Shielding plate in plasma for uniformity improvement

Abstract

An apparatus comprising a plasma chamber containing a plasma for a plasma-assisted material process upon a substrate; a shielding plate within the plasma chamber to actively direct ion flux to desired areas of the substrate; and a supporting structure to support the shielding plate within the chamber is disclosed.

What is claimed is:  
     
         1 . An apparatus comprising: 
 a plasma chamber containing a plasma for a plasma-assisted material process upon a substrate;    a shielding plate within said plasma chamber to actively direct ion flux to desired areas of the substrate; and    a supporting structure to support said shielding plate within said chamber.    
     
     
         2 . The apparatus of  claim 1  wherein the plasma-assisted material process is a plasma-assisted etching process.  
     
     
         3 . The apparatus of  claim 1  wherein the plasma-assisted material process is a plasma-enhanced chemical vapor deposition process.  
     
     
         4 . The apparatus of  claim 1  wherein the shielding plate and the supporting structure are composed of a dielectric material.  
     
     
         5 . The apparatus of  claim 1  wherein the supporting structure further comprises three or more supporting members.  
     
     
         6 . The apparatus of  claim 1  wherein the shielding plate is solid to suppress ion flux at the center of the substrate.  
     
     
         7 . The apparatus of  claim 1  wherein the shielding plate has one or more perforations that allow ion flux to pass, such that the ion flux within a localized area of the substrate is fitted to meet the requirements of a desired material process.  
     
     
         8 . The apparatus of  claim 1  wherein the dimensions of the plate are dependent upon the dimensions of the plasma chamber and the substrate.  
     
     
         9 . The apparatus of  claim 8  wherein the thickness of the plate is 2-5 mm.  
     
     
         10 . The apparatus of  claim 1  wherein the distance between a member of said supporting structure and said substrate is greater than the mean free path of a reactive particle.  
     
     
         11 . The apparatus of  claim 1  wherein the width of a member of said supporting plate is less than the mean free path of a reactive particle.  
     
     
         12 . The apparatus of  claim 1  wherein the edge of said plate is rounded.  
     
     
         13 . The apparatus of  claim 1  wherein the plate is circular.  
     
     
         14 . The apparatus of  claim 1  wherein the plasma-assisted material process is carried out in high-density plasma.  
     
     
         15 . A method comprising: 
 optimizing the dimensions, geometry, and location of a shielding plate to generate a desired ion flux in a plasma-assisted material process conducted in a plasma chamber;    inserting the plate above a substrate in the chamber; and    carrying out the desired material process upon the substrate by the ion flux generated.    
     
     
         16 . The method of  claim 15  further comprising optimizing the dimensions, geometry, and location of the shielding plate by numerical simulation.  
     
     
         17 . The method of  claim 16  further comprising performing the optimization process such that a set of numerically simulated plasma potential contour lines are as close to parallel to the plane of a simulated substrate surface as possible.  
     
     
         18 . The method of  claim 15  further comprising varying localized ion flux across said substrate by perforating said plate.  
     
     
         19 . The method of  claim 14  further comprising optimizing the uniformity of energy flux across the substrate surface.  
     
     
         20 . A method comprising: 
 actively directing ion flux within a plasma chamber by the insertion of a plate into the chamber; and    regulating ion flux to different areas of the substrate by altering properties of the plate.    
     
     
         21 . The method of  claim 20  further comprising conducting a plasma-assisted etching process upon the substrate.  
     
     
         22 . The method of  claim 20  further comprising conducting a plasma-enhanced chemical vapor deposition process upon the substrate.  
     
     
         23 . A method comprising: 
 placing a shielding plate within a plasma chamber to actively direct ion flux, such that the ratio of (neutrons)/(neutrons+ions) bombarding a substrate is regulated.    
     
     
         24 . The method of  claim 23  further comprising controlling the rates of horizontal and vertical etching upon the substrate.  
     
     
         25 . The method of  claim 24  further comprising producing cavities in the substrate having the desired critical dimensions by the directed ion flux.  
     
     
         26 . The method of  claim 25  further comprising customizing the dimensions of each cavity according to the requirements of a plasma-assisted etching process.  
     
     
         27 . A method comprising: 
 actively directing ion flux within a plasma chamber by the insertion of a shielding plate such that the accumulation of etching by-products across the surface of a substrate is regulated.    
     
     
         28 . The method of  claim 27  further comprising improving etch uniformity across the substrate.  
     
     
         29 . The method of  claim 27  further comprising: 
 preventing the non-uniform accumulation of etching by-products at the center of a substrate; and  
 increasing the etching rate at the center of the substrate.