• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.10
• /
• pp.881-884
• /
• 2008

In this study, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) in the composition from 51/49, was deposited on platinum for a metal-ferroelectric-metal structure. From XRD patterns, the 70 nm- and 140 nm-thick PVDF-TrFE films showed the intensity peak of near $20^{\circ}$ connected to a ferroelectric phase. Moreover, the thicker film indicated the higher intensity than thinner one. The difference of the remanent polarization (2Pr) at 0 V is decreased gradually from 10.19 to $5.7{\mu}C/cm^2$ as the thickness decrease from 140 to 70 nm. However, when the thickness decreased to 50 nm, the 2Pr rapidly drop to $1.6{\mu}C/cm^2$ so the minimum critical thickness might be at least 70 nm for device. Both different thickness films, 70 and 140 nm, indicated that the characteristic of current density-voltage was measured for $10^{-6}{\sim}10^{-7}A/cm^2$ below 15 V and the thicker film maintained relatively lower current density than thinner one. From these results, we can expect that the electrical properties for the devices particularly ferroelectric thin film transistor using PVDF-TrFE copolymer were able to be on the trade-off relationship between the remanent polarization with the bias voltage and the leakage current.

• Journal of the Microelectronics and Packaging Society
• /
• v.11 no.4 s.33
• /
• pp.87-91
• /
• 2004

We have investigated the effects of W-N/Pt bottom electrode on the ferroelectric degradation of $Sr_{0.8}Bi_{2.4}Ta_2O_9(SBT)/Pt$ due to hydrogen annealing at $350^{\circ}C$ in $N_2$ gas atmosphere containing $5{\%}\;H_2$ gas for 1hr. As a result, inserting the W-N thin films between SBT and Pt, this W-N thin film prevents hydrogen molecules to be chemisorbed at the Pt electrode surface of at the electrode/ferroelectric interface during hydrogen annealing. These hydrogen atoms can diffuse into the SBT and react with the oxide causing the oxygen deficiency in the SBT film, which will result in the ferroelectric degradation. Experimental results show that W-N thin film is a good diffusion barrier during the hydrogen annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.213-216
• /
• 2001

Etching behaviors of ferroelectric $YMnO_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric $YMnO_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of $YMnO_3$ thin film is $300{\AA}/min$ at $Ar/Cl_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of $30^{\circ}C$. Addition of $CF_4$ gas decrease the etch rate of $YMnO_3$ thin film. From the results of XPS analysis, YFx compounds were found on the surface of $YMnO_3$ thin film which is etched in $Ar/Cl/CF_{4}$ plasma. The etch profile of $YMnO_3$ film is improved by addition of $CF_4$ gas into the $Ar/Cl_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on $YMnO_3$.

• Journal of the Korean Vacuum Society
• /
• v.9 no.2
• /
• pp.136-143
• /
• 2000

$SrBi_2Ta_2O_9;(SBT)$ films were deposited on p-type Si(100) at room temperature by rf magnetron sputtering method to confirm the possibility of application of $Pt/SBT/Pt/Ti/SiO_2/Si$ structure (MFM) for destructive read out ferroelectric RAM (random access memory). Their structural characteristics with the various annealing times and Ar/$O_2$ gas flow ratios in sputtering were observed by XRD (X-ray diffractometer) and the surface morphologies were observed by FE-SEM (field emission scanning electron microscopy), and their electrical properties were observed by P-V (polarization-voltage measurement) and I-V (current-voltage measurement). The Ar/$O_2$ gas flow ratios of sputtering gas were changed from 1 : 4 to 4 : 1 and SBT thin films were deposited at room temperature. The films show (105), (110) peaks of SBT by XRD measurement. SBT thin films deposited at room temperature were crystallized by furnace annealing at 80$0^{\circ}C$ in oxygen atmosphere during either one hour or two hours. Among their electrical properties, P-V curves showed shaped hysteresis curves, but the SBT thin films showed the asymmetric ferroelectric properties in P-V curves. When Ar/$O_2$ gas flow ratios are 1 : 1, 2: 1, the leakage current density values of SBT thin films are good, those values of 3 V, 5 V, and 7 V are respectively $3.11\times10^{-8} \textrm{A/cm}^2$, $5\times10^{-8}\textrm{A/cm}^2$, $7\times10^{-8}\textrm{A/cm}^2$.After two hours of annealing time, their electrical properties and crystallization are improved.

