Development of Etching Process of CoFeB and IrMn Thin Films for Application of Magnetic Random Access Memory

Title
Development of Etching Process of CoFeB and IrMn Thin Films for Application of Magnetic Random Access Memory
Authors
소우빈
Keywords
developmentofetchingprocessofcofebandirmnthinfilmsforapplicationofmagneticrandomaccessmemory
Issue Date
2011
Publisher
인하대학교
Abstract
Etching is a process that involved in many fields and applications that plays an important role in semiconductor industry, such as fine pattern transfer in the microcircuit fabrication process. Magnetic random access memory (MRAM) based on the integration of magnetic tunnel junction (MTJ) and CMOS has the potential to be competitive with existing semiconductor memories was one of the popular topic in plasma etching field. For the realization of high density MRAM, the etching of MTJ stack which is composed of magnetic materials such as CoFeB, IrMn, and FePt thin films is one of the vital processes to be overcome. In this research, an inductively coupled plasma reactive ion etching of CoFeB and IrMn magnetic thin films patterned with Ti hard mask was studied in a CH3OH/Ar gas mix. As the CH3OH concentration increased, the etch rates of CoFeB, IrMn thin films and Ti hard mask decreased which means the etching of CoFeB and IrMn thin films does not obey the mechanism of reactive ion etching. While as the CH3OH concentration increased, the etch profiles improved with high degree of anisotropy. Moreover, the effects of coil rf power, dc-bias voltage to substrate and gas pressure on the etch characteristics were also investigated. The etch rate increased and the etch profile improved with increasing coil rf power, dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy revealed that Co3O4, Co2O3, FeO was formed on the surface of CoFeB and IrOx was formed on the surface of IrMn thin film after etching which confirmed that the chemical reaction between the two magnetic films and CH3OH gas occurred, leading to the clean and good etch profile with high degree of anisotropy of 90 degree.
Description
Abstract -i Tables of contents ii List of figures iV List of tables - Vii 1. Introduction - 1 2. Theoretical background - 4 2.1 Introduction of MRAM - 4 2.2 Overview of Etching Process 7 2.3 Wet Etching 9 2.4 Dry Etching- 10 3. Experimental - 17 3.1 Sample Preparation and Experimental Procedure 17 3.2 Experimental Apparatus - 20 3.3 Analysis Techniques of Experimental Results 20 4. Results and Discussion 22 4.1 Ti Hard Mask Etching 22 4.2 CoFeB Thin Film Etching- 30 4.3 IrMn Thin Film Etching 38 5. Conclusions 47 6. References 48 7. Acknowledgements - 52
URI
http://dspace.inha.ac.kr/handle/10505/22873
Appears in Collections:
College of Engineering(공과대학) > Chemical Engineering (화학공학) > Theses(화학공학 석박사 학위논문)
Files in This Item:
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