• Title, Summary, Keyword: $Ta_2O_5$

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Electrical Characteristics of Pt/SBT/${Ta_2}{O_5}/Si$ Structure for Non-Volatile Memory Device (비휘발성 메모리를 위한 Pt/SBT/${Ta_2}{O_5}/Si$ 구조의 전기적 특성에 관한 연구)

  • Park, Geon-Sang;Choe, Hun-Sang;Choe, In-Hun
    • 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.

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Electrical Conductivity of YO$_{1.5}$-TaO$_{2.5}$-MgO Based Fluorite Phase (YO$_{1.5}$-TaO$_{2.5}$-MgO 계 Fluorite 상의 전기전도도)

  • Choi, Soon-Mok;Kim, Shin;Lee, Hong-Lim
    • Journal of the Korean Ceramic Society
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    • v.35 no.5
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    • pp.521-527
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    • 1998
  • Electrical conductivity of fluorite structure phases in the {{{{ {Y }_{0.8 } }}{{{{ { Ta}_{ 0.2} {O }_{1.7 }-MgO }} system has been studied. Electrical conductivity of 8mol% MgO doped {{{{ {Y }_{0.8 } }} {{{{ {Ta }_{0.2 } {O }_{1.7 } }} fluorite phase was lower than that of the undoped {{{{ {Y }_{0.8 } }}{{{{ {Ta }_{0.2 } {O }_{1.7 } }} When {{{{ { P}_{H2O } }} was increased electrical conductivity of {{{{ {Y }_{0.8 } }}{{{{ {Ta }_{0.2 } {O }_{1.7 } }} increased linealy with {{{{ { P}`_{H2O } ^{ {1 } over {2 } } }} The {{{{ {Y }_{0.8 } }}{{{{ {Ta }_{0.2 } {O }_{1.7 } }} fluorite phase exhibited higher electrical conductivity in wet atmosphere than in dry atmosphere. The identical trend was observed from the 8mol% MgO doped {{{{ {Y }_{0.8 } }}{{{{ {Ta }_{0.2 } {O }_{1.7 } }} fluorite phase.

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Dielectric Characteristics of the ${Ta_2}{O_5}/{Al_2}{O_3}$ Multilayer Thin Films Processed by Reactive Sputtering (반응성 스퍼터링으로 제조한 ${Ta_2}{O_5}/{Al_2}{O_3}$ 다충박막의 유전특성)

  • Choe, Jae-Hun;O, Tae-Seong
    • Korean Journal of Materials Research
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    • v.11 no.12
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    • pp.1080-1085
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    • 2001
  • Dielectric properties and leakage current characteristics of 100 nm-thick $Ta_2O_5/Al_2O_3$multilayer thin films, which were fabricated by reactive sputtering of$Al_2O_3$and$Ta_2O_5$ successively on top of each other for total 9 layers, have been investigated with variation of the$Al_2O_3$content$(i.e,\;Ta_2O_5/Al_2O_3 \;thickness\;ratio)$.$Ta_2O_5/Al_2O_3$films were amorphous regardless of the$Al_2O_3$content. With increasing the$Al_2O_3$content from 0% to 100%, refractive index of the $Ta_2O_5/Al_2O_3$films decreased linearly from 2.03 to 1.56 and dielectric constant was lowered from 23.9 to 7.7 Variation of the dielectric constant with the$Al_2O_3$content was in good agreement with the behavior that was obtained by assuming parallel capacitors of$Al_2O_3$and Ta_2O_5$. Leakage current characteristics of $Ta_2O_5/Al_2O_3$ multilayer films were superior to those of $Ta_2O_5$ and$Al_2O_3$films. $Ta_2O_5/Al_2O_3$ films of 5% and 10%$Al_2O_3$content exhibited excellent leakage current densities which were lower than $10^{-7} A/cm^2$ at 1MV/cm.

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Dielectric Characteristics of $Ta_2O_5$ Thin Films Prepared by ECR-PECVD (ECR-플라즈마 화학 증착법에 의해 제조된 $Ta_2O_5$ 박막의 유전 특성)

  • 조복원;안성덕;이원종
    • Journal of the Korean Ceramic Society
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    • v.31 no.11
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    • pp.1330-1336
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    • 1994
  • Ta2O5 films were deposited on the p-Si(100) substrates by ECR-PECVD and annealed in O2 atmosphere. The thicknesses of Ta2O5/SiO2 layers were measured by an ellipsometer and a cross-sectional TEM. Annealing in O2 atmosphere enhanced the stoichiometry of the Ta2O5 film and reduced the impurity carbon content. Ta2O5 films were crystallized at the annealing temperatures above 75$0^{\circ}C$. The best leakage current characteristics and the maximum dielectric constant of Ta2O5/SiO2 film capacitor were observed in the specimen annealed at $700^{\circ}C$ and 75$0^{\circ}C$, respectively. The flat band voltage of the Al/Ta2O5/SiO2/p-Si MOS capacitor was varied in the range of -0.6~-1.6 V with the annealing temperature. The conduction mechanism in the Ta2O5 film, the variation of the effective oxide charge density with the annealing temperature, and the effective electric field distribution in the Ta2O5/SiO2 double layer were also discussed.

