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Titanium dioxide thin films for next-generation memory devices

Published online by Cambridge University Press:  19 July 2012

Seong Keun Kim ,
Kyung Min Kim ,
Doo Seok Jeong ,
Woojin Jeon ,
Kyung Jean Yoon  and
Cheol Seong Hwang
Seong Keun Kim
Affiliation:
Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 130-650, Korea
Kyung Min Kim
Affiliation:
Semiconductor Laboratory, Samsung Advanced Institute of Technology, Gyeonggi-Do 446-712, Korea
Doo Seok Jeong
Affiliation:
Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 130-650, Korea
Woojin Jeon
Affiliation:
Department of Materials Science and Engineering, WCU Hybrid Materials Program, Seoul National University, Seoul 151-744, Korea; and Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-744, Korea
Kyung Jean Yoon
Affiliation:
Department of Materials Science and Engineering, WCU Hybrid Materials Program, Seoul National University, Seoul 151-744, Korea; and Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-744, Korea
Cheol Seong Hwang*
Affiliation:
Department of Materials Science and Engineering, WCU Hybrid Materials Program, Seoul National University, Seoul 151-744, Korea; and Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-744, Korea
*
a)Address all correspondence to this author. e-mail: cheolsh@snu.ac.kr
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Abstract

The synthesis, structure, and electrical performances of titanium dioxide (TiO2 and also doped TiO2) thin films, a capacitor dielectric for dynamic random access memory (DRAM) and a resistance switching material in resistance switching RAM (ReRAM), are reviewed. The three-dimensionality of these structures and the extremely small feature sizes (<20 nm) of these memory devices require the synthesis method of TiO2-based layers to exhibit high degree of conformality. Atomic layer deposition is, therefore, the method of choice in respect of film growth for these applications. The unique arrangement of the TiO6-octahedra in the rutile structure, which results in the value for dielectric constant of the dielectric layer, εr (>100), makes the material especially attractive as the capacitor dielectric layer in DRAM. Removing some of the oxygen ions from the rutile structure and arranging the resulting oxygen vacancies on a specific crystallographic plane results in the so called Magnéli phase materials, which show distinctive conducting semiconductor or metallic characteristics. External electrical stimuli can cause the repeated formation and rupture of conducting channels that consist of these Magnéli phase materials in the insulating TiO2 matrix, and this aspect makes the material a very feasible choice for applications in ReRAM. This article reviews the material properties, fabrication process, integration issues, and prospect of TiO2 films for these applications.

Keywords

TiO2high εr materialresistance switching
Type
Reviews
Information
Journal of Materials Research , Volume 28 , Issue 3: Focus Issue: Titanium Dioxide Nanomaterials , 14 February 2013 , pp. 313 - 325
Copyright
Copyright © Materials Research Society 2012

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