• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.109-112
• /
• 1999

The PZT(10/90)/(90/17) heterolayered thin films were fabricated by the spin-coaling on the Pt/Ti/SiO$_2$/Si substrate using the PZT(10/90) and PZT(70/10) metal alkoxide solutions. The effect of heterolayered thin films on the ferroelectrics and electrical properties have been investigated. The lower PZT layers provided the nucleation site for the formation of a perovskite phase of the upper PZT films. Dielectric constant increased with increasing the number of coatings, and it was about 569.9 at PZT-6 heterolayered films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.2
• /
• pp.178-183
• /
• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.667-670
• /
• 2004

The dielectric properties of PZT(4060)/(6040) multilayered thin films with substrate temperature were investigated. PZT(4060)/(6040) thin films were deposited by RF sputtering method on Pt/Ti/$SiO_2$/Si substrates with different substrate temperature of $200{\sim}700^{\circ}C$. Increasing the substrate temperature, perovskite structure was increased, and PZT (001), (110), (002), (200) peaks were increased. The relative dielectric constant and dielectric loss of PZT(4060)/(6040) multilayered thin films at the substrate temperature of $700^{\circ}C$ were 843 and 2.45, respectively at 1000(Hz).

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.2
• /
• pp.307-314
• /
• 1998

PZT thin films were fabricated by the Sol-gel method. Starting materials used for the preparation of the stock solution were Pb-acetate trihydrate, Zr-normal propoxide and Ti-isopropoxide. 2-Methoxyethanol and iso-propanol were used for solution. For studying the diffusion of Pb ion into the substrates. We used bare Si substrate, $SiO_2/Si$ substrates which was produced by thermal oxidation and $TiO_2/SiO_2/Si$ which was mad by Sol-gel method. Densification and adhesion of thin films were observed by SEM. Phase formation of thin films and diffusion of Pb ion into the substrate were examined by XRD and ESCA, respectively. In the case of bare Si and $SiO_2/Si$ substrate, we obtained the perovskite phase at $700^{\circ}C$ and restricted a little the diffusion of Si ion into the film with $SiO_2$ buffer layer. In the case of $TiO_2/SiO_2/Si$, perovskite phase were obtained at $500^{\circ}C$ and the diffusion of Pb ion and Si ion were restriced.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.37-37
• /
• 2003

Ferroelectric random acess memories (FeRAMs) 재료로 주목받고 있는 강유전 물질은 이미 여러 해 전부터 많은 물질들에 대해 연구가 진행되어 왔다. 그 중 낮은 공정 온도를 가지며 큰 remanent polarization 값을 갖는 lead zirconium titanate (PZT) 박막에 대해 많은 연구가 진행되고 있다. 하지만 Pt 기판위에 증착된 PZT 박막은 높은 피로 현상을 보이는 문제가 있다. 최근 Pulsed laser deposition이나 metal-organic vapor phase epitaxy (MOVPE) 등의 방법에 의해 epitaxial substituted-$Bi_4Ti_3O_{12}$ (La, Nd) 박막에 대해 보고가 되고 있다. 본 연구에서는 높은 remanent polarization 값을 갖는 $(Bi,Ce)_4Ti_3O_{12}$ (BCT) 박막을 pulsed laser deposition 방법을 사용하여 증착하였다. 또한 Bismuth의 양을 변화시켜 Bismuth의 양에 따른 remanent polarization의 변화를 확인하여 보았다. 사용된 기판은 Pt/$TiO_2$/$SiO_2$/Si 기판을 사용하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.2
• /
• pp.98-102
• /
• 2000

Ferroelectric PZT heterolayered thin films were fabricated by spin coating method on the Pt/Ti/SiO2/Si substrate using PZT(10/90) and PZT(90/10) m7etal alkoxide solutions. All PZT heterolayered films showed a homogeneous grain structures without presence of rosette structure. It can be assumed that the lower PZT layers played a role of nucleation site for the formation of the upper PZT layer. Pb-deficient PZT phase was formed at PZT/Pt interface due to the diffusion of Pb element into a Pt bottom electrode. The relative dielectric constant and the dielectric loss of the PZT-6 film were 567 and 3.6%, respectively. Increasing the number of coatings, remanent polarization and coercive field were decreased and the values of the PZT-6 heterolayered film were $7.18\muC/cm^2$ and 68.5kV/cm, respectively. Leakage current densities were increased with increasing the number of coatings, and the value of the PZT-4 film was about $7\times10-8A/cm^2$ at 0.05MV/cm.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.7
• /
• pp.514-520
• /
• 1999

Ferroelectric PZT(30/70)/PZT(70/30) heterolayered thin films were fabricated by spin-coating method on the $Pt/Ti/SiO_2Si$ substrate alternately using(30/70) and PZT(70/30) alkoxide solutions prepared by sol-coating method. The coating and heating procedure was repeated six times to form PZT heterolayered films, and thickness of the film obtained by one-times drying/sintering process was about 40-50 nm. All PZT heterolayered films, showed dense and homogeneous structure without the presence of rosette sturctrue. The relative dielectric constant, remanent polarization and leakage current density of PZT heterolayered films were superior to those of single composition PZT(30/70) and PZT(70/30) films, and those values for the PZT-6 film were 975, $21 \muC/cm^2\; and\; 8\times10^{-9}\; A/cm^2$, respectively. And the PZT-6 heterolayered film showed fairly good fatigue characteristics of remanent polarization and coercive field after application of $10^8$ switching cycles.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1618-1620
• /
• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] multilayered thin films were deposited by RF Sputtering method on the Pt/Ti/$SiO_2$/Si substrate. This procedure was repeated several times to form PZT(4060)/(6040) heterolayerd thin films. The effects on the structural and dielectric properties of PZT multilayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(4060)/(6040) multilayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) multilayered thin films. The relative dielectric constant and dielectric loss at 100Hz of the PZT(4060)/(6040)-5 multilayered thin films were about 1106 and 0.016, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.1
• /
• pp.24-29
• /
• 2001

PZT thin films(4000A) have prepared onto 1737 corning glass and ITO coated glass substrates with a RF magnetron sputtering system using Pb_{1.05}(Zr_{0.52},Ti_{0.48})O_3$ceramic target, Electrical properties of PZT thin film deposited after ITO coated glass were P${\gamma}$ was decreased by 25% after 109cycles, respectively. With the RTA treatment duration and temperature increased, the crystallization of PZT thin films were enhanced, however, the leakage current density became higher. The leakage current mechanism was found to be space charge conduction by the defects and oxygen vacancies existing in PZT and PZT/bottom electrode interfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.39-42
• /
• 2000

The effect of excess Pb contents on the etching of PZT thin films and their electrical properties has been investigated. Ferroelectric PZT(53/47) thin films were prepared by the metal alkoxide-based Sol-Gel method, in which they were spin-coating on P7Ti/Si02/Si substrate using the PZT(53/47) stock solutions with various excess Pb contents. Etching of PZT film was performed using planar inductively coupled Ar/Cl$_2$/BCl$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$.