Silicon carbon nitride (SiCN) thin films are promising materials for copper diffusion barriers and hybrid bonding in semiconductor processes. Oxidation-resistant films are increasingly critical for realizing high-reliability devices, highlighting the need for process control and property evaluation. In this study, we analyzed the thin film properties as a function of tetramethylsilane (4MS) gas partial pressure ratio (PPR), deposition temperature, and dual-power plasma conditions in a PECVD-based SiCN deposition process. Based on the results, we experimentally demonstrated that the refractive index can be a valid indicator for oxidation resistance evaluation. The application of dual-power plasma conditions was instrumental in enhancing oxidation resistance. Under these conditions, the refractive index reached approximately 1.90 even at 200℃, comparable to values observed in films deposited at 350℃. These findings provide a basis for predicting oxidation resistance and optimizing low-temperature conditions, with applications in next-generation semiconductor and packaging technologies requiring high reliability.
We demonstrated a crack-free α-Ga2O3 on sapphire substrate by horizontal halide vapor phase epitaxy (HVPE). Oxygen-and gallium chloride-synthesized Ga metal and HCl were used as the precursors, and N2 was used as the carrier gas. The HCl flow and growth temperature were controlled in the ranges of 10~30 sccm and 450~490℃, respectively. The surface of α-Ga2O3 template grown at 470℃ was flat and the root-mean-square (RMS) roughness was ~2 nm. The full width at half maximum (FWHM) values for the symmetric-plane diffractions, were as small as 50 arcsec and those for the asymmetric-plane diffractions were as high as 1,800 arcsec. The crystal quality of α-Ga2O3 on sapphire can be controlled by varying the HCl flow rate and growth temperature.
In this paper, we discuss β-Ga2O3 thin films that have been grown on freestanding GaN (FS-GaN) using furnace oxidation. A GaN template was grown by horizontalhydride vapor phase epitaxy (HVPE), and FS-GaN was fabricated using the laser lift off (LLO) system. To obtain β-Ga2O3 thin film, FS-GaN was oxidized at 900~1,100℃. Surface and cross-section of prepared β-Ga2O3 thin films were observed by field emission scanning electron microscopy (FE-SEM). The single crystal FS-GaNs were changed to poly-crystal β-Ga2O3. The oxidized β-Ga2O3 thin film at 1,100℃ was peel off from FS-GaN. Next, oxidation of FS-GaNwas investigated for 0.5~12 hours with variation of the oxidation time. The thicknesses of β-Ga2O3 thin films were measured from 100 nm to 1,200 nm. Moreover, the 2-theta XRD result indicated that (-201), (-402), and (-603) peaks were confirmed. The intensity of peaks was increased with increased oxidation time. The β-Ga2O3 thin film was generated to oxidize FS-GaN.
TeOx thin films were deposited at various O2/Ar gas-flow ratios by a reactive RFmagneton sputtering technique from TeO2 and Te targets. X-ray diffraction (XRD) results revealed that the TeOx thin films were amorphous. The structure and chemical composition of the TeOx thin films were investigated by fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The optical characteristics of the TeOx thin films were investigated by an Ellipsometer and a UV-VIS-NIR spectrophotometer. According to the O2/Ar gas-flow ratios, the atomic composition ratio of TeOx thin films was divided into two regions(x=1-2, 2-3). Different optical characteristics were shown in each region. With an increasing O2/Ar gas-flow ratio, the refractive index of the TeOx thin films decreased and the optical bandgap of the films increased.
ZrO2/PSS thin film with a high refractive index was fabricated on a glass substrate by a layer-by-layer self-assembly method. The surface morphology and thickness of the fabricated ZrO2/PSS thin films were measured as a function of the number of (ZrO2/PSS)n. As the number of (ZrO2/PSS)n increased from n = 5 to n = 20, RMS roughness decreased from 29.01 nm to 8.368 nm. The ZrO2 thin films exhibited high transmittance of 85% or more; and the 15-bilayer thin film exhibited the highest transmittance among the samples. The transmittance of the fabricated (ZrO2/PSS)15 thin film was ca. 90.8% in the visible range. The refractive index of the glass substrate coated by a (ZrO2/PSS)15 thin film with a thickness of 160 nm increased from ca. 1.52 to 1.74 at the 632 nm wavelength.
