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

Jinjun Qiu, Kebin Li, Guchang Han, Zaibing Guo, Yihong Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
JournalMaterials Research Society Symposium - Proceedings
Volume672
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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