Thin dielectric layers and non-thermal formation thereof

Abstract

A method of forming a dielectric layer suitable for use as the gate dielectric layer in a MOSFET includes passivating the surface of a semiconductor substrate at a temperature less than approximately 80° C. and nitridizing the passivation layer. In particular embodiments, passivating a silicon wafer includes forming a hydroxy-silicate layer at approximately 24° C. In a further aspect of the present invention, an integrated circuit includes a plurality of insulated gate field effect transistors, wherein various ones of the plurality of transistors have gate dielectric layers of the nitridized passivation layer.

What is claimed is:  
     
         1 . An microelectronic device, comprising: 
 a semiconductor substrate; and    a nitridized hydroxy-silicate layer.    
     
     
         2 . The microelectronic device of  claim 1 , wherein the nitridized hydroxy-silicate layer comprises a silicon oxynitride.  
     
     
         3 . The microelectronic device of  claim 2 , wherein the silicon oxynitride is a material in accordance with the expression SiO x N (4-2x)/3  where 0≦x≦2.  
     
     
         4 . The microelectronic device of  claim 2 , wherein the silicon oxynitride has a thickness less than approximately 7 angstroms.  
     
     
         5 . The microelectronic device of  claim 2 , wherein the semiconductor substrate comprises a silicon wafer.  
     
     
         6 . The microelectronic device of  claim 4 , further comprising a gate electrode disposed over the silicon oxynitride layer.  
     
     
         7 . The microelectronic device of  claim 6 , further comprising a pair of source/drain terminals disposed in the semiconductor substrate, substantially adjacent to the gate electrode.  
     
     
         8 . A field effect transistor, comprising: 
 a gate electrode;    a pair of source/drain terminals disposed in a substrate, substantially adjacent the gate electrode; and    a gate dielectric disposed between the gate electrode and the substrate, the gate dielectric comprising a silicon oxynitride layer less than or equal to approximately 7 angstroms.    
     
     
         9 . A method of forming a dielectric layer on a surface of a substrate, the method comprising: 
 passivating the surface of the substrate; and    nitridizing the passivated surface.    
     
     
         10 . The method of  claim 9 , wherein passivating the surface of the substrate comprises forming a hydroxy-silicate layer.  
     
     
         11 . The method of  claim 10 , wherein the hydroxy-silicate layer is a material in accordance with the expression (SiO 2-x ,(OH) 2x nH 2 O where 0≦x≦1, n≧0).  
     
     
         12 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with a base and treating the surface with an acid.  
     
     
         13 . The method of  claim 9 , wherein passivating the surface of the substrate comprises: 
 subjecting the wafer to a bath in deionized water at approximately 24° C. for approximately 200 seconds;    subjecting the wafer to a 5:1:1 solution of H 2 O:H 2 O 2 :NH 4 OH at approximately 24° C. for approximately 10 minutes;    rinsing the wafer with deionized water at approximately 24° C. for approximately 315 seconds;    subjecting the wafer to a bath in a 5:1:1 solution of H 2 O:H 2 O 2 :HCl at approximately 24° C. for approximately 10 minutes; and    rinsing the wafer with deionized water at approximately 24° C. for approximately 315 seconds.    
     
     
         14 . The method of  claim 9 , further comprising drying the wafer after passivating the surface.  
     
     
         15 . The method of  claim 14 , wherein drying comprises subjecting the wafer to an isopropyl alcohol vapor jet at approximately 80° C. for approximately 10 minutes.  
     
     
         16 . The method of  claim 14 , wherein drying comprises exposing to the wafer to a pressure that is less than atmospheric pressure.  
     
     
         17 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with phosphoric acid.  
     
     
         18 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with sulfuric acid and hydrogen peroxide.  
     
     
         19 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with ammonium hydroxide, hydrogen peroxide and water.  
     
     
         20 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with nitric acid.  
     
     
         21 . The method of  claim 9 , wherein passivating the surface of the substrate comprises treating the surface with ozonated water.  
     
     
         22 . A method of making a field effect transistor, comprising: 
 forming an oxide layer on a substrate;    removing the oxide layer;    forming a hydroxy-silicate layer on the surface of the substrate at temperature approximately equal to 24° C.;    converting the hydroxy-silicate layer to a silicon oxynitride layer;    forming a gate electrode layer over the oxynitride layer;    patterning the gate electrode layer to form a gate electrode; and    forming source/drain terminals substantially adjacent the gate electrode.    
     
     
         23 . The method of  claim 22 , wherein the silicon oxynitride layer is less than approximately 7 angstroms.  
     
     
         24 . The method of  claim 22 , wherein converting the hydroxy-silicate layer to the oxynitride layer comprises plasma nitridation.  
     
     
         25 . The method of  claim 24 , wherein plasma nitridation comprises placing the substrate in a parallel plate plasma chamber with a plate spacing in the range of 200 to 1000 mils, an RF power in the range of 300 to 600W, a gas flow in the range of 0.5 to 3 liters/minute of N 2 , a pressure in the range of 1 to 5 Torrs, at a temperature in the range of 200 to 500° C., for the range of 10 to 90 seconds.  
     
     
         26 . The method of  claim 22 , wherein converting the hydroxy-silicate layer to the oxynitride layer comprises rapid thermal nitridation using NH3 for approximately 30 seconds at approximately 900° C.