Etch Characteristics of Nanoscale Patterned Magnetic Tunnel Junction Stacks Using Pulse-Modulated Radio Frequency Source Plasma

Magnetic tunnel junctions (MTJs) patterned with 70 × 70 nm2 square arrays were etched in a CH4/O2/Ar gas mixture by pulse-modulated inductively coupled plasma reactive ion etching (ICPRIE). A good etch profile of MTJs with etch slope of approximately 82° was achieved by adjusting the on–off duty ratio of the plasma and pulse frequency. Langmuir probe analysis and optical emission spectroscopy confirmed that the balance between the formation of the passivation layer as an etch byproduct and sputtering effect is responsible for the etch selectivity and etch profile with a high degree of anisotropy. It is concluded that the application of pulse-modulated plasma on ICPRIE can be an effective method to obtain the anisotropic etch profile of nanometer-scale MTJs.

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Pulse-Modulated Plasma Etching of Copper Thin Films via CH3COOH/Ar

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19462 ◽

2021 ◽

Vol 21 (11) ◽

pp. 5628-5634

Author(s):

Jin Su Ryu ◽

Eun Taek Lim ◽

Moon Hwan Cha ◽

Chee Won Chung

Keyword(s):

Plasma Etching ◽

Photoelectron Spectroscopy ◽

Continuous Wave ◽

Optical Emission ◽

Duty Ratio ◽

Pulsed Plasma ◽

X Ray ◽

Copper Compounds ◽

Ar Gas ◽

Etch Profile

Pulse-modulated plasma etching of copper masked using SIO2 films was conducted via a CH3COOH/Ar. The etch characteristics were examined under pulse-modulated plasma. As the duty ratio of pulse decreased and the frequency of pulse increased, the etch selectivity and etch profile were improved. X-ray photoelectron spectroscopy and indicated that more copper oxides (Cu2O and CuO) and Cu(CH3COO)2 were formed using pulse-modulated plasma than those formed using continuous-wave (CW) plasma. As the concentration of CH3COOH gas in pulse-modulated plasma increased, the formation of these copper compounds increased, which improved the etch profiles. Optical emission spectroscopy confirmed that the active ingredients of the plasma increased with decreasing pulse duty ratio and increasing frequency. Therefore, the optimized pulsed plasma etching of copper via a CH3COOH/Ar gas provides better etch profile than that by CW plasma etching.

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Inductively Coupled Plasma Reactive Ion Etching of Magnetic Tunnel Junction Stacks in a CH3COOH/Ar Gas

ECS Solid State Letters ◽

10.1149/2.0071510ssl ◽

2015 ◽

Vol 4 (10) ◽

pp. P77-P79 ◽

Cited By ~ 8

Author(s):

A. A. Garay ◽

J. H. Choi ◽

S. M. Hwang ◽

C. W. Chung

Keyword(s):

Tunnel Junction ◽

Inductively Coupled Plasma ◽

Reactive Ion Etching ◽

Magnetic Tunnel Junction ◽

Ion Etching ◽

Inductively Coupled ◽

Ar Gas

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Investigation of ETCH Profiles in Etching of PZT and Pt Thin Films

MRS Proceedings ◽

10.1557/proc-493-119 ◽

1997 ◽

Vol 493 ◽

Cited By ~ 4

Author(s):

Chee Won Chung ◽

Inyong Song ◽

Jong Sig Lee

Keyword(s):

Thin Films ◽

Photoelectron Spectroscopy ◽

Inductively Coupled Plasma ◽

Secondary Ion Mass Spectrometry ◽

X Ray ◽

Inductively Coupled ◽

Gas Chemistry ◽

Pzt Films ◽

Ar Gas ◽

Etch Profile

ABSTRACTReactive ion etching of PbZrxTi1−xO3 (PZT) and Pt thin films was studied by using chlorine and fluorine gas chemistry in an Inductively Coupled Plasma (ICP). PZT films were etched by varying the etching parameters including coil RF power, dc-bias voltage to substrate, and gas pressure. Etching characteristics of PZT films were investigated in terms of etch rate, etch selectivity, etch profile. Etch profile along with etch anisotropy was observed as a function of etching parameter by field emission scanning electron microscopy (FESEM). For the understanding of etching mechanism, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analysis for the film composition were utilized. Platinum thin films have been etched by using Cl2/Ar in an ICP for the development offence-free etching. The redeposited materials formed on the pattern sidewall by using Cl2/Ar gas combination were analyzed by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). We found that the redeposited material was mainly PtCh compound. Based on this result, SiCl4/Cl2/Ar gas chemistry has been proposed as a new etching gas and demonstrated good etching profile of Pt films without unwanted redeposition.

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