• Journal of the Korean institute of surface engineering
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• v.30 no.4
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• pp.231-238
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• 1997

Tantalum oxide thin filme has an amorphous structure and a high resistivity. Its stoichiometric structure was $Ta_2O_{5.3}$ and the transmission ratio was 80%. The high resistivity of $Ta_2O_{5.3}$ thin film electrolyte made an EC windows without electrical shottness, but the bleached/colored cur rent was very low because of the low ion conductivith. Upon adding moisture into the system, the $\Delta$T increased upto 25 %. proton concentration increase was the main cases to improve optical property. The influence of adding precious or transition metal film(~100 $\AA$ thickness) in $Ta_2O_5$layer on the color change performance was observed. The metal insertion layers had formed hydroxide and they behaved as a stable proton source. The transmission diffrnece and cycle life were greatly enhanced in the case of Ti inssertion.The $\Delta$T was 50% and the cycle life was 18, 000.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.246-254
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• 1993

In order to increase the capacitance of storage electrode in the DRAM capacitor, two approaches were performed. First, hemispherical and rugged poly silicon films were made by LPCVD to increase the effective surface area of storage electrode. The even surface morphology of conventional poly silicon electrode was changed into the uneven surface of hemispherical of rugged poly silicon films. Second, PECVD $Ta_2O_5$ dielectric films were deposited and thermally treated to study the dielectrical characteristics of $Ta_2O_5$ film on each electrode. MIS capacitors with $Ta_2O_5$ films were electrically characterized by I-V, C-V and TDDB measurements. As a result, the capacitance of the electrode with uneven surface were increased by a factor of 1.2~1.5 and leakage current was increased compared with those of even surface. TDDB result indicates that the electrode with uneven surface has dielectrically more degraded than that of even surface. These results can be helpful as a basic research to develop new generation DRAM capacitors with $Ta_2O_5$ films.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.57-57
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• 2003

High dielectric constant materials (high K) have attracted a great deal of interest because of the dramatic scaling down of DRAM capacitor reaching its physical limit in terms of reduction of thickness. Among high-K materials that can replace silicon dioxide, tantalum pentoxide (Ta2O5) thin film, with their high dielectric constant (∼25) and good step coverage, is the candidate of choice.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.320-321
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• 2000

전기장 발광현상(Electroluminescence, 이하 EL)은 1936년 Destriau$^{[1]}$ 가 ZnS:Cu 분말에서 처음 전기장 발광현상을 발견한 이래 TFEL(Thin Film EL)소자의 구동전압을 감소시키는 문제는 ACTFEL(Alternating Current Thin Film EL)소자의 개발이후 계속적인 관심의 대상이 되어왔다. TFEL 소자는 전기적으로 용량소자이므로 전기장 인가시 각 층의 정전용량의 역수에 비례하는 전압이 분배되므로 동일한 조건의 형광막 사용시 소자의 구동전압을 낮추기 위해서는 절연박막의 두께를 줄이는 방법과 유전율이 높은 물질을 사용하는 방법이 있으나, 전자의 경우에는 박막의 결함이 생기기 쉬워 한계가 있기 때문에 고유전율 특성을 갖는 새로운 물질을 개발하는 것이 바람직하다. Ta$_2$O$_{5}$ 박막의 경우 작은 누설전류 특성과 고유전율 특성으로 인해 고집적을 요하는 반도체 분야에서 많은 연구가 진행되어 왔다. 또한 EL소자 응용시 효율면에서 우수한 특성이 기대되며, 특히 수분에 강한 특성을 가지고 있어 EL소자의 안정성이 예견되는 바이다. 본 연구에서는 Ta$_2$O$_{5}$ 박막의 산소 결핍에 따른 전기적 특성에 대해 연구하였고 Ta$_2$O$_{5}$ 박막을 이용한 저전압에서 구동가능한 전기장 발광소자를 제작하여 전기광학적 특성에 대해 연구하였다. (중략

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.05a
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• pp.22.2-22.2
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• 2006

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.106-106
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• 2000

