• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.257-257
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• 2010

최근 저항 변화 메모리는 종래의 비휘발성 기억소자인 Flash memory보다 access time(writing)이 105배 이상 빠르고, DRAM과 같이 2~5 V 이하의 낮은 전압 특성 및 간단한 제조 공정 등으로 차세대 비휘발성 메모리 소자로 주목 받고 있지만, 여전히 소자의 Endurance 및 Retention 특성 등의 신뢰성 문제를 해결해야 할 과제로 안고 있다. 이러한 문제점들을 해결하기 위해 페로브스카이트계 산화물 또는 이원 산화물 등의 다양한 저항 변화 물질에 대한 연구가 진행되고 있다. 하지만, 현재 주로 연구되고 있는 금속 산화물계 물질들은 그 제조 공정상 산소에 의한 다수의 산소 디펙트 형성과 제작 시 쉽게 발생할 수 있는 표면 오염의 문제점을 안고 있다. 본 연구는 기존의 금속 산화물계 박막의 제조 공정에서 발생하는 문제점을 해결하기 위해 질화물계 박막을 저항변화 물질로 도입함으로써, 기존의 저항 변화 물질의 장점인 간단한 공정 및 저전압/고속 동작 특성을 동일하게 유지 할 뿐 아니라, 그 제조 공정상 발생하는 다수의 산소 디펙트와 표면 오염의 문제를 해결함으로써, 보다 고효율을 가지며 재현성이 우수한 메모리 소자를 구현 하고자 한다 [1, 2]. 본 연구를 위해 Pt/AlN/Pt 구조의 Metal/Insulator/Metal(MIM) 저항 변화 메모리를 제작 하였다. 최적의 저항 변화 특성 조건을 확인하기 위해 70~200nm까지 두께 구분과 N2 가스 분위기의 열처리 온도를 $200{\sim}600^{\circ}C$까지 진행 하였다. 본 소자의 저항 변화 특성 실험은 Keithley 4200-SCS을 이용하여 진행 하였다. 실험 결과, AlN의 최적의 두께 및 열처리 온도 조건은 130nm/$500^{\circ}C$였으며, 안정적인 unipolar 저항 변화 특성을 확인 활 수 있었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.10a
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• pp.119-119
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• 2003

Plasma polymerized organic thin films were deposited on Si(100) glass and Copper substrates at 25 ∼ 100 $^{\circ}C$ using cyclohexane and ethylcyclohexane precursors by PECVD method. In order to compare physical and electrochemical properties of the as-grown thin films, the effects of the RF plasma power in the range of 20∼50 W and deposition temperature on both corrosion protection efficiency and physical properties were studied. We found that the corrosion protection efficiency (P$\_$k/), which is one of the important factors for corrosion protection in the interlayer dielectrics of microelectronic devices application, was increased with increasing RF power. The highest P$\_$k/ value of plasma polymerized ethylcyclohexane film (92.1% at 50 W) was higher than that of the plasma polymerized cyclohexane film (85.26% at 50 W), indicating inhibition of oxygen reduction. Impedance analyzer was utilized for the determination of I-V curve for leakage current density and C-V for dielectric constants. To obtain C-V curve, we used a MIM structure of metal(Al)-insulator(plasma polymerized thin film)-metal(Pt) structure. Al as the electrode was evaporated on the ethylcyclohexane films that grew on Pt coated silicon substrates, and the dielectric constants of the as-grown films were then calculated from C-V data measured at 1㎒. From the electrical property measurements such as I-V ana C-V characteristics, the minimum dielectric constant and the best leakage current of ethylcyclohexane thin films were obtained to be about 3.11 and 5 ${\times}$ 10$\^$-12/ A/$\textrm{cm}^2$ and cyclohexane thin films were obtained to be about 2.3 and 8 ${\times}$ 10$\^$-12/ A/$\textrm{cm}^2$.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.174-179
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• 2013

