The Influences of Iodide Ion on Cu Electrodeposition and TSV Filling

Abstract

Through silicon via (TSV) technology has been researched for 3-dimensional packaging of electronic devices, and Cu electrodeposition has been used for TSV filling. The organic additives are one of the most important factors in Cu electrodeposition affecting Cu gap-filling, and the leveler usually plays a decisive role. In this research, iodide ion (I − ) is adopted instead of organic leveler for Cu bottom-up filling. The behaviors of I − are investigated by various types of electrochemical analyses. Especially, the influences of I − on the adsorption of the accelerator and suppressor are extensively studied, and it is confirmed that I − makes the suppression layer robust while reducing the adsorption of the accelerator. Also, it was observed that the effect of I − is greater under the strong convection of electrolytes than without convection, meaning that I − could induce selective deposition at the bottom of the features. Based on this, TSV-scaled trenches are successfully filled by potentiostatic Cu electrodeposition in the presence of the accelerator, suppressor, and I − without any organic levelers.

Isotropic Iodide Adsorption Causes Anisotropic Growth of Copper Microplates

“…The Cl − adsorbed on a Cu surface has been shown to activate Cu deposition, 55 but adsorbed I − suppresses Cu deposition. 56 The relatively covalent Cu−I bond is stronger than the relatively ionic Cu−Cl bond and involves a greater amount of charger transfer from I − to Cu. This stronger interaction between I − and Cu hinders atomic addition.…”

“…Addition of I – replaces Cl – on the {111} facet, leading to its passivation. The Cl – adsorbed on a Cu surface has been shown to activate Cu deposition, but adsorbed I – suppresses Cu deposition . The relatively covalent Cu–I bond is stronger than the relatively ionic Cu–Cl bond and involves a greater amount of charger transfer from I – to Cu.…”

Role of Lithium Iodide Addition to Lithium Thiophosphate: Implications beyond Conductivity

“…The solution-based electrodeposition of metals has been extensively studied academically as well as provided industrial solutions for practical devices. , One interesting and applicable avenue of research has been the use of surface modifiers to affect the structure and morphology of deposited metals, for example, surfactants, organic molecules, and halide salts . In liquid-based electrochemical deposition, iodine adsorption on metal surfaces is well known to influence the kinetics of crystallization and the morphology of metal growth and has been frequently utilized to form compact, uniform films. − For solid-state electrodeposition, several research teams have shown that modification of the lithium-metal surface has significantly improved the galvanic cycling properties using solid-state electrolytes; − however, iodine adsorption has not been evident during the solid-state deposition of lithium metal nor has its influence on cell failure. Understanding the electrochemical interphase is a vital step to engineering practical SSBs.…”

Cyclic Voltammetry Stripping Analysis to Determine Iodide Ion Concentration in Cu Plating Bath

“…To determine C I − in the target plating bath, a RC-CVS analysis was performed as follows: (1) assessment of Q 0 from the CVS analysis of the base solution (volume: 52 mL), (2) measurement of Q after adding the standard solution to the base solution (addition volume: 1 mL), (3) consecutive repetition (eight times) of the procedure (2) to generate a response curve, (4) preparation of a new bath and the appraisal of Q 0 (5), evaluation of Q t after adding the target solutions to the base solution (addition volume: 3 mL), ( 6) determination of C I − in the target solutions by interpolating the Q t /Q 0 value to the response curve by using Eq. 2. where C St was the known concentration of I − in the standard solution (400 μM), V T the addition volume of the target solution (3 mL), x * the addition volume value in the response curve at the same Q/Q 0 with Q t /Q 0 obtained from the target solution, and V V the pre-dosed volume of the base solution (52 mL).…”