Highly Reliable Ultra-Thin Tantalum Oxide Capacitors for ULSI DRAMs

Satoshi KAMIYAMA  Hiroshi SUZUKI  Pierre-Yves LESAICHERRE  Akihiko ISHITANI  

IEICE TRANSACTIONS on Electronics   Vol.E77-C    No.3    pp.379-384
Publication Date: 1994/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Quarter Micron Si Device and Process Technologies)
Category: Device Technology
tantalum oxide,  rapid thermal nitridation (RTN),  SiO2 equivalent thickness,  leakage current,  time dependent dielectric breakdown (TDDB),  

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This paper describes the formation of ultra-thin tantalum oxide capacitors, using rapid thermal nitridation (RTN) of the storage-node polycrystalline-silicon surface prior to low-pressure chemical vapor deposition of tantalum oxide, using penta-ethoxy-tantalum [(Ta(OC2H5)5) and oxygen gas mixture. The films are annealed at 600-900 in dry O2 atmosphere. Densification of the as-deposited film by annealing in dry O2 is indispensable to the formation of highly reliable ultra-thin tantalum oxide capacitors. The RTN treatment reduces the SiO2 equivalent thickness and leakage current of the tantalum oxide film, and improves the time dependent dielectric breakdown characteristics of the film.