• Korean Journal of Materials Research
• /
• v.34 no.6
• /
• pp.283-290
• /
• 2024

The aggressive scaling of dynamic random-access memory capacitors has increased the need to maintain high capacitance despite the limited physical thickness of electrodes and dielectrics. This makes it essential to use high-k dielectric materials. TiO₂ has a large dielectric constant, ranging from 30~75 in the anatase phase to 90~170 in rutile phase. However, it has significant leakage current due to low energy barriers for electron conduction, which is a critical drawback. Suppressing the leakage current while scaling to achieve an equivalent oxide thickness (EOT) below 0.5 nm is necessary to control the influence of interlayers on capacitor performance. For this, Pt and Ru, with their high work function, can be used instead of a conventional TiN substrate to increase the Schottky barrier height. Additionally, forming rutile-TiO₂ on RuO₂ with excellent lattice compatibility by epitaxial growth can minimize leakage current. Furthermore, plasma-enhanced atomic layer deposition (PEALD) can be used to deposit a uniform thin film with high density and low defects at low temperatures, to reduce the impact of interfacial reactions on electrical properties at high temperatures. In this study, TiO₂ was deposited using PEALD, using substrates of Pt and Ru treated with rapid thermal annealing at 500 and 600 ℃, to compare structural, chemical, and electrical characteristics with reference to a TiN substrate. As a result, leakage current was suppressed to around 10^-6 A/cm² at 1 V, and an EOT at the 0.5 nm level was achieved.

• Journal of Environmental Science International
• /
• v.17 no.6
• /
• pp.581-589
• /
• 2008

This study was carried out to evaluate the effect of water quality of cooling tower on Legionella pneumophila disinfection using Ru/Ti electrode. The influences of parameters such as pH, turbidity, $CaCO_3$ and TOC were investigated using laboratory scale batch reactor. Oxidants such as free Cl, $ClO_2,\;H_2O_2\;and\;O_3$ were measured. The results showed that all of the water quality parameters of cooling tower had deteriorated disinfection of Legionella pneumophila. When the turbidity, $CaCO_3$ and TOC was increased, oxidants which was generated during electrolysis was decreased. pH, free Cl, $ClO_2\;and\;H_2O_2$ concentration were decreased with the increase of pH, whereas $O_3$ concentration was increased with the increase of pH. The order of effect of water quality on the disinfection performance for Legionella pneumophila was turbidity > $CaCO_3$ > TOC > pH. To obtain the safety standard (1000 CFU/L), the simultaneous increase current and NaCl dosage was needed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.12-12
• /
• 2008

Ruthenium is one of the noble metals having good thermal and chemical stability, low resistivity, and relatively high work function(4.71eV). Because of these good physical, chemical, and electrical properties, Ru thin films have been extensively studied for various applications in semiconductor devices such as gate electrode for FET, capacitor electrodes for dynamic random access memories(DRAMs) with high-k dielectrics such as $Ta_2O_5$ and (Ba,Sr)$TiO_3$, and capacitor electrode for ferroelectric random access memories(FRAMs) with Pb(Zr,Ti)$O_3$. Additionally, Ru thin films have been studied for copper(Cu) seed layers for Cu electrochemical plating(ECP) in metallization process because of its good adhesion to and immiscibility with Cu. We investigated Ru thin films by thermal ALD with various deposition parameters such as deposition temperature, oxygen flow rate, and source pulse time. Ru thin films were grown by ALD(Lucida D100, NCD Co.) using RuDi as precursor and $O_2$ gas as a reactant at 200~$350^{\circ}C$.

• The Korean Journal of Ceramics
• /
• v.3 no.4
• /
• pp.274-278
• /
• 1997

(Ba, Sr) TiO$_3$(BST) thin films were prepared on RuO$_2$/Si substrates by rf magnetron sputtering and annealing was followed at temperatures ranging from 550 to 80$0^{\circ}C$ in $N_2$or $O_2$atmosphere. The effects of annealing conditions on the properties of BST film deposited on RuO$_2$bottom electrodes were investigated. It was found that the crystallinity. surface roughness, and grain size of BST films vary with the annealing temperature but they are not dependent upon the annealing atmosphere. The flat region in the current-voltage (I-V) curves of BST capacitors shortened with increasing annealing temperature under both atmospheres. This is believed to be due to the lowering of potential barrier caused by unstable interface and the increase of charge The shortening of the flat region by $O_2$annealing was more severe than that by $N_2$-annealing. As a result, there was no flat region when the films were annealed at 700 and 80$0^{\circ}C$ in $O_2$atmosphere. The dielectric properties of BST films were improved by annealing in either atmosphere. however, a degradation with frequency was observed when the films were annealed at relatively high temperature under $O_2$atmosphere.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.920-923
• /
• 2000

