The effect of a lithium niobate heating on the etching rate in SF<sub>6</sub> ICP plasma

Осипов, А. А.; Alexandrov, Sergei; Iankevich, Gleb A.

doi:10.1088/2053-1591/aafa9d

Cited by 13 publications

(11 citation statements)

References 11 publications

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“…A small etching angle of a mesa could create poor polarization retention and a strong depolarization field, resulting in imprinted domain switching hysteresis and a high coercive electric field ( E c ) that reduces memory performance . Moreover, the “dead layers” between electrodes and LNO mesas could thicken during etching and degrade the DW current. − To mitigate these problems, we proposed fabricating embedded electrodes by diffusing them thickness-wise into the film with no etching of the LNO material …”

Section: Introductionmentioning

confidence: 99%

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

Zheng

Zhong

et al. 2021

ACS Appl. Mater. Interfaces

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With the formation of mesa-like cells at their surfaces, LiNbO3 thin films are useful for integrating high-density domain wall memory. However, the material is too hard and inert to etch the cells with inclined side edges that help to diminish polarization retention. Moreover, etching could damage the ferroelectricity of the film. To overcome these drawbacks in forming memory cells directly, we developed a technique to deposit two gapped electrodes in the film surface, without needing to etch the film. While applying an in-plane write voltage above a coercive voltage, the domain within the gap is reversibly switched along with the creation/erasure of conducting domain walls against the peripheral unswitched domain. This technique enables “on”/“off” current read of the written information. Unfortunately, the switched domain within the gap generally has poor retention and a weak wall current arises from the presence of a strong depolarization field. To overcome this problem, we fabricated a type of embedded electrode that diffuses thickness-wise into the LiNbO3 thin film to form a parallel-plate-like structure to screen the depolarization field. The switched domains now had good retention and carry large wall currents. Alternatively, without the embedded electrodes, the switched domains within the cells can be stabilized with increasing gap distance above a critical length of 320 nm. The two methods foreshadow the possibility in the future to fabricate damage-free LiNbO3 memory cells without etching.

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Section: Introductionmentioning

confidence: 99%

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

Zheng

Zhong

et al. 2021

ACS Appl. Mater. Interfaces

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“…F lines 685.9, 690.9, 703.9, 731.3, 775.4 nm, N lines 574.8, 747.0, 818.8, 868.3 nm and Xe lines 823.3, 841.1, 882.1, 904.7, 916.5, 979.9 nm were chosen for analysis. Increasing the temperature on the substrate holder, hence the temperature of the lithium niobate wafer is known to affect the acceleration of the chemical part of the etching process because of the removal of the etching reaction product NbF5 (boiling point 235℃) [9]. However, as can be seen from the plots in figure 3a, changing the temperature on the substrate holder has no effect on the intensities of all considered spectral lines.…”

Section: Resultsmentioning

confidence: 99%

OES diagnostics of NF₃/Xe plasma for deep structures in LiNbO₃

Осипов

Gagaeva

Speshilova

et al. 2022

J. Phys.: Conf. Ser.

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In this work, in situ non-perturbing method of optical emission spectroscopy is used to examine the features of the emission spectra of NF3/Xe plasma, which can be used for the process of continuous plasma-chemical etching of lithium niobate. To understand the physicochemical processes occurring in plasma, the influence of high-frequency power, pressure in the chamber, bias voltage and substrate temperature on the emission intensities of the F, N, Xe lines was studied. It was determined that increasing the bias voltage from -300 to -50 V and the temperature from 50 to 300°C doesn’t change the relative intensities of the analysed spectral lines, while increasing the high-frequency power from 500 to 750W and decreasing the pressure from 1.95 to 0.95Pa increase the intensities of the F, N, Xe lines.

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“…Indeed, other research groups tried to etch lithium niobate material for ridge and rib structures, using fluorine dry etching. This typically shows less verticality, between 60 • and 78 • , with a visibly rough side wall [39,40]. Unfortunately, the literature on LN tends to not report the quantitative values of the smoothness of the side walls.…”

Section: Experiments and Resultsmentioning

confidence: 99%

High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

et al. 2022

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The exceptional material properties of Lithium Niobate (LiNbO3) make it an excellent material platform for a wide range of RF, MEMS, phononic and photonic applications; however, nano-micro scale device concepts require high fidelity processing of LN films. Here, we reported a highly optimized processing methodology that achieves a deep etch with nearly vertical and smooth sidewalls. We demonstrated that Ti/Al/Cr stack works perfectly as a hard mask material during long plasma dry etching, where periodically pausing the etching and chemical cleaning between cycles were leveraged to avoid thermal effects and byproduct redeposition. To improve mask quality on X- and Y-cut substrates, a H2-plasma treatment was implemented to relieve surface tension by modifying the top surface atoms. Structures with etch depths as deep as 3.4 µm were obtained in our process across a range of crystallographic orientations with a smooth sidewall and perfect verticality on several crystallographic facets.

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The effect of a lithium niobate heating on the etching rate in SF₆ ICP plasma

Cited by 13 publications

References 11 publications

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

OES diagnostics of NF₃/Xe plasma for deep structures in LiNbO₃

High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

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The effect of a lithium niobate heating on the etching rate in SF6 ICP plasma

Cited by 13 publications

References 11 publications

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO3 Thin Films

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO3 Thin Films

OES diagnostics of NF3/Xe plasma for deep structures in LiNbO3

High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

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Product

Resources

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The effect of a lithium niobate heating on the etching rate in SF₆ ICP plasma

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

OES diagnostics of NF₃/Xe plasma for deep structures in LiNbO₃