Spatially and dimensionally non-uniform channelled plate for tailored hydrodynamics during electroplating

Abstract

An ionically resistive ionically permeable element for use in an electroplating apparatus includes ribs to tailor hydrodynamic environment proximate a substrate during electroplating. In one implementation, the ionically resistive ionically permeable element includes a channeled portion that is at least coextensive with a plating face of the substrate, and a plurality of ribs extending from the substrate-facing surface of the channeled portion towards the substrate. Ribs include a first plurality of ribs of full maximum height and a second plurality of ribs of smaller maximum height than the full maximum height. In one implementation the ribs of smaller maximum height are disposed such that the maximum height of the ribs gradually increases in a direction from one edge of the element to the center of the element.

1 . An electroplating apparatus comprising:
 (a) an electroplating chamber configured to contain an electrolyte and an anode while electroplating metal onto a substrate;   (b) a substrate holder configured to hold the substrate such that a plating face of the substrate is separated from the anode during electroplating;   (c) an ionically resistive element comprising:
 (i) a channeled plate adapted to provide ionic transport through the ionically resistive element during electroplating; 
 (ii) a substrate-facing side that is parallel to the plating face of the substrate and separated from the plating face of the substrate by a gap; and 
 (iii) a plurality of ribs positioned on the substrate-facing side of the ionically resistive element, wherein the plurality of ribs comprises a first plurality of ribs of full maximum height and a second plurality of ribs of smaller maximum height than the full maximum height; 
   (d) an inlet to the gap for introducing cross flowing electrolyte to the gap; and   (e) an outlet to the gap for receiving cross flowing electrolyte flowing in the gap,   
       wherein the inlet and outlet are positioned proximate azimuthally opposing perimeter locations on the plating face of the substrate during electroplating. 
     
     
         2 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element is positioned such that the second plurality of ribs of smaller maximum height is proximate the inlet to the gap. 
     
     
         3 . The electroplating apparatus of  claim 1 , wherein all ribs are parallel to each other and are perpendicular to a direction of a flow of the cross flowing electrolyte in the gap. 
     
     
         4 . The electroplating apparatus of  claim 1 , wherein the second plurality of ribs comprises at least two ribs of different maximum heights. 
     
     
         5 . The electroplating apparatus as in any of the  claim 1 , wherein the ribs in the second plurality of ribs are arranged such that the maximum rib height increases in a direction from an edge to the center of the ionically resistive plate, and wherein the second plurality of ribs of lower height are disposed only on one side of the ionically resistive plate. 
     
     
         6 . The electroplating apparatus of  claim 1 , wherein the total number of ribs is between about 15-30, and the second plurality of ribs of lower maximum height has between about 2-10 ribs. 
     
     
         7 . The electroplating apparatus of  claim 1 , wherein the full maximum height of the ribs is less than about 5 mm. 
     
     
         8 . The electroplating apparatus of  claim 1  wherein the full maximum height of the ribs is about 1-3 mm. 
     
     
         9 . The electroplating apparatus of  claim 1 , wherein the gap between the bottom portion of the substrate holder and the ionically resistive element is less than about 20 mm. 
     
     
         10 . The electroplating apparatus of  claim 1 , wherein at least some of the ribs have variable height. 
     
     
         11 . The electroplating apparatus of  claim 1 , wherein at least some of the ribs have variable height, and wherein rib height decreases gradually in a direction toward an edge of the rib. 
     
     
         12 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element comprises a region, where rib height is lower than the full maximum height, and wherein the region is generally crescent-shaped. 
     
     
         13 . The electroplating apparatus of  claim 12 , wherein the region is located proximate either the inlet or the outlet from the gap. 
     
     
         14 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element comprises a region, where rib height is lower than the full maximum height, and wherein the region is generally annular. 
     
     
         15 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element comprises a region, where rib height is lower than the full maximum height, and wherein the region has a martini glass shape. 
     
     
         16 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element comprises a plurality of non-communicating channels. 
     
     
         17 . The electroplating apparatus of  claim 1 , wherein the ionically resistive element comprises a 3-D network of communicating channels. 
     
     
         18 . The electroplating apparatus of  claim 1 , further comprising a cross flow injection manifold fluidically coupled to the inlet. 
     
     
         19 . The electroplating apparatus of  claim 18 , wherein the cross flow injection manifold is at least partially defined by a cavity in the ionically resistive element. 
     
     
         20 . The electroplating apparatus of  claim 1 , further comprising a flow confinement ring positioned over a peripheral portion of the ionically resistive element. 
     
     
         21 . The electroplating apparatus of  claim 1 , wherein the inlet spans an arc between about 90-180° proximate the perimeter of the plating face of the substrate. 
     
     
         22 . An ionically resistive plate for use in an electroplating apparatus to plate material on a semiconductor wafer of standard diameter, comprising:
 a circular portion that has a plurality of channels that is coextensive with a plating face of the semiconductor wafer, wherein the plate has a thickness between about 2-25 mm;   a plurality of ribs extending from the circular portion, wherein the plurality of ribs comprises a first plurality of ribs of full maximum height and a second plurality of ribs of smaller maximum height than the full maximum height.   
     
     
         23 . A method for electroplating a substrate comprising:
 (a) receiving a substrate in a substrate holder, wherein a plating face of the substrate is exposed, and wherein the substrate holder is configured to hold the substrate such that the plating face of the substrate is separated from an anode during electroplating;   (b) immersing the substrate in an electrolyte, wherein a gap is formed between the plating face of the substrate and an ionically resistive element plane,
 wherein the ionically resistive element is at least about coextensive with the plating face of the substrate, 
 wherein the ionically resistive element comprises a channeled plate adapted to provide ionic transport through the ionically resistive element during electroplating, and 
 wherein the ionically resistive element comprises a plurality of ribs positioned on the substrate-facing side of the ionically resistive element, wherein the plurality of ribs comprises a first plurality of ribs of full maximum height and a second plurality of ribs of smaller maximum height than the full maximum height; 
   (c) flowing electrolyte in contact with the substrate in the substrate holder (i) from a side inlet, into the gap, and out a side outlet, wherein the side inlet and side outlet are designed or configured to generate cross flowing electrolyte in the gap during electroplating;   (d) rotating the substrate holder; and   (e) electroplating material onto the plating face of the substrate while flowing the electrolyte as in (c).   
     
     
         24 . The method of  claim 23 , wherein the electroplated material comprises tin and silver. 
     
     
         25 . The method of  claim 23 , wherein the electroplated material comprises copper. 
     
     
         26 . The method of  claim 23 , further comprising the steps of:
 applying photoresist to the semiconductor substrate;   exposing the photoresist to light;   patterning the photoresist and transferring the pattern to the semiconductor substrate;   and selectively removing the photoresist from the semiconductor substrate.   
     
     
         27 . A non-transitory computer machine-readable medium comprising program instructions for control of an apparatus configured for substrate processing, wherein the program instructions comprise code configured to effect electrodeposition of material in accordance with the method of  claim 23 .