• Journal of the Korean Vacuum Society
• /
• v.7 no.s1
• /
• pp.57-77
• /
• 1998

Heteroepitaxial $Y_2O_3$ films were grown on a Si(111) substrate by ionized cluster beam deposition(ICBD) in ultra high vacuum, and its qualities such as crystllitnity, film stress, and morphological characteristics were investigated using the various measurement methods. The crystallinity was investigated by x-ray diffraction (XRD) and reflection high energy electron diffraction (RHEED). Interface crystallinity was also examined by Rutherford backscattering spectroscopy(RBS) channeling, transmission electron microscopy(TEM). The stress of the films was measured by RBS channeling and XRD. Surface and interface morphological characteristics were investigated by atomic force microscopy (AFM) and x-ray scattering method. Comparing the interface with the surface characteristics, we can conclude that many defects at the interface region were generated by interface reaction between the yttrium metal and SiO2 layer and by ion beam characteristic such as shallow implantation, so that they influenced the film qualities. The film quality was dominantly depended on the characteristic temperature range. In the temperature range from $500^{\circ}C$ to $600^{\circ}C$, the crystallinity was mainly improved and the surface roughness was drastically decreased. On the other hand, in the temperature range from $600^{\circ}C$ to $700^{\circ}C$, the compressive stress and film density were dominantly increased, and the island size was more decreased. Also the surface morphological shape was transformed from elliptical shape to triangular. The film stress existed dominantly at the interface region due to the defects generation.

• Journal of Sensor Science and Technology
• /
• v.18 no.5
• /
• pp.349-352
• /
• 2009

This paper describes the fabrication and characteristics of micro heaters built on AlN($0.1{\mu}m$)/3C-SiC($1{\mu}m$) suspended membranes by surface micromachining technology. In this work, 3C-SiC and AlN films are used for high temperature environments. Pt thin film was used as micro heaters and temperature sensor materials. The resistance of temperature sensor and the power consumption of micro heaters were measured and calculated. The heater is designed for operating temperature up to about $800^{\circ}C$ and can be operated at about $500^{\circ}C$ with a power of 312 mW. The thermal coefficient of the resistance(TCR) of fabricated Pt resistance of temperature detector(RTD)'s is 3174.64 ppm/$^{\circ}C$. A thermal distribution measured by IR thermovision is uniform on the membrane surface.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.4 no.2
• /
• pp.131-133
• /
• 1994

Deposition of silicon on pretreated sapphire substrates has been investigated by the liquid phase epitaxy method at low temperatures. An average 14 $\mu\textrm{m}$ thickness of silicon was grown over a large area on sapphire substrate originally coated with a much thinner silicon layer $[0.5 \mu\textrm{m} (100) Si/(1102) sapphire]$ at low temperatures from $(380^{\circ}C to 460^{\circ}C)$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.7
• /
• pp.624-630
• /
• 2006

ZnO deposition parameters are not independent and have a nonlinear and complex property. To propose a method that could verify and predict the relations of process variables, neural network was used. At first, ZnO thin films were deposited by using RF magnetron sputtering process with various conditions. Si, GaAs, and Glass were used as substrates. The temperature, work pressure, and RF power of the substrate were $50\sim500^{\circ}C$, 15 mTorr, and $180\sim210W$, respectively : the purity of the target was ZnO 4 N. Structural properties of ZnO thin films were estimated by using XRD (0002) peak intensity. The structure of neural network was a form of 4-7-1 that have one hidden layer. In training a network, learning rate and momentum were selected as 0.2, 0.6 respectively. A backpropagation neural network were performed with XRD (0002) peak data. After training a network, the temperature of substrate was evaluated as the most important parameter by sensitivity analysis and response surface. As a result, neural network could capture nonlinear and complex relationships between process parameters and predict structural properties of ZnO thin films with a limited set of experiments.

• Korean Journal of Materials Research
• /
• v.15 no.3
• /
• pp.149-154
• /
• 2005

Teflon like fluorocarbon thin films have been deposited on silicon and oxide molds as an antistiction layer for the hot embossing process by an inductively coupled plasma (ICP) chemical vapor deposition (CVD) method. The process was performed at $C_4F_8$ gas flow rate of 2 sccm and 30 W of plasma power as a function of substrate temperature. The thickness of film was measured by a spectroscopic ellipsometry. These films were left in a vacuum oven of 100, 200 and $300^{\circ}C$ for a week. The change of film thickness, contact angle and adhesion and friction force was measured before and after the thermal test. No degradation of film was observed when films were treated at $100^{\circ}C$. The heat treatment of films at 200 and $300^{\circ}C$ caused the reduction of contact angles and film thickness in both silicon and oxide samples. Higher adhesion and friction forces of films were also measured on films treated at higher temperatures than $100^{\circ}C$. No differences on film properties were found when films were deposited on either silicon or oxide. A 100 nm silicon template with 1 to $500\;{\mu}m$ patterns was used for the hot embossing process on $4.5\;{\mu}m$ thick PMMA spun coated silicon wafers. The antistiction layer of 10 nm was deposited on the silicon mold. No stiction or damages were found on PMMA surfaces even after 30 times of hot embossing at $200^{\circ}C$ and 10 kN.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.4 no.2
• /
• pp.119-130
• /
• 1994

To deposit silicon on borosilicate glass substrates, 18 different substrate combinations were investigated because of the difficulty of direct deposition of silicon. Sucessful results were obtained from Al-and Mg-treated glass and furnace annealed sputtered silicon deposited glass substrates. A continuous silicon thin film on a large area substrates was obtained in the temperatures ranges from $420^{\circ}C to 520^{\circ}C$. These thin films might be applied to lower the cost of solar cells and solar cell modules.

