• Title/Summary/Keyword: Ferroelectric thin film

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Characteristics of Surface Morphology and Defects by Polishing Pressure in CMP of BLT Films (BLT 박막의 CMP 공정시 압력에 따른 Surface Morphology 및 Defects 특성)

  • Jung, Pan-Gum;Lee, Woo-Sun
    • Proceedings of the KIEE Conference
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    • 2006.10a
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    • pp.101-102
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    • 2006
  • PZT thin films, which are the representative ferroelectric materials in ferroelectric random access memory (FRAM), have some serious problem such as the imprint, retention and fatigue which ferroelectric properties are degraded by repetitive polarization. BL T thin film capacitors were fabricated by plasma etching, however, the plasma etching of BLT thin film was known to be very difficult. In our previous study, the ferroelectric materials such as PZT and BLT were patterned by chemical mechanical polishing (CMP) using damascene process to top electrode/ferroelectric material/bottom electrode. It is also possible to pattern the BLT thin film capacitors by CMP, however, the CMP damage was not considered in the experiments. The properties of BLT thin films were changed by the change of polishing pressure although the removal rate was directly proportional to the polishing pressure in CMP process.

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Ferroelectirc Properties of Sm-doped PZT Thin films (Sm이 첨가된 PZT 박막의 강유전 특성)

  • 손영훈;김경태;김창일;이병기;장의구
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.2
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    • pp.178-183
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    • 2004
  • PBT thin film was known to be a representative for the FeRAM devices because of its good ferroelectric proporties and the ease in fabricating the thin film. However, there have been several problems such as polarization fatigue and leakage current in memory devices with a PZT thin film. In this study, Sm-dolled PZT thin films were fabricated by the so1-gel method, and their ferroelectric and dielectric proportrics were compared as a function of Sm content. We investigated the effect of the Sm dopant on structural and electrical properties of PZT film. Sm-doped PZT thin films on the Pt/Ti/SiO$_2$/Si substrates have been prepared by a sol-gel method. The remanent polarization and coercive field decreased with increasing the concentration of Sm. The dielectric constant and dielectric loss decreased with Increasing Sm content. Sm-doped PZT thin films showed improved fatigue characteristics compared to the undoped PZT thin film.

Characterization of Ferroelectric Thin Film in Microwave Region (마이크로파대에서의 강유전 박막 유전 특성 평가)

  • Park, Jeong-Heum
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.10
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    • pp.1061-1067
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    • 2004
  • In this study, ferroelectric (Ba,Sr)TiO$_3$ and high temperature superconductor YBCO thin films were fabricated by PLD (Pulsed Laser Deposition) method and tuneable bandstop filters were implemented with two different IDC(Interdigital Capacitance) gap patterns, 20${\mu}{\textrm}{m}$ and 30${\mu}{\textrm}{m}$ using these two thin film layers. The resonant frequency was changed by DC bias voltage. By comparing measured results with simulation, the dielectric properties of ferroelectric thin film have been extracted. The permittivity was 820 ~ 900 at 30 K and had an acceptable error range but the loss tangent had a great difference, 0.018 in 30${\mu}{\textrm}{m}$ IDC gap pattern and 0.037 in 20 ${\mu}{\textrm}{m}$.

Device Characteristics of MFSFET with the Fatigue of the Ferroelectric Thin Film (강유전박막의 피로현상을 고려한 MFSFET 소자의 특성)

  • 이국표;강성준;윤영섭
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.191-194
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    • 1999
  • Switching behaviour of the ferroelectric thin film and device characteristics of the MFSFET (Metal-Ferroelectric-Semiconductor FET) are simulated with taking into account the accumulation of oxygen vacancies near interface between the ferroelectric thin film and the bottom electrode caused by the progress of fatigue. We show net switching current decreases due fatigue in the switching model. It indicates that oxygen vacancy strongly suppresses polarization reversal. The difference of saturation drain current of the device before fatigue is shown by the dual threshold voltages in I$_{D}$-V$_{D}$ curve as 6㎃/$\textrm{cm}^2$ and decreases as much as 50% after fatigue. Our simulation model is expected to play an important role in estimation of the behavior of MFSFET device with various ferroelectric thin films.lms.

