Dynamically variable field shaping element
AssigneeNovellus Systems, Inc.
InventorsRobert J. Contolini, Andrew J. McCutcheon, Steven T. Mayer
Life of this patent
Estimating the term…
Abstract
In an electrochemical reactor used for electrochemical treatment of a substrate, for example, for electroplating or electropolishing the substrate, one or more of the surface area of a field-shaping shield, the shield's distance between the anode and cathode, and the shield's angular orientation is varied during electrochemical treatment to screen the applied field and to compensate for potential drop along the radius of a wafer. The shield establishes an inverse potential drop in the electrolytic fluid to overcome the resistance of a thin film of conductive metal on the wafer.
Claims27
A method of performing electrochemical operations, including electroplating and electropolishing, in an electrochemical reactor with use of an inflatable bladder to shield a portion of surface area of an object from applied field to improve control of thickness profile, said method comprising:
- retaining an object between a cathode and an anode in an electrochemical reactor to present a surface of said object for electrochemical reaction;
- applying an electric field by flowing current through an electrolyte between said cathode and said anode in said electrochemical reactor;
- and
- dynamically inflating or deflating an inflatable bladder during an electrochemical operation to shield a corresponding portion of surface area of said surface from a portion of said applied electric field.
An apparatus having a variable field-shaping capability for use in electropolishing a surface of a substrate, comprising:
- a container for holding electrolytic fluid;
- a cathode disposed in said container;
- a substrate holder configured to present a surface of a substrate for electrochemical reaction;
- a shield disposed in said container between said cathode and said substrate holder, said shield configured for shielding a portion of said surface of said substrate;
- and
- a means, operable during electropolishing operations, for dynamically varying a parameter selected from the group consisting of:
- a quantity of shielded surface area of a substrate, a distance separating said shield from said substrate holder, a distance separating said substrate holder from said cathode, and combinations thereof.
A method of electropolishing a surface of a substrate, comprising:
- providing electrolytic fluid in a container, said container containing a cathode, and said container further containing a shield;
- immersing a substrate held in a substrate holder into said electrolytic fluid, such that said shield is disposed between a surface of said substrate and said cathode;
- applying an electric field by flowing current between said surface and said cathode through said electrolytic fluid such that said shield shields a portion of surface area of said substrate from a portion of said applied electric field;
- and
- actuating said shield to vary dynamically said applied electric field around said substrate holder during electropolishing operations,
- wherein said actuating a shield includes actuating said shield during electropolishing operations to vary dynamically a parameter selected from the group consisting of:
- a quantity of shielded surface area of said substrate;
- a distance separating said shield from said substrate;
- a distance separating said substrate from said cathode;
- and combinations thereof.
Dependencies are inferred from the claim text.