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Bath Additive and Current Density Effects on Copper Electroplating Fill of Cu Damascene Structures

Published online by Cambridge University Press:  10 February 2011

Robert D. Mikkola
Affiliation:
Sematech, 2706 Montopolis Dr., Austin, TX 78741. APRDL, Motorola Inc., 3501 Ed Bluestein Boulevard, Austin, TX 78721.
Qing-Tang Jiang
Affiliation:
Sematech, 2706 Montopolis Dr., Austin, TX 78741. National Semiconductor Inc., 2900 Semiconductor Dr., Santa Clara, CA 95052.
Ronald Carpio
Affiliation:
Sematech, 2706 Montopolis Dr., Austin, TX 78741.
Brad Carpenter
Affiliation:
Semitool Inc., 655 West Reserve Dr., Kalispell, MT 59901.
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Abstract

Copper electroplating has become the leading technology for gap fill of damascene structures on advanced interconnects. A key to developing a robust electroplating process that produces deposits free of voids and seams is understanding the role of the additive components, i.e., levelers, brighteners and wetting agents, and their relative diffusion/adsorption characteristics. Additionally, obtaining insight about the cathodic current/potential relationship is critical for maximizing the effectiveness of the additive components.

Our results indicate that bath additive composition and the plating parameters (plating pulse frequency, and current density play critical roles in the outcome of the Cu fill. SEM cross sectional analysis of timed partial electroplating fill studies show two types of fill, 1) conformal and 2) bottom-up. Conformal fill of features smaller than 0.25 μm with an aspect ratio (AR) of 4.0 tends to form seam voids in the center of the structure. These seam voids can lead to early electromigration failures. On the other hand, bottom-up fill leads to a void free Cu deposit within the feature.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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