Process development of sub-0.5 μm nonvolatile magnetoresistive random access memory arrays

Nordquist, Kevin J.; Pendharkar, S. V.; Durlam, M.; Resnick, Douglas J.; Tehrani, S.; Mancini, Derrick C.; Zhu, Tiancong; Shi, Jingwen

doi:10.1116/1.589628

Cited by 36 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nanoparticle arrays are now patterned more and more precisely with various methods, such as sub-micron sphere self-assembly lithography techniques [1][2][3][4][5], selective ion irradiation [6][7][8][9] and film growth technologies [10,11]. Ferromagnetic nanomaterials are of special interest due to their potential application in magnetic data storage and spintronic devices, such as MRAM, microwave oscillators, magnetic nanosensors [12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Kuźma

Zieliński

2020

Magnetochemistry

View full text Add to dashboard Cite

Periodic systems of magnetic nanoparticles are now of interest as they support GHz spin waves. Their equilibrium configurations, switchable with the external magnetic field, are crucial for such applications. We study infinite and finite chains of particles of two shapes (i) ellipsoidal and (ii) rectangular stripes with long axes perpendicular to the chain axis. A variable magnetic field is applied parallel to the long axes. Micromagnetic simulations are compared with the corresponding discrete spin models (Stoner-Wohlfarth model, S-W). An antiferromagnetic configuration is the ground state for all the systems at vanishing field but a ferromagnetic configuration occurs when the field is strong enough. The switching of the infinite chains to the reversed ferromagnetic configuration proceeds directly for the ellipsoids and by an intermediate configuration, in which the magnetization within the particle is non-uniform, in the case of the stripes. The non-uniform configurations are well represented by tilted states in S-W model. Important differences are found in the finite analogs: the switching of ellipsoids becomes multistage and starts from the innermost particles relatively well reproduced with S-W model, whereas the reversal of the stripes, starts from the outermost particles and has no analog in S-W model. Practical consequences of the findings are discussed.

show abstract

Section: Introductionmentioning

confidence: 99%

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Kuźma

Zieliński

2020

Magnetochemistry

View full text Add to dashboard Cite

show abstract

“…Among these nonvolatile memory devices, spin transfer torque magnetic random access memory (STT-MRAM) is one of the promising candidates due to high density storage, fast access time, infinite rewrite, low operating voltage, etc. [1][2][3][4][5] In the STT-MRAM device, the multilayer of the magnetic tunnel junction (MTJ) is the most important material, which is generally consisted of CoFeB/MgO/CoFeB, because the main data are recorded in the MTJ stack. [6][7][8] For high storage density, high performance, and nonvolatile STT-RAM devices, the precise etching of multilayer MTJ materials needs to be developed.…”

Section: Introductionmentioning

confidence: 99%

Etch characteristics of magnetic tunnel junction materials using substrate heating in the pulse-biased inductively coupled plasma

Jeon

Yang

Lee

et al. 2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

View full text Add to dashboard Cite

Magnetic tunnel junction (MTJ)-related materials such as CoFeB, MgO, and W were etched in a pulse-biased inductively coupled plasma etch system using a CO/NH 3 gas combination, and the effects of substrate temperature (room temperature $200 C) in the pulse-biased condition on the etch characteristics of the MTJ-related material were investigated. The etch selectivity of MTJ materials over W was improved by substrate heating possibly due to the easy removal of the compounds from the etched CoFeB surface during the pulse-on time at the elevated substrate temperature. At high substrate temperature, decreased thickness of etch residue was observed not only on the bottom surface but also on the sidewall surface during the etching, which indirectly indicated the increased volatility of the etch compounds at higher substrate temperature. The etching of CoFeB features masked with W also showed a more anisotropic etch profile by heating the substrate up to 200 C possibly due to the increased the etch selectivity of CoFeB over W and the decreased redeposition of etch products on the sidewall of the CoFeB features. V

show abstract

“…MRAM devices can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage, and high storage density. 1,2 MRAM devices are composed of a magnetic tunnel junction (MTJ) stack and CMOS. The MTJ stack is a key part of MRAM devices and the realization of high-density MRAMs as a nonvolatile emerging memory requires new etching processes of MTJ stacks that can delineate the nanometer-sized patterns on the MTJ stacks.…”

mentioning

confidence: 99%

Influence of O₂Gas on Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₄/O₂/Ar Plasma

