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Surface roughness control of the Al and Al2O3 thin films deposited by using pulsed DC magnetron sputtering

Published online by Cambridge University Press:  21 March 2011

Jinjun Qiu ,
Kebin Li ,
Guchang Han ,
Zaibing Guo  and
Yihong Wu
Jinjun Qiu
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore119260
Kebin Li
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore119260
Guchang Han
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore119260
Zaibing Guo
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore119260
Yihong Wu
Affiliation:
Data Storage Institute, DSI Building, 5 Engineering Drive 1, Singapore117608)
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Abstract

The thickness of the Al2O3 layer used in the magnetic tunneling junctions FM1/Al2O3/FM2 is less than 2 nm, here FM1 is for the ferromagnetic layer 1 and FM2 is for ferromagnetic layer 2. In order to obtain ultra-thin Al2O3 layer with higher breakdown voltage and pinhole free, extremely smooth surface roughness of this layer is required. The influence of the sputtering gas pressure, DC pulsed frequency, DC pulsed power, substrate bias and buffer layer on surface roughness and properties of Al thin films were studied. The single layer Al films are usually amorphous, texture (111) Al films can be obtained while using thin Ta 5 nm or Ta5/NiFe2 as underlayer. Very smooth Al thin film can be sputtered on Si/SiO2 (100) wafer with Ta/NiFe buffer layer at f=15 kHz (DC pulsed frequency) and with RF substrate biasing (Vpp is about 21 V). High quality MTJs with high MR ratio up to 44.6% and high field sensitivity up to 19.3%/Oe were finally demonstrated after optimization of thin film deposition process.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 672: Symposium O – Mechanisms of Surface and Microstructure Evolution in Deposited Films and Film Structures , 2001 , O8.36
Copyright
Copyright © Materials Research Society 2001

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References

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