Investigations of solution variables in a contactless copper electrodeposition process for 3D packaging applications

Application of Process Simulation for Comparison of Contactless and Conventional Electrodeposition Methods for 3D Packaging

“…A nickel seed layer was deposited onto the bottom of the via using a method discussed elsewhere but without the use of surfactant. 20 The electrodeposition experiments were carried out in the two-chamber cell system, [4][5][6] where the front side of the wafer (via side) was in contact with 1 M CuSO 4 and 0.2 M H 2 SO 4 deposition solution and the back side of the wafer contacted a SiO 2 etchant solution (e.g. dilute HF).…”

“…This ion concentration gradient causes preferential deposition at the mouth of the via leading to a pinch-off effect where the bottom of the via is closed to the electrolyte before being completely filled with metal. [4][5][6] The formation of these voids increases the via resistance and results in reliability issues in ICs.…”

“…4 The effect of various processing parameters and solution variables using this technique has been examined and discussed elsewhere. 5,6 In this process, the top surfaces of the wafer (regions outside the via) and the via sidewalls were coated with SiO 2 , while a conductive Ni layer was deposited at via bottom. Therefore, Cu ions were reduced and deposited at via bottom only by accepting electrons resulting from electrochemical oxidation and etching occurring on the silicon back side.…”

Contactless bottom-up electrodeposition of nickel for 3D integrated circuits

“…Previously, 8,23 the effect of different solution parameters like temperature, copper sulfate concentration and sulfuric acid concentration on the deposition of copper were investigated. Previously, 8,23 the effect of different solution parameters like temperature, copper sulfate concentration and sulfuric acid concentration on the deposition of copper were investigated.…”

“…Electrodeposition for metallization is comprised of fairly well understood phenomena, however because the contactless technique used in this publication requires the continuous oxidation of silicon and etching of oxide 22 to complete the current circuit, the system is much more complex. Previously, 8,23 the effect of different solution parameters like temperature, copper sulfate concentration and sulfuric acid concentration on the deposition of copper were investigated. The emphasis of the current work has been on nickel deposition and parameters affecting the process.…”