nitride (TiAlN), tantalum carbide (TaC), tantalum nitride (TaN), or an arbitrary combination of titanium aluminum nitride (TiAlN), tantalum carbide (TaC), and tantalum nitride (TaN). 
     
     
         14 . The metal gate structure of  claim 12 , wherein the P-type metal material comprises titanium nitride (TiN), tungsten (W), tungsten nitride (WN), molybdenum nitride (MoN), molybdenum aluminum nitride (MoAlN), or an arbitrary combination of titanium nitride (TiN), tungsten (W), tungsten nitride (WN), molybdenum nitride (MoN), and molybdenum aluminum nitride (MoAlN).