Aluminum passivation in saturated TMAHW solutions for IC-compatible microstructures and device isolation

Pasqualina M. Sarro; Sebastiano Brida; W. van der Vlist

doi:10.1117/12.251213

23 September 1996 Aluminum passivation in saturated TMAHW solutions for IC-compatible microstructures and device isolation

Pasqualina M. Sarro, Sebastiano Brida, W. van der Vlist

Author Affiliations +

Proceedings Volume 2879, Micromachining and Microfabrication Process Technology II; (1996) https://doi.org/10.1117/12.251213
Event: Micromachining and Microfabrication '96, 1996, Austin, TX, United States

Abstract

Tetramethyl ammonium hydroxide (TMAH) solutions have been used to realize IC-compatible micromachined structures and device isolation. THe very low etch rate of PECVD dielectric layers and the possibility to passivate the aluminum metalization by doping the solution with silicon, increase the range of applications of this etchant and simplify both the post processing and the etch set-up configuration. Solutions of TMAH and water with addition of solid silicon or silicic acid have been used to study the effect of solution saturation on the passivation of aluminum. The etch rate of silicon, selectivity to masking materials and quality of the etched surfaces has been evaluated in both types of doped solutions in the temperature range 70 degrees-90 degrees C. An etch rate of less than 10nm/hr for the Al/1 percent Si metal layer has been measured in the saturated solutions. Further, the use of additives, such as IPA and pyrocatechol, on the etchant characteristics has been investigated. The addition of IPA has little or no influence on the etching characteristics, while very little quantities of pyrocatechol are sufficient to cause major improvements on the etching uniformity and surface quality, with no negative effect on the aluminum passivation.

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Pasqualina M. Sarro, Sebastiano Brida, and W. van der Vlist "Aluminum passivation in saturated TMAHW solutions for IC-compatible microstructures and device isolation", Proc. SPIE 2879, Micromachining and Microfabrication Process Technology II, (23 September 1996); https://doi.org/10.1117/12.251213

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