High density plasma etching of amorphous CoZrNb films for thin film magnetic devices

Shin, Byul; Park, Ik Hyun; Lee, Jang Woo; Kim, Tae Wan; Chung, Chee Won

doi:10.1016/j.tsf.2005.08.292

Cited by 11 publications

(2 citation statements)

References 12 publications

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“…This bias controls the energy of ions bombarding the substrate surface. 17 In this report, the effect of the O 2 concentration on the etch profile of MTJ stacks was examined by ICPRIE using CH 4 /O 2 /Ar gas mixes. The etch rates of the films were obtained using a surface profilometer (Tencor P-10) and the etch profile of the MTJ stacks were observed by FESEM.…”

Section: Methodsmentioning

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.

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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 ...

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Section: Methodsmentioning

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.

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“…A dc-bias voltage induced by rf power at 13.56 MHz was capacitively coupled to the substrate susceptor to control the ions' energy in the plasma. 16 In this study, the effects of the concentration of CH 3 OH gas on the etch rate and etch profile of MTJ stacks were investigated. The etch rates of the films were obtained using a surface profilometer (Tencor P-10).…”

mentioning

confidence: 99%

Evolution of Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₃OH/Ar Plasma

Kim

Lee

Chung

2012

J. Electrochem. Soc.

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Etch characteristics of magnetic tunnel junction (MTJ) stacks masked with W/TiN films were investigated using an inductively coupled plasma reactive ion etching in a CH 3 OH/Ar gas. The effect of CH 3 OH concentration on the etch rate, etch selectivity and etch profile of MTJ stacks was examined. The high degree of anisotropy of etched MTJ stacks at high CH 3 OH concentrations resulted from the high etch selectivity of MTJ stacks to hard mask which was closely related with the high ratio of [H]/[Ar] peaks obtained by optical emission spectroscopy. The evolution of etch profile of MTJ stacks was examined to elucidate the etch mechanism in a CH 3 OH/Ar gas. Transmission electron microscopy of the etched MTJ stacks revealed the redeposition on the sidewall of MTJ stacks occurred during the early stage of etching and the gradual sputtering-off of the redeposited materials during further etching, resulting in a high degree of anisotropy. In addition, the redeposited materials turn out to be mainly Pt and Mn with low levels of Co and Fe by using energy dispersive X-ray spectroscopy Development of magnetic random access memory (MRAM) devices has been the object of recent research, as a replacement for the 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 consist of a magnetic tunnel junction (MTJ) stack and CMOS. The MTJ stack is a key part of MRAM devices and the continued increasing density of MRAMs demands new etching processes that can produce nanometer-sized patterns on the MTJ stacks. 3,4 The development of new methods to pattern and etch MTJ stacks, which consist of various magnetic materials, metals and metal oxides, is key for the realization of high-density MRAM. Dry etching of MTJ stacks is very difficult because the magnetic materials and metals rarely react with chemically reactive species in a plasma. Ion beam etching was first used to etch magnetic materials and MTJ stacks. However, ion beam etching involves physical sputtering by energetic ions; this approach has several undesirable attributes including slow etch rate, sidewall redeposition, and etching damages, and is of very limited use. Conventional reactive ion etching and chemical assisted ion etching techniques were also applied to etch the magnetic materials but the etch results were similar to those obtained by ion beam etching. 5-7 High density plasma reactive ion etching of magnetic materials and MTJ stacks using Cl 2 /Ar, BCl 3 /Ar, HBr/Ar, CO/NH 3 , and CH 4 /H 2 /Ar gases have been employed to improve the etching process but the etch profiles with the slanted etch slope were not satisfactory. [8][9][10][11][12][13][14] Recently, a CH 3 OH gas was used to etch the MTJ stacks. 15 However, the etch profiles of the MTJ stacks with nanometersized patterns were inadequate and in need of improvement, and the etch mechanism is still unclear. In this study, an inductively coupled plas...

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Soft magnetic properties of amorphous-CoZr/ polycrystalline-M (M = Cu, Ag, Al, Cr) multilayers

Song

Zong

et al. 2007

Appl. Phys. A

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High density plasma etching of amorphous CoZrNb films for thin film magnetic devices

Cited by 11 publications

References 12 publications

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

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

Evolution of Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₃OH/Ar Plasma

Soft magnetic properties of amorphous-CoZr/ polycrystalline-M (M = Cu, Ag, Al, Cr) multilayers

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High density plasma etching of amorphous CoZrNb films for thin film magnetic devices

Cited by 11 publications

References 12 publications

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

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

Evolution of Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH3OH/Ar Plasma

Soft magnetic properties of amorphous-CoZr/ polycrystalline-M (M = Cu, Ag, Al, Cr) multilayers

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

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

Evolution of Etch Profile of Magnetic Tunnel Junction Stacks Etched in a CH₃OH/Ar Plasma