Method and apparatus to form a planarized Cu interconnect layer using electroless membrane deposition

Abstract

A planarized conductive material is formed over a substrate including narrow and wide features. The conductive material is formed through a succession of deposition processes. A first deposition process forms a first layer of the conductive material that fills the narrow features and at least partially fills the wide features. A second deposition process forms a second layer of the conductive material within cavities in the first layer. A flexible material can reduce a thickness of the first layer above the substrate while delivering a solution to the cavities to form the second layer therein. The flexible material can be a porous membrane attached to a pressurizable reservoir filled with the solution. The flexible material can also be a poromeric material wetted with the solution.

1 . A method for producing a planarized surface, comprising: 
 providing a substrate having a narrow feature and a wide feature defined therein;    forming a first layer above the substrate, the first layer 
 filling the narrow feature  
 at least partially filling the wide feature, and  
 having a cavity defined therein and aligned with the wide feature;  
   forming a sacrificial layer in the cavity; and    removing at least some of the first and sacrificial layers together in a planarization process.    
   
   
       2 . The method of  claim 1  wherein forming the sacrificial layer includes 
 contacting a flexible material with the first layer, and    introducing a relative lateral motion between the flexible material and the first layer.    
   
   
       3 . The method of  claim 2  wherein the relative lateral motion includes a rotational component.  
   
   
       4 . The method of  claim 2  wherein the relative lateral motion includes a vibrational component.  
   
   
       5 . The method of  claim 2  wherein the relative lateral motion includes an orbital component.  
   
   
       6 . The method of  claim 1  wherein the first layer completely fills the wide feature and removing at least some of the first and sacrificial layers includes completely removing the sacrificial layer.  
   
   
       7 . The method of  claim 1  wherein removing at least some of the first and sacrificial layers does not completely remove the sacrificial layer.  
   
   
       8 . The method of  claim 1  wherein removing at least some of the first and sacrificial layers includes a stress-free planarization.  
   
   
       9 . The method of  claim 1  wherein removing at least some of the first and sacrificial layers includes a Chemical Mechanical Planarization.  
   
   
       10 . The method of  claim 1  wherein removing at least some of the first and sacrificial layers includes exposing the substrate between the narrow and wide features.  
   
   
       11 . A method for producing a planarized surface, comprising: 
 providing a substrate including a narrow feature and a wide feature;    forming a first layer above the substrate, the first layer 
 filling the narrow feature,  
 at least partially filling the wide feature, and  
 including a cavity aligned with the wide feature;  
   contacting a flexible material with at least a portion of the first layer;    using the flexible material to deliver a solution to the cavity;    forming a sacrificial layer in the cavity from the solution; and    removing portions of the first layer and sacrificial layer.    
   
   
       12 . The method of  claim 11  wherein the substrate includes a dielectric material with a dielectric constant less than a dielectric constant of SiO 2 .  
   
   
       13 . The method of  claim 12  wherein the dielectric material includes OSG, FSG, or a low-k material.  
   
   
       14 . The method of  claim 11  wherein the narrow feature has a lateral dimension of about 100 mm or less.  
   
   
       15 . The method of  claim 11  wherein the wide feature has a lateral dimension greater than about 100 nm.  
   
   
       16 . The method of  claim 15  wherein the wide feature has a lateral dimension of about 500 μm.  
   
   
       17 . The method of  claim 11  wherein forming the first layer includes forming a first conductive layer by electrochemically depositing a conductive copper material.  
   
   
       18 . (canceled)  
   
   
       19 . (canceled)  
   
   
       20 . The method of  claim 11  wherein the flexible member includes a porous membrane.  
   
   
       21 . The method of  claim 20  further comprising pressurizing a reservoir containing the solution and adjoining the membrane on a side opposite a side contacting the first layer.  
   
   
       22 . The method of  claim 20  wherein the porous membrane includes a combination of polyurethane and an abrasive.  
   
   
       23 . The method of  claim 20  further comprising introducing a relative lateral motion between the porous membrane and the substrate.  
   
   
       24 . The method of  claim 23  wherein the porous membrane is effective to polish the portion of the first layer.  
   
   
       25 . (canceled)  
   
   
       26 . The method of  claim 11  wherein the flexible material includes a poromeric material including a closed-cell structure with open pores exposed at a surface thereof.  
   
   
       27 . (canceled)  
   
   
       28 . The method of  claim 26  further comprising wetting the poromeric material with the solution.  
   
   
       29 . The method of  claim 26  wherein delivering the solution to the cavity includes developing a pressure between the poromeric material and the first layer.  
   
