Additive-Assisted Nucleation and Growth of Thin Films: Controlled Experiments and Multiscale Simulations
Willis, Matthew P.
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Permalink
https://hdl.handle.net/2142/82420
Description
Title
Additive-Assisted Nucleation and Growth of Thin Films: Controlled Experiments and Multiscale Simulations
Author(s)
Willis, Matthew P.
Issue Date
2008
Doctoral Committee Chair(s)
Alkire, Richard C.
Department of Study
Chemical Engineering
Discipline
Chemical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Chemical
Language
eng
Abstract
An electron-beam-lithography (EBL) method was used to fabricate a region of uniformly repeated surface features of Cu on a Au film. Experiments were performed to evaluate how the (1) additives, (2) applied potential, and (3) seed spacing affect the trade-off between seed cluster growth and wild nucleation during copper electrodeposition. Additive compositions that served to suppress the deposition rate (high chloride (10 ppm) and high PEG (3000 ppm)) slowed the deposition rate on the Cu seeds and increased the level of wild nucleation on the Au substrate. Decreased levels of PEG (3 ppm) and chloride (0.1 ppm) served to decrease the level of wild nucleation and also to slightly increase the deposition rate on the Cu seeds. Elevated levels of SPS served to increase the deposition rate slightly and thus increase the Cu seed growth rate, while decreased levels of SPS depressed the rate of Cu seed growth. The SPS concentration had little impact on the level of wild nucleation. The level of chloride concentration was found to be able to mediate the extent of seed growth versus wild nucleation. Low levels of chloride (0.1 ppm) yielded growth only at the Cu seeds (average seed size 72.5 +/- 7.7 nm after 1 second of deposition) with zero wild nuclei. Progressively higher levels of chloride, 1 and 10 ppm, yielded lower deposition rates at the Cu seeds (average seed size 65.1 +/- 7.1 and 24.4 +/- 5.1 nm for 1 and 10 ppm Cl-, respectively) and proportionally higher levels of wild nucleation (6.6 +/- 0.1 x 10 9 and 9.8 +/- 0.4 x 109 cm-2 (200 nm seed spacing) for 1 and 10 ppm Cl-, respectively). Island dynamic simulations for copper deposition onto a patterned gold substrate were compared to experimental observations. The computational results were qualitatively similar to the additive trends observed experimentally. However, the simulations indicated that the additive composition had little impact on the seed growth rate, which contrasts with experimental observations. The integration of the current experimental data with improved mathematical models for predicting nucleation and growth dynamics holds promise for improved engineering procedures for the design of additive systems. (Abstract shortened by UMI.).
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