Aluminum Cleaning on Single Wafer Tool: A Case Study with Diluted HF

Abstract:

For integrated circuit fabrication on 300 mm wafers, copper interconnections cleaning is generally done with single wafer tools. In this study, we focused on the cleaning of aluminum interconnections, on single wafer tool, with a cheap and easy to use chemistry. Aluminum compatibility with diluted HF solutions was first evaluated, then short and efficient cleaning processes were developped for two kind of applications : cleaning after aluminum line etching and cleaning after final dielectric etching over the aluminum pad. It was demonstrated that cleaning efficiency was poor for the shorter process time (20 s), but improved with process time increase, highlighting a lift-off mechanism for polymers removal. Best process was achieved with 40 s of HF 0.2%, that offers a good compromise between polymer removal and lateral recess of the aluminum.

• Periodical: Solid State Phenomena (Volume 282)
• Pages: 226-231
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.282.226
• Online since: August 2018
• Authors: Lucile Broussous*
• Keywords: Aluminum Cleaning, Diluted HF, Single Wafer Tool

References

[1] Handbook of Cleaning for Semiconductor Manufacturing, fundamentals and applications. Ed. K. A. Reinhardt and R. F. Reidy, Wiley (2011).

[2] D. J. Maloney, Aluminum Interconnect Cleaning and Drying,, Handbook of Cleaning for semiconductor manufacturing, Ed. K. A. Reinhardt , Wiley. 2011, p.327.

DOI: 10.1002/9781118071748.ch9

[3] H. Sohn et al., Using cost-effective dilute-acid chemicals to perform post-etch interconnect cleans, MICRO, 23 (5) p.67 (2005).

[4] R. Ravikumar et al., New Aqueous Clean for Aluminum Interconnects: Part II. Applications,, in Proceedings of the International Symposium on Ultra Clean Processing of Silicon Surfaces (UCPSS 2000) (Zurich-Uetikon, Switzerland: Scitech Publications, 2002), 51–54.

[5] N. Sato Effects of wafer spin speed during dry etch post-wet cleaning on a metal line, Microelectronic Engineering 134 (2015) 38–42.

DOI: 10.1016/j.mee.2015.02.002

[6] S. Verhaverbeke, C. Beaudry, P. Boelen, Aqueous Single pass single wafer Al/Via Cleaning, ECS proceedings, Abs. 761, 204th Meeting, © 2003 The Electrochemical Society, Inc.

[7] M. Pourbaix, Atlas d'équilibres électrochimiques à 25°C. Ed. Gauthier-Villars and Cie, Paris (1963).

[8] CHESS Software for chemical equilibrium of species and surfaces modelisation.

[9] R.C. Santore, C.T. Driscoll, the CHESS Model for calculating Chemical Equilibria in Soils and Solutions,, Chemical Reaction and Reaction Models, Soil Science Society of America special issue 42, (1995) chap.7, pp.357-375.

DOI: 10.2136/sssaspecpub42.c17