Investigations of the electrochemical performance and filling effects of additives on electroplating process of TSV

Houya Wu,Wenhui Zhu,Zhiyi Li,Yan Wang

doi:10.1038/s41598-020-66191-7

Abstract

Through silicon via (TSV) is one of the most important technologies used in three dimension (3D) packaging. The void-free filling of TSV can be achieved by adding additives into the electrolyte bath during the electrodeposition process. This paper focuses on the effects of three types of commercial additives (the suppressor, the leveler and the accelerator) and analyses additives’ interaction on electroplating through experimental investigations. The results showed that the suppressor, the leveler and the accelerator all have chemical behaviour of inhibition in different degrees to the copper electroplating. The interaction experiments of additives in pairs indicated that the suppressor absorbed on the cathode surface was gradually displaced by the accelerator as the concentration of the accelerator increased; the accelerator and the leveler presented a competitive adsorption relationship; the suppressor and the leveler had a synergistic effect for electroplating inhibition especially under high potential and low suppressor concentration. Experiments of micro via filling by electrodeposition have been conducted to investigated the effects of singular additive and multiple additives on the filling process of the micro vias.

Highlights

Through silicon via (TSV) is one of the most important technologies used in three dimension (3D) packaging
As the micro structure of the TSV is too small, non-uniform distribution of flow field, concentration field and electric field appears in the local region of the micro via, which leads to non-uniform filling rate between the opening and bottom of the TSV, especially of TSVs with high aspect ratio (AR)[8,9,10,11,12,13]
Hasegawa et al investigated the effect of Janus green B (JGB) as leveler on micro via filling, and reached the conclusion that JGB inhibits the overfill phenomenon in the later stages of the deposition process, but the inhibition become greater with higher concentrations of JGB, resulting in void formation[33]

Summary

Introduction

Through silicon via (TSV) is one of the most important technologies used in three dimension (3D) packaging. The void-free filling of TSV can be achieved by adding additives into the electrolyte bath during the electrodeposition process. The results showed that the suppressor, the leveler and the accelerator all have chemical behaviour of inhibition in different degrees to the copper electroplating. Hasegawa et al investigated the effect of Janus green B (JGB) as leveler on micro via filling, and reached the conclusion that JGB inhibits the overfill phenomenon in the later stages of the deposition process, but the inhibition become greater with higher concentrations of JGB, resulting in void formation[33]. The suppressor (AESS), accelerator (M) and leveler (PNI) are purchased from Jiangsu Mengde New Materials Technology Co., Ltd, and their interaction effects on electrodeposition were investigated. Experiments of micro via filling by electrodeposition were conducted, and the results were obtained by a scanning electron microscope (SEM)

Methods

Results

Conclusion