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In this study, we prepared liquid crystal emulsion composed of amphiphilic substance C14-22 alcohol, C12-20 alkyl glucoside, behenyl alcohol and studied liquid crystal emulsion of properties and in vitro skin permeation. The results of formulation experiments, the clear liquid crystalline structure was observed in the ratio of C14-22 alcohol 0.8%, C12-20 alkyl glucoside 3.2%, behenyl alcohol 4% in the formulation. The results of physical property measurements, the viscosity of liquid crystal emulsion and O/W emulsion applied as a control group was respectively 1871.26 ∼ 1.15 Pa⋅s, 1768.69 ∼ 1.14 Pa⋅s and the shear stress of O/W emulsion was 178.68 ∼ 909.18 Pa, that of liquid crystal emulsion was 190.45 ∼ 919.38 Pa. The storage modulus of O/W emulsion was 3428.53 ∼ 9157.45 Pa, that of liquid crystal emulsion was 4487.82 ∼ 8195.59 Pa. The tan (delta) value of O/W emulsion which means a ratio of viscosity to elasticity was 0.43 ∼ 0.19, and that of liquid crystal emulsion was 0.23 ∼ 0.25. The water content value on the skin for liquid crystal emulsion was significantly higher from 1 h to 6 h compared with that of O/W emulsion and the transepidermal water loss on the skin was significantly superior in skin moisture loss suppression from 30 min to 4 h compared with that of O/W emulsion. The results of skin permeation using glycyrrhizic acid, the result of skin permeation amount of liquid crystal emulsion for 24 h was 64.58 μg/cm2, that of O/W emulsion was 37.07 μg/cm2, that of butylene glycol solution was 41.05 μg/cm2. Hourly permeability results, it is showed that skin penetration effect of the liquid crystal emulsion increases after 8 h. These results suggest that liquid crystal emulsions are effective for skin moisturizing effect and function as potential efficacy ingredient delivery system for the transdermal delivery.

Layer-by-Layer (LbL) technology, based on the electrostatic interaction of polyelectrolytes, is used to improve the stability of drug delivery systems. In the present study, we developed multilayered liposomes with up to 10 alternating layers based on LbL deposition of hyaluronate-chitosan for transdermal delivery. Dihexadecyl phosphate was used to provide liposomes with a negative charge; the liposomes were subsequently coated with cationic chitosan (CH) followed by anionic sodium hyaluronate (HA). The resulting particles had a cumulative size of 528.28±29.22nm and an alternative change in zeta potential. Differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) revealed that the multilayered liposomes formed a spherical polyelectrolyte complex (PEC) after deposition. Observations in size distribution after 1 week found that the particles coated with even layers of polyelectrolytes, hyaluronate and chitosan (HA-CH), were more stable than the odd layers. Membrane stability in the presence of the surfactant Triton X-100 increased with an increase in bilayers as compared to uncoated liposomes. An increase in the number of bilayers deposited on the liposomal surface resulted in a sustained release of quercetin, with release kinetics that fit the Korsmeyer-Peppas model. In an in vitro skin permeation study, negatively charged (HA-CH)-L and positively charged CH-L were observed to have similar skin permeability, which were superior to uncoated liposomes. These results indicate that multilayered liposomes properly coated with polyelectrolytes of HA and CH by electrostatic interaction improve stability and can also function as potential drug delivery system for the transdermal delivery of the hydrophobic antioxidant quercetin.

Multi-compartmentalized capsosomes are polyelectrolyte capsules with liposomes as cargo, and are prepared by combining liposomes and polymer capsules. They offer additional functionality while maintaining the advantages and compensating for the weak points of both systems. In this study, a polyelectrolyte multilayered liposome was prepared by alternating adsorption of negatively charged sodium hyaluronate (HA) and positively charged chitosan (CH) on the surface of a cationic core liposome (CL) via layer-by-layer (LbL) deposition. Then, smaller sized liposomes (L) were coated onto the multilayered liposome. Lastly, the particle surfaces were coated with HA as a capping layer to obtain a novel type of capsosome with a liposomal core. The amount of adsorbed liposome was measured for different pH values (pH 2-10) and with liposome solutions of different concentrations (1-3%). The highest liposome adsorption occurred at pH 10 in the 3% solution, respectively. Finally, capsosomes in the size range of 500nm to 2μm were observed and the attached liposomes were located both on the surface and within the polymer shell. In conclusion, the cell-mimicking, liposome-based capsosomes could have infinite applications in the field of medicine, pharmaceuticals, and cosmetics as compartmentalized microreactors, multi-drug delivery systems with controlled release, or functional artificial cells in the future.