• Progress in Superconductivity
• /
• v.9 no.2
• /
• pp.177-182
• /
• 2008

[ $MgB_2$ ] thin films were fabricated using hybrid physical-chemical vapor deposition (HPCVD) method on silicon substrates with buffers of alumina grown by using atomic layer deposition method. The growth war in a range of temperatures $500\;{\sim}\;600^{\circ}C$ and under the reactor pressures of $25\;{\sim}\;50\;Torr$. There are some interfacial reactions in the as-grown films with impurities of mostly $Mg_2Si$, $MgAl_2O_4$, and other phases. The $T_c$'s of $MgB_2$ films were observed to be as high as 39 K, but the transition widths were increased with growth temperatures. The magnetization was measured as a function of temperature down to the temperature of 5 K, but the complete Meissner effect was not observed, which shows that the granular nature of weak links is prevailing. The formation of mostly $Mg_2Si$ impurity in HPCVD process is discussed, considering the diffusion and reaction of Mg vapor with silicon substrates.

• Journal of the Korean Society for Heat Treatment
• /
• v.22 no.5
• /
• pp.290-297
• /
• 2009

In case of using Asymmetric Bipolar Pulsed DC (ABPD) power generator, thin film is efficiently deposited as ions are getting higher energy by suppressing target poisoning and electric arc. In this article, the mechanical properties of CNx thin films deposited on the STS 316L were compared with DC and ABPD power generators. The CNx thin films deposited with ABPD clearly improved wear resistance by higher ratio of sp3CN as compared with DC. Nb interlayer affected to increase the value of 10N of adhesion between CNx thin films and substrate. But, CNx thin films deposited with ABPD couldn't endure to wear load and decreased wear resistance as the films were too thinner than substrate. Nevertheless the higher substrate bias energy applied to perform the dense films, it wasn't shown benefits about the wear properties from DC sputtering. But, in case of using ABPD sputtering, the wear resistance was largely improved without changing morphology despite of thin films.

• Journal of the Korean Ceramic Society
• /
• v.49 no.6
• /
• pp.620-624
• /
• 2012

The role of moisture remaining inside the deposition chamber during the formation of the cubic boron nitride (c-BN) phase in BN film was investigated. BN films were deposited by an unbalanced magnetron sputtering (UBM) method. Single-crystal (001) Si wafers were used as substrates. A hexagonal boron nitride (h-BN) target was used as a sputter target which was connected to a 13.56 MHz radiofrequency electric power source at 400 W. The substrate was biased at -60 V using a 200 kHz high-frequency power supply. The deposition pressure was 0.27 Pa with a flow of Ar 18 sccm - $N_2$ 2 sccm mixed gas. The inside of the deposition chamber was maintained at a moisture level of 65% during the initial stage. The effects of the evacuation time, duration time of heating the substrate holder at $250^{\circ}C$ as well as the plasma treatment on the inside chamber wall on the formation of c-BN were studied. The effects of heating as well as the plasma treatment very effectively eliminated the moisture adsorbed on the chamber wall. A pre-deposition condition for the stable and repeatable deposition of c-BN is suggested.

• Progress in Superconductivity
• /
• v.3 no.2
• /
• pp.135-139
• /
• 2002

We have fabricated high-quality c-axis-oriented $MgB_2$ thin films by using a pulsed laser deposition technique. The thin films grown on (1 1 0 2) $Al_2$$O_3$ substrates show an onset transition temperature of 39.2 K with a sharp transition width of ~0.15 K. X-ray diffraction patterns indicate a c-axis-oriented crystal structure perpendicular to the substrate surface. We observed high critical current densities ($J_{c}$) of ~ 16 $MA/\textrm{cm}^2$ at 15 K and under self-field, which is comparable to or exceeds those of cuprate high-temperature superconductors. The extrapolation $J_{c}$ at 5 K was estimated to be ~ 40 MA/$\textrm{cm}^2$, which is the highest record for $MgB_2$ compounds. At a magnetic field of 5 T, the $J_{c}$ of~ 0.1 $MA/\textrm{cm}^2$ was detected at 15 K, suggesting that this compound is very promising candidate for the practical applications at high temperature with lower power consumption. As a possible explanation for the high current-carving capability, the vortex-glass phase will be discussed.d.d.d.