In Situ Stress Measurements During Copper Electrodeposition on (111)-Textured Au
Gery R. Stafford, O E. Kongstein, Carlos R. Beauchamp
In situ stress measurements were made during copper electrodeposition onto (111)-textured Au from acidic sulfate electrolyte using the wafer curvature method. In the Cu upd region, the intermediate honeycomb structure where sulfate form an ordered ((surd)3R30(degrees) adlayer and Cu occupies the remaining 3-fold sites creates a surface stess that is tensile when compared to taht of the sulfate-adsorbed electrode at positive potential or the complete (1 x 1)Cu monolayer at more negative potentials. This behavior is consistent with surface-induced charge redistribution models that appear in the literature. During the bulk deposition of Cu, there is a rapid increase in tensile stress during the first 20 nm of growth due to nuclei coalescence and grain boundary formation. The magnitude of the tensile stress as well as the nominal film thickness at which the maximum stress nucleation density. When the films are continuous, the total stress is the superposition of the coalescence-induced tensile stress and a compressive stress which we attribute to the incorporation of mobile ad-atoms on the surface into the grain boundaries. The tensile stress component dominates thin films deposited at hgih overpotential whereas thick films deposited at low overpotential have a net compressive stress. When deposition is interrupted both tensile and compressive components of the stress relax somewhat but are quickly re-estalished when deposition is resumed. The development of the growth stress that we describe here is very similar to that which has been reported for Cu deposition from the vapor phase.
, Kongstein, O.
and Beauchamp, C.
In Situ Stress Measurements During Copper Electrodeposition on (111)-Textured Au, To Be Determined, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=853333
(Accessed December 11, 2023)