All solid-state thin film supercapacitor(TFSC) based on $RuO_2$ electrode was fabricated. Ruthenium oxide$(RuO_2)$ thin film was deposited on Pt/Ti/Si subsrate by d.c. magnetron sputtering. LiPON(lithium phosphorus oxynitride) thin film were deposited by r.f. reactive sputtering. X-ray diffraction patterns of $RuO_2$ and LiPON films revealed that crystal structures of both films were amorphous. To decrease resistivity of $RuO_2$ thin film, $RuO_2$ thin film was deposited with $H_2O$ vapor. In order to decide the maximum ionic conductivity, the LiPON films were prepared by various sputtering condition. The maximum ionic conductivity was $9.5\times{10}^7S/cm$. A charge-discharge measurements showed the capacity of $3\times{10-2}\;F/cm^2-\mu{m}$ for the as-fabricated TFSC. The discharging efficiency was decreased after 500 cycles by 40 %.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.3
• /
• pp.39-45
• /
• 1998

SrBi$_{2}$Ta$_{2}$O$_{9}$ (SBT) ferroelectric thin films for nonvolatile memory were prepared on Pt/Ti/SiO$_{2}$/Si and RuO$_{2}$/SiO$_{2}$/Si substrates by RF magnetron sputtering. The dependences of crystalline and electrical properties on the lower electrode type(Pt and RuO$_{2}$) and the annealing temperatures were investigated. SBT films regardless of their electrode types showed typeical Bi layered peroviskite crystal structures. The crystalline quality of as-deposited SBT films was improved by the rapid thermal annealing at 650.deg. C for 30 sec. The remanetn polarization of 2Pr (Pr+-Pr-) of the annealed SBT films deposited on Pt/Ti/SiO$_{2}$/Si substrates were about 11 .mu.C/cm$^{2}$ and 3 .mu.C/cm$^{2}$, respectively. The leakage currents at 3 V bias voltage were about 0.8 .mu.A/cm$^{2}$ for SBT/ Pt/Ti/SiO$_{2}$/Si and about 1 .mu.A/cm$^{2}$ for SBT/RuO$_{2}$/SiO$_{2}$/Si sample. SBT films annealed at 650 .deg. C showed no degradation in Pr values after 10$^{11}$ polarization switching cycles, indicating good fatigue properties. In addition, for SBT samples deposited on Pt/Ti/SiO$_{2}$/Si, Pr values increased to more than that of initial state, suggesting the increament of leakage current caused by repeated polarization.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1998.10a
• /
• pp.64-65
• /
• 1998

• Journal of the Microelectronics and Packaging Society
• /
• v.11 no.3 s.32
• /
• pp.63-70
• /
• 2004

The structural, electrical properties of $(Ba, Sr)TiO_3[BSTO]/RuO_2$ thin films were examined by the addition of amorphous BSTO layer between crystlline BSTO film and $RuO_2$ substrate. We prepared BSTO films with double-layered structure, that is, amorphous layers deposited at $60^{\circ}C$ and crystalline films. Crystalline films were prepared at 550 on amorphous BSTO layer. The thickness of the amorphous layers was varied from 0 to 170 nm. During the deposition of crystalline films, the crystallization of the amorphous layers occurred and the structure was changed to circular while crystalline BSTO films showed columnar structure. Due to insufficient annealing effect, amorphous BSTO phase was observed when the thickness of the amorphous layers exceeded 30 nm. Amorphous BSTO layer could also prevent the formation of oxygen deficient region in $RuO_2$ surface. Leakage current of total BSTO films decreased with increasing amorphous layer thickness due to structural modifications. Dielectric constant showed maxi-mum value of 343 when amorphous layer thickness was 30 nm at which the improvement by grain growth and the degradation by amorphous phase were balanced.

• Transactions on Electrical and Electronic Materials
• /
• v.1 no.4
• /
• pp.30-39
• /
• 2000

The variation of electrical properties of (Ba, Sr)TiO$_3$[BST] thin films deposited of RuO$_2$electrode with (Ba+Sr)/Tr ration was investigated. BST thin films with various (Ba+Sr)/Tr ration were deposited on RuO$_2$/Si substrates using in-situ RF magnetron sputtering. It was found that the electrical properties of BST films depends on the composition in the film. The dielectric constant of the BST films is about 190 at the (Ba+Sr)/Tr ration of 1.0, 1,025 and does not change markedly. But , the dielectric constant degraded to 145 as the (Ba+Sr)/Tr ratio increase to 1.0. In particular, the leakage current mechanism of the films shows the strong dependence on the (Ba+Sr)/Tr ration in the films. At the ration (Ba+Sr)/Tr=1,025, the Al/BST/RuO$_2$ capacitor show the most asymmetric behavior in the leakage current density, vs, electric field plot. It is considered that the leakage current of the (Ba+Sr)/Tr=1,025 thin films is controlled by the battier-Iimited process, i,e, Schottky emission.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.266-267
• /
• 2014

$TiO_2$ 기반의 DSA 전극에 촉매제를 동시에 도핑할 수 있는 양극산화 단일 공정을 연구하였다. 에틸렌 글리콜 용매하에 $KRuO_4$와 $NH_4F$를 전해질로 사용하여 타이타늄을 양극산화 할 때 도핑과 나노구조 제어를 동시에 수행할 수 있었다. TEM과 XPS 분석 결과, 균일한 Ru 산화물이 $TiO_2$ 구조 내에 분포함을 확인할 수 있었다.