Method and apparatus for spatially uniform electropolishing and electrolytic etching

An apparatus for electropolishing and electrolytically etching a workpiece, comprising;

• a containment vessel for containing electrolytic solution;
• a cathode mounted in the containment vessel;
• a substantially flat anode containing the workpiece positioned in the containment vessel;
• separation means positioned between the anode and cathode for preventing bubble transport from the cathode to the anode and for passing electric current between the cathode and anode;
• wherein the anode comprises a holder and means for retaining the workpiece thereon;
• wherein the holder comprises an outer portion and an inner recessed region wherein the workpiece fits within the recessed region with its top surface substantially flush with the top surface of the outer portion.

An apparatus for electropolishing and electrolytically etching a workpiece, comprising:

• a containment vessel for containing electrolytic solution;
• a cathode mounted in the containment vessel;
• a substantially flat anode containing the workpiece positioned in the containment vessel;
• separation means positioned between the anode and cathode for preventing bubble transport from the cathode to the anode and for passing electric current between the cathode and anode;
• a power supply electrically connected to the anode and cathode;
• a reference electrode positioned in the containment vessel and connected to the power supply to maintain stability of anode voltage.

An apparatus for electropolishing and electrolytically etching a workpiece, comprising:

• a containment vessel for containing electrolytic solution;
• a cathode mounted in the containment vessel;
• a substantially flat anode containing the workpiece positioned in the containment vessel;
• separation means positioned between the anode and cathode for preventing bubble transport from the cathode to the anode and for passing electric current between the cathode and anode;
• fluid inlets and outlets for directing electrolytic solution into and out of the containment vessel;
• wherein the fluid inlets are positioned to direct electrolytic solution against the anode.

An apparatus for electropolishing and electrolytically etching a workpiece, comprising:

• a containment vessel for containing electrolytic solution;
• a cathode mounted in the containment vessel;
• a substantially flat anode containing the workpiece positioned in the containment vessel;
• separation means positioned between the anode and cathode for preventing bubble transport from the cathode to the anode and for passing electric current between the cathode and anode;
• endpoint detection means for shutting off anode current when polishing or etching is completed.

A method for electropolishing and electrolytically etching a workpiece, comprising:

• electrically connecting the workpiece to a substantially flat anode of a voltage source;
• placing the anode and a cathode in an electrolytic solution;
• rotating the anode;
• flowing a current of sufficient density through the anode to electropolish or electrolytically etch the workpiece;
• separating the anode from the cathode by separation means which prevent bubble transport from the cathode to the anode and pass electric current between the cathode and anode, the separation means being configured to produce substantially uniform current distribution at the anode.

A method for electropolishing and electrolytically etching a workpiece, comprising:

• electrically connecting the workpiece to a substantially flat anode of a voltage source;
• forming the anode of a holder and means for retaining the workpiece thereon;
• placing the anode and a cathode in an electrolytic solution;
• flowing a current of sufficient density through the anode to electropolish or electrolytically etch the workpiece;
• separating the anode from the cathode by separation means which prevent bubble transport from the cathode to the anode and pass electric current between the cathode and anode, the separation means being configured to produce substantially uniform current distribution at the anode.

A method for electropolishing and electrolytically etching a workpiece, comprising:

• electrically connecting the workpiece to a substantially flat anode of a voltage source;
• placing the anode and a cathode in an electrolytic solution;
• flowing a current of sufficient density through the anode to electropolish or electrolytically etch the workpiece;
• separating the anode from the cathode by separation means which prevent bubble transport from the cathode to the anode and pass electric current between the cathode and anode, the separation means being configured to produce substantially uniform current distribution at the anode;
• recirculating and filtering the electrolytic solution.

A method for electropolishing and electrolytically etching a workpiece, comprising:

• electrically connecting the workpiece to a substantially flat anode of a voltage source;
• placing the anode and a cathode in an electrolytic solution;
• flowing a current of sufficient density through the anode to electropolish or electrolytically etch the workpiece;
• separating the anode from the cathode by separation means which prevent bubble transport from the cathode to the anode and pass electric current between the cathode and anode, the separation means being configured to produce substantially uniform current distribution at the anode;
• detecting an endpoint on the workpiece that has been completely electropolished or etched and shutting off anode current when the endpoint is detected.

Apparatus for electropolishing/electrolytic etching a workpiece, comprising:

• a containment vessel;
• a cathode mounted in the vessel;
• an extended anode positioned horizontally face down in the vessel and having the workpiece mounted thereon, with a sacrificial polishable/etchable border of the same material as the workpiece surrounding and flush with the workpiece;
• a voltage source electrically connected to the anode and cathode;
• an electropolishing/etching solution filling the vessel;
• means for rotating the anode connected thereto;
• a solid nonconducting barrier surrounding the anode and separating the anode from the cathode, the barrier extending below the level of the cathode to prevent bubble transport from the cathode to the anode and having a base raised from the bottom of the vessel and containing a virtual cathode aperture in the base which allows current flow from the cathode to the anode, the barrier and aperture being configured to provide substantially uniform current distribution at the anode;
• a reference electrode positioned in the barrier and electrically connected to the voltage source to maintain a stabilized anode voltage;
• solution inlet/outlet means extending into the vessel and into the barrier;
• vertical baffles mounted in the barrier extending radially around the virtual cathode aperture.

An apparatus for electropolishing and electrolytically etching a workpiece, comprising:

• a containment vessel for containing electrolytic solution;
• a cathode mounted in the containment vessel;
• a substantially flat anode containing the workpiece positioned in the containment vessel;
• a solid nonconducting barrier surrounding the anode and positioned between the anode and cathode for preventing bubble transport from the cathode to the anode, the barrier having a base spaced apart from the bottom of the containment vessel and a virtual cathode aperture formed in the base for passing electric current between the cathode and anode;
• wherein the aperture has a largest dimension less than the largest dimension of the anode, is separated from the anode by a distance larger than the largest anode dimension, and is sufficiently large to prevent charge crowding near its edge.