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Tantalum Pentoxide for Advanced DRAM Applications

Published online by Cambridge University Press:  10 February 2011

K. A. McKinley  and
N. P. Sandier
K. A. McKinley
Affiliation:
Lam Research Corporation, 49026 Milmont Drive, Fremont, CA 94538
N. P. Sandier
Affiliation:
Lam Research Corporation, 49026 Milmont Drive, Fremont, CA 94538
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Abstract

Tantalum pentoxide (Ta2O5) films were deposited from the reaction of tantalum pentaethoxide (Ta(OC2H5)5) and oxygen (O2) using the Lam Research Corporation DSM™9800 advanced LPCVD reactor. Typical films were deposited at a rate of 0.9 – 1.1 nm/min at 400°C. The films were stoichiometric with an O/Ta ratio of 2.57/1.00 and excellent compositional uniformity. Conformity was >95% indicating that the process is surface reaction rate limited. Films with non‐uniformities <2.2% were deposited on 300 mm wafers. The deposited non‐uniformity on 150mm and 200mm wafers was <2.0% ‐1σ within a wafer, wafer to wafer within a batch, and batch to batch. The dielectric constant for as‐deposited films was 22–24, and as high as 34 for films which were heat treated. Various post deposition heat treatments were performed to improve the capacitor's electrical properties. Superior results were obtained from rapid thermal annealing (RTA) in N2O compared with RTA in O2 and two‐step UV‐O3 followed by high temperature annealing in dry O2. Values for the leakage current of <10-8 A/cm2 at 1.2 volts negative bias (worst case) and breakdown >5 MV/cm at 1.6μΑ with tegox<2.5 nm have been obtained. These values meet the requirements for 256 Mbit DRAM memory devices Bottom and top electrode formation and integration issues are also addressed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 446: Amorphous and Crystalline Insulating Thin Films–1996 , 1996 , 299
Copyright
Copyright © Materials Research Society 1997

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