Electrodeposition of copper in an alternating electric field Nicholas LeCompte, Prof. Daniel Lathrop
Electrodeposition of copper in an alternating electric field
Nicholas LeCompte, Prof. Daniel Lathrop
Process – DC Electrodeposition●Electrocell: two copper electrodes in a cupric sulfate solution
●Cu – 2e- → Cu 2+ oxidation at the anode, ion released
●ions flow across electrocell under electric field governed by Laplace equation, with on the cathode
●Cu 2+ + 2e- → Cu reduction at the cathode, sticks to electrode
Mullins-Sekerka instability causes growth to become nonuniform and ramified
∇2V≈0
V=V 0
Motivation – AC ElectrodepositionScientific:
● First (to our knowledge) direct experimental study of Laplacian pattern formation with non-constant boundary condition● Study of AC-biased electrochemistry
Applications:
● Electroplating shown to be smoother under AC field conditions● Formation of nanoscale electronics
Figure taken from J. Xu, K. Wang, Y. Xu 2007. Chemistry Letters 36 868
Procedure
2D experiments
3D experiments
VAC VDC 2.0 4.0 3.0 3.0 5.0 2.5 6.0 2.0
VAC = 5.0VVDC = 5.0V
Prediction:
δ= Dc
f
Results
●δ ~ f -0.12± 0. 04
●Poor agreement with expectation
● However, we still showed monotonic decrease in length scale w / increasing frequency
●Possible explanation of increasing uniformity on phase diagram
For more information, please visit my poster.
Acknowledgements
Thanks to:
●Doug Kelley, Daniel Lathrop, Don Martin, Matt Paoletti, Santiago Triana, Daniel Zimmerman, and the rest of Lathrop Lab for their technical assistance, valuable discussions, amusing lunches, and the cowbell
● the FabLab for their friendliness and donation of deionized water