Lee

Kim

Lee

et al. 2012

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The etch characteristics of magnetic tunnel junction (MTJ) stacks patterned with W/TiN films were examined using an inductively coupled plasma of a CH 4 /O 2 /Ar gas mix. The effect of the O 2 concentration on the etch rate, etch selectivity and etch profile of the MTJ stacks was examined. The etch profile of the MTJ stacks in 60% CH 4 /Ar gas appeared to be the best. The addition of 10% O 2 gas in CH 4 /Ar gas led to an improved etch profile with less redeposition on the sidewall of the MTJ stacks. This was attributed to the increase in [H]/[Ar] and [O]/[Ar] intensity ratios with increasing O 2 concentration to 20%. Transmission electron microscopy of the etched MTJ stacks revealed redeposited materials on the sidewall of the MTJ stacks etched in CH 4 /Ar gas that were indentified to be mainly Pt, Mn, Co, Ru and Ti. On the other hand, the amount of redeposited materials decreased significantly with the addition of 10% O 2 in CH 4 /Ar gas. The formation of metal oxides and protection layer in CH 4 /O 2 /Ar gas mix resulted in a high degree of anisotropy without redeposited materials in the etch profile of MTJ stacks.The rapid growth of smart devices such as smart phone, smart tab and smart TV requires new emerging semiconductor memory with the features of high density, fast speed, high endurance and nonvolativity. Among a variety of memory devices containing phase-change random access memory (PCRAM), resistive random access memory (ReRAM) and magnetic random access memory (MRAM), MRAM devices have attracted considerable attention as a replacement for current dynamic random access memory (DRAM) and flash memory. MRAM devices can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage, and high storage density. 1,2 MRAM devices are composed of a magnetic tunnel junction (MTJ) stack and CMOS. The MTJ stack is a key part of MRAM devices and the realization of high-density MRAMs as a nonvolatile emerging memory requires new etching processes of MTJ stacks that can delineate the nanometer-sized patterns on the MTJ stacks. 3,4 The development of an etch process for patterning MTJ stacks, which consist of magnetic materials, metals and metal oxides, is important for the fabrication of high density MRAM with nanometersized patterns. Generally, dry etching of magnetic thin films is extremely difficult because the metals and magnetic materials barely react with the chemically active species in plasma. Initially, ion beam etching of magnetic thin films was used to etch the magnetic materials and metals but often, several undesirable attributes were produced, including slow etch rate, sidewall redeposition, and etching damages because of the etch mechanism by physical sputtering. Therefore, ion beam etching was of limited use in etching MTJ stacks as well as magnetic films. Chemically assisted ion etching and reactive ion etching were applied to etch the magnetic films but similar etch results to those obtained by ion beam etching were achieved. 5-7 Recently, high density plasma etching ...

show abstract

Process development of sub-0.5 μm nonvolatile magnetoresistive random access memory arrays

Cited by 36 publications

References 7 publications

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Etch characteristics of magnetic tunnel junction materials using substrate heating in the pulse-biased inductively coupled plasma

Influence of O₂Gas on Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₄/O₂/Ar Plasma

Contact Info

Product

Resources

About

Process development of sub-0.5 μm nonvolatile magnetoresistive random access memory arrays

Cited by 36 publications

References 7 publications

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles

Etch characteristics of magnetic tunnel junction materials using substrate heating in the pulse-biased inductively coupled plasma

Influence of O2Gas on Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH4/O2/Ar Plasma

Contact Info

Product

Resources

About

Influence of O₂Gas on Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₄/O₂/Ar Plasma