Crystal growth method of oxide, cerium oxide, promethium oxide, multi-layered structure of oxides, manufacturing method of field effect transistor, manufacturing method of ferroelectric non-volatile memory and ferroelectric non-volatile memory

Abstract

An epitaxial rare earth oxide ( 001 )/silicon ( 001 ) structure is realized by epitaxially growing a rare earth oxide such as cerium dioxide in the ( 001 ) orientation on a ( 001 )-oriented silicon substrate. For this purpose, the surface of the ( 001 )-oriented Si substrate is processed into a dimer structure by 2×1, 1×2 surface reconstruction, and a rare earth oxide of a cubic system or a tetragonal system, such as CeO 2 film, is epitaxially grown in the ( 001 ) orientation on the Si substrate by molecular beam epitaxy, for example. During this growth, a source material containing at least one kind of rare earth element is supplied after the supply of an oxidic gas is supplied onto the surface of the Si substrate. If necessary, annealing is conducted in vacuum after the growth.

What is claimed is:  
     
         1 . A crystal growth method of an oxide comprising the steps of: 
 processing a surface of a (001)-oriented silicon substrate into a dimer structure by 2×1, 1×2 surface reconstruction; and    epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate.    
     
     
         2 . The crystal growth method of an oxide according to  claim 1  wherein, when said rare earth oxide is epitaxially grown, a source material containing at least one kind of rare earth element is supplied after the supply of an oxidic gas onto the surface of said silicon substrate is started.  
     
     
         3 . The crystal growth method of an oxide according to  claim 1  wherein said source material containing at least one kind of rare earth element is made up of at least one kind of rare earth element.  
     
     
         4 . The crystal growth method of an oxide according to  claim 2  wherein said source material containing at least one kind of rare earth element is made up of a rare earth oxide.  
     
     
         5 . The crystal growth method of an oxide according to  claim 1  further comprising the step of annealing said rare earth oxide in vacuum with a pressure not higher than 1×10 −6  Torr at a temperature not lower than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         6 . The crystal growth method of an oxide according to  claim 1  further comprising the step of homoepitaxially growing another rare earth oxide on said rare earth oxide at a growth temperature higher than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         7 . The crystal growth method of an oxide according to  claim 1  further comprising the step of epitaxially growing another a functional oxide on said rare earth oxide rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         8 . The crystal growth method of an oxide according to  claim 1  wherein a silicon oxide film or a defective layer not thicker than 5 nm is formed along the interface between said silicon substrate and said rare earth oxide.  
     
     
         9 . The crystal growth method of an oxide according to  claim 1  wherein said functional oxide has a perovskite structure or a layered perovskite structure.  
     
     
         10 . The crystal growth method of an oxide according to  claim 1  wherein said rare earth oxide is cerium dioxide or yttrium oxide.  
     
     
         11 . A crystal growth method of an oxide comprising the steps of: 
 processing a surface of a (001)-oriented silicon substrate into a dimer structure by 2×1, 1×2 surface reconstruction; and    epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate by using a source material containing at least one kind of rare earth element in an atmosphere containing an oxidic gas.    
     
     
         12 . The crystal growth method of an oxide according to  claim 11  wherein, when said rare earth oxide is epitaxially grown, a source material containing at least one kind of rare earth element is supplied after the supply of an oxidic gas onto the surface of said silicon substrate is started.  
     
     
         13 . The crystal growth method of an oxide according to  claim 11  wherein said source material containing at least one kind of rare earth element is made up of at least one kind of rare earth element.  
     
     
         14 . The crystal growth method of an oxide according to  claim 11  wherein said source material containing at least one kind of rare earth element is made up of a rare earth oxide.  
     
     
         15 . The crystal growth method of an oxide according to  claim 11  further comprising the step of annealing said rare earth oxide in vacuum with a pressure not higher than 1×10 −6  Torr at a temperature not lower than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         16 . The crystal growth method of an oxide according to  claim 11  further comprising the step of homoepitaxially growing another rare earth oxide on said rare earth oxide at a growth temperature higher than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         17 . The crystal growth method of an oxide according to  claim 11  further comprising the step of epitaxially growing a functional oxide on said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         18 . The crystal growth method of an oxide according to  claim 11  wherein a silicon oxide film or a defective layer not thicker than 5 nm is formed along the interface between said silicon substrate and said rare earth oxide.  
     
