Characterization of the NiFe sputter etch process in a rf plasma

Kropewnicki, Thomas J.; Paterson, Alex; Panagopoulos, Theodoros; Holland, J.

doi:10.1116/1.2187998

Cited by 8 publications

(4 citation statements)

References 19 publications

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“…We can apply an Ar sputter etch process with the usual plasma etch apparatus. 25) One of the authors reported that the process showed almost the same performance with Ar milling. The major difficulty in the Ar sputter etch process was an electrical short failure due to conductive redeposition at the side wall of the MgO barrier.…”

Section: Introductionmentioning

confidence: 96%

Damage Recovery by Reductive Chemistry after Methanol-Based Plasma Etch to Fabricate Magnetic Tunnel Junctions

Kinoshita

Yamamoto

Honjo

et al. 2012

Jpn. J. Appl. Phys.

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The damage recovery process for magnetic tunnel junctions (MTJs) after methanol-(Me-OH) based plasma etch has been demonstrated. Me-OH and O 2 plasma, which contain oxygen in the molecule, caused unavoidable modification of magnetic materials in the MTJ stack. For example, the magnetization saturation and MR ratio decreased. H 2 base reductive plasma treatment was effective in recovering from this deterioration. No harmful side effects were observed in other aspects of MTJ performance such as MTJ resistance, hysteresis loop offset, and switching field. Heavier initial damage required a longer treatment time for recovery. Other types of reductive chemistry such as NH 3 plasma deteriorated the MTJ when the treatment lasted more than 15 s, probably due to nitridation. The use of a highly selective Ar/Me-OH etch process along with He/H 2 plasma recovery treatment is very promising for the MTJs' etch process to fabricate high-density magnetic random access memory (MRAM) and non-volatile logic devices. #

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Section: Introductionmentioning

confidence: 96%

Damage Recovery by Reductive Chemistry after Methanol-Based Plasma Etch to Fabricate Magnetic Tunnel Junctions

Kinoshita

Yamamoto

Honjo

et al. 2012

Jpn. J. Appl. Phys.

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“…15 24 Previously, ion beam etching (IBE) has been used for the etching of MTJ materials by using Ar ions; however, due to the lack of volatile compounds during the etching, heavily redeposited etch residue was observed on the surface and sidewall of the etched MTJ features when the MTJ pattern was not severely over-etched. [25][26][27] In this current study however, instead of an Ar ion beam, a reactive ion beam (RIB) etching system was investigated in the etching of MTJ materials to increase the volatility of etch residue formed during the etching with reactive gases. For the effective etching of MTJ patterns, various etch gases such as Ar, NF 3 , CH 3 OH, and CO/NH 3 gas mixture were used and their etch characteristics were analyzed.…”

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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“…Therefore, up to now, the metals used in magnetic devices have been etched by Ar ion milling [4][5][6] or pure Ar ion etching. 7) Wafer tilt and rotation allow for the removal of redeposited metals on the pattern side wall in the Ar ion milling process. However, it is difficult to utilize the technique for manufacturing VLSIs with high density, as it causes a shadow effect depending on the angle of the incident ion beam and pattern height.…”

Section: Introductionmentioning

confidence: 99%

Process-induced damage and its recovery for a CoFeB–MgO magnetic tunnel junction with perpendicular magnetic easy axis

Kinoshita

Honjo

Fukami

et al. 2014

Jpn. J. Appl. Phys.

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We investigate the effect of process-induced damage (PID) caused by reactive ion etching using methanol (Me-OH) gas on the magnetic properties of the CoFeB free layer in a magnetic tunnel junction with a perpendicular easy axis (p-MTJ), and on the tunnel magnetoresistance (TMR) ratio of CoFeB-MgO p-MTJs. The dot pattern of the MTJ stack with size varied from 65 to 430 nm etched by the Me-OH plasma showed a smaller coercivity (H c ) than that fabricated by Ar ion milling. The increase in H c was observed in the dot pattern of large size (430 nm) upon increasing He/H 2 plasma treatment temperature after the Me-OH etching. A possible origin of the increase in H c is the increase in nucleation field after He/H 2 treatment. This suggests that H c of the large dot pattern has the potential to be an index for detecting PID during the MTJ fabrication process. The TMR ratio of CoFeB-MgO p-MTJ deteriorated after the Me-OH plasma etching. This PID was considered to be due to oxidation from the pattern edge of the CoFeB free layer of the MTJ. The recovery process by the He/H 2 plasma treatment was examined just after the Me-OH etching to reduce the oxidized part. The median TMR ratio of 102%, which is 5% higher than that of the sample without the He/H 2 treatment, was observed after applying this reductive treatment at 180 °C. In addition, the recovery process had scalability with MTJ size, as the effect was observed more clearly in the MTJ smaller than 97 nm.

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Characterization of the NiFe sputter etch process in a rf plasma

Cited by 8 publications

References 19 publications

Damage Recovery by Reductive Chemistry after Methanol-Based Plasma Etch to Fabricate Magnetic Tunnel Junctions

Damage Recovery by Reductive Chemistry after Methanol-Based Plasma Etch to Fabricate Magnetic Tunnel Junctions

Etching of Magnetic Tunnel Junction Materials Using Reactive Ion Beam

Process-induced damage and its recovery for a CoFeB–MgO magnetic tunnel junction with perpendicular magnetic easy axis

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