Multilayer high k dielectric films and method of making the same

Abstract

A new multilayer dielectric film for improving dielectric constant and thermal stability of gate dielectrics is provided. The multilayer dielectric film comprises a first layer formed of a metal oxide material having a high dielectric constant, and a second layer formed on the first layer. The second layer is formed of a metal silicate material having a dielectric constant lower than the dielectric constant of the first layer. A semiconductor transistor incorporating the multilayer dielectric film is also provided.

1 . A method of forming a multilayer dielectric film on a substrate, comprising the steps of: 
 forming a metal silicate layer on the surface of the substrate; and    forming a metal oxide layer atop the metal silicate layer.    
   
   
       2 . The method of  claim 1 , further comprising: 
 forming another metal silicate layer atop the metal oxide layer.    
   
   
       3 . The method of  claim 1  or  2  wherein said forming steps are carried out by any one of, or combination of, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), aerosol pyrolysis, spray coating or spin-on-coating.  
   
   
       4 . The method of  claim 1  or  2  wherein said forming steps are carried out by chemical vapor deposition (CVD) and using an oxygen source selected from the group consisting of O 2 , O 3 , NO, N 2 O, H 2 O, OH − , alcohol, alkoxides, and H 2 O 2 .  
   
   
       5 . The method of  claim 1  or  2  wherein said metal oxide layer has a dielectric constant  K;  and said metal silicate layer has a dielectric constant lower than the dielectric constant of said metal oxide layer.  
   
   
       6 . The method of  claim 5  wherein said metal oxide layer has a dielectric constant in a range of 15 to 200 and said metal silicate layer has a dielectric constant in a range of 5 to 100.  
   
   
       7 . The method of  claim 5  wherein said metal oxide has the formula of M x O y , where M is a metal selected from the group consisting of Zr, Hf, Ti, V, Nb, Ta, Cr, Mo, W, Mn, Zn, Al, Ga, In, Ge, Sr, Pb, Sb, Bi, Sc, Y, La, Be, Mg, Ca, Sr, Ba, Th, Lanthanides (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), and mixtures thereof, x is a number in the range of 1 to 3, and y is a number in the range of 2 to 5.  
   
   
       8 . The method of  claim 7  wherein said metal oxide includes more than one metal element.  
   
   
       9 . The method of  claim 5  wherein said metal oxide is selected from the group consisting of ZrO 2  and HfO 2 .  
   
   
       10 . The method of  claim 5  wherein said metal silicate has the formula of M x SiO y , where M is a metal selected from the group consisting of Zr, Hf, Ti, V, Nb, Ta, Cr, Mo, W, Mn, Zn, Al, Ga, In, Ge, Sr, Pb, Sb, Bi, Sc, Y, La, Be, Mg, Ca, Sr, Ba, Th, Lanthanides (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), and mixtures thereof, x is a number in the range of 1 to 3, and y is a number in the range of 2 to 5.  
   
   
       11 . The method of  claim 10  wherein said metal silicate includes more than one metal element.  
   
   
       12 . The method of  claim 10  wherein said metal silicate is selected from the group consisting of Zr—Si—O and Hf—Si—O.  
   
   
       13 . The method of  claim 1  or  2  wherein said metal silicate layer has a thickness smaller than a thickness of said metal oxide.  
   
   
       14 . The method of  claim 13  wherein said metal oxide layer has a thickness in a range of about 30 to 80 Å.  
   
   
       15 . The method of  claim 13  wherein said second metal silicate layer has a thickness of one to two atomic layers.