This paper presents a capacitor loaded tunable bandpass chip filter using multiple split ring resonators (MSRRs) with two transmission zeros. To obtain high selectivity and minimize the chip size, asymmetric feed lines are adopted to make a pair of transmission zeros located on each side of passband. Compared with conventional filters using cross-coupling or source-load coupling techniques, the proposed filter uses only two resonators to achieve high selectivity through a pair of transmission zeros. In order to optimize selectivity and sensitivity (insertion loss) of the filter, the effect of the position of asymmetric feed line on transmission zeros and insertion loss is analyzed. The SOI-CMOS switched capacitor composed of metal-insulator-metal (MIM) capacitor and stacked-FETs is loaded at outer rings of MSRRs to tune passband frequency and handle high power signal up to +30 dBm. By turning on or off the gate of the transistors, the passband frequency can be shifted from 4GH to 5GHz. The proposed on-chip filter is implemented in 0.18-${\mu}m$ SOI CMOS technology that makes it possible to integrate high-Q passive devices and stacked-FETs. The designed filter shows miniaturized size of only $4mm{\times}2mm$ (i.e., $0.177{\lambda}g{\times}0.088{\lambda}g$), where ${\lambda}g$ denotes the guided wave length of the $50{\Omega}$ microstrip line at center frequency. The measured insertion loss (S21)is about 5.1dB and 6.9dB at 5.4GHz and 4.5GHz, respectively. The designed filter shows out-of-band rejection greater than 20dB at 500MHz offset from center frequency.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.37-42
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• 2006

The preparation and processing of PVP-gate insulators on the device performance have been studied in the fabrication of organic thin film transistors (OTFTs). One of polyvinyl series, poly-4-vinyl phenol(PVP) was used as a solute and propyleneglycol monomethyl etheracetate(PGMEA) as a solvent in the formation of organic gate solutions. The cross-linking of organic insulators was also attempted by adding the thermosetting material, poly (melamine-co-formaldehyde) as a hardener in the compounds. From the measurements of electrical insulating characteristics of metal-insulator-metal (MIM) samples, PVP-based insulating layers showed lower leakage current according to the increase of concentration of PVP and poly (melamine-co-formaldehyde) to PGMEA in the formation of organic solutions. The PVP(20 wt%) copolymer with composition of 20 wt% PVP to PGMEA and cross-linked PVPs in which 5 wt% and 10 wt% poly (melamine-co-formaldehyde) hardeners had been additional]y mixed into PVP(20 wt%) copolymers were used as gate dielectrics in the fabrication of OTFTs, respectively. In our experiments, the maximum field effect mobility of $0.31cm^2/Vs$ could be obtained in the 5 wt% cross-linked PVP(20 wt%) device and the highest on/off current ratio of $1.92{\times}10^5$ in the 10 wt% cross-linked PVP(20 wt%) device.

• Korean Journal of Materials Research
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• v.18 no.4
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• pp.169-174
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• 2008

The structural and electrical properties of amorphous $BaSm_2Ti_4O_{12}$ (BSmT) films on a $TiN/SiO_2/Si$ substrate deposited using a RF magnetron sputtering method were investigated. The deposition of BSmT films was carried out at $300^{\circ}C$ in a mixed oxygen and argon ($O_2$ : Ar = 1 : 4) atmosphere with a total pressure of 8.0 mTorr. In particular, a 45 nm-thick amorphous BSmT film exhibited a high capacitance density and low dissipation factor of $7.60\;fF/{\mu}m2$ and 1.3%, respectively, with a dielectric constant of 38 at 100 kHz. Its capacitance showed very little change, even in GHz ranges from 1.0 GHz to 6.0 GHz. The quality factor of the BSmT film was as high as 67 at 6 GHz. The leakage current density of the BSmT film was also very low, at approximately $5.11\;nA/cm^2$ at 2 V; its conduction mechanism was explained by the the Poole-Frenkel emission. The quadratic voltage coefficient of capacitance of the BSmT film was approximately $698\;ppm/V^2$, which is higher than the required value (<$100\;ppm/V^2$) for RF application. This could be reduced by improving the process condition. The temperature coefficient of capacitance of the film was low at nearly $296\;ppm/^{\circ}C$ at 100 kHz. Therefore, amorphous BSmT grown on a TiN substrate is a viable candidate material for a metal-insulator-metal capacitor.