Investigation of Cu-BTA complex formation and removal on various Cu surface conditions

The effect of Cu surface conditions on Cu-BTA complex was investigated using ex-situ electrochemical impedance spectroscopy method. Cu-BTA complex is generated during Cu CMP process because BTA which is the most common corrosion inhibitor in Cu CMP slurry react with Cu and form a strong complex. Then it is very important to remove Cu-BTA complex during post-Cu CMP cleaning because Cu-BTA complex cause severe problem such as particle contamination and watermark due to its hydrophobic characteristic. The Cu-BTA complex formation at various Cu surfaces was investigated to understand its behavior, so the effective development will be possible in post-Cu CMP cleaning process.

I. Introduction

Copper is widely used as an interconnecting material to replace aluminum in integrated circuits due to its useful properties, such as low resistivity and high electromigration resistance [1]. Copper is deposited by an electrochemical deposition process and the excess copper has to be removed by chemical mechanical planarization (CMP) which is also called damascene process. In general, Cu CMP slurry consists of abrasive particles, an oxidizing agent, a chelating agent and a corrosion inhibitor.