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Effect of RTA on Leakage Current of $Ta_2O_5$ Thin Films Deposited by PECVD (PECVD법으로 증착된 $Ta_2O_5$박막의 누설전류에 미치는 RTA의 영향)

  • Kim, Jin-Beom;Lee, Seung-Ho;So, Myeong-Gi
    • Korean Journal of Materials Research
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    • v.4 no.5
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    • pp.550-555
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    • 1994
  • The effects of RTA treatment on the leakage current have been studied for tantalum pentoxide( $Ta_2O_5$) films deposited by PECVD on P-type(100) Si substrate using $TaCl_5$(99.99%) and $N_2O$(99.99%) gaseous mixture. The refractive index increased with increasing the deposition temperature and the maximum deposition rate was obtained at $500^{\circ}C$. The Ta-0 bond peak intensity of as-deposited $Ta_2O_5$ increased with increasing the deposition temperature through FT-IR analysis and the leakage current value was decreased with increasing the deposition temperature. The small leakage current value obtained after RTA treatment of as-deposited $Ta_2O_5$ was found to be due to the reduction of 0-deficient structure in the film. The increases of the oxygen coacentration and the Ta-0 bond peak intensity in the film after RTA treatment were measured by AES and FT-IR analyses.

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The Effects of $Ta_2O_5$ on Microstructure and Dielectric Properties of $B_a(Zn_{1/3}Ta_{2/3})O_3$ Ceramics. ($Ta_2O_5$ 첨가가 $Ba(Zn_{1/3}Ta_{2/3})O_3$ 세라믹의 미세구조와 유전특성에 미치는 영향)

  • Jeong, Young-Hun;Kim, Min-Han;Son, Jin-Ok;Nahm, Sahn;Park, Jong-Cheol;Kang, Nam-Kee;Lee, Hwack-Joo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.639-643
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    • 2004
  • [ $Ta_2O_5$ ]가 첨가된 $Ba(Zn_{1/3}Ta_{2/3})O_3$[BZT] 세라믹은 1:2 규칙화 정도가 증가하고 $Ba_3Ta_5O_{15}의 이차상이 새롭게 형성된다. $1580^{\circ}C$ 보다 높은 온도에서 소결된 BZT 세라믹은 $Ta_2O_5$를 첨가하면 입자의 성장이 일어나고 액상이 형성된다. 품질계수(Q) 값은 $1580^{\circ}C$ 보다 높은 온도에서 소결할 경우 미량의 $Ta_2O_5$ 첨가만으로도 상당히 증가한다. 상대밀도는 $Ta_2O_5$ 첨가량에 따라 감소하기 때문에 Q값의 증가는 상대밀도와는 무관하다. 반면에, $Ta_2O_5$의 첨가량에 따라 입자의 성장은 증가하였기 때문에 Q값의 향상은 입자크기와 관계가 있음을 알 수 있다. 많은 양의 $Ta_2O_5$ 첨가시 비록 입자 크기가 증가했음에도 불구하고 Q값이 매우 낮은 것을 볼 때, Q값의 감소는 $Ba_3Ta_5O_{15}$ 상의 영향과 낮은 밀도 값에 기인한 것이다.

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In-situ Synchrotron Radiation Photoemission Spectroscopy Study of Properties Variation of Ta2O5 Film during the Atomic Layer Deposition

  • Lee, Seung Youb;Jeon, Cheolho;Jung, Woosung;Kim, Yooseok;Kim, Seok Hwan;An, Ki-Seok;Park, Chong-Yun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.283.2-283.2
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    • 2013
  • The variation of chemical and interfacial state during the growth of Ta2O5 films on the Si substrate by atomic layer deposition (ALD) was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor Ta(NtBu)(dmamp)2Me was used as the metal precursor, with Ar as a purging gas and H2O as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of Ta2O5 growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the Ta5+ state, which corresponds with the stoichiometric Ta2O5, only appeared after 4.0 cycles. Additionally, tantalum silicate was not detected at the interfacial states between Ta2O5 and Si. The measured valence band offset value between Ta2O5 and the Si substrate was 3.08 eV after 2.5 cycles.