To minimize the formation of unwanted interfacial layers, thin interfacial layer (ZrCN layer) was deposited between TiN bottom electrode and ZrO2 dielectric in TiN/ZrO2/TiN capacitor. Carbon and nitrogen were also involved in the layer because ZrCN layer was thermally deposited using TEMAZ without any reactant. Electrical characteristics of TiN/ZrO2/TiN capacitor were improved by insertion of ZrCN layer. The oxidation of TiN bottom electrode was largely inhibited at TiN/ZrCN/ZrO2 structure compared to TiN/ZrO2 structure. While the sheet resistance of TiN/ZrCN/ZrO2 structure was constantly sustained with increasing ZrO2 thickness, the large increase of sheet resistance was observed in TiN/ZrO2 structure after 6 nm ZrO2 deposition. When ZrO2 films were deposited on ZrCN layer, the deposition rate of ZrO2 also increased. It is believed that ZrCN layer acted both as a protection layer of TiN oxidation and a seed layer of ZrO2 growth.

High-k dielectrics like Ta2O5, TiO2 etc. should overcome high leakage current due to the low energy band-gap property for applying to the future DRAM device below 50nm design rule beyond. Various techniques including metal doping and bi-layer scheme were studied to improve the leakage current of I-V characteristics. The leakage current of Dy or Zr doped TiO2 could be improved depending on the doping concentration. Nb doping in Ta2O5 could increase the dielectric constant within the appropriate level of leakage current at the operation voltage. Bi-layer scheme of high-k dielectrics like HfO2-TiO2 or ZrO2-TiO2 also applied to reduce the leakage current with the high work function Ru electrode. Combination of high work function Ru as a top electrode with the bottom TiN electrode could reduce the leakage current by increasing band offset at the interface between the high-k and the electrode.

Due to the downscaling of the devices like DRAM capacitor, introduction of new metal electrodes and high-k materials is indispensable for meeting the future device performance. A wide variety of DRAM capacitor electrodes are currently being evaluated as replacements for TiN including ZrN, HfN, and Ru. Rubase electrode has advantage of high work function but also has cost and integration problem. Thermally robust HfN/HfO2 gate stack structure was reported with scaling down of equivalent oxide thickness (Toxeq.) less than 10 and several attempts to prepare HfN films with organometallic Hf precursors by metal organic chemical vapor deposition (MOCVD) have been continued [1,2]. Even though Zirconium nitride exhibits high melting point, chemical inertness, and about 0.5eV-higher work function than TiN, very little is known about its qualities as capacitor electrode [3]. On the other hand, ZrO2 film has been spotlighted as new dielectric material in TiN/Insulator/TiN (TIT) capacitor replacing HfO2 film, due to its high dielectric constant, wide band gap, and thermal stability [4]. In this study, we fabricated new MIM capacitor using ZrN electrode and ALD ZrO2 dielectric for DRAM capacitor. ZrN films (100~1000 ) were deposited at different temperatures ranging from 25 to 500 by reactive magnetron sputtering. ZrO2 films were used as a dielectric by atomic layer deposition (ALD) method with Tetra-Ethyl-Methyl-Amino-Zirconium (TEMAZ) liquid precursor and O3 reactant at the temperature of 250 . Electrical properties of MIM capacitor with ZrN/ZrO2 combination such as capacitance, leakage current density and dielectric constant were compared with TiN/ZrO2 stack. Composition, interfacial reaction, and crystalline structure of ZrN and ZrO2 films were analyzed by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Furthermore, the specific resistivites and the work functions of the films were evaluated and the results will be discussed in detail.

