Electroplating apparatus

Abstract

A electroplating apparatus which is suitable for depositing a metal layer of substantially uniform thickness across the center and edge regions of a semiconductor wafer substrate is disclosed. The apparatus includes a reservoir for containing an electrolytic fluid. A cathode, to which is mounted a wafer, and an anode in the electrolytic fluid are connected to an electroplating current source. A shield is provided between the cathode and anode to facilitate a more uniform deposit of the metal onto the wafer across the entire surface, including the center and edge regions, of the wafer.

Description

FIELD OF THE INVENTION [0001] The present invention relates to electrochemical plating (ECP) apparatuses and processes used to deposit metal layers on semiconductor wafer substrates in the fabrication of semiconductor integrated circuits. More particularly, the present invention relates to an elecroplating apparatus which includes a shield interposed between an anode and a cathode to reduce the electroplating deposition rate at the edge region of a substrate and facilitate deposition of a metal film having a substantially uniform thickness across the entire surface of a wafer. BACKGROUND OF THE INVENTION [0002] In the fabrication of semiconductor integrated circuits, metal conductor lines are used to interconnect the multiple components in device circuits on a semiconductor wafer. A general process used in the deposition of metal conductor line patterns on semiconductor wafers includes deposition of a conducting layer on the silicon wafer substrate; formation of a photoresist or oth...

AI Technical Summary

Benefits of technology

[0021] In accordance with these and other objects and advantages, the present invention is generally directed to a novel electroplating apparatus which is suitable for depositing a metal layer of substantially uniform thickness across the center and edge regions of a semiconductor wafer substrate. The apparatus includes a reservoir for containing an electrolytic fluid. A cathode, to which is mounted a wafer, and an anode in the electrolytic fluid are connected to an electroplating current source. A shield is provided between the cathode and anode to facilitate a more uniform deposit of the metal onto the wafer across the entire surface, including the center and edge regions, of the wafer.

[0023] The electrically-conductive shield may be connected to a shield current source. A switch may be provided between the shield current source and the shield. The switch may be manipulated to apply a negative charge to the shield, in which case the shield acts as a cathode and reduces the quantity of metal cations in the electrolytic fluid in the area adjacent to the edge region as compared to the area adjacent to the center region of the wafer. Consequently, the electroplating metal deposition rate at the edge region is reduced to compensate for the normally lower metal deposition rate at the center region of the wafer, thus enhancing the overall thickness uniformity of the electroplated metal.

[0024] The switch may be manipulated to apply a positive charge to the shield, in which case the shield acts as an anode. Accordingly, the concentration of metal cations in the electrolytic fluid in the area adjacent to the edge region relative to the center region of the wafer is increased, to increase the electroplating deposition rate of the metal onto the edge region of the wafer, as deemed necessary. By the alternating application of positive and negative charges to the wafer using the switch, the thickness of metal electroplated onto the edge region of the wafer can be precisely controlled to provide a layer of electroplated metal having a substantially uniform thickness across the entire surface of the wafer.

Problems solved by technology

Due to the ever-decreasing size of semiconductor components and the ever-increasing density of integrated circuits on a wafer, the complexity of interconnecting the components in the circuits requires that the fabrication processes used to define the metal conductor line interconnect patterns be subjected to precise dimensional control.

These voids or open circuits may cause device failure or burn-in.

However, one of the drawbacks of the conventional electroplating system 10 is that the current density at the contact ring 24 is higher than the current density at the central region of the wafer 22.

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