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Structural and ferroelectric characteristics of sol-gel $Pb(Zr_{1-x}Ti_x)O_3$ thin films according to the sintering conditions and Zr/Ti mol% (소성 조건과 Zr/Ti 몰비에 따른 졸겔 $Pb(Zr_{1-x}Ti_x)O_3$ 박막의 구조 및 강유전 특성)

  • 김준한;윤현상;박정흠;장낙원;박창엽
    • Electrical & Electronic Materials
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    • v.9 no.8
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    • pp.836-850
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    • 1996
  • In this study, we have analyzed structural analysis and measured ferroelectric characteristics of PZT thin films prepared by sol gel process with different sintering conditions and different Zr/Ti mot%. When the Zr mot% of PZT thin film was increased, it was found that the remanent. polarization and coercive field were decreased and increased, respectively. Also, the maxium dielectric constant of PZT(50/50) thin film was 786.8. We got double hysteresis(anti-fcrroelectric) curve from PbZrO$_{3}$ thin film. As heating rate goes up, pyrochlore phase of PZT thin film was decreased and dielectric and ferroelectric characteristics were improved. As a result of variation of sintering temperature and time 500.deg. C-800.deg. C and 5 sec.-8 hours, respectively, we got optimal sintering temperature and time. The optimium sintering temperature and time of conventional furnace method and rapid thermal processing method were 650.deg. C-700.deg. C for 30-60 minutes and 700.deg. C/20 seconds-2 minutes, respectively.

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A Hystesis Loop Modeling of Ferroelectric Thin Film Using Numerical Integration Method (수치적분을 이용한 강유전체의 이력곡선 모델링)

  • 강성준;정양희;유일현
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.05a
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    • pp.696-699
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    • 2003
  • In this study, we suggested the model to precisely evaluate the ferroelectric hysteresis loop, using the modified Sawyer-Tower circuit and the ferroelectric capacitor with a MDFM(Metal-Dielectric-ferroelectric-Metal) structure. The mathematical expression of dipole polarization is applied to the numerical integration algorithm, and the fatigue property can be considered including the dielectric layer between ferroelectrics and bottom electrode. The validity of our model is proved comparing the estimated value of our model and the measured results of PLT(10) thin film.

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Dry Etch Characteristic of Ferroelectric $YMnO_3$ Thin Films Using High Density $Ar/Cl_{2}/CF_{4}$ $PAr/Cl_{2}/CF_{4}$ ($Ar/Cl_{2}/CF_{4}$ 코밀도 플라즈마를 이용한 강유전체 $YMnO_3$의 건식식각 특성연구)

  • 박재화;김창일;장의구;이철인;이병기
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.213-216
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    • 2001
  • Etching behaviors of ferroelectric YMn $O_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric YMn $O_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of YMn $O_3$ thin film is 300 $\AA$/min at Ar/C $l_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of 3$0^{\circ}C$. Addition of C $F_4$ gas decrease the etch rate of YMn $O_3$ thin film. From the results of XPS analysis, Y $F_{X}$ compunds were found on the surface of YMn $O_3$ thin film which is etched in Ar/C1/C $F_4$ plasma. The etch profile of YMn $O_3$ film is improved by addition of C $F_4$ gas into the Ar/C $l_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on YMn $O_3$.>.

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Ferroelectric Properties of Bi3.25La0.75Ti3O12 Thin Films with Various Drying Temperature for FRAM Applications (FRAM 응용을 위한 건조온도에 따른 BLT 박막의 강유전 특성)

  • 김경태;김동표;김창일;김태형;강동희;심일운
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.4
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    • pp.265-271
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    • 2003
  • Ferroelectric lanthanum-substituted Bi$_4$Ti$_3$O$_{12}$(BLT) thin films were fabricated by spin-coating onto a Pt/Ti/SiO$_2$/Si substrate by metalorganic decomposition technique. The grain size in BLT thin films were prepared with controlled by various drying process. The effect of grain size on the crystallization and ferroelectric properties were investigated by x-ray diffraction and field emission scanning electron microscope. The dependence of crystallization and electrical properties are related to the grain size in BLT thin films with different drying temperature. The remanent polarization of BLT thin film increases with the increasing grain size. The value of 2P$_{r}$ and E$_{c}$ of BLT thin film dried at 45$0^{\circ}C$ were 25.9 $\mu$C/$\textrm{cm}^2$ and 85 kV/cm, respectively. The BLT thin film with larger grain size has better fatigue properties. The fatigue properties revealed that small grained film showed more degradation of switching charge than large grained films.lms.s.

Ferroelectric Thin Film as a substitute for Non-volatile Memory (비휘발성 메모리용 대체 강유전체 박막)

  • 김창영;장승우;우동찬;남효덕;이희영
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.509-512
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    • 1999
  • Ferroelectric Sr$_2$(Nb, Ta)$_2$O$_{7}$(SNTO), La$_2$Ti$_2$O$_{7}$(LTO) thin films were prepared by sol-gel processes. SNTO, LTO thin films were spin-coated on Pt/TiO$_2$/SiO$_2$/Si(100). Pt/Ti/SiO$_2$/Si(100). PT/ZrO$_2$/SiO$_2$/Si(100) substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. Dielectric and other relevant electrical properties were measured and the results showed a little possibility in ferroelectric gate random access memory devices.ces.

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