     
         19 . The crystal growth method of an oxide according to  claim 11  wherein said functional oxide has a perovskite structure or a layered perovskite structure.  
     
     
         20 . The crystal growth method of an oxide according to  claim 11  wherein said rare earth oxide is cerium dioxide or yttrium oxide.  
     
     
         21 . The crystal growth method of an oxide according to  claim 11  wherein said rare earth oxide is epitaxially grown at a growth temperature lower than 300° C.  
     
     
         22 . The crystal growth method of an oxide according to  claim 11  wherein said rare earth oxide is epitaxially grown at a growth temperature not higher than 100° C.  
     
     
         23 . A crystal growth method of an oxide comprising the steps of: 
 vaporizing a silicon oxide film from the surface of a (001)-oriented silicon substrate by heating it in vacuum with a pressure not higher than 1×10 −6  Torr; and    epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate from which said silicon oxide film is vaporized.    
     
     
         24 . The crystal growth method of an oxide according to  claim 23  wherein, when said rare earth oxide is epitaxially grown, a source material containing at least one kind of rare earth element is supplied after the supply of an oxidic gas onto the surface of said silicon substrate is started.  
     
     
         25 . The crystal growth method of an oxide according to  claim 24  wherein said source material containing at least one kind of rare earth element is made up of at least one kind of rare earth element.  
     
     
         26 . The crystal growth method of an oxide according to  claim 24  wherein said source material containing at least one kind of rare earth element is made up of a rare earth oxide.  
     
     
         27 . The crystal growth method of an oxide according to  claim 23  further comprising the step of annealing said rare earth oxide in vacuum with a pressure not higher than 1×10 −6  Torr at a temperature not lower than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         28 . The crystal growth method of an oxide according to  claim 23  further comprising the step of homoepitaxially growing another rare earth oxide on said rare earth oxide at a growth temperature higher than the growth temperature of said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         29 . The crystal growth method of an oxide according to  claim 23  further comprising the step of epitaxially growing a functional oxide on said rare earth oxide after said rare earth oxide is epitaxially grown.  
     
     
         30 . The crystal growth method of an oxide according to  claim 23  wherein a silicon oxide film or a defective layer not thicker than 5 nm is formed along the interface between said silicon substrate and said rare earth oxide.  
     
     
         31 . The crystal growth method of an oxide according to  claim 23  wherein said functional oxide has a perovskite structure or a layered perovskite structure.  
     
     
         32 . The crystal growth method of an oxide according to  claim 23  wherein said rare earth oxide is cerium dioxide or yttrium oxide.  
     
     
         33 . A cerium oxide having a bixbyite structure.  
     
     
         34 . A promethium oxide having a bixbyite structure.  
     
     
         35 . A multi-layered structure of oxides comprising: 
 a (001)-oriented silicon substrate;    a first CeO 2  film grown on said silicon substrate at a first growth temperature; and    a second CeO 2  film epitaxially grown on said first CeO 2  film at a second growth temperature higher than said first growth temperature.    
     
     
         36 . The multi-layered structure of oxides according to  claim 35  wherein said second CeO 2  film is (001)-oriented.  
     
     
         37 . The multi-layered structure of oxides according to  claim 35  wherein a SiO x  film lies along the interface between said silicon substrate and said first CeO 2  film.  
     
     
         38 . A multi-layered structure of oxides comprising: 
 a (001)-oriented silicon substrate;    a SiO x  film on said silicon substrate;    an amorphous CeO y  film on said SiO x  film; and    a (001)-oriented CeO 2  film epitaxially arranged with respect to said silicon substrate on said amorphous CeO y  film.    
     
     
         39 . A manufacturing method of a field effect transistor comprising the steps of: 
 processing a surface of a (001)-oriented silicon substrate into a dimer structure by 2×1, 1×2 surface reconstruction; and    forming a gate insulating film by epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate.    
     