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Dielectric properties of ${Ta_2}{O_5}$ thin film capacitor with $SnO_2$ thin film underlayer ($SnO_2$ 박막을 이용한 ${Ta_2}{O_5}$박막 커패시터의유전특성)

  • Kim, Jin-Seok;Jeong, Gang-Min;Lee, Mun-Hui
    • Korean Journal of Materials Research
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    • v.4 no.7
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    • pp.759-766
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    • 1994
  • Our investigation aimed to reduce the leakage current of $Ta_2O_5$ thin film capacitor by layering SnOz thin film layer under Ta thin film, thereby supplying extra oxygen ions from the $SnO_{2}$ underlayer to enhance the stoichiometry of $Ta_2O_5$ during the oxidation of Ta thin film. Tantalum was evaporated by e-beam or sputtered on p-Si wafers with various deposition temperatures and was oxidized by dry--oxygen at the temperatures between $500^{\circ}C$ and $900^{\circ}C$. Aluminum top and bottom electrodes were formed to make Al/$Ta_2O_5$/p-Si/Al or $Al/Ta_2O_5/SnO_2$p-Si/AI MIS type capacitors. LCR meter and pico-ammeter were used to measure the dielectric constants and leakage currents of the prepared thm film capacitors. XRD, AES and ESCA were employed to confirm the crystallization of the thin f~lm and the compositions of the films. Dielectric constant of $Ta_2O_5$ thin film capacitor with $SnO_{2}$ underlayer was found to be about 200, which is about 10 times higher than that of $Ta_2O_5$ thin film capacitor without $SnO_{2}$ underlayer. In addition, higher oxidation temperatures increased the dielectric constants and reduced the leakage current. Higher deposition temperature generally gave lower leakage current. $Ta_2O_5/SnO_2$ capacitor deposited at $200^{\circ}C$ and oxidized at $800^{\circ}C$ showed significantly lower leakage current, $10^{-7}A/\textrm{cm}^2$ at $4 \times 10^{5}$V/cm, compared to the one without $SnO_{2}$ underlayer. XRD showed that $Ta_2O_5$ thin film was crystallized above $700^{\circ}C$. AES and ESCA showed that initially the $SnO_{2}$, underlayer supplied oxygen ions to oxidize the Ta layer, however, Sn also diffused into the Ta thin film layer to form a new $Ta_xSn_YO_Z$ , ternary oxide layer after all.

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The Effects of Electrode Materials on the Electrical Properties of $Ta_2O_5$ Thin Film for DRAM Capacitor (DRAM 커패시터용 $Ta_2O_5$ 박막의 전기적 특성에 미치는 전극의존성)

  • Kim, Yeong-Wook;Gwon, Gi-Won;Ha, Jeong-Min;Kang, Chang-Seog;Seon, Yong-Bin;Kim, Yeong-Nam
    • Korean Journal of Materials Research
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    • v.1 no.4
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    • pp.229-235
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    • 1991
  • A new electrode material for $Ta_2O_5$ capacitor was developed to obtain both high dielectric constant and improved electrical properties for use in DRAM. High leakage current and low breakdown field of as-deposited $Ta_2O_5$ film on Si is due to the reduction of $Ta_2O_5$ by silicon at $Ta_2O_5$/electrode interface. $Dry-O_2$ anneal improves the electrical properties of $Ta_2O_5$ capacitor with Si electrode, but it thickens the interfacial oxide and lowers the dielectric constant, subsequently. $Ta_2O_5$ capacitor with TiN exectrode shows better electrical properties and higher dielectric constant than post heat treated $Ta_2O_5$ film on Si. No interfacial oxide layer at $Ta_2O_5$/TiN interface suggests that there\`s no Interaction between $Ta_2O_5$ and electrode. TiN is a adequate electrode material for $Ta_2O_5$ capacitor.

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Electrical Properties of Ta/$Ta_2O_5$/Ta Thin Film Capacitor deposited on $Al_2O_3$ Substrate ($Al_2O_3$ 기판 위에 제작된 Ta/$Ta_2O_5$/Ta 박막 커패시터의 전기적 특성)

  • Kim, Hyun-Ju;Song, Jae-Sung;Kim, In-Sung;Kim, Sang-Su
    • Proceedings of the KIEE Conference
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    • pp.1502-1504
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    • 2003
  • 최근 전자기기의 경박단소화 추세는 전자기기의 크기와 가격의 감소를 이끌었으며 이러한 추세는 앞으로 지속될 것이다. 이와 같은 현상으로 전자기기를 구성하는 요소의 절반이상을 차지하는 단위수동소자의 경우 소형화를 넘어 박막화 및 집적화가 절실히 요구되는 실정이다. 따라서 본 연구에서는 현재 GHz 대역의 휴대용 무선통신 송 수신부 등에 사용되고 있는 기판이 $Al_2O_3$ 기판인 점을 고려하여 기판의 공통화를 위해 $Al_2O_3$ 기판 위에 Ta/$Ta_2O_5$/Ta 구조를 갖는 MIM 박막커패시터를 제작하여 그 특성을 고찰하였다. 모든 박막의 증착은 RF-magnetron reactive sputtering법에 의해 이루어졌으며, 유전체 열처리는 $700^{\circ}C$ 진공상태에서 60 sec 동안 수행하였다. XRD 분석결과, as-deposited $Ta_2O_5$ 박막은 열처리 후에 비정질상에서 결정질상으로 변환되었다. Ta/$Ta_2O_5$/Ta/Ti/$Al_2O_3$ 커패시터의 전기적 특성으로는 C-F, C-V, I-V 를 측정하였다.

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