We demonstrated that self-separation FS-GaN (freestanding-GaN) was grown on MELO (maskless epitaxially lateral overgrowth) GaN template by horizontal HVPE (hydride vapor phase epitaxy). Before thick GaN grwoth, MELO GaN template was grown on patterned GaN template by MOCVD (metal organic chemical vapor deposition). The laterally overgrown GaN would consist of a continuous well coalesced layer. The mixed TDD (threading dislocation density) of seed and wing region were 8 × 108 cm-2 and 7 × 107 cm-2, respectively. After thick GaN grown by HVPE, the self-separation between thick GaN and sapphire substrate was generated at seed region. The regions of self-separation for FS-GaN and sapphire were observed by FE-SEM. Moreover, Raman results indicated that the compressive strain of seed and wing regions at FS-GaN substrate were slightly released compared to that of thick GaN grown on conventional GaN template. The optical properties of the FS-GaN substrate were examined by using PL (photoluminescence). The PL exhibited that donor bound exciton and donor acceptor pair were observed at low temperature. The effects on optical and structural properties of FS-GaN substrate have been discussed in detail.
In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ω-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.
The basic characteristics of glass are highly fragile and brittle consequences the ultimate purpose of glass manufacturing is to make a transparent glass with complex shape. In order to solve this problem, mechanical properties of glass can be increased by crystallization of its amorphous glass. However, glass-ceramics has become opaque through crystallization process due to the distracted interface of glass by precipitated particles. This study has been investigated thermal processing conditions of LAS transparent glass-ceramic by using DTA (differential thermal analysis), in order to control size of precipitated particle and then fabricate transparent glass-ceramic. DTA indicated that crystallization peak area was declined with increased nucleation temperature. Subsequently, we have been established optimum temperature for crystallization depending on the nucleation temperature. The transmission and thermal expansion were measured after crystallization, and the size of precipitated particle was identified in range of 20~100 nm by FE-SEM. In addition, by setting the optimized crystallization condition, with high transmission and low thermal expansion glass was synthesized through this experiment.
In this paper, we have studied the effect of mechanical polishing to Ga-polar face for reducing the wafer bowing and strain in free-standing GaN. After the mechanical polishing to Ga-polar face, the bowing of the free-standing GaN substrate significantly decreased with increasing the size of diamond slurry, and eventually changed the bowing direction from concave to convex. Furthermore, the full width at half maximum (FWHM) of high-resolution X-ray diffraction (HR-XRD) were decreased, especially the FWHM of (1 0 2) reflection for 1.0 μm size of diamond slurry was significantly decreased from 630 to 203 arcsec. In the case, we confirmed that the compressive strain in Ga-polar face was fully released by Raman measurement.
Anti-reflective (AR) thin film was fabricated on a glass substrate by sol-gel method. The coating solution was synthesized with TEOS (tetraethlyorthosilicate) and poly ethylene glycol (PEG, 4.0 wt%). As the withdrawal speed of coating was changed from 0.1 mm/sec to 0.3 mm/sec, the thickness and refractive index of prepared thin films were changed. The reflectance and transmittance of coating glass fabricated by the withdrawal speed of 0.1 mm/sec were 0.62% and 95.0% in visible light range. The refractive index and thickness of single layer thin film were n= 1.29 and ca. 99.0 nm.
In this paper, high quality AlN layers were regrown on AlN nanopillar structure with SiO2-dots by HVPE. Surface morphology of AlN layer regrown exhibited flatter than a conventional AlN template. The laterally overgrown AlN regions would consist of a continuous well coalesced layer with lower dislocation density than in the template because of the dislocation blocking and dislocation bending effects. Moreover, result of Raman spectroscopy suggest that the AlN nanopillar structure with SiO2-dots relieves the strain in the AlN layer regrown by HVPE.
We proposed and demonstrated a simultaneous measurement method to detect the refractive index and temperature of a medium using a side-polished fiber involving FBG (fiber Bragg grating). The temperature of a medium was obtained by using the Bragg wavelength shift of FBG, while the refractive index of medium were calculated by using the transmission loss. The Bragg wavelength is independent on the refractive index of the covering medium placed on surface of side-polished fiber, while the transmission loss at off-Bragg wavelength highly depends on the environmental temperature because of thermo-optic effect of the medium.
In this paper, a measurement method to obtain the optical properties of a liquid base on a side-polished single mode fiber was proposed and demonstrated. The device showed periodic resonance coupling against wavelengths. The refractive index and dispersion characteristics of a liquid were calculated by use of the spacings of periodic resonance wavelengths of the device. The thermo-optic coefficient of the liquid was obtained by monitering the shift of resonance wavelengths of the devices with change of environmental temperature.
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