반도체 소자가 미세화 됨에 따라 게이트 유전막으로 사용되는 SiO2의 박막화가 요구되나, boron penetration에 의한 Vt shift, 게이트 누설전류, 다결정 실리콘 게이트의 depletion effect 그리고 quantum mechanical effect 때문에 ~20 급에서 한계를 나타내고 있다. 이에 0.1$\mu\textrm{m}$이상의 design rule을 갖는 logic이나 memory 소자에서 요구되어지는 ~10 급 게이트 산화막은 SiO2(K=3.9)를 대신하여 고유전율을 갖는 재료의 채택이 필수 불가결하게 되었다. 고유전 박막 재료를 사용하면, 두께를 두껍게 해도 동일한 inversion 특성이 유지되고 carrier tunneling 이 덜하여 등가 산화막의 두께를 줄일 수 있다. 이러한 고유전박막 재료중 가장 활발히 연구되고 있는 재료는 Ta2O5, Al2O3, STO 그리고 BST 등이 있으나 Ta2O5, STO, BST 등은 실리콘 기판과 직접 반응을 한다는 문제를 가지고 있으며, Al2O3는 유전율이 낮의 재료가 최근 주목받고 있다. 본 실험에서는 ZrO2, HfO2 또는 그 silicates 등의 재료가 최근 주목 받고 있다. 본 실험에서는 ZrO2 박막의 증착조건에 따른 물리적, 전기적 특성 변화에 대하여 연구하였다. RCA 방식으로 세정한 P-type (100) 실리콘 기판위에 reactive DC sputtering 방법으로 압력 5mtorr, power 100~400W, 기판온도는 100-50$0^{\circ}C$로 변화시켜 ZrO2 박막을 증착한 후 산소와 아르곤 분위기에서 400-80$0^{\circ}C$, 10-120min으로 열처리하였다. 증착직후의 시편들과 열처리한 ZrO2 박막의 미세구조와 전기적 특성 변화를 관찰하였다. 우선 굴절율(RI)를 이용해 ZrO2 박막의 밀도를 예측하여 power와 기판온도에 따라 이론값 2.0-2.2 에 근접한 구조를 얻은 후 XRD, XPS, AFM, 그리고 TEM을 사용하여 ZrO2 박막의 chemical bonding, surface roughness 그리고 interfacial layer의 특성을 관찰하였다. 그리고 C-V, I-V measurement를 이용해 capacitance, 유전율, 누설전류 등의 전기적 특성을 관찰해 최적 조건을 설정하였다.

• 전자공학회논문지 IE
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• v.43 no.1
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• pp.1-4
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• 2006

The characteristics of polymeric thin-film transistors(TFTs) can be controlled by chemically modifying the surface of the gate dielectric prior to the organic semiconductor. The chemical treatment consists of derivative the tantalum pentoxide($Ta_2O_5$) surface with organic materials to form self-assembled monolayer(SAM). The deposition of an octadecyl-trichlorosilane(OTS), hexamethy-ldisilazone(HMDS), aminopropyltreithoxysilane(ATS) SAM leads to a mobility of $0.01\sim0.06cm2/V{\cdot}s$ in a poly-3-hexylthiophene(P3HT) conjugated polymer. The mobility enhancement mechanism is likely to involve molecular interactions between the polymer and SAM. These result can be used for polymer TFT's dielectric material.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.199-203
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• 2000

$Ta_2_O5$ and $Sr_0.8Bi_2.4Ta_2O_9$ films were deposited on p-type Si(100) substrates by a rf-magnetron sputtering and the metal organic decomposition (MOD), respectively.The electrical characteristics of the $Pt/SBT/Ta_2O_5/Si$ structure were obtained as the functions of $O_2$ gas flow ratio during the $Ta_2_O5$ sputtering and $Ta_2_O5$ thickness. And to certify the role of $Ta_2_O5$ as a buffer layer, the electrical characteristics of $Pt/SBT/Ta_2O_5/Si$ were compared. $Pt/SBT/Ta_2O_5/Si$ capacitor with 20% $O_2$ gas flow ratio during the $Ta_2_O5$ sputtering did now show typical C-V curve of metal/ferroelectric/insulator/semiconductor (MFIS) structure. The capacitor with 20% $O_2$ gas flow ratio during the $Ta_2_O5$ sputtering had the largest memory window. And the memory window was decreased as the $Ta_2_O5$ gas flow ratio during the $Ta_2_O5$ sputtering was increased to 40%, 60%. In the C-V characteristics of the $Pt/SBT/Ta_2O_5/Si$ capacitors with the different $Ta_2_O5$ thickness, the capacitor with 26nm thickness of $Ta_2_O5$ had the largest memory window. The C-V and leakage current characteristics of the Pt/SBT/Si structure were worse than those of $Pt/SBT/Ta_2O_5/Si$ structure. These results and Auger electron spectroscopy (AES) measurement showed that $Ta_2_O5$ films as a buffer layer tool a role to prevent from the formation of intermediate phase and interdiffusion between SBT and Si.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.184-190
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• 2003

$Sr_{0.9}Bi_{2.1}Ta_2O_9$thin films were deposited on $IrO_2$ electrode by spin coating method using photosensitive sol-gel solution. To ensure the UV-exposure effect on SBT thin films, UV irradiated films and non-UV irradiated films were analyzed by XRD, SEM. As a result, UV-irradiation on SBT thin films promoted grain growth of SBT compared with no UV irradiation. In case of the UV irradiated films annealed at$740{\circ}C$for 1 h in an oxygen ambient, the 2Pr value and Pr/Ps at${pm}5$V were$11.48{mu}C/cm^2$and 0.53, respectively. 2Pr values of the UV irradiated SBT thin films at$660-740{circ}C were approximately 12% higher than those of non-UV irradiated thin films.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.111.2-111
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• 2002