• Korean Journal of Materials Research
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• v.15 no.5
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• pp.348-352
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• 2005

Gallium oxyhydroxide (GaOOH) powders were heat-treated in a flowing ammonia gas to form GaN, and the reaction kinetics of the oxide to nitride was quantitatively determined by X-ray diffraction analysis. GaOOH turned into intermediate mixed phases of $\alpha-\;and\;\beta-Ga_2O_3$, and then single phase of GaN. The reaction time for full conversion $(t_c)$ decreased as the temperature increased. There were two-types of rapid reaction processes with the reaction temperature in the initial stage of nitridation at below $t_c$, and a relatively slow processes followed over $t_c$ does not depends on temperatures. The nitridation process was found to be limited by the rate of an interfacial reaction with the reaction order n value of 1 at $800^{\circ}C$ and by the diffusion-limited reaction with the n of 2 at above $1000^{\circ}C$, respectively, at below $t_c$. The activation energy for the reaction was calculated to be 1.84 eV in the temperature of below $830^{\circ}C$, and decreased to 0.38 eV above $830^{\circ}C$. From the comparative analysis of data, it strongly suggest the rate-controlling step changed from chemical reaction to mass transport above $830^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.252-252
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• 2009

In this work, the nanocrystalline ZnO/polycrystalline (poly) aluminum nitride (AlN)/Si structure was fabricated for humidity sensor applications based on surface acoustic wave (SAW). In this structure, the ZnO film was used as sensing material layer. These ZnO and AlN(0002) were deposited by so-gel process and a pulse reactive magnetron sputtering, respectively. These experimental results showed that the obtained SAW velocity on AlN film was about 5128 m/s at $h/\lambda$=0.0125 (h and $\lambda$ is thickness and wavelength, respectively). For ZnO sensing layers coated on AlN, films have hexagonal wurtzite structure and nanometer particle size. The crystalline size of ZnO films annealed at 400, 500, and 600 $^{\circ}C$ is 10.2, 29.1, and 38 nm, respectively. Surface of the film exhibits spongy which can adsorb steam in the air. The best quality of the ZnO film was obtained with annealing temperature at 500 $^{\circ}Cis$. The change in frequency response (127.9~127.85 MHz) of the SAW humidity sensor based on ZnO/AlN structure was measured along the change in humidity (41~69%). The structural properties of thin films wereinvestigated by XRD and SEM.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1128-1135
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• 2001

In this paper, a new HSG-Si formation technology, "seeding method', which employs Si$_2$H$_{6}$-molecule irradiation and annealing, was applied for realizing 64Mbit DRAMs. By using this technique, grain size controlled HSG-Si can be fabricated on in-situ phosphorous-doped amorphous-Si electrode. The new HSG-Si fabrication technology achieves twice the storage capacitance with high reliability for the stacked capacitors. In this technique, optimum process conditions of the phosphorous concentration, storage polysilicon deposition temperature and thickness of hemispherical grain silicon are in the range of 3.0-4.0E19atoms/㎤, 53$0^{\circ}C$ and 400$\AA$, respectively. In the 64M bit DRAM capacitor using optimum process conditions, limit thickness of dielectric nitride is about 65$\AA$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.63-63
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• 2003

The nanotopography of silicon wafers has emerged as an important factor in the STI process since it affects the post-CMP thickness deviation (OTD) of dielectric films. Ceria slurry with surfactant is widely applied to STI-CMP as it offers high oxide-to-nitride removal selectivity. Aiming to control the nanotopography impact through ceria slurry characteristics, we examhed the effect of surfactant concentration and abrasive size on the nanotopography impact. The ceria slurries for this study were produced with cerium carbonate as the starting material. Four kinds of slurry with different size of abrasives were prepared through a mechanical treatment The averaged abrasive size for each slurry varied from 70 nm to 290 nm. An anionic organic surfactant was added with the concentration from 0 to 0.8 wt %. We prepared commercial 8 inch silicon wafers. Oxide Shu were deposited using the plasma-enhanced tetra-ethyl-ortho-silicate (PETEOS) method, The films on wafers were polished on a Strasbaugh 6EC. Film thickness before and after CMP was measured with a spectroscopic ellipsometer, ES4G (SOPRA). The nanotopogrphy height of the wafer was measured with an optical interferometer, NanoMapper (ADE Phase Shift)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.9
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• pp.671-675
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• 2010

