Towards the sub-50nm magnetic device definition: Ion beam etching (IBE) vs plasma-based etching

Peng, Xilin; Wakeham, Stacey; Morrone, A.; Axdal, Steven; Feldbaum, Michael; Hwu, Justin J.; Boonstra, T.; Chen, Yonghua; Ding, Jian Ning

doi:10.1016/j.vacuum.2008.12.003

Cited by 30 publications

(23 citation statements)

References 15 publications

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“…[10][11][12] To overcome these etch problems, several etch chemistries such as CO/NH 3 , CH 3 OH gases which probably increase the volatility of etch byproducts have been intensively investigated. [13][14][15][16][17][18] However, the volatility of etch byproducts is not high due to low chemical reaction between etchant gases and MTJ materials even though these reactive gases were used in the conventional plasma etching method.…”

Section: Introductionmentioning

confidence: 99%

Effect of RF Pulsing Biasing on the Etching of Magnetic Tunnel Junction Materials Using CH<SUB>3</SUB>OH

Jeon¹,

Yun²,

Yang³

et al. 2014

j nanosci nanotechnol

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The magnetic tunnel junction (MTJ)-related materials such as CoFeB, CoPt, MgO, and Ru, and W were etched using CH3OH in a pulse-biased inductively coupled plasma system and the effect of bias pulsing (100% 30% duty percentage) on the etch characteristics of the MTJ-related materials was investigated at the substrate temperature of 200 degrees C. The etch selectivity of MTJ-related materials over W was improved by using pulse-biasing possibly due to the formation of more stable and volatile etch products during the pulse-off time and the removal of the compounds more easily on the etched CoFeB surface during the pulse-on time. X-ray photoelectron spectroscopy also showed that the use of lower duty percentage decreases the residue thickness remaining on the etched MTJ materials indirectly indicated the higher volatility of the etch products by the bias pulsing. The etching of nano-patterned CoFeB masked with W also showed more anisotropic etch profile by pulse-biasing probably 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. The most anisotropic CoFeB etch profiles could be observed by using CH3OH gas in the pulse biasing of 30% duty ratio.

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Section: Introductionmentioning

confidence: 99%

Effect of RF Pulsing Biasing on the Etching of Magnetic Tunnel Junction Materials Using CH<SUB>3</SUB>OH

Jeon¹,

Yun²,

Yang³

et al. 2014

j nanosci nanotechnol

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show abstract

“…8,9 For such device applications, pattering, and therefore etching, the component magnetic materials becomes a critical process for fabricating stable devices. Reactive ion etching (RIE) [10][11][12][13]15 based on chlorine and methanol gases has been used for nanoscale magnetic materials etching. But it shows after-corrosion and oxidation problems.…”

Section: Introductionmentioning

confidence: 99%

“…But it shows after-corrosion and oxidation problems. Ion beam etching (IBE) 14,15 has also been used for magnetic material etching which also has many problems, such as sidewall redeposition, mechanical etch damage, and low selectivity. Despite these problems for MTJ pattering, the deposition and etch back technique employing a hard mask layer to increase selectivity during processing is widely used.…”

Section: Introductionmentioning

confidence: 99%

“…Despite these problems for MTJ pattering, the deposition and etch back technique employing a hard mask layer to increase selectivity during processing is widely used. Ta hard masks [15][16][17] are generally used for RIE and IBE processes due to relatively good selectivity over magnetic metals. However, tapering of the Ta mask is unavoidable which results in the underlying MTJ to become trapezoidal.…”

Section: Introductionmentioning

confidence: 99%

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Negative electron-beam resist hard mask ion beam etching process for the fabrication of nanoscale magnetic tunnel junctions

Chun

Kim

Kwon

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors have demonstrated fabrication of 30 nm diameter perpendicular anisotropy magnetic tunnel junctions (MTJs) using negative electron-beam resist (NER) as the ion beam etching (IBE) hard mask. The NER pillar of 30 nm diameter and 105 nm thickness was fabricated by electron-beam lithography. The redeposition of the MTJ etching debris generated during the IBE on the outer surface of the NER pillar increased the lateral etch resistance of the resist polymer, allowing the edge profile to remain constant for the duration of the MTJ etching, resulting in a vertical MTJ sidewall profile. A multistep IBE (repetition of 45° primary etching and 30° secondary etching) was conducted to reduce the MTJ sidewall redeposition while reducing mechanical damage. The measurement results showed a tunnel magneto-resistance ratio of 22% at 30 nm junction diameter.

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“…Chlorine compound 5,6 and methanol 7 based reactive ion etching [8][9][10] have been used with Ta hard masks for the fabrication of sub 50 nm MTJ pillars. 11 Although they showed good etching characteristics, after-corrosion and oxidation issues exist and at sub 30 nm scales the effects could become amplified. Also, the use of the hard mask adds to the layer thickness, requiring that the pattern defining polymer resist layer becomes thicker to endure longer etching times, which reduces pattern scalability at sub 30 nm range.…”

mentioning

confidence: 99%

Multi-step ion beam etching of sub-30 nm magnetic tunnel junctions for reducing leakage and MgO barrier damage

Chun

Kim

Kwon

et al. 2012

Journal of Applied Physics

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Towards the sub-50nm magnetic device definition: Ion beam etching (IBE) vs plasma-based etching

Cited by 30 publications

References 15 publications

Effect of RF Pulsing Biasing on the Etching of Magnetic Tunnel Junction Materials Using CH<SUB>3</SUB>OH

Effect of RF Pulsing Biasing on the Etching of Magnetic Tunnel Junction Materials Using CH<SUB>3</SUB>OH

Negative electron-beam resist hard mask ion beam etching process for the fabrication of nanoscale magnetic tunnel junctions

Multi-step ion beam etching of sub-30 nm magnetic tunnel junctions for reducing leakage and MgO barrier damage

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