Icp source design for plasma uniformity and efficiency enhancement

Abstract

An ICP A plasma reactor having an enclosure wherein at least part of the ceiling forms a dielectric window. A substrate support is positioned within the enclosure below the dielectric window. An RF power applicator is positioned above the dielectric window to radiate RF power through the dielectric window and into the enclosure. A plurality of gas injectors are distributed uniformly above the substrate support to supply processing gas into the enclosure. A circular baffle is situated inside the enclosure and positioned above the substrate support but below the plurality of gas injectors so as to redirect the flow of the processing gas.

What is claimed is: 
     
         1 . A plasma reactor comprising:
 an enclosure having a cylindrical sidewall and a ceiling, wherein at least part of the ceiling forms a dielectric window;   a substrate support positioned within the enclosure below the dielectric window;   an RF power applicator positioned above the dielectric window to radiate RF power through the dielectric window and into the enclosure;   a plurality of gas injectors distributed uniformly above the substrate support to supply processing gas into the enclosure; and,   a circular baffle situated inside the enclosure and positioned above the substrate support but below the plurality of gas injectors so as to redirect flow of the processing gas, wherein the baffle has a central aperture having a variable diameter.   
     
     
         2 . The plasma chamber of  claim 1 , wherein the central aperture diameter can be varied from the outside of the chamber. 
     
     
         3 . The plasma reactor of  claim 1 , wherein the baffle comprises one of anodized aluminum, ceramic, or quartz. 
     
     
         4 . The plasma reactor of  claim 2 , wherein the baffle comprises a ring and a plurality of blades, wherein the blades are actuated by the rotation of the ring to thereby vary the diameter of the aperture. 
     
     
         5 . The plasma reactor of  claim 4 , further comprising manual mechanical means configured to rotate the ring. 
     
     
         6 . The plasma reactor of  claim 4 , further comprising a stepper motor configured to rotate the ring. 
     
     
         7 . The plasma reactor of  claim 1 , further comprising a step motor configured to move the baffle vertically so as to lower or raise the baffle. 
     
     
         8 . The plasma reactor of  claim 1 , wherein the baffle comprises a dielectric material and further comprises a coil embedded within the dielectric material. 
     
     
         9 . A method of fabricating a semiconductor substrate, comprising:
 placing the substrate on a substrate support positioned within a plasma reactor, wherein the plasma reactor comprises an enclosure having a cylindrical sidewall and a ceiling, wherein at least part of the ceiling forms a dielectric window, an RF power applicator is positioned above the dielectric window to radiate RF power through the dielectric window and into the enclosure, and a plurality of gas injectors are distributed uniformly above the substrate;   varying gas flow distribution by positioning a circular baffle having an aperture inside the enclosure such that the baffle is above the substrate support but below the plurality of gas injectors so as to define a gap above the substrate;   supplying processing gas to the injectors; and, p 1  applying an RF power to the RF power applicator.   
     
     
         10 . The method of  claim 9 , further comprising a varying diameter of the aperture. 
     
     
         11 . The method of  claim 10 , wherein varying diameter of the aperture comprises activating a stepper motor. 
     
     
         12 . The method of  claim 10 , wherein varying diameter of the aperture comprises mechanically rotating a ring from outside the plasma reactor. 
     
     
         13 . The method of  claim 9 , wherein the step of varying gas flow distribution comprises generating radially uneven gas flow. 
     
     
         14 . The method of  claim 9 , further comprising moving the baffle vertically so as to lower or raise the baffle. 
     
     
         15 . The method of  claim 9 , wherein the baffle comprises a dielectric material and the method further comprising energizing a coil embedded within the dielectric material. 
     
     
         16 . The method of  claim 15 , wherein energizing the coil comprises applying to the coil RF power separately from the RF power applied to the RF power applicator. 
     
     
         17 . The method of  claim 9 , further comprising applying to the baffle a vertical ring extension set to be orthogonal to the baffle.