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Various Methods to Reduce Defect States in Tantalum Oxide Capacitors for DRAM Applications

Published online by Cambridge University Press:  01 February 2011

W.S. Lau
Affiliation:
Nanyang Technological University, School of Electrical and Electronic Engineering, Block S2.1, Nanyang Avenue, Singapore 639798, Republic of Singapore
G. Zhang
Affiliation:
Data Storage Institute, DSI Building, 5, Engineering Drive 1, Singapore 117608, Republic of Singapore
L.L. Leong
Affiliation:
Nanyang Technological University, School of Electrical and Electronic Engineering, Block S2.1, Nanyang Avenue, Singapore 639798, Republic of Singapore
P.W. Qian
Affiliation:
Nanyang Technological University, School of Electrical and Electronic Engineering, Block S2.1, Nanyang Avenue, Singapore 639798, Republic of Singapore
Taejoon Han
Affiliation:
Lam Research Corporation, 4650 Cushing Parkway, Fremont, California 94538
J. Das
Affiliation:
Lam Research Corporation, 4650 Cushing Parkway, Fremont, California 94538
Nathan P. Sandler
Affiliation:
Lam Research Corporation, 4650 Cushing Parkway, Fremont, California 94538
P.K. Chu
Affiliation:
City University of Hong Kong, Department of Physics and Materials Science, Tat Chee Avenue, Kowloon, Hong Kong
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Abstract

Tantalum oxide has attracted world-wide interest for DRAM (dynamic random access memory) capacitor applications because of its relative high dielectric constant compared to silicon dioxide or nitride. We would like to point out that tantalum oxide behaves very much like a large bandgap n-type semiconductor with 3 main types of donors responsible for leakage current. Native oxygen vacancies are very deep double donors with Ec – Ed = 0.8 eV approximately, where Ec is the bottom of the conduction band and Ed is the energy leVel of the defect state. Si-O vacancy complexes are relatively shallow single donors with Ec – Ed = 0.2-0.4 eV. C-O vacancy complexes are relatively shallow single donors with Ec – Ed = 0.5-0.6 eV. The key points regarding how to suppress these 3 types of donor defects will be discussed for the purpose of leakage current reduction.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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