Spatially Resolved Spectro-Electrochemistry Using Soft X-Ray Scanning Transmission X-Ray Microscopy

We are using soft X-ray scanning transmission X-ray microscopy (STXM) [1] at CLS beamline 10ID1 (SM) and at ALS beamline 5.3.2.2 to investigate Cu deposition onto, and stripping from a Au surface. Electrochemical reduction of Cu(II) under acid conditions is a commonly used process to deposit copper for integrated circuit interconnects. The reduction of Cu(II) to Cu(0) proceeds via a Cu(I) intermediate, which can be detected under neutral or basic conditions. Cu 2p and O 1s spectromicroscopy is used to analyze initial and final states, follow the process in situ, and search for intermediate species. The apparatus and techniques for spectro-electrochemical-microscopy will be described. Ex situ and in situ deposition & stripping of copper from CuCl2(aq) and CuSO4(aq) electrolytic solutions will be described. Progress towards an in situ flow electrochemical cell and a faster response time for kinetics measurements will be presented. STXM performed on BL 10ID1 at CLS and on BL 5.3.2.2 at ALS. Research supported by NSERC and the Catalyst Research for Polymer Electrolyte Fuel Cells (CaRPE-FC) network. [1] A.P. Hitchcock, Soft X-ray Imaging and Spectromicroscopy in Handbook on Nanoscopy, eds. G. Van Tendeloo, D. Van Dyck and S. J. Pennycook 2012. (Wiley) Figure 1