Multi-layer gate dielectric

Abstract

A transistor gate dielectric including a first dielectric material having a first dielectric constant and a second dielectric material having a second dielectric constant different from the first dielectric constant.

What is claimed:  
     
         1 . A transistor gate dielectric comprising: 
 a first dielectric material having a first dielectric constant; and    a second dielectric material having a second dielectric constant different from the first dielectric constant.    
     
     
         2 . The transistor gate dielectric of    claim 1   , wherein the second dielectric constant is greater than the first dielectric constant.  
     
     
         3 . The transistor gate dielectric of    claim 1   , wherein the first material has a first thickness and the second material has a second thickness, the combination of the first thickness and the second thickness defining a total thickness less than one- third of the length of a transistor gate adapted to overly the gate dielectric.  
     
     
         4 . The gate dielectric of    claim 3   , wherein the first material thickness and the second material thickness are determined by the relationship  
       
         t 
         1 
         /k 
         1 
         +t 
         2 
         /k 
         2 
         =t 
         ox 
         /k 
         ox  
       
       wherein 
 t 1  is the first material thickness,  
 t 2  is the second material thickness,  
 t ox  is the minimum thickness for a gate dielectric of silicon dioxide for a chosen gate length,  
 k 1  is the dielectric constant for the first dielectric material,  
 k 2  is the dielectric constant for the second dielectric material, and  
 k ox  is the dielectric constant of silicon dioxide.  
 
     
     
         5 . The gate dielectric of    claim 1   , wherein the first gate dielectric material is selected from one of silicon nitride, HfO 2 , BaO, La 2 O 3 , Y 2 O 3 , and ZrO 2 .  
     
     
         6 . The gate dielectric of    claim 1   , wherein the second dielectric material is selected from one of BST and PZT.  
     
     
         7 . The gate dielectric of    claim 1   , further comprising a third dielectric material having a third dielectric constant.  
     
     
         8 . A transistor having a gate electrode overlying a gate dielectric comprising: 
 a first dielectric material having a first dielectric constant; and    a second dielectric material having a second dielectric constant different from the first dielectric constant.    
     
     
         9 . The transistor of    claim 8   , wherein the second dielectric of the gate dielectric has a dielectric constant greater than the first dielectric constant.  
     
     
         10 . The transistor of    claim 8   , wherein the first material of the gate dielectric has a first thickness and the second material of the gate dielectric has a second thickness, the combination of the first thickness and the second thickness defining a total thickness less than one-third of a length of the transistor gate electrode.  
     
     
         11 . The transistor of    claim 8   , wherein the first material thickness and the second material thickness are determined by the relationship  
       
         t 
         1 
         /k 
         1 
         +t 
         2 
         /k 
         2 
         =t 
         ox 
         /k 
         ox  
       
       wherein 
 t 1  is the first material thickness,  
 t 2  is the second material thickness,  
 t ox  is the minimum thickness for a gate dielectric of silicon dioxide for a chosen gate electrode length,  
 k 1  is the dielectric constant for the first dielectric material,  
 k 2  is the dielectric constant for the second dielectric material, and  
 k ox  is the dielectric constant of silicon dioxide.  
 
     
     
         12 . The transistor of    claim 8   , wherein the first gate dielectric material is selected from one of silicon nitride, HfO 2 ,BaO, La 2 O 3 , Y 2 O 3 , and ZrO 2 .  
     
     
         13 . The gate dielectric of    claim 8   , wherein the second dielectric material is selected from one of BST and PZT.  
     
     
         14 . The gate dielectric of    claim 8   , further comprising a third dielectric material having a third dielectric constant.