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Anisotropic Plasma Etching of Barium-Strontium-Titanate Thin Films for 4 Gbit DRAM Devices

Published online by Cambridge University Press:  10 February 2011

Stefan Schneider ,
Mark A. Kennard  and
Raine Waser
Stefan Schneider
Affiliation:
Institut für Festkörperforschung, Forschungszentrum Jülich, Germany
Mark A. Kennard
Affiliation:
Lam Research Corporation, Fremont, USA
Raine Waser
Affiliation:
Institut für Festkörperforschung, Forschungszentrum Jülich, Germany
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Abstract

Reactive Ion Etching of Ba0.7Sr0.3TiO3 (BST) thin films was studied using a Lam Research Corporation TCP™ 9400SE high density, low pressure plasma reactor. The BST thin films were etched with a variety of reactive gas combinations in a transformer coupled plasma (TCP) by varying etching parameters such as plasma density, DC bias to wafer susceptor, gas pressure, and -flow. The etch process was characterized by measuring the etch rate, etch selectivity to photo resist and SiO2 etch profiles, side wall deposition (fence), and etch product residues. Plasma etching of BST was found to be dominated by physical sputtering. With the chemistries used, the etch products have little or no volatility. Such a process regime is expected to contaminate the wafer with sidewall deposition (fences) and residues, which are both detrimental for further processing and may cause a possible particle problem and a low mean time between cleaning the process tool. The photoresist mask thickness and slope were varied to characterize the relationship between profile and residue. The photoresist mask was sloped using in situ plasma processing. Through optimization of mask and etch parameters, an etch process suitable for integration of BST capacitors into ULSI structures was achieved.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 596: Symposium Y – Ferroelectric Thin Films VIII , 1999 , 109
Copyright
Copyright © Materials Research Society 2000

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