Plating method

Abstract

A plating method can form a plated film having a uniform thickness over the entire surface, including the peripheral surface, of a substrate. The plating method includes: disposing an anode so as to face a conductive film, formed on a substrate, which serves as a cathode, and disposing an auxiliary cathode on an ring-shaped seal member for sealing a peripheral portion of the substrate; bringing the conductive film, the anode and the auxiliary cathode into contact with a plating solution; and supplying electric currents between the anode and the conductive film, and between the anode and the auxiliary cathode to carry out plating.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a plating method, and more particularly to a plating method used for filling interconnect recesses formed in a surface of a substrate, such as a semiconductor wafer, with an electrical conductor (interconnect material), such as copper or silver, so as to form interconnects.[0003]2. Description of the Related Art[0004]In recent years, instead of using aluminum or aluminum alloys as a metallic material for forming interconnect circuits on a semiconductor substrate; there is an eminent movement towards using copper (Cu) that has a low electric resistivity and high electromigration resistance. Copper interconnects are generally formed by filling copper into fine interconnect recesses formed in a surface of a substrate. Various techniques are known for forming such copper interconnects, including CVD, sputtering, and plating. According to any such technique, a copper film is formed in a subst...

AI Technical Summary

Benefits of technology

[0008]In recent years, the sizes of trenches and contact holes are becoming smaller for the purpose of increasing the integration density of semiconductor devices. With the trend toward smaller-sized trenches and contact holes, the following problem has become serious: When a seed layer 7 having a conventional thickness is formed on a surface of a barrier layer 5 which covers surfaces of smaller-sized trenches 4 and contact holes 3, the seed layer 7 may considerably hang inwardly over the openings of the trenches 4 and contact holes 3 such that it blocks in the openings, thus narrowing the openings, as shown in FIG. 2. This impedes electrode position of copper in the trenches 4 and contact holes 3 in the next plating step, whereby voids are likely to be formed within the interconnects formed of a plated film, lowering the reliability of the interconnects.

[0024]The plating method of the present invention makes it possible to easily correct a thickness profile of a plated film simply by adjusting the current applied to the auxiliary cathode. This enables a lower-cost and flexible apparatus operation in a semiconductor device manufacturing process. Further, the provision of the auxiliary cathode in the seal member by forming the auxiliary cathode integrally with the seal member or fixing the auxiliary cathode on the seal member, can secure good accessibility of the maintenance worker to the auxiliary cathode, facilitating maintenance of the apparatus.

Problems solved by technology

This impedes electrode position of copper in the trenches 4 and contact holes 3 in the next plating step, whereby voids are likely to be formed within the interconnects formed of a plated film, lowering the reliability of the interconnects.

When carrying out CMP or the like of the substrate, having such a thick plated film formed in the peripheral region, to remove an extra plated film and flatten an entire surface of the substrate, a longer processing (polishing) time is needed in a CMP process or the like, thus lowering the productivity.

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