Epitaxial Growth Using Atmospheric Plasma Preparation Steps

Abstract

After CMP and before an epitaxial growth step, the substrate is prepared by an atmospheric plasma which includes not only a reducing chemistry, but also metastable states of a chemically inert carrier gas. This removes residues, oxides, and/or contaminants. Optionally, nitrogen passivation is also performed under atmospheric conditions, to passivate the substrate surface for later epitaxial growth.

What is claimed is 
     
         1 . A process for epitaxial growth of a crystalline thin film on a crystalline substrate, comprising the steps of:
 a) forming an atomically ordered crystalline surface on the crystalline substrate;   b) flowing an activated gas mixture, which contains activated metastable states of a noble gas as well as one or more unstable reactive chemical species, through a glow discharge and downstream onto the surface of the crystalline substrate under atmospheric pressure, to thereby remove residues and/or oxidation from the ordered crystalline surface without disturbing the atomic order of the crystalline surface;   c) enclosing the crystalline substrate in a reaction vessel which is not open to the atmosphere, and depositing a layer of a crystalline material onto the ordered crystalline surface, as a crystalline extension of the substrate crystallinity.   
     
     
         2 . The method of  claim 1 , further comprising performing said forming step by CMP. 
     
     
         3 . The method of  claim 1 , further comprising performing said flowing step at approximately room temperature. 
     
     
         4 . The method of  claim 1 , further comprising passivating the ordered crystalline surface between said flowing step and said enclosing step. 
     
     
         5 . A system which automatically performs step b) of  claim 1 . 
     
     
         6 . A process for epitaxial growth of a crystalline thin film on a crystalline substrate, comprising the steps of:
 a) forming an atomically ordered crystalline surface on the crystalline substrate;   b) flowing an activated gas mixture, which contains activated metastable states of a noble gas as well as one or more unstable reducing chemical species, through a glow discharge and downstream through an aperture onto the surface of the crystalline substrate under atmospheric pressure, to thereby remove residues and/or oxidation from the ordered crystalline surface without disturbing the atomic order of the crystalline surface; wherein all portions of the substrate's surface are exposed to the activated gas mixture within less than two milliseconds after the activated gas mixture has exited the glow discharge;   c) enclosing the crystalline substrate in a reaction vessel which is not open to the atmosphere, and depositing a layer of a crystalline material onto the ordered crystalline surface, as a crystalline extension of the substrate crystallinity.   
     
     
         7 . The method of  claim 6 , further comprising performing said forming step by CMP. 
     
     
         8 . The method of  claim 6 , wherein said aperture is a linear aperture. 
     
     
         9 . The method of  claim 6 , wherein said flowing step is performed at approximately room temperature. 
     
     
         10 . The method of  claim 6 , further comprising passivating the ordered crystalline surface between said flowing step and said enclosing step. 
     
     
         11 . A system which automatically performs step b) of  claim 6 . 
     
     
         12 . A process for high-vacuum epitaxial growth of a crystalline thin film on a crystalline substrate, comprising the steps of:
 a) forming an atomically ordered crystalline surface on the crystalline substrate;   b) flowing an activated gas mixture, which contains activated metastable states of a noble gas as well as one or more unstable reactive chemical species, through a glow discharge and downstream onto the surface of the crystalline substrate under atmospheric pressure, to thereby remove residues and/or oxidation from the ordered crystalline surface without disturbing the atomic order of the crystalline surface;   c) enclosing the crystalline substrate in a reaction vessel which is not open to the atmosphere, and   evacuating the reaction chamber to a pressure of less than 10 −5  Torr, and   heating the crystalline substrate under vacuum to desorb materials from the ordered crystalline surface, and   depositing a layer of a crystalline material onto the ordered crystalline surface, as a crystalline extension of the substrate crystallinity.   
     
     
         13 . The method of  claim 12 , further comprising performing said step a) by CMP. 
     
     
         14 . The method of  claim 12 , further comprising performing said step b) at approximately room temperature. 
     
     
         15 . The method of  claim 12 , further comprising passivating the ordered crystalline surface between said step b) and said step c). 
     
     
         16 . A system which automatically performs step b) of  claim 12 . 
     
     
         17 . A process for epitaxial growth of a crystalline thin film on a crystalline substrate, comprising the steps of:
 a) forming an atomically ordered crystalline surface on the crystalline substrate;   b) flowing an activated gas mixture, which contains activated metastable states of a noble gas as well as one or more unstable reducing chemical species, through a glow discharge and downstream through an aperture onto the surface of the crystalline substrate under atmospheric pressure, to thereby remove residues and/or oxidation from the ordered crystalline surface without disturbing the atomic order of the crystalline surface; sweeping the relative positions of the nozzle and the crystalline substrate so that all portions of the substrate's surface are exposed to the activated gas mixture within less than two milliseconds after the activated gas mixture has exited the glow discharge;   c) enclosing the crystalline substrate in a reaction vessel which is not open to the atmosphere, and depositing a layer of a crystalline material onto the ordered crystalline surface, as a crystalline extension of the substrate crystallinity.   
     
     
         18 . The method of  claim 17 , further comprising performing said forming step by CMP. 
     
     
         19 . The method of  claim 17 , wherein said aperture is a linear aperture. 
     
     
         20 . The method of  claim 17 , wherein said flowing step is performed at approximately room temperature. 
     
     
         21 . The method of  claim 17 , further comprising passivating the ordered crystalline surface between said flowing step and said enclosing step. 
     
     
         22 . A system which automatically performs step b) of  claim 17 .