Gallium nitride (GaN), wide bandgap semiconductor, has attracted much attention because they are projected to have much better performance than silicon. In this paper, effects of design parameters change of GaN power static induction transistor (SIT) on the electrical characteristics (breakdown voltage, on resistance) were analyzed by computer simulation. According to the analyzed results, the optimization was performed to get power GaN SIT that has 600 V class breakdown voltage. As a result, we could get optimized 600 V class power GaN SIT that has higher breakdown voltage and lower On resistance with a thin (a several micro-meters) thickness of the channel layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.660-664
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• 2008

Titanium nitride (TiN) thin films are widely used for hard coatings due to their superior hardness, chemical stability, low friction and good adhesion properties. In this study, we investigated the effect of DC power on the characteristics of TiN thin films deposited on Si and glass substrates by DC magnetron sputtering using TiN target. We made TiN films of 300 nm thickness with various DC powers. The structural properties of films are investigated by x-ray diffractions (XRD) and tribological properties are measured by nano-indentation, nano-scratch tester. The rms roughness was measured by atomic forced microscopy (AFM). In the result, TiN films had the smooth surface and exhibited (111) directions with the increase of DC Power. Also, especially in case of 175 W DC power, TiN film exhibited the maximum hardness about 8 GPa, and the critical load near 25.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.5
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• pp.270-275
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• 2017

Current progress in the development of semiconductor technology in applications involving high electron mobility transistors (HEMT) and power devices is hindered by the lack of adequate ways todissipate heat generated during device operation. Concurrently, electronic devices that use gallium nitride (GaN) substrates do not perform well, because of the poor heat dissipation of the substrate. Suggested alternatives for overcoming these limitations include integration of high thermal conductivity material like diamond near the active device areas. This study will address a critical development in the art of GaN on diamond (GOD) structure by designing for ideal heat dissipation, in order to create apathway with the least thermal resistance and to improve the overall ease of integrating diamond heat spreaders into future electronic devices. This research has been carried out by means of heat transfer simulation, which has been successfully demonstrated by a finite-element method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.250-254
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• 2003

A film bulk acoustic resonator (FBAR) device for 2 GHz radio frequency (RF) bandpass filter application is presented. This FBAR device consists of an aluminum nitride (AlN) film sandwiched between top(Al) and bottom(Au) electrodes and an acoustic multilayer reflector of a silicon dioxide/tungsten (SiO2/W). The A/N film deposited using a RF sputtering was observed to have small columnar grains with a strongly preferred orientation towards c axis. In addition to a high quality factor (4300), a large return loss of 37.19 dB was obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.759-762
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• 2010

In this investigation, the effects of $N_2/(Ar+N_2)$ gas partial pressure on the structural, electrical, and thermal properties of AlN dielectric layers prepared on aluminum substrates using RF-magnetron sputtering method were analyzed. Among the films, the AlN dielectric film deposited under $N_2/(Ar+N_2)$ gas partial pressure of 75% exhibit the highest AlN (002) preferred orientation, which was grain size of about 15.32 nm and very dense structure. We suggest the possibilities of it's application as a dielectric layer for metal PCB because the AlN films prepared at optimized gas partial pressure can improving the insulating property, the thermal conductivity, and thermal diffusivity of the films.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.76-79
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• 2010

본 논문에서는 고 효율 및 고 출력 특성을 가지는 질화갈륨(GaN) 소자를 이용하여 WiMAX 및 LTE System에 사용될 수 있는 DPD용 Pallet Amplifier를 제작하였다. 제작된 Pallet Amplifier는 Pre-drive로써 저 전류의 MMIC를 채택하고, Drive 단과 Main 단에 15W 급과 30W 급의 질화갈륨 소자를 사용 하였으며, 추가적인 효율 개선을 위해 PCB상에 Doherty Structure를 적용함으로써 보다 높은 효율을 구현하였다. 제작된 Pallet Amplifier는 음 전원 Bias 제어 회로, 온도에 따른 Gain 보상회로, Sequence 회로 및 Main 전원 Drop에 따른 보호 회로를 구현하였다. WiMAX Signal을 이용한 Modulation Power 10Watt Test에서 약 36.8~38.3%의 Pallet 효율과 DPD Solution인 TI GC5325SEK DPD Board 사용 시 ACLR은 약 46dBc 이상을 가지는 것으로 측정되었다. 본 논문에서 제작된 Pallet Amplifier는 Upper Band와 Lower Band로 나누어 제작되었던 기존 Pallet Amplifier와 달리 하나의 Pallet Amplifier로 2496~2690MHz에서 모두 사용하면서 종전에 사용되고 있는 Pallet Amplifier에 비해 Size가 최소 10% 이상 축소되어 효율 및 크기 면에서 종전 Pallet Amplifier보다 큰 이점을 갖는다.