Zr-TiO2 thin films were prepared by the atomic layer deposition using Zr(OtBu)4 and Ti(OtBu)4 cocktail sources. 8- inch Ru/SiO2/Si wafers were used for the substrates. It was found that the composition ratio of Zr and Ti in Zr-TiO2 films was similar to the mixing ratio of the precursors. The dielectric constant of as deposited Zr-TiO2 film was 35, which was 1.5 times higher than that of ZrO2. In addition, the leakage currents of Zr-TiO2 film was several orders lower than those of TiO2. The leakage currents of 100 Aå Zr-TiO2 films were less than 100nA/cm2 at 1.0 V, which satisfied the requirements for the DRAM capacitor

Ta"2O"5/Nb"2O"5 bi-layers were prepared on Ru/SiO"2/Si substrate by Atomic Layer Deposition, and post annealed up to 575^oC. The crystallization temperature of the bi-layers was 550^oC, which was 100^oC lower than that of Ta"2O"5 single layer. The thickness of the dielectric layers was also important parameter for the crystallization temperature. Transmittance Electron Microscopy image and depth profile analysis showed that Ta"2O"5 and Nb"2O"5 mixed each other during the crystallization. It was suggested that inter diffusion of two layers decreased the crystallization temperature of the bi-layers. Equivalent oxide thickness of crystalline Ru/Ta"2O"5/Nb"2O"5/Ru capacitor was 7.6A with less than 100nA/cm^2 leakage currents, which satisfied the requirements for 60nm generation DRAM capacitor and beyond.

The oxide electrode (Ba,Sr)RuO 3 , which enhances the properties of (Ba,Sr)TiO 3 film owing to its similarity in structure and chemical composition, was deposited on a four inch p-type Si wafer by MOCVD using METHD based sources. Ba(METHD) 2 . Sr(METHD) 2 , Ru(METHD) 3 precursors and a solvent (n-butylacetate) were mixed together into a single cocktail source. As-deposited BSR films showed (110) preferred orientation when the mole ratio of Ba:Sr:Ru in the source was 0.035:0.025:0.021 [mol L -1 ] at a source flow rate of 0.075 sccm. Among the various deposition conditions, the oxygen flow rate turned out to be the most critical for determining phase formation. The dielectric constants of these capacitors were observed to be above 500.

Degradation of (Ba,Sr)TiO3 during a forming gas anneal was examined and the effect of a SiO2 capped (Ba,Sr)RuO3 electrode was studied. All the samples were prepared by a rf magnetron sputtering technique and the forming gas (10% H2+90% N2) anneal was carried out at 400 °C for 30 min. The (Ba,Sr)RuO3 film directly exposed to H2 ambient was damaged severely, which resulted in the reduction and phase separation into BaO and Ru. On the other hand, the SiO2 capped (Ba,Sr)RuO3 film was not damaged during H2 annealing. By adopting the SiO2 capped (Ba,Sr)RuO3 as an electrode of (Ba,Sr)TiO3, the degradation of (Ba,Sr)TiO3 could be inhibited. SiO2 capping also decreased the extent of the reduction of a Pt/(Ba,Sr)TiO3/Pt structured capacitor, which is known to degrade dramatically. It is believed that the major cause of the tolerance to the forming gas anneal is the blocking capability of SiO2 against the diffusion of reaction products such as H2O.

(Ba,Sr)RuO 3 films have been tailored as an electrode for (Ba,Sr)TiO 3 which is a promising material for the high dielectric in ULSI DRAM. In this study, BSR conductive oxide film was deposited on 4-inch Si-wafer by metal organic chemical vapor deposition (MOCVD) using single cocktail source for the practical device application. Liquid delivery system (LDS) and vaporization cell were utilized for the delivery and vaporization of single cocktail source, respectively. The source feeding rate was controlled by liquid mass flow controller(LMFC). Ba(METHD) 2 , Sr(METHD) 2 , Ru(METHD) 3 precursors and solvent [n-butylacetate(C 6 H 12 O 2 )] were mixed for single coctail source. Among the various deposition parameters, control of the oxygen flow rate turned out to be crucial for determining the phase formation, resistivity, and the composition ratio of (Ba,Sr)RuO 3 films. Highly (110)-textured (Ba,Sr)RuO 3 film was obtained when Ar/O 2 ratio was 100/300sccm with the source flow rate of 0.075sccm. Oxygen annealin...

The influence of two-step deposition on the electrical properties of sputtered (Ba,Sr)TiO3 thin films was investigated. BST thin films with thickness 40 nm were deposited by a simple two-step radio frequency-magnetron sputtering technique, where the BST thin film consisted of a seed layer and a main layer. The dielectric constant was strongly dependent on the thickness of seed layer, but there was no dependence on deposition temperature of the seed layer. For a 2 nm seed layer, the dielectric constants were higher by about 29% than those of single-step BST thin films due to higher crystallinity and the leakage current was nearly the same as that of a single-step sample in bias voltage from −2 to 2.5 V. However, an improvement of the dielectric constant was not observed for samples having above 4 nm thick seed layers. A 40 nm thick BST film with 2 nm thick seed layer deposited by a two-step method exhibited a SiO2 equivalent thickness of 0.385 nm and a leakage current density of 2.74 × 10−8A/cm2at+1.5V after post-annealing under an atmosphere of flowing N2 for 30 min at 750°C.

