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Lindsay Boehme - PhD Dissertation.pdf (4.17 MB)

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Additives Screening Techniques and Process Characterization for Electroplating of Semiconductor Interconnects

Boehme, Lindsay Erin
http://rave.ohiolink.edu/etdc/view?acc_num=case1402058542

Abstract Details

2014, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
All semiconductor devices incorporate metallic interconnects, which provide the electrical network within the device. The interconnects are fabricated by electroplating copper from electrolytes containing special additives, enabling bottom-up fill of the vias and trenches. The study herein focuses on identifying new additives screening techniques and characterizing the associated process parameters through systematic experimental investigation and analytical modeling. A new improved test for characterizing the efficacy of the additives system has been developed and validated as a replacement for the classical injection technique. Results of the test have been implemented in a quantitative model indicating the expected gap-fill in wafer plating of small features. Additionally, a computer-based model of the additives co-injection test has been developed. This model accounts for the flow field external to the features and characterizes the actual wafer plating process more precisely than previous models. Fitting experimental data to the model provides more accurate estimates of process parameters, including additive adsorption rates, than heretofore possible. Several process parameters were characterized. Temperature was found to affect additives (polyethylene glycol [PEG] serving as a suppressor and bis(3-sulfopropyl) disulfide [SPS] serving as anti-suppressor) activity. An optimal process temperature of ~30oC was identified, where the SPS depolarized electrode reverts to pure copper plating kinetics and maximal polarization is achieved. The effects of pH, in the range 0.5-2, on the deposition kinetics were found to be minor; however, corresponding effects on seed stability were substantial, with improved seed stability at the higher pH. Substituting chloride with bromide provided slight improvement in the deposition kinetics. With bromide, displacement of the suppressor by the anti-suppressor was slow compared to displacement in the presence of chloride, possibly indicating stronger binding of the suppressor to the copper substrate. The effect of PEG molecular weight was studied. PEG 4000 was found to provide optimal adsorption and displacement rates. Commercially available compounds were tested for suppression capability. Pluronic L31 exhibited the largest polarization (220 mV at a current density of 10 mA/cm2) among the tested additives.
Uziel Landau (Advisor)
Rohan Akolkar (Committee Member)
Heidi Martin (Committee Member)
Daniel Scherson (Committee Member)
Robert Preisser (Committee Member)
197 p.
Chemical Engineering
Additives Screening, Plating Additives, Copper Electroplating, Semiconductor Interconnect, Bottom-up Fill, Electrochemical Modeling

Recommended Citations

Citations

  • Boehme, L. E. (2014). Additives Screening Techniques and Process Characterization for Electroplating of Semiconductor Interconnects [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1402058542

    APA Style (7th edition)

  • Boehme, Lindsay. Additives Screening Techniques and Process Characterization for Electroplating of Semiconductor Interconnects. 2014. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1402058542.

    MLA Style (8th edition)

  • Boehme, Lindsay. "Additives Screening Techniques and Process Characterization for Electroplating of Semiconductor Interconnects." Doctoral dissertation, Case Western Reserve University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402058542

    Chicago Manual of Style (17th edition)

case1402058542
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© 2014, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.