Superpolishing for Planarizing Copper Damascene Interconnects

Abstract

We demonstrate a superpolishing electrolyte, which consists of acid additives in conventional Cu polishing electrolytes for efficiently planarizing Cu damascene features. The significant additive concentration gradient in features, resulting in a selective Cu dissolution rate within features, is explored as a major mechanism that yields such electrolytes with high planarization efficiency. Moreover, another additive, polyethylene glycol as a suppressor, is also employed to reduce oxygen bubbling on polished films. Consequently, a smooth surface with a complete step height elimination is obtained in a 70 μm trench after electropolishing. © 2003 The Electrochemical Society. All rights reserved.