A perovskite (Sr,Ca)RuO3 [SCR] electrode has been explored in order to utilize its advantages in structural match with (Ba,Sr)TiO3 [BST] films, which may enhance the electrical properties of BST films. The SCR electrode led to the leakage current density (10−7 A/cm2) of BST films an order lower than that on RuO2. The leakage current was not sensitive to the composition of the SCR electrodes, while the dielectric constant of the BST thin film capacitor ranged from 160 to 280 depending on the Sr/Ca ratio in SCR electrodes. The BST/SCR (Sr/Ca = 7/3) system resulted in a 5–nm thick interfacial layer. Furthermore, the interfacial layer turned out to be partially crystallized according to the lattice image taken by an HRTEM. It is believed that such enhancement in electrical properties of BST films could be induced by the improvement of interfacial characteristics through structural matching.

Degradation of ferroelectric properties of Pt/Pb(Zr,Ti)O3/Pt capacitor by the back-end process of ferroelectric random access memory (FRAM) device fabrication process was studied, particularly by the interlayer dielectric (ILD). The influence of ILD layer on the ferroelectric properties of Pt/Pb(Zr,Ti)O3/Pt capacitor was investigated. The SiO2 film for ILD layer was deposited by two methods; electron cyclotron resonance chemical vapor deposition (ECR CVD) using SiH4/N2O gas and atmospheric pressure thermal CVD using tetra ethyl ortho-silicate (TEOS) and O3(O3-TEOS CVD). The SiO2 deposition changed the ferroelectric properties of Pt/Pb(Zr,Ti)O3/Pt capacitor, varied according to the deposition condition and method. The degradation of ferroelectric property of Pt/Pb(Zr,Ti)O3/Pt capacitor by O3-TEOS SiO2 was less than that of ECR CVD-SiO2. However, both method could make the nonvolatile remanent polarization (NVPr) to be above 10 μC/cm2 at 5 V, which makes those processes valuable as ILD process of F...

To minimize the formation of unwanted interfacial layers, thin interfacial layer (ZrCN layer) was deposited between TiN bottom electrode and ZrO2 dielectric in TiN/ZrO2/TiN capacitor. Carbon and nitrogen were also involved in the layer because ZrCN layer was thermally deposited using TEMAZ without any reactant. Electrical characteristics of TiN/ZrO2/TiN capacitor were improved by insertion of ZrCN layer. The oxidation of TiN bottom electrode was largely inhibited at TiN/ZrCN/ZrO2 structure compared to TiN/ZrO2 structure. While the sheet resistance of TiN/ZrCN/ZrO2 structure was constantly sustained with increasing ZrO2 thickness, the large increase of sheet resistance was observed in TiN/ZrO2 structure after 6 nm ZrO2 deposition. When ZrO2 films were deposited on ZrCN layer, the deposition rate of ZrO2 also increased. It is believed that ZrCN layer acted both as a protection layer of TiN oxidation and a seed layer of ZrO2 growth.

As a new alternative for the DRAM capacitor of 50 nm generation, Ru/Insulator/TiN (RIT) capacitor with the lowest Toxeq of 0.85 nm has been successfully developed for the first time. TiO/sub 2//HfO/sub 2/ and Ta/sub 2/O/sub 5//HfO/sub 2/ double-layers were used as dielectric materials. After full integration into 512 Mbits DRAM device, the RIT capacitor showed good electrical properties and thermal stability up to 550/spl deg/C and its time-dependent-dielectric-breakdown behavior sufficiently satisfied 10-year lifetime within a DRAM operation voltage.

