Electrolytic processing apparatus and method

Abstract

The present invention provides an electrolytic processing apparatus which can suppress the growth of a gas, which is inevitably generated during electrochemical processing, into bubbles thereby effectively preventing the formation of pits in a surface of a workpiece. The electrolytic processing apparatus includes an electrode section (44) including processing electrodes (76) and feeding electrodes (78) both having a diameter of not more than 1 mm, a substrate holder (42) for holding a workpiece (W), a power source (46) for applying a voltage between the processing electrodes and the feeding electrodes, a fluid supply section (72) for supplying a fluid between the electrode section and the workpiece, and a drive section (56, 62) for moving the electrode section and the workpiece relative to each other in such a manner that the processing electrodes pass every point in a processing surface of the workpiece.

Description

TECHNICAL FIELD [0001] This invention relates to an electrolytic processing apparatus and method, and more particularly to an electrolytic processing apparatus and method useful for processing a conductive material formed in a surface of a substrate, such as a semiconductor wafer, or for removing impurities adhering to a surface of a substrate. BACKGROUND ART [0002] In recent years, instead of using aluminum or aluminum alloys as a material for forming circuits on a substrate such as a semiconductor wafer, there is an eminent movement towards using copper (Cu) which has a low electric resistivity and high electromigration endurance. Copper interconnects are generally formed by filling copper into fine recesses formed in the surface of a substrate. There are known various techniques for forming such copper interconnects, including chemical vapor deposition (CVD), sputtering, and plating. According to any such technique, a copper film is formed in the substantially entire surface of a...

AI Technical Summary

Benefits of technology

"The present invention provides an electrolytic processing apparatus and method that can prevent the formation of pits in a surface of a workpiece during processing. The apparatus includes an electrode section with a plurality of processing electrodes and feeding electrodes, which are electrically isolated from each other. A substrate holder holds the workpiece close to the electrode section, and a power source applies a voltage between the processing electrodes and the feeding electrodes. A fluid supply section supplies a fluid between the electrodes and the workpiece. The apparatus removes processing by the interaction of reactant ions and the workpiece, resulting in a higher density of hydroxide ions near the surface of the workpiece. The apparatus uses a liquid with low resistivity to reduce the voltage applied and power consumption. The apparatus can perform removal processing without impairing the properties of the material being processed. The use of ultrapure water as the electrolyte reduces contamination of the surface of the workpiece. The electrodes and workpiece are moved relative to each other to carry out processing."

Problems solved by technology

Under these circumstances, with a conventional mechanical processing method in which a processing object in a workpiece is physically destroyed and removed from the workpiece by a tool, many defects may be produced, deteriorating the properties of the workpiece.

Such an obstacle may include a processing product which is generated during processing by the electrochemical reaction between the workpiece and the ions at the surface of the workpiece, a substance produced and released from an ion exchanger during a relative movement between the ion exchanger and the workpiece, and bubbles (gas) generated by a side reaction at the surfaces of the workpiece and the electrode, etc.

Such an obstacle, present between the electrode and the workpiece, impedes the migration of ions, and therefore prevents obtaining a constant and uniform processing amount.

Bubbles, in particular, can also cause the formation of pits in the surface of the workpiece.

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