Monitoring the Superfilling of Blind Holes with Electrodeposited Copper

Abstract

Blind holes 5 m in diameter and 25 m deep were filled with copper electrodeposited from a copper sulfate electrolyte containing chloride ions, a suppressor, and an accelerator. A thin tantalum layer was deposited on top of a copper seed layer to locally inhibit the subsequent electrodeposition of copper. A clear difference appeared in the evolution of the cathode potential recorded during the galvanostatic deposition of copper on either copper metallized flat substrates or substrates containing copper metallized recessed blind holes and selectively coated with Ta at the outside. The different steps during the filling of blind holes by electrolytic copper were monitored and analyzed based on the evolution of the cathode potential during electrodeposition. An electrochemical depolarization of the electrode surface induced by an accelerating species occurred first. The subsequent evolution of the potential was dominated by a change in the electrode surface that occurs during the superfilling of blind holes with copper. Finally, the time to achieve a complete filling of blind holes with electrolytic copper was determined. A deeper insight on the superfilling mechanism with electrodeposited copper was obtained.

Sensitivity Enhancement for Quantitative Electrochemical Determination of a Trace Amount of Accelerator in Copper Plating Solutions

“…2R À S À M [7] 2R À S À M þ Cu 2þ ! M À S À R À Cu 2þ ÀR À S À M [8] M À S À R À Cu 2þ ! ÀR À S À M þ 2e À !…”

Modeling the Bottom-Up Filling of Through-Silicon vias Through Suppressor Adsorption/Desorption Mechanism

“…Void-free filling was achieved for TSVs with various sizes using different additives. [1][2][3][4] However, the underlying mechanism is still not completely understood and under active study. Different models were proposed to explain the void-free filling mechanism of vias with various sizes and geometries.…”

Nanoscale Cu Wiring by Electrodeposition in Supercritical Carbon Dioxide Emulsified Electrolyte

“…The low pH and O 2 dissolved in the electrolyte could accelerate the dissolution of Cu according to Equation (3). The weight of Cu lost in the pH 3.0 base electrolyte shown in Fig.…”

“…Cu electrodeposition is a key technology for the fabrication of interconnects used in microelectronic devices and related packaging technologies [2]. Especially for densification of the microelectronics, electrodeposition is often used in the fabrication of the threedimensional structures [3]. On the other hand, voids and pinholes found in the Cu wiring of the integrated device can cause problems for the miniaturized device.…”

“…There are various studies on the bottom-up filling [9][10][11][12][13]. For example, additives such as accelerators and suppressors in copper-sulfate-sulfuric acid electrolyte are used for filling the vias to allow defect-free bottom-up filling [3]. However, the additives can cause problems such as impurity and grain refinement, which lead to high electric resistance because of the accumulation of impurity atoms in the grain boundary regions, and the grain boundary itself can also be a barrier for electrical conduction [14].…”