Modulation of applied current during sealed rotational electroplating

Abstract

The embodiments herein relate to methods and apparatus for electroplating one or more materials onto a substrate. Typically, the embodiments herein utilize a channeled plate positioned near the substrate, creating a cross flow manifold between the channeled plate and substrate, and on the sides by a flow confinement ring. A seal may be provided between the bottom surface of a substrate holder and the top surface of an element below the substrate holder (e.g., the flow confinement ring). During plating, the apparatus may switch between a sealed state and an unsealed state, for example by lowering and lifting the substrate and substrate holder as appropriate to engage and disengage the seal. A higher level of applied current or applied voltage may be provided to the substrate when the apparatus is in the sealed state compared to the unsealed state.

What is claimed is: 
     
         1 . A method for electroplating on a substrate, the method comprising:
 (a) receiving a substrate in a substrate holder, where the substrate holder is configured to hold the substrate such that a plating face of the substrate is separated from an anode during electroplating;   (b) immersing the substrate in electrolyte, where a gap is formed between the plating face of the substrate and an upper surface of an ionically resistive element, the gap forming a cross flow manifold, wherein the ionically resistive element is adapted to provide ionic transport through the ionically resistive element during electroplating;   (c) flowing electrolyte in contact with the substrate in the substrate holder from below the ionically resistive element, through the ionically resistive element, into the cross flow manifold, and out a side outlet;   (d) modulating the cross flow manifold between a sealed state and an unsealed state by engaging and disengaging a sealing member proximate the cross flow manifold;   (e) modulating a current or voltage applied to the substrate, wherein a first current or first voltage is applied to the substrate when the cross flow manifold is in the sealed state, wherein a second current or second voltage is applied to the substrate when the cross flow manifold is in the unsealed state, and wherein the second current or second voltage is lower than the first current or first voltage, respectively; and   (f) electroplating material onto the plating face of the substrate while flowing electrolyte as stated in (c) and while modulating the cross flow manifold and the current or voltage applied to the substrate as stated in (d) and (e).   
     
     
         2 . The method of  claim 1 , wherein when the sealing member is engaged, the cross flow manifold is in the sealed state, and when the sealing member is not engaged, the cross flow manifold is in the unsealed state, wherein electroplating material in (f) comprises
 (i) electroplating material while rotating the substrate when the cross flow manifold is in the unsealed state,   (ii) electroplating material while engaging the sealing member to seal the cross flow manifold,   (iii) electroplating material while maintaining the substrate rotationally stationary when the cross flow manifold is in the sealed state, and   (iv) electroplating material while disengaging the sealing member to unseal the cross flow manifold.   
     
     
         3 . The method of  claim 2 , wherein operations (i)-(iv) of electroplating material in (f) are performed at least three times during electroplating on the substrate. 
     
     
         4 . The method of  claim 1 , wherein the cross flow manifold is in the sealed state for more than half of a total plating time. 
     
     
         5 . The method of  claim 1 , wherein no more than a negligible amount of material is electroplated onto the substrate when the cross flow manifold is in the unsealed state. 
     
     
         6 . The method of  claim 1 , wherein (d) and (e) comprise:
 (i) lowering the substrate holder such that the sealing member is engaged and the cross flow manifold reaches the sealed state,   (ii) increasing an applied current or an applied voltage applied to the substrate to thereby apply a first current or first voltage to the substrate while the cross flow manifold is in the sealed state,   (iii) raising the substrate holder such that the sealing member is not engaged and the cross flow manifold reaches the unsealed state, and   (iv) decreasing the applied current or applied voltage applied to the substrate to thereby apply a second current or second voltage to the substrate while the cross flow manifold is in the unsealed state, wherein the second current or second voltage is lower than the first current or first voltage, respectively.   
     
     
         7 . The method of  claim 6 , wherein the applied current or applied voltage begins increasing toward the first current or first voltage in (ii) only after the cross flow manifold reaches the sealed state in (i). 
     
     
         8 . The method of  claim 7 , wherein the substrate holder is raised in (iii) only after the applied current or applied voltage reaches the second current or second voltage in (iv). 
     
     
         9 . The method of  claim 6 , further comprising waiting for a duration between about 100-500 ms after instructing a power supply to apply the second current or second voltage to the substrate in (iv) and before raising the substrate holder in (iii). 
     
     
         10 . The method of  claim 6 , wherein the applied current or applied voltage is increased to a magnitude above a magnitude of the second current or second voltage only when the cross flow manifold is in the sealed state. 
     
     
         11 . The method of  claim 1 , wherein the first current or first voltage would exceed a limiting current or limiting voltage, respectively, if applied to the substrate when the cross flow manifold is in the unsealed state. 
     
     
         12 . The method of  claim 1 , wherein when the cross flow manifold is in the unsealed state, the apparatus comprises a leakage gap between the substrate holder and a flow confinement element, wherein the leakage gap is wholly or partially sealed when the cross flow manifold is in the sealed state. 
     
     
         13 . The method of  claim 12 , wherein the sealing member seals at least about 75% of the leakage gap when the cross flow manifold is in the sealed state. 
     
     
         14 . The method of  claim 13 , wherein the sealing member seals about 100% of the leakage gap between when the cross flow manifold is in the sealed state. 
     
     
         15 . 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 including a substrate-facing surface that is separated from the plating face of the substrate by a gap, the gap forming a cross flow manifold between the ionically resistive element and the substrate, wherein the ionically resistive element is adapted to provide ionic transport through the ionically resistive element during electroplating;   (d) a side outlet to the cross flow manifold for receiving electrolyte flowing in the cross flow manifold;   (e) a sealing member for wholly or partially sealing one or more outlets to the cross flow manifold other than the side outlet; and   (f) a controller comprising executable instructions for electroplating material onto the substrate by:
 (i) lowering the substrate holder such that the sealing member is engaged and the cross flow manifold reaches a sealed state, 
 (ii) increasing an applied current or an applied voltage applied to the substrate to thereby apply a first current or first voltage to the substrate while the cross flow manifold is in the sealed state, 
 (iii) raising the substrate holder such that the sealing member is not engaged and the cross flow manifold reaches an unsealed state, and 
 (iv) decreasing the applied current or applied voltage applied to the substrate to thereby apply a second current or second voltage to the substrate while the cross flow manifold is in the unsealed state, wherein the second current or second voltage is lower than the first current or first voltage, respectively. 
   
     
     
         16 . The apparatus of  claim 15 , wherein the controller comprises executable instructions for repeating (i)-(iv) throughout at least a portion of the electroplating material onto the substrate. 
     
     
         17 . The apparatus of  claim 15 , wherein the controller further comprises executable instructions for rotating the substrate while the apparatus is in the unsealed state. 
     
     
         18 . The apparatus of  claim 17 , wherein the controller further comprises executable instructions for not rotating the substrate while the apparatus is in the sealed state. 
     
     
         19 . The apparatus of  claim 15 , wherein the controller comprises executable instructions to (1) begin increasing the applied current or applied voltage in (ii) only after the substrate holder is lowered and the cross flow manifold reaches the sealed state in (i), and to (2) begin raising the substrate holder to unseal the cross flow manifold in (iii) only after the second current or second voltage is applied to the substrate in (iv). 
     
     
         20 . The apparatus of  claim 15 , further comprising a flow confinement element positioned peripherally in the cross flow manifold between the ionically resistive element and the substrate holder.