(151d) Study on the Mechanism of SPS with Chloride Ion during Cu Microvia Pulse-Reverse Electrodeposition

Due to limitations in semiconductor performance development through simple miniaturization, the development direction of the foundry industry is expanding from ultra-fine processes to packaging processes that stack multi-layer chips in a certain area or efficiently arrange them. Types of these packaging interconnects include Cu TSV, RDL, post, and microvia, and various types of organic additives or techniques such as pulse or pulse-reverse are used to induce a defect-free filling process of the interconnect. Among them, the pulse-reverse technique consists of an on-time plating of copper and a reverse step in which the electrodeposited copper is dissolved. Pulse-reverse electrodeposition can control the characteristics of electroplated copper, such as reducing the resistivity of the electrodeposited copper, and to induce a defect-free copper filling process. Although Cu⁺ dissolved in the reverse step is known to behave as a major mechanism of pulse-reverse electrodeposition, research on the exact mechanism of pulse-reverse plating related to additives is still insufficient.

In this study, we focused on identifying the pulse-reverse electrodeposition mechanism involving additives, especially SPS and Cl^-. This study was conducted to analyze the mechanism related to SPS and chloride ion during pulse-reverse plating through electrochemical analysis such as pulse-reverse chronopotentiometry using RDE (rotating disk electrode) and Cu microvia filling results according to additive combinations. Due to the interaction between SPS and Cl^- during the reverse current, an acceleration effect occurred at low convection, and bottom-up filling of Cu microvia could be induced when only SPS was added.