The application of electrochemical metrologies for investigating chemical mechanical polishing of Al with a Ti barrier layer

• Published in: Materials chemistry and physics 2003-11, Vol.82 (2), p.444-451
• Main Authors: Chiu, Shao-Yu, Wang, Ying-Lang, Liu, Chuan-Pu, Lan, Jin-Kun, Ay, Chyung, Feng, Ming-Shiann, Tsai, Ming-Shih, Dai, Bau-Tong
• Format: Article
• Language: English
• Subjects: Aluminum; Applied sciences; Chemical and electrochemical properties; Chemical mechanical polishing; Exact sciences and technology; Metals. Metallurgy; Polishing. Blast cleaning; Production techniques; Selectivity; Surface treatment; Titanium
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/S0254-0584(03)00312-2

In situ electrochemical measurements were performed for Al and Ti disks in various slurries during polishing and static conditions. The electrochemical results obtained from the corrosion potential drop of Al polishing have verified that the maximum removal rate of metal CMP can be achieved when the removal rate of the surface oxide was equal to its growth rate. However, Ti polishing did not exist maximum removal rate. The effects of H 2O 2%, pH values and pressure on the Al and Ti polishing behaviors were explored by using potentiodynamic scan. The corrosion potential drop was found to be a good index for polishing removal rate. The corrosion potential drop changed with increasing H 2O 2% for Al polishing and there existed a maximum value. But the corrosion potential drop increased with increasing H 2O 2% for Ti polishing. The pH value had different effects on Al and Ti polishing. Higher pH values gave higher Al removal rate but lower Ti removal rate. The Al polishing showed more pressure sensitive than Ti polishing did. The galvanic current was measured for Al/Ti polishing. For slurry with 6 vol.% H 2O 2 and pH=4, the abraded Al electrode obtained a negative current, which implied Ti oxidation was enhanced.