New technologies for sub 0.1 /spl mu/m DRAM devices are reviewed and discussed in views of shallow trench isolation and capacitor process. In order to enhance the gap filling and reduce the accumulated mechanical stress in STI, Polysilazane-SOG pillar is introduced at the trench bottom. Additionally, poly-Si filling process is also developed to minimize channel edge effect. HfO/sub 2/ deposited by atomic layer deposition is employed to lower the Toxeq. down to about 25/spl Aring/. Toxeq. can be reduced further by introduction of TiN metal electrode. TiN electrode capacitor of Toxeq. 15/spl Aring/ shows the stable leakage current. Ru electrode help Toxeq. scale down to 10/spl Aring/. It is concluded that sub 0.1 /spl mu/m devices can be manufacturable through the introduction of new technologies and materials.

We have successfully developed a MIM capacitor process technology with a HfO/sub 2/ single layer deposited by ALD (atomic layer deposition), where a Hf(NEtMe)4 and CVD-TiN cylinder-type storage-node were used as a Hf liquid source and bottom electrode for 90 nm-scale DRAMs. Our experimental results indicated that NH/sub 3/-plasma treatment on HfO/sub 2/ film promoted crystallization below 400/spl deg/C as well as the formation of a HfO/sub x/N/sub y/ layer on the surface of the HfO/sub 2/ film. With this treatment, it was possible to solve the degradation problem of the leakage current depending on deposition method of the top electrode, and a stable leakage current without degradation was obtained up to 550/spl deg/C. As a result, a TiN/HfO/sub 2//TiN (TIT) capacitor with 1.4 /spl mu/m-height storage node was successfully demonstrated with stable leakage current of 1fA/cell at +1.2 V and high cell capacitance of 40 fF after metal-2 integration.

We have developed a cylindrical TiN/HfO/sub 2//TiN (TIT) capacitor for 70 nm DRAMs application. TIT capacitors with HfO/sub 2/ films deposited by ALD(Atomic Layer Deposition) using Hf(NEtMe)/sub 4/ precursor and O/sub 2/ plasma as a reactant is shown to be applicable to DRAM device below 70 nm design rule for the first time. It shows the thermal budget endurance against back-end process of DRAM device as well as the very low enough Toxeq of about 13 /spl Aring/ to provide the sufficient cell capacitance.

For the first time, a novel robust (square-shape cylinder type) TiN/AHO (Al/sub 2/O/sub 3/-HfO/sub 2/)/TiN capacitor with Co-silicide on landing cell pad suitable for both stand-alone and embedded DRAMs are successfully developed with 88nm (pitch 176nm) feature size, which is the smallest feature size ever reported in DRAM technology, using ArF lithography for aiming 70nm stand-alone and embedded DRAM technology. The capacitor with Toxeq of 1.5nm and leakage current of less than 1 fA/cell is achieved. The cell contact resistance is greatly improved by using Co-silicidation on landing cell pad and metal storage node contact plug, which results in high performance.

In this paper, the Ru/crystalline-Ta/sub 2/O/sub 5//Ru capacitor was investigated. We studied the electrical properties and introduced an Al/sub 2/O/sub 3/ capping layer to prohibit the degradation of the leakage current resulted from H/sub 2/ annealing. Also, the Ru cylinder-type structure was suggested as a 3-dimensional storage node shape and was confirmed in its extendibility to 0.1 /spl mu/m-scaled design rule.

We first developed a novel self-aligned electroplating process to fabricate Pt electrodes for integrated high-dielectric capacitors. Electroplated Pt filled 120 nm-wide buried contact (BC) holes (aspect ratio 2:1). Pt pillars of 210 nm diameter and 650 nm height were successfully fabricated. The leakage current density of sputtered BST capacitors using electroplated bottom Pt was less than 200 nA/cm/sup 2/ at /spl plusmn/1.5 V. The oxide-equivalent thickness T/sub oxeq/ and dissipation factor of 40 nm-thick BST films were 0.70 nm and 0.0080 at 0 V, respectively.

Recently, 1 Gb DRAM based on the 0.18 /spl mu/m technology node (generation) and 0.15 /spl mu/m technology node for 4 Gb DRAM have been successfully demonstrated. These two technology generations are based on MIS capacitors using Ta/sub 2/O/sub 5/ dielectric. The extension of Ta/sub 2/O/sub 5/ MIS capacitors below 0.15 /spl mu/m technology is considered to be difficult due to insufficient cell capacitance. It is widely accepted that the MIM capacitor using high dielectric constant material is inevitable for 0.15 /spl mu/m technology and beyond. Although many studies to use high dielectric material have been reported, those studies are not adequate for 0.15 /spl mu/m technology and beyond because most of the studies are either based on a simple capacitor module process or based on large feature size design rules. In this paper, for the first time, a DRAM technology using BaSrTiO/sub 3/ (BST) MIM capacitors is developed with 0.15 /spl mu/m technology.