   
       30 . The method of  claim 26  wherein delivering the solution to the cavity includes introducing a relative lateral motion between the substrate and the poromeric material.  
   
   
       31 . The method of  claim 11  wherein the solution includes an electroless plating solution.  
   
   
       32 . The method of  claim 11  wherein forming the second sacrificial layer includes forming a second conductive layer.  
   
   
       33 . The method of  claim 32  wherein forming the second conductive layer includes an electroless deposition of a conductive material.  
   
   
       34 . The method of  claim 33  wherein the conductive material is copper.  
   
   
       35 . The method of  claim 11  wherein removing portions of the first and sacrificial layers includes applying a stress-free polishing technique.  
   
   
       36 . The method of  claim 11  wherein forming the first layer includes completely filling the wide feature.  
   
   
       37 . The method of  claim 36  wherein the first layer forms an overfill above the wide feature that extends about 10% to about 20% of a depth of the wide feature above a level of a top surface of the substrate.  
   
   
       38 . The method of  claim 36  wherein removing portions of the first and sacrificial layers includes removing the sacrificial layer.  
   
   
       39 . The method of  claim 11  wherein forming the first layer includes filling less than the entire wide feature.  
   
   
       40 . The method of  claim 39  wherein about 10% to about 30% of a depth of the wide feature is filled by the first layer.  
   
   
       41 . The method of  claim 39  wherein removing portions of the first and sacrificial layers includes removing less than the entire sacrificial layer.  
   
   
       42 . The method of  claim 11  wherein the first and sacrificial layers are formed of the same conductive material.  
   
   
       43 . The method of  claim 11  wherein contacting the flexible material with at least the portion of the first layer inhibits the deposition of the sacrificial layer above an overburden of the first layer.  
   
   
       44 . An apparatus for producing a planarized surface, comprising: 
 a wafer support for securing a wafer having an area;    a workpiece including 
 a reservoir containing an electroless plating solution and having a flexible and porous membrane spanning a side;  
   an engagement mechanism capable of bringing the workpiece and the wafer into contact with each other; and    means for introducing a relative lateral motion between the workpiece and the wafer.    
   
   
       45 . The apparatus of  claim 44  wherein the reservoir is pressurizable.  
   
   
       46 . The apparatus of  claim 44  wherein the porous membrane has an area less than the area of the wafer.  
   
   
       47 . The apparatus of  claim 46  wherein the means for introducing relative lateral motion includes means for linearly translating the workpiece.  
   
   
       48 . The apparatus of  claim 47  wherein the means for introducing relative lateral motion further includes means for rotating the workpiece around an axis.  
   
   
       49 . The apparatus of  claim 46  wherein the means for introducing relative lateral motion includes means for rotating the wafer support around an axis.  
   
   
       50 . The apparatus of  claim 46  wherein the means for introducing relative lateral motion includes means for vibrating the workpiece.  
   
   
       51 . The apparatus of  claim 44  wherein the porous membrane has an area equal to or larger than the area of the wafer.  
   
   
       52 . The apparatus of  claim 51  wherein the means for introducing relative lateral motion includes means for rotating the wafer support around an axis.  
   
   
       53 . The apparatus of  claim 51  wherein the means for introducing relative lateral motion includes means for rotating the workpiece around an axis.  
   
   
       54 . The apparatus of  claim 44  wherein the wafer support is a vacuum chuck.  
   
   
       55 . The apparatus of  claim 44  wherein the porous membrane includes polyurethane.  
   
   
       56 . The apparatus of  claim 44  wherein the porous membrane includes a fluorocarbon material.  
   
   
       57 . The apparatus of  claim 44  wherein the porous membrane includes a sintered polymeric material.  
   
   
       58 . The apparatus of  claim 44  wherein the porous membrane includes a ceramic.  
   
   
       59 . The apparatus of  claim 44  wherein the porous membrane has a thickness between about 0.1 mm to about 3.0 mm.  
   
   
       60 . The apparatus of  claim 44  wherein the porous membrane includes open-cell pore structure.  
   
   
       61 . The apparatus of  claim 44  wherein the porous membrane includes a number of holes disposed therethrough.  
   
   
       62 . The apparatus of  claim 44  wherein the porous membrane includes an amount of porosity between about 5% to about 50%.  
   
   
       63 . The apparatus of  claim 44  wherein the porous membrane includes an amount of porosity between about 10% to about 20%.  
   
   
       64 . The apparatus of  claim 44  wherein the porous membrane includes an abrasive.  
   
   
       65 - 75 . (canceled)