[en] We investigate the effects of glass-forming elements, such as Si, Al, and Bi, on the crystallization and the electrical properties of Zr-based oxide films for alternative gate dielectric applications. It is observed that the crystallization temperature increases and the dielectric constants are reduced as the amount of glass-forming additive is increased. Addition of Si results in the most stable amorphous phase with a significant reduction of the dielectric constant. When the atomic ratio of Zr over (Si + Zr) is about 0.45 and the film is annealed at 950 .deg. C for 1min, no crystallization behaviors are noticed and the dielectric constant is 12. On the other hand, substitution of Bi for Zr keeps the dielectric constant at 20 while it reduces the crystallization temperature to lower than 600 .deg. C. Addition of Al causes a moderate improvement in the crystallization behavior with a small sacrifice in the dielectric constant. Amorphous films of Zr_XAl_1-XO_y (X = 0.45) remain amorphous up to 800 .deg. C anneals and have a dielectric constant of 15.

[en] The shadowing effect is one of the most urgent issues yet to be solved in high-volume manufacturing using extreme ultraviolet lithography (EUVL). Many studies have been conducted to mitigate the unexpected results caused by shadowing effects. The simplest way to mitigate the shadowing effect is to reduce the thickness of the absorber. Since nickel has high extinction coefficients in the EUV wavelengths, it is one of more promising absorber material candidates. A Ni based absorber exhibited imaging performance comparable to a Tantalum nitride absorber. However, the Ni-based absorber showed a dramatic reduction in horizontal-vertical critical dimension (H-V CD) bias. Therefore, limitations in fabricating a EUV mask can be mitigated by using the Ni based absorber.

[en] Ultra-thin hafnium-oxide gate dielectric film and TaN electrode film were deposited by using atomic layer deposition and DC magnetron sputter, respectively, and the thermal and electrical properties were investigated. In this article, it is shown that TaN on ALD-HfO₂ has a midgap work function of ∼ 4.67 eV and no interaction occurs between gate and dielectric. Capacitance-voltage measurements show equivalent oxide thickness of about 1.5 nm for 5.0 nm HfO₂ with TaN electrode. Also, the dielectric constant and the leakage current density of ALD-HfO₂ film are 13.3 ∼ 16.3 and 1 X 10^-6 A/cm² at 1.0 V from flat band voltage, respectively. TEM showed that the interfaces of HfO₂/Si and TaN/HfO₂ are stable at least up to 600 .deg. C.

[en] Indium vacancies in Bi-doped In₃SbTe₂ (BIST) cause local distortion or and faster phase transition of BIST with good stability. The formation energy of the In vacancy in the BIST is relatively lower compared to that in IST due to triple negative charge state of the In vacancy (V 3- In ) and higher concentration of the V 3- In in BIST. The band gap of BIST is substantially reduced with increasing concentrations of the V 3-In and the hole carriers, which results in a higher electrical conductivity. The phase-change memory (PRAM) device fabricated with the BIST shows very fast, stable switching characteristics at lower voltages.

[en] Despite their high energy densities, Li-rich layered oxides suffer from low capacity retention and continuous voltage decay caused by the migration of transition-metal cations into the Li layers. The cation migration stabilizes oxidized oxygen anions through the decoordination of oxygen from the metal once the anions participate in the redox reaction. Structural disordering is thus considered inevitable in most Li-rich layered oxides. However, herein, a Mg-substituted Li-rich layered oxide, Li${}_{1.2}$Mg${}_{0.2}$Ru${}_{0.6}$O${}_2$, with high structural and electrochemical stability is presented. Although using both cationic and anionic redox reactions, Ru migration in Li${}_{1.2-<!--\; ???\; -->x}$Mg${}_{0.2}$Ru${}_{0.6}$O${}_2$ is thermodynamically unfavored as a result of selectively oxidized O ions, suppressed structural disordering, and the formation of short (1.75 Å) Ru=O bonds enabled within the layered framework, which effectively decoordinate the oxidized O ions. The unprecedentedly high structural stability of Li${}_{1.2}$Mg${}_{0.2}$Ru${}_{0.6}$O${}_2$ leads to not only a high energy density of 964 Wh kg${}^{-<!--\; ???\; -->1}$ but also outstanding rate capability and cycle performance. These findings demonstrate the potential of this practical strategy for the stabilization of Li-rich layered oxides even with prolonged cycling. (© 2021 Wiley-VCH GmbH)