A new two-step post-annealing process to prevent degradation of integrated BST capacitors was developed. By this process, the increment of capacitance and the reduction of leakage current were obtained without barrier oxidation. A concave-type capacitor structure with buried barrier using Pt electrodes and MOCVD BST films was demonstrated in order to solve the integration problems such as Pt etching and the contact between the BST and the barrier. The electrical properties of MOCVD BST capacitor in 3-dimensional structure were investigated.

A new EBL (encapsulating barrier layer), Al/sub 2/O/sub 3/, was developed in order to preserve the excellent ferroelectric characteristics of PZT capacitors throughout the integration process of FRAMs. From the fully working double-level metal, one-poly, 1T/1C 64 k PZT FRAM, Al/sub 2/O/sub 3/ films with thickness in the range of 60 /spl Aring/ to 100 /spl Aring/ showed excellent barrier properties against the hydrogen attack, reaction between PZT film and IMD, and out diffusion of the volatile component in the capacitor. Moreover, the excellent insulating properties of ultra-thin Al/sub 2/O/sub 3/ EBL offered the reduction of one photo/etch step during the full integration process, which required for the conventional TiO/sub 2/ one.

RIR(Ru/Crystalline-Ta/sub 2/O/sub 5/Ru) capacitor with concave structure was studied for the application into multigigabit-scale DRAM device. In this work, several novel technologies were successfully developed to solve current issues in the fabrication of RIR concave capacitor; such as 1) two-step deposition of Ta/sub 2/O/sub 5/ films 2) formation of Ta/sub 2/O/sub 5/ spacer 3) new separation process of Ru storage node using maskless etch-back method 4) H/sub 2/ pre-annealing and 5) Ar plasma pre-treatment on Ru bottom electrode. The RIR concave capacitor (design rule/spl sim/0.12 /spl mu/m, node height/spl sim/0.85 /spl mu/m) fabricated with these novel technologies showed excellent electrical properties (25fF/cell, 1fA/cell at /spl plusmn/ 1V), which indicates that RIR structure is the one of the most promising candidate for the next generation DRAM capacitor.

To realize the gigabit-scale DRAM capacitor, it is necessary to develop new electrode materials instead of poly-Si and TiN. Among them, Ruthenium has been the most promising electrode material in advance of Pt or Ir because it can be easily etched by oxygen plasma and shows good electrical properties as a capacitor electrode. But, a CVD-Ru film with good conformality and smooth morphology actually applicable to gigabit-scale DRAM generations has not been known up to now. In this work, we present the development of novel CVD process for application in real device with 3-dimensional structure and the electrical properties of capacitor using CVD-Ru electrode.

We have investigated the electrical properties of metal/Ta/sub 2/O/sub 5//metal (MIM-Ta/sub 2/O/sub 5/) capacitor for multigigabit-scale DRAMs. CVD-TiN film was used as a bottom electrode, whereas PVD-TiN, CVD-TiN and CVD-Ru metals were compared for a top electrode. Our results, including electrical properties and step coverage, showed that a CVD-Ru film is the most promising top electrode material. Based on this result, a CVD-Ru/Ta/sub 2/O/sub 5//CVD-TiN capacitor with cylinder-type storage node was developed, and the cell capacitance of 40fF/cell with the leakage current of 0.1fA/cell at /spl plusmn/1 V applied voltage was accomplished.

Thin film electrodes of the perovskite oxide (Ba,Sr)RuO3 (BSR) were deposited on 4 inch ptype Si wafers by metal organic chemical vapor deposition (MOCVD) for the practical (Ba,Sr)TiO3 (BST) capacitor application using a new single cocktail source. The source materials used for the MOCVD BSR process were Ba(METHD)2, Sr(METHD)2 and Ru(METHD)3 and these were dissolved in n-butyl acetate. The source-feeding rate was precisely controlled by liquid mass flow controllers (LMFC). As-deposited BSR films possessed a (110)-oriented structure, with good uniformity and adherence on bare Si wafer. The phase formation was strongly affected by the oxygen flow rate and the input source rate. As the oxygen flow rate increased, the Ru/(Ba+Sr) composition ratio in the film decreased, while the Ba/(Ba+Sr) ratio was almost independent of the oxygen flow rate. The dielectric constants of BST capacitors fabricated using these electrodes was greater than 500.

