Electrochemical methods for the formation of protective features on metallized features

Abstract

Electrochemical processes and apparatus are described for forming a protective feature on the exposed surface of a metallized feature. The protective feature provides a diffusion barrier and protects the metallized feature from corrosion and contamination. Protective features formed from nickel, cobalt, and alloys of these metals are described.

Description

FIELD OF THE INVENTION [0001] The present invention relates to electrochemical methods for the formation of protective features on metallized features formed on microelectronic workpieces. BACKGROUND OF THE INVENTION [0002] A microelectronic workpiece can have repeating layers of insulating regions and conducting regions bonded to one another. An inherent problem when joining two dissimilar materials is a tendency of one or both materials to migrate or diffuse across the common interface into the other material. Thus, in order to be effective, the materials chosen to form the insulating regions and the conducting regions must be properly isolated from each other so that one material does not diffuse into the adjacent dissimilar material. [0003] Typically, metals have been used as materials for conducting regions. Metals can be used to form interconnections between differing layers or regions, or they can be used to form intraconnections in the same layer. The newest generation of mi...

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Benefits of technology

[0009] The present invention provides electrochemical methods for encapsulating conductive features, such as copper features, to prevent diffusion of copper into surrounding structures such as dielectrics deposited over the conductive features and to prevent diffusion of undesired materials into the conductive features themselves. The present invention achieves this goal by encapsulating a metallized feature formed on a microelectronic workpiece with a conductive protective feature, wherein a surface of the metallized feature is covered by the conductive protective feature prior to deposition of a dielectric material over the metallized feature.

[0015] The methods and apparatuses of the present invention provide for the selective and controllable deposition of a conductive protective feature onto an exposed metallized feature that isolates the exposed top surface(s) from a layer of dielectric deposited after the metallized feature is formed. In a preferred embodiment, the metallized feature is encapsulated by the protective feature. The method of the present invention provides a protective feature on the metallized feature and does not suffer from the nonselective nature of prior processes for depositing diffusion barrier layers and is a more controllable and less costly alternative to sputter deposition, and physical or chemical vapor deposition techniques.

Problems solved by technology

An inherent problem when joining two dissimilar materials is a tendency of one or both materials to migrate or diffuse across the common interface into the other material.

While copper exhibits desirable conductivity and resistivity characteristics, it has been found to have a high tendency to diffuse into surrounding dielectric materials or corrode, which degrades the integrity of the interconnection features as well as the surrounding devices or dielectric structures.

Sputter deposition and physical or chemical vapor deposition, however, are costly because they involve time-consuming processing steps when compared to electrochemical deposition processes.

Furthermore, such processes are nonselective and are less than desirable when it comes to deposition on vertically oriented features or features with high aspect ratios.

When dielectric is deposited over these sidewalls, the possibility for diffusion of the copper into the dielectric and corrosion of the copper exists.

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