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This study presents a detailed fabrication method, together with validation, discussion, and analysis, for state-of-the-art silicon carbide (SiC) etching of vertical and bevelled structures by using inductively coupled plasma reactive ion etching (ICP-RIE) for microelectronic applications. Applying different gas mixtures, a maximum bevel angle of 87° (almost vertical), large-angle bevels ranging from 40° to 80°, and small-angel bevels ranging from 7° to 17° were achieved separately using distinct gas mixtures at different ratios. We found that SF6 with additive O2 was effective for vertical etching, with a best etching rate of 3050 Å/min. As for the large-angle bevel structures, BCl3 + N2 gas mixtures show better characteristics, exhibiting a controllable and large etching angle range from 40° to 80° through the adjustment of the mixture ratio. Additionally, a Cl2 + O2 mixture at different ratios is applied to achieve a small-angel bevels ranging from 7° to 17°. A minimum bevel angel of approximately 7° was achieved under the specific volume of 2.4 sccm Cl2 and 3.6 sccm O2. These results can be used to improve performance in various microelectronic applications including MMIC via holes, PIN diodes, Schottky diodes, JFETs’ bevel mesa, and avalanche photodiode fabrication.

The possibility of fabricating a full graphene device was investigated by utilizing atomic layer etching (ALET) technology. By using O2 ALET which functions by oxygen radical adsorption followed by the removal of the oxygen chemisorbed on carbon, the removal of exactly one graphene layer per ALET cycle was detected through the increase of the transmittance by 2.3% after one ALET cycle and by the decrease of the G peak in the Raman spectra. The Raman spectra also showed an increase of the D peak after ALET, indicating the formation of physical damage on the graphene surface layer. This damage was mostly recovered by hydrogen annealing at 1000 °C after ALET. Full graphene field effect transistors (source, drain: 3 layer, channel: 1, 2, 3 layer) were fabricated by reducing the channel layers using ALET, followed by annealing, and the electrical characteristics of the devices showed the possibility of fabricating fully functional graphene devices composed of an all graphene source/drain and graphene channel by utilizing ALET.

The effect of the fluorination of aluminum oxide (Al2O3) in an oxide-nitride-aluminum oxide (SiO2-Si3N4-Al2O3, ONA) layer through fluorine (F) ion and neutral-beam treatments on the characteristics of the ONA layer was investigated to study the effect of charge-related damage during F ion beam treatment. The treatment with an F beam at approximately 10 eV energy produced an about-5-nm-thick fluorinated alumina layer by replacing the aluminum-oxygn (Al-O) bonding with Al-F bonding for both the F neutral-beam and F ion beam treatments. Moreover, no significant differences in the physical and chemical properties of the ONA layers treated with the two beams were observed. When the electrical characteristics of the metal-oxide-semiconductor (MOS) devices were compared, however, the lowest leakage current and highest memory window characteristics were observed in the MOS device fabricated with an F neutral beam, due to the Al-F layer formed on the Al2O3 surface. In the case of the MOS device fabricated with the F-ion-beam-treated ONA layer, however, lower electrical characteristics were observed compared to the MOS device fabricated with the F-neutral-beam-treated ONA layer, possibly due to the charge-related damage that occurred during the F ion beam treatment, even though the memory characteristics were improved compared to the reference due to the Al-F layer formed on the Al2O3 surface.

A Ni-Zn ferrite-enhanced U-shaped internal inductive antenna (240 mm × 2300 mm) operated at 2 MHz was used as a linear plasma source for an ultralarge-area plasma, and its plasma and electrical characteristics were investigated and compared with those of the antenna operated at 13.56 MHz without the ferrite. By the magnetic field enhancement, the operation of the source showed higher power transfer efficiency, lower antenna impedance, and lower RF rms voltage compared to that operated at 13.56 MHz without the ferrite. When photoresist etch uniformity was measured by etching the photoresist using a 40-mtorr Ar/O2 (7:3) mixture at 2 MHz by locating three U-shaped antennas in parallel, the etch uniformity less than 11% could be obtained on the substrate size of 2300 mm × 2000 mm.

Characteristics of atomic layer etching of (100) GaAs and (111) GaAs have been investigated using Ne neutral beam and Cl2 gas. By using a Ne neutral beam dose and a Cl2 gas pressure higher than critical values of 3.03 × 1016 atoms/cm2·cycle and 0.4 mTorr, respectively, steady state etch rates of 1.41 A/cycle for (100) GaAs and 1.63 A/cycle for (111) GaAs which correspond to the etch rate of one atomic layer/cycle could be obtained. At the monolayer etching condition, the roughness of the GaAs surface was remaining similar to that of the unetched GaAs surface. In addition, the GaAs etched by the atomic layer etching showed the surface composition similar to that before the etching while the GaAs etched by a conventional reactive ion etching such as an inductively coupled plasma etching showed significant change in the surface composition.

This study examined the etch characteristics of ZrO2 etched using an atomic layer etching (ALET) system with BCl3 gas for adsorption and an Ar neutral beam for desorption. The effect of the BCl3 gas pressure and Ar neutral beam dose on the etch characteristics was examined. The results showed that the ZrO2 etch rate was maintained at a constant etch rate of 1.07 angstroms/cycle at a BCl3 gas pressure > 0.15 mTorr and an Ar beam flux > 1.485 x 1016 atoms/cm2 x cycle. Under these constant etch rate conditions, the surface roughness of the etched ZrO2 was similar to that of the as-received ZrO2. The surface composition of ZrO2 etched by ALET was compared with that etched by BCl3 inductively coupled plasma (ICP). The surface composition of ZrO2 etched by ALET showed a similar composition to that of the as-received ZrO2 while that etched by BCl3 ICP showed a Zr-rich surface.

We describe methods to fabricate extreme ultraviolet lithography (EUVL) absorber mask patterns by atomic force microscope (AFM) lithography and inductively coupled plasma (ICP) etching. AFM lithography, based on anodization and cross-linking polymer resist, was applied to fabricate trench structures using only Ta and Cr/Ta bilayers. In particular, the top Cr layer was used not only as a hard mask to etch the underlying Ta in dry-etching, but also as an absorber material together with Ta. The Cr oxide or Ta with respect to Cr was eliminated due to the clear etch-selectivity of ICP dry-etching using C4F8 gas. This is a simple fabrication technique using AFM lithography fabricated metal trenches for the production of isolated metal structures as well as for producing EUVL absorber patterns.

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Precise etch depth control of ultra-thin HfO2 (3.5 nm) films applied as a gate oxide material was investigated by using atomic layer etching (ALET) with an energetic Ar beam and BCl3 gas. A monolayer etching condition of 1.2 A/cycle with a low surface roughness and an unchanged surface composition was observed for ultra-thin, ALET-etched HfO2 by supplying BCl3 gas and an Ar beam at higher levels than the critical pressure and dose, respectively. When HfO2-nMOSFET devices were fabricated by ALET, a 70% increase in the drain current and a lower leakage current were observed compared with the device fabricated by conventional reactive ion etching, which was attributed to the decreased structural and electrical damage.

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