Method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure and an oxygen- or nitrogen-terminated silicon nanocrystalline structure formed by the method

Abstract

A substrate is set at a predetermined temperature in a plasma treatment chamber, then the inside of the plasma treatment chamber is regulated at a reduced pressure containing at least a silicon hydride gas and a hydrogen gas, a high-frequency electric field is applied to form a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on the substrate. Thereafter, application of the high-frequency electric field is terminated, then the inside of the plasma treatment chamber is replaced by an oxidizing or nitriding gas, and a high-frequency electric field is applied again for plasma oxidizing treatment or plasma nitriding treatment of the silicon film formed on the substrate. Thereby, a silicon nanocrystalline structure can be formed on a silicon substrate by using a process of producing silicon integrated circuits with achieving high luminous efficiency, and terminating reliably with oxygen or nitrogen on the surface thereof. According to the method of the present invention, the particle diameter of the oxygen- or nitrogen-terminated silicon nanocrystals can be regulated in an accuracy of 1 to 2 nm, the density thereof per unit area can be increased, and the silicon nanocrystalline structure can be produced easily and inexpensively.

1 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure, which comprises a step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate and a step of oxidizing or nitriding the formed silicon film with ions and radicals formed from an oxidizing gas or a nitriding gas.  
   
   
       2 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure, wherein a step comprising of the first step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate and the sequential second step of oxidizing or nitriding the formed silicon film with ions and radicals formed from an oxidizing gas or a nitriding gas is conducted plural times.  
   
   
       3 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 1 , wherein the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is carried out by using a thermal catalysis reaction in a gas system containing at least a silicon hydride gas and a hydrogen gas.  
   
   
       4 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 2 , wherein the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is carried out by using a thermal catalysis reaction in a gas system containing at least a silicon hydride gas and a hydrogen gas.  
   
   
       5 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 1 , wherein the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is carried out by setting the substrate at a predetermined temperature in a plasma treatment chamber and then applying a high-frequency electric field while regulating the inside of the plasma treatment chamber at a reduced pressure containing at least a silicon hydride gas and a hydrogen gas.  
   
   
       6 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 2 , wherein the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is carried out by setting the substrate at a predetermined temperature in a plasma treatment chamber and then applying a high-frequency electric field while regulating the inside of the plasma treatment chamber at a reduced pressure containing at least a silicon hydride gas and a hydrogen gas.  
   
   
       7 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 5 , wherein the frequency of the high-frequency electric field applied in the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       8 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 6 , wherein the frequency of the high-frequency electric field applied in the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate is a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       9 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 1 , wherein the step of oxidizing or nitriding the silicon film formed on a substrate with ions and radicals formed from an oxidizing gas or a nitriding gas is plasma oxidizing treatment or plasma nitriding treatment of the silicon film by arranging the substrate having the silicon film formed thereon in a plasma treatment chamber, replacing the atmosphere in the plasma treatment chamber by an oxidizing or nitriding gas atmosphere and then applying a high-frequency electric field.  
   
   
       10 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 2 , wherein the step of oxidizing or nitriding the silicon film formed on a substrate with ions and radicals formed from an oxidizing gas or a nitriding gas is plasma oxidizing treatment or plasma nitriding treatment of the silicon film by arranging the substrate having the silicon film formed thereon in a plasma treatment chamber, replacing the atmosphere in the plasma treatment chamber by an oxidizing or nitriding gas atmosphere and then applying a high-frequency electric field.  
   
   
       11 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 9 , wherein the plasma oxidizing treatment or plasma nitriding treatment is composed of plasma oxidizing treatment or plasma nitriding treatment in an oxidizing or nitriding gas atmosphere, subsequent etching treatment, with an HF-based gas, of the surface of fine silicon crystals in the silicon film formed on the substrate, or plasma etching treatment of the surface of fine silicon crystals in the silicon film formed on the substrate in a molecular gas system containing fluorine, and subsequent plasma oxidizing treatment or plasma nitriding treatment in an oxidizing or nitriding gas atmosphere.  
   
   
       12 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 10 , wherein the plasma oxidizing treatment or plasma nitriding treatment is composed of plasma oxidizing treatment or plasma nitriding treatment in an oxidizing or nitriding gas atmosphere, subsequent etching treatment, with an HF-based gas, of the surface of fine silicon crystals in the silicon film formed on the substrate, or plasma etching treatment of the surface of fine silicon crystals in the silicon film formed on the substrate in a molecular gas system containing fluorine, and subsequent plasma oxidizing treatment or plasma nitriding treatment in an oxidizing or nitriding gas atmosphere.  
   
   
       13 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 9 , wherein the high frequency of the high-frequency electric field applied in the plasma oxidizing treatment or plasma nitriding treatment is a high frequency having an LF-range high frequency applied to a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       14 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 10 , wherein the high frequency of the high-frequency electric field applied in the plasma oxidizing treatment or plasma nitriding treatment is a high frequency having an LF-range high frequency applied to a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       15 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 11 , wherein the high frequency of the high-frequency electric field applied in the plasma oxidizing treatment or plasma nitriding treatment is a high frequency having an LF-range high frequency applied to a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       16 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 12 , wherein the high frequency of the high-frequency electric field applied in the plasma oxidizing treatment or plasma nitriding treatment is a high frequency having an LF-range high frequency applied to a VHF-range high frequency having a higher frequency than 60 MHz.  
   
   
       17 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 1 , wherein in the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate, the thickness of the silicon film is from 1 to 10 nm.  
   
   
       18 . A method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure according to  claim 2 , wherein in the step of forming a silicon film of nanometer scale thickness composed of fine silicon crystals and amorphous silicon on a substrate, the thickness of the silicon film is from 1 to 10 nm.  
   
   
       19 . A silicon nanocrystalline structure formed by the method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure as described in  claim 1 .  
   
   
       20 . A silicon nanocrystalline structure formed by the method of forming an oxygen- or nitrogen-terminated silicon nanocrystalline structure as described in  claim 2.