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The contact resistance (R C) between a Ru electrode and a TiN plug in a crystalline Ta2O5 capacitor using Ru electrodes was evaluated. The TiN plug was oxidized in TiO x to increase the R C to failure. Two origins of oxygen are determined by Auger electron spectroscopy (AES) analysis, namely, the seed step of Ru deposition and the initial step of Ta2O5 deposition. During Ta2O5 crystallization annealing at 700°C, the oxygen molecules from Ru diffused into the TiN plug, forming TiO x . Ru films with Ti exhibited a decreased R C below 1 kΩ/contact and an increased leakage current of a Ru/Ta2O5/Ru capacitor according to the applied voltage, compared with Ru films without Ti. The atomic layer deposition (ALD) Ru process including a H2 plasma treatment decreased the R C to 2.5 kΩ/contact on average. The fabrication scheme for the crystalline Ta2O5 capacitor using the Ru electrode for reducing RC between the Ru storage node and the TiN plug was proposed.

Ru thin films were prepared by metalorganic chemical vapor deposition (MOCVD) using cyclopentadienyl-propylcyclopentadienlylruthenium(II) [RuCp(i-PrCp)] and the nucleation behaviors of Ru films on Ta2O5, TiN, Si3N4, SiO2, TiO2 substrates were investigated. It appeared that the difference in nucleation behaviors on various substrates is due to the bonding type between atoms in substrate materials. The nucleation property of Ru films on TiN was successfully improved by plasma treatment of the TiN substrate using Ar before film deposition. It was found that the Ar plasma treatment selectively removes N ions from the surface, makes the TiN surface more metallic or ionic (due to the residual Ti-O bonding), and reduces the nucleation barrier. In addition, the oxidation resistance of Ru/TiN layers was improved by H2 annealing, which made the Ru films more dense.

Variations in the cation concentration ratio of metallorganic chemically vapor deposited SrTiO 3 (STO) thin films along a capacitor hole having a diam of 0.15 μm, were investigated. Even under the deposition conditions that produce stoichiometric STO films on a nonpatterned wafer, the Sr/Ti ratio is greatly decreased along the depth direction of the hole. The degree of variation depended on the flow rate of the precursors. In some cases, a film having a Ti concentration of more than 90% was deposited at the bottom of the hole with a Ti concentration of less than 30% at the top of the hole. A plausible reason for the compositional variation was suggested on the basis of the decreased diffusion speed of the precursor molecules in the small sized holes.

The annealing of (Ba,Sr)RuO3 films which are structurally and chemically matched with (Ba,Sr)TiO3 films was performed in oxygen and nitrogen atmospheres in the temperature range of 600–750 °C for 30 min. The effects of annealing the (Ba,Sr)RuO3 on the physical and electrical properties of the (Ba,Sr)TiO3 films were investigated. The x-ray diffraction peak of the annealed (Ba,Sr)RuO3 film at high temperatures revealed that the (Ba,Sr)TiO3 film is thermally more stable than RuO2. The (Ba,Sr)RuO3 film under N2 annealed showed lower electrical resistivity and larger surface roughness compared with those under O2. In addition, from the sequential two-step annealing process using O2 and N2, and by reversing the annealing sequence, the electrical resistivity and the surface roughness of the (Ba,Sr)RuO3 film turned out to be reversible. The (Ba,Sr)TiO3 film on the N2 annealed (Ba,Sr)RuO3 showed a higher leakage current than that on the O2 annealed bottom electrode because rough surface can cause a high local elec...

As one candidate capacitor for dynamic random access memories (DRAMs) of 4 Gbit and beyond, we investigated the electrical properties of Ru/Ta2O5/Ru. In this paper, the dielectric constant of Ta2O5 was measured as a function of annealing temperature and, also, its dependence on film thickness was studied. The effect of postannealing, which was performed after forming a capacitor, on the leakage current of Ru/crystalline-Ta2O5/Ru capacitor was evaluated. Additionally, the leakage current was investigated as a function of Ta2O5 film thickness. Through these experiments, a reliable 7 Å Toxeq. of Ta2O5 with a Ru electrode was obtained, which indicates that the Ru/crystalline-Ta2O5/Ru capacitor is a promising candidate for DRAMs of 4 Gbit and beyond.