[en] In micro/nano electro-mechanical system, silicon nitride (SiNx) membrane has been widely used in sensors, energy harvesting and optical filters because of its mechanical/chemical stability. However, it is necessary to verify mechanical and thermal properties of nanoscale SiNx membranes to ensure the desirable reliability and durability of a device because the properties of nanoscale films vary with thickness which is severely depending on changes in density, grain size, and crystallinity. In this paper, SiNx membranes were fabricated by low pressure chemical vapor deposition followed by reactive ion etching and KOH wet etching. The composition, surface roughness, thickness uniformity and residual stress of the deposited SiNx films were measured to confirm the reliability of the deposition process. Plane-strain modulus, failure stress and emissivity were evaluated by bulge test and heat load test. As a result, the failure stress of the membrane was enhanced by decreasing SiNx thickness while the plane-strain modulus was insensitive to the thickness variation. Through the UV laser heat-load test, it was found that the thermal durability of the thinner membrane deteriorated due to decreased emissivity. To investigate the emissivity depending on membrane thickness, a finite element method simulation was performed based on the experimental results. The calculated emissivity of each membrane coincided with the reported values within 8% difference.

[en] The impact of carbon contamination on imaging performance was analyzed using an in-situ accelerated contamination system (ICS) combined with coherent scattering microscopy (CSM) at the 11B extreme ultraviolet lithography (EUVL) beamline of the Pohang Accelerator Laboratory (PAL). The CSM/ICS is composed of the CSM for measuring imaging properties and the ICS for accelerating the carbon contamination. The CD (critical dimension) and the reflectivity of the mask were compared before and after carbon contamination through acceleration exposure. The reflectivity degradation was 1.3%, 2.1%, and 2.5% after 1-, 2-, and 3-hour exposures, respectively, due to carbon contamination of 5, 10, and 20 nm as measured by using a Zygo interferometer. The mask CD change of an 88-nm line and space pattern was analyzed using CSM and CD SEM (scanning electron microscope), and the result showed a similar trend, but a different absolute value. This difference confirmed the importance of the actinic inspection technique, which employs exactly the same imaging condition as the exposure tool.

[en] This paper reports a simple process to enhance the extraction efficiency of photoluminescence from Eu-doped yttrium oxide (Y₂O₃: Eu³⁺) thin-film phosphor. The two-dimensional (2D) SiO₂ photonic crystal layer was fabricated by vacuum nano-imprint method using a conventional spin-on dielectric solution as a nano-imprint resin and a 2D patterned Si stamp. The applied pressure and temperature of the patterning and annealing process facilitates the conversion of the spin-on dielectric solution into a SiO₂ hemisphere structure resulting in high definition transfer of the 2D reverse pattern of the Si mold. The light extraction efficiency of the Y₂O₃: Eu³⁺ thin-film phosphor assisted by 2D SiO₂ photonic crystal layer was approximately 1.72 times higher than that of the conventional Y₂O₃: Eu³⁺ thin-film phosphor. - Highlights: • Convenient nano-imprint on two-dimensional photonic crystals is proposed. • Direct patterning process of inorganic material was achieved by sol–gel transition. • The photonic crystal improved light extraction of the thin-film phosphor

[en] To prevent ablation caused by sudden hydrogen eruption during crystallization of hydrogenated amorphous Si (a-Si:H) thin films, a wide dehydrogenation thermal annealing (wDTA) system was developed to reduce hydrogen content in a-Si:H film prior to its crystallization process. The annealed a-Si:H films were fully dehydrogenated and nanocrystallized by the wDTA system. Raman scattering measurement revealed that the dehydrogenation process lowers the hydrogen content through disappearance of the peak intensity at 2000 cm⁻¹. The a-Si:H film was transformed into nanocrystallized Si with lower residual stress. The major advantage of this wDTA was the large area uniformity of the thermal and the resulting material properties for 8 generation display. The uniform material characteristics of the hydrogen content, thickness, energy bandgap, and transmittance of the annealed Si films in the overall area was confirmed by Raman spectroscopy, spectroscopic ellipsometry, and UV–vis spectrometer measurement. (paper)

[en] In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%