Apparatus and method for modulating azimuthal uniformity in electroplating

Abstract

An apparatus for electroplating metal on a semiconductor substrate with improved azimuthal uniformity includes in one aspect: a plating chamber configured to contain an electrolyte and an anode; a substrate holder configured to hold the semiconductor substrate; an ionically resistive ionically permeable element (“the element”) configured to be positioned proximate the substrate; and a shield configured for providing azimuthally asymmetrical shielding and positioned between the substrate holder and the element such that the closest distance between the substrate-facing surface of the shield and the working surface of the substrate is less than 2 mm. In some embodiments there is an electrolyte-filled gap between the substrate-facing surface of the element and the shield during electroplating. The substrate-facing surface of the shield may be contoured such that the distance from different positions of the shield to the substrate is varied.

1 - 20 . (canceled) 
     
     
         21 . An electroplating apparatus comprising:
 (a) a plating chamber configured to contain an electrolyte and an anode while electroplating metal onto a semiconductor substrate;   (b) a substrate holder configured to hold and rotate the semiconductor substrate; and   (c) a shield positioned in the plating chamber and configured for providing azimuthally asymmetric shielding, wherein the shield has a central angle of between about 100-180 degrees, and wherein the shield is positioned such that the closest distance between a substrate-facing surface of the shield and the semiconductor substrate is less than about 2 mm during electroplating.   
     
     
         22 . The electroplating apparatus of  claim 21 , wherein the shield is positioned such that the vertex of the central angle of the shield is located at a radial position of between about 10-40 mm from a radial position corresponding to an edge of the semiconductor substrate during electroplating. 
     
     
         23 . The electroplating apparatus of  claim 21 , wherein the shield has one or more electrolyte-permeable openings. 
     
     
         24 . The electroplating apparatus of  claim 21 , wherein the shield has varied thickness. 
     
     
         25 . The electroplating apparatus of  claim 21 , wherein a peripheral portion of the shield is thicker than a central portion of the shield. 
     
     
         26 . The electroplating apparatus of  claim 21 , further comprising an ionically resistive ionically permeable element comprising a substrate-facing surface and an opposing surface, wherein the element allows for flow of ionic current through the element towards the substrate during electroplating, wherein the ionically resistive ionically permeable element comprises a plurality of channels, and wherein the ionically resistive ionically permeable element is positioned such that a closest distance between the substrate-facing surface of the element and a working surface of the substrate is about 10 mm or less; and wherein the shield is positioned such that there is an electrolyte-filled gap between the shield and the ionically resistive ionically permeable element during electroplating. 
     
     
         27 . The electroplating apparatus of  claim 21 , wherein the closest distance between the substrate-facing surface of the shield and the semiconductor substrate is about 0.5 mm-1.5 mm. 
     
     
         28 . The electroplating apparatus of  claim 21 , wherein the substrate-facing surface of the shield is contoured such that a distance from the substrate-facing surface of the shield to the semiconductor substrate is varied radially for a selected azimuthal position. 
     
     
         29 . A method of electroplating a metal on a semiconductor substrate while controlling azimuthal uniformity, the method comprising:
 (a) providing the semiconductor substrate into an electroplating apparatus configured for rotating the substrate during electroplating, wherein the electroplating apparatus comprises a shield, configured for providing azimuthally asymmetric shielding, wherein the shield has a central angle of between about 100-180 degrees, and wherein the shield is positioned such that the closest distance between a substrate-facing surface of the shield and the semiconductor substrate is less than about 2 mm during electroplating; and   (b) electroplating the metal on the substrate while rotating the substrate relative to the shield such that a selected portion of the substrate at a selected azimuthal position dwells in a shielded area for a different amount of time than a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position.   
     
     
         30 . The method of  claim 29 , wherein electroplating comprises rotating the substrate at a first speed when the selected portion of the substrate is less shielded, and at a second speed when the selected portion of the substrate is more shielded, wherein one full rotation of the substrate comprises a first period of rotation at the first speed and a second period of rotation at the second speed. 
     
     
         31 . The method of  claim 29 , wherein the second speed is smaller than the first speed. 
     
     
         32 . The method of  claim 29 , wherein electroplating comprises rotating the substrate such that the substrate slows down two or more times during one full rotation of the substrate, such that two selected separate azimuthal portions on the substrate dwell longer in the shielded area than analogous non-selected azimuthal portions. 
     
     
         33 . The method of  claim 29 , wherein the electroplating apparatus comprises a plurality of shields configured for azimuthally asymmetric shielding, wherein each shield is positioned within 2 mm from the working surface of the substrate. 
     
     
         34 . The method of  claim 29 , wherein the shield is positioned such that there is an electrolyte-filled gap between the substrate-facing surface of the ionically resistive ionically permeable element and the shield during electroplating. 
     
     
         35 . The method of  claim 29 , wherein the electroplating comprises rotating the semiconductor substrate bidirectionally. 
     
     
         36 . The method of  claim 29 , wherein the shield is positioned such that the vertex of the central angle of the shield is located at a radial position of between about 10-40 mm from a radial position corresponding to an edge of the semiconductor substrate during electroplating. 
     
     
         37 . The method of  claim 29 , wherein the electroplating comprises at least five variable-speed full rotations of the semiconductor substrate. 
     
     
         38 . The method of  claim 29 , wherein the semiconductor substrate is an azimuthally asymmetric substrate. 
     
     
         39 . The method of  claim 29 , wherein the semiconductor substrate has a missing die region. 
     
     
         40 . The method of  claim 29 , wherein the semiconductor substrate provided in (a) comprises a plurality of through-resist recessed features.