Ion Beam Etching Technology for High-Density Spin Transfer Torque Magnetic Random Access Memory

Sugiura, K.; Takahashi, Shigeki; Amano, M.; Kajiyama, Tisato; Iwayama, M.; Asao, Y.; Shimomura, N.; Kishi, T.; Ikegawa, S.; Yasuda, Hiroaki; Nitayama, A.

doi:10.1143/jjap.48.08hd02

Cited by 57 publications

(37 citation statements)

References 8 publications

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“…After MTJ multi-layer deposition and annealing, the next crucial step is to pattern individual MTJ nanopillars [42]. Typically, ion beam etching (IBE) is widely used to pattern MTJ nanopillars [43,44]. During the MTJ etching process, it is extremely difficult to obtain MTJ nanopillars with steep sidewall edges, while avoiding sidewall redeposition and magnetic layer corrosion [36].…”

Section: Beol Defectsmentioning

confidence: 99%

Defect and Fault Modeling Framework for STT-MRAM Testing

Rao

Taouil

et al. 2021

IEEE Trans. Emerg. Topics Comput.

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STT-MRAM mass production is around the corner as major foundries worldwide invest heavily on its commercialization. To ensure high-quality STT-MRAM products, effective yet cost-efficient test solutions are of great importance. This paper presents a systematic device-aware defect and fault modeling framework for STT-MRAM to derive accurate fault models which reflect the physical defects appropriately, and thereafter optimal and high-quality test solutions. An overview and classification of manufacturing defects in STT-MRAMs are provided with an emphasis on those related to the fabrication of magnetic tunnel junction (MTJ) devices, i.e., the data-storing elements. Defects in MTJ devices need to be modeled by adjusting the affected technology parameters and subsequent electrical parameters to fully capture the defect impact on both the device's electrical and magnetic properties, whereas defects in interconnects can be modeled as linear resistors. In addition, a complete single-cell fault space and nomenclature are defined, and a systematic fault analysis methodology is proposed. To demonstrate the use of the proposed framework, resistive defects in interconnect and pinhole defects in MTJ devices are analyzed for a single 1T-1MTJ memory cell. Test solutions for detecting these defects are also discussed.

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Section: Beol Defectsmentioning

confidence: 99%

Defect and Fault Modeling Framework for STT-MRAM Testing

Rao

Taouil

et al. 2021

IEEE Trans. Emerg. Topics Comput.

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“…[6][7][8] Currently, the etching of MTJ-related materials using conventional reactive ion etching (RIE) methods incurs problems in STT-MRAM device fabrication such as low etch selectivity with hard mask, etch damage, and redeposition of etch residue on the sidewall of the etched MTJ feature, etc. [9][10][11][12] To alleviate these etch related problems during the etching of MTJ materials, many people have intensively investigated various methods to increase the volatility of etch residue during the etching, thus improving the etch characteristics of MTJ materials. [13][14][15][16] Various etch gases that possibly form volatile etch compounds with MTJ-related materials have been studied by some research groups to improve the etch selectivity and etch profile.…”

Section: Introductionmentioning

confidence: 99%

Etching of Magnetic Tunnel Junction Materials Using Reactive Ion Beam

Hwan¹,

Chae²,

Woo³

et al. 2016

j nanosci nanotechnol

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Magnetic tunnel junction (MTJ) materials such as CoPt, CoFeB, and MgO and the hard mask material such as W were etched with a reactive ion beam system using Ar, NF 3 , CH 3 OH, and CO/NH 3 as etch gases. The effects of etch gas and the energy of the ion beam on the etch characteristics were then investigated. When the MTJ materials were etched with an Ar ion beam, the etch selectivities of the MTJ materials over W and the etch profiles of the etched MTJ patterns masked with W were generally poor, possibly due to the nonselective etching, physical sputtering without chemical reaction, and severe redeposition of the nonvolatile etch residues on the sidewall of the etched features. The use of NF 3 → CH 3 OH → CO/NH 3 reactive ion beam showed better etch selectivities over W and better etch profiles due to the higher etch selectivities of MTJ materials over W and less sidewall deposition. For reactive gases such as CH 3 OH and CO/NH 3 , the use of higher ion energy by increasing the 1st grid voltage of the ion beam up to +250 V also improved the MTJ etch profiles, possibly due to the increased effective chemical assisted physical sputtering of the etch products and the minimization of sidewall etch residues by removing etch products more effectively.

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“…Also extensively investigated has been ion milling. It is limited by miniaturization, sidewall re-deposition and physical sputtering damage due to high ion energy [1][2][3]. Transition metal etching by gas cluster ion beam (GCIB) using acetic acid and high energy (10-20keV) oxygen cluster ion beam has also been reported [7].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature and damage-free transition metal and magnetic material etching using a new metallic complex reaction

et al. 2015

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A neutral beam etching process has been developed that achieves damage-free (chemically and physically) etching. Recently, it was found that transition metals could be etched using neutral beam etching through metallic complex reactions. In this process, a neutral beam is extracted from a plasma generation region into a reaction chamber. Complex reactant gases are injected into a reaction chamber which is screened from the plasma during neutral beam etching. In this paper, etching of Pt and CoFeB, candidate materials for MRAM structures by a neutral beam system is described. It was found that etch rate enhancement of Pt/CoFeB surfaces resulted from their exposure to a neutral beam from Ar/O2 plasma with simultaneous injection of EtOH /acetic acid into the reaction chamber. Etching damage was also evaluated and no magnetic hysteresis degradation has been observed. Neutral beam etching technology has the capability to make breakthrough for fabricating MRAM device.

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Ion Beam Etching Technology for High-Density Spin Transfer Torque Magnetic Random Access Memory

Cited by 57 publications

References 8 publications

Defect and Fault Modeling Framework for STT-MRAM Testing

Defect and Fault Modeling Framework for STT-MRAM Testing

Etching of Magnetic Tunnel Junction Materials Using Reactive Ion Beam

Low-temperature and damage-free transition metal and magnetic material etching using a new metallic complex reaction

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