     
         40 . The manufacturing method of a field effect transistor according to  claim 39  wherein said gate insulating film is formed by epitaxially growing said rare earth oxide on said silicon substrate by using a source material containing at least one rare earth element in an atmosphere containing an oxidic gas.  
     
     
         41 . The manufacturing method of a field effect transistor according to  claim 39  wherein said gate insulating film is formed by epitaxially growing said rare earth oxide on said silicon substrate at a growth temperature lower than 300° C.  
     
     
         42 . The manufacturing method of a field effect transistor according to  claim 41  wherein said gate insulating film is formed by epitaxially growing said rare earth oxide on said silicon substrate at a growth temperature lower than 100° C.  
     
     
         43 . The manufacturing method of a field effect transistor according to  claim 39  wherein said surface of the silicon substrate is processed into said dimer structure by heating said silicon substrate in vacuum with a pressure not higher than 1×10 −6  Torr and thereby vaporizing a silicon oxide film from said surface, and said gate insulating film is formed by epitaxially growing said rare earth oxide on said silicon substrate.  
     
     
         44 . The manufacturing method of a field effect transistor according to  claim 39  further comprising the step of epitaxially growing a ferroelectric film on said gate insulating film.  
     
     
         45 . A manufacturing method of a field effect transistor comprising the steps of: 
 processing a surface of a (001)-oriented silicon substrate into a dimer structure by 2×1, 1×2 surface reconstruction; and    forming a gate insulating film by epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate in an atmosphere containing an oxidic gas at a growth temperature lower than 300° C. by using a source material containing at least one kind of rare earth element.    
     
     
         46 . A manufacturing method of a field effect transistor comprising the steps of: 
 vaporizing a silicon oxide film from a surface of a (001)-oriented silicon substrate by heating said silicon substrate in vacuum with a pressure not higher than 1×10 −6  Torr;    forming a gate insulating film by epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate from which said silicon oxide film is vaporized.    
     
     
         47 . A field effect transistor comprising: 
 a (001)-oriented silicon substrate;    a gate insulating film made of a (001)-oriented rare earth oxide of a cubic system or tetragonal system which is epitaxially grown on said silicon substrate; and    a ferroelectric film epitaxially grown on said gate insulating film.    
     
     
         48 . A manufacturing method of a ferroelectric non-volatile memory, comprising the steps of: 
 processing a surface of a (001)-oriented silicon substrate into a dimer structure by 2×1, 1×2 surface reconstruction;    epitaxially growing a rare earth oxide of a cubic system or tetragonal system in the (001) orientation on said silicon substrate; and    epitaxially growing a ferroelectric film on said rare earth oxide.    
     
     
         49 . A ferroelectric non-volatile memory characterized in the use of a field effect transistor which includes: 
 a (001)-oriented silicon substrate;    a gate insulating film made of a (001)-oriented rare earth oxide of a cubic system or tetragonal system which is epitaxially grown on said silicon substrate; and    a ferroelectric film epitaxially grown on said gate insulating film.    
     
     
         50 . A ferroelectric non-volatile memory comprising: 
 a (001)-oriented silicon substrate;    a (001)-oriented rare earth oxide of a cubic system or tetragonal system which is epitaxially grown on the surface of a first region of said silicon substrate;    a capacitor using a ferroelectric film which is epitaxially grown on said rare earth oxide; and    MIS-FET formed in a second region of said silicon substrate,    said capacitor and a gate electrode of said MIS-FET gate being connected to each other by wiring.    
     
     
         51 . A ferroelectric non-volatile memory comprising: 
 a single-crystal insulating substrate;    a (001)-oriented rare earth oxide of a cubic system of tetragonal system which is epitaxially grown on the surface of a first region of said single-crystal insulating substrate;    a capacitor using a ferroelectric film which is epitaxially grown on said rare earth oxide; and    MIS-FET formed in a silicon film which is epitaxially grown on the surface of a second region of said single-crystal insulating substrate,    said capacitor and a gate electrode of said MIS-FET being connected to each other by wiring.