• Journal of the Korean Ceramic Society
• /
• v.40 no.4
• /
• pp.398-400
• /
• 2003

The YMnO$_3$ thin films were prepared on platinized-silicon substrates by chemical solution deposition and annealed at 750 to 85$0^{\circ}C$ for 1 h under various oxygen pressures, from 2 mTorr to 760 Torr. Effects of annealing oxygen pressures on the crystallization behavior and electrical properties of YMnO$_3$ thin films were investigated. Crystallinity and c-axis preferred orientation of YMnO$_3$ thin film were improved by decreasing the oxygen pressure but were deteriorated at extremely low oxygen pressure, 2 mTorr. Leakage current density of the YMn03 thin film decreased as the oxygen pressure decreased. The film annealed at 80$0^{\circ}C$ under 2 Torr, which had the best crystallinity and the highest c-axis preferred orientation. showed the best-developed ferroelectric C-V hysteresis.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2006.10a
• /
• pp.166-169
• /
• 2006

A promising capacitor, which has conformable step coverage and good uniformity of thickness and composition, is needed to manufacture high-density non-volatile FeRAM capacitors with a stacked cell structure. In this study, ferroelectric $Bi_{3.61}Nd_{0.39}Ti_3O_{12}$ (BNT) thin films were prepared on $Pt(111)/Ti/SiO_2/Si$ substrates by the liquid delivery system MOCVD method. In these experiments, $Bi(ph)_3$, $Nd(TMHD)_3$ and $Ti(O^iPr)_2(TMHD)_2$ were used as the precursors and were dissolved in n-butyl acetate. The BNT thin films were deposited at a substrate temperature and reactor pressure of approximately $600^{\circ}C$ and 4.8 Torr, respectively. The microstructure of the layered perovskite phase was observed by XRD and SEM. The remanent polarization value (2Pr) of the BNT thin film was $31.67\;{\mu}C/cm^2$ at an applied voltage of 5 V.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1434-1436
• /
• 1996

In this study, ferroelectric $PbTiO_3$ thin films were deposited on the Pt/$SiO_2$/Si substrate by Sol-Gel method. $PbTiO_3$ stock solution was made and spin-cooled at 4000[rpm] for 30[sec.]. Coated specimens were dried at $400[^{\circ}C]$ for 10[min.] and then annealed at $500{\sim}800[^{\circ}C]$ for 1 hour. Annealing temperature were examined to optimize micro structural and dielectric properties of the films. The ferroelectric perovskite phase was observed in the file annealed at $700[^{\circ}C]$ for 1 hour. In the case of $PbTiO_3$ thin films annealed at $700[^{\circ}C]$ for hour, dielectric constant and dielectric loss showed the good value of 324, 2.0[%], respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.58-62
• /
• 2002

Pb($Zr_{0.52}Ti_{0.48}$)$O_3$ (PZT) thin films deposited on the Pt/Ti and Ru/$RuO_2$ bottom electrode by rf magnetron sputtering methode. Ru/$RuO_2$ bottom electrode deposited on the p-type wafer as Ru thickness by in-situ process. Our results show that all PZT films indicated perovskite polycrystalline structure with perferred orientation (110) and no pyrochlore phase is observed. A well-fabricated $RuO_2$/PZT/Ru(100nm)/$RUO_2$ capacitor showed a leakage current density in the order of $2.13{\times}10^{-7}A/cm^2$ as 100 kV/cm, a remanent polarization of 7.20 ${\mu}C/cm^2$, and a coercive field of 58.37 kV/cm. The results show that the new Ru/$RuO_2$ bottom electrodes are expected to reduce the degradation ferroelectric fatigue and excellent ferroelectric properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.341-344
• /
• 1999

The effects of post annealing treatments of ferroelectrlclty in PZT(P $b_{1.05}$(Z $r_{0.52}$, $Ti_{0.48}$) $O_3$ thin film deposited on Pt/ $SiO_2$/Si substrate by RF-Magnetron sputtering methode was Investigated. Analyses by RTA(Rapid Thermal Annealing) treatments reveled that the crystallization process strongly depend on the healing temperature. The Perovskite structure with strong PZT (101) plan was obtained by RTA treatments at 75$0^{\circ}C$ With increasing RTA temperature of PZI thin films, the coercive field and remanent Polarization decreased, while saturation polarization( $P_{r}$) was decreased. P-E curves of Pt/PZT/Pt capacitor structures demonstrate typical hysteresiss loops. The measure values of $P_{r}$,. $E_{c}$ and dielectric constants by post annealed at 75$0^{\circ}C$ were 38 $\mu$C/$\textrm{cm}^2$ 35KV/cm and 974, respectively. Switching polarization versus fatigue characteristic showed 12% degradation up to 10$^{7}$ cycles.s.s.s.s.s.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.202-203
• /
• 2007

Ferroelectric SBT($SrBi_2Ta_2O_9$) thin films were deposited on Pt/Ti/$SiO_2$/Si substrate using R.F. magnetron sputtering method. The ferroelectric and electric characteristics were investigated with various post-annealing of Pt at $200{\sim}600^{\circ}C$. Compared with SBT thin film which had not post-annealed, the electrical properties and crystallizations of the SBT thin films were relatively improved by the post-annealing of Pt bottom electrode. The crystallization were characterized by X-ray diffraction (XRD). The electrical properties characteristics were observed by HP 4192A and precision LC.