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A novel chemical vapor deposition (CVD)-Al technique of "bottom-up growth" was developed using methylpyrrolidine alane as a precursor and a (PVD)-TiN/CVD-TiN stacked barrier in a damascene structure. Poor step coverage of PVD-TiN caused an absence of PVD-TiN at the bottom of trenches, resulting in selective Al growth. The new method filled a 40-nm-wide trench (aspect ratio = 7.5) completely and showed robust electrical properties. The lowest line resistance was obtained at a stacked layer of PVD-TiN/CVD-Ru due to the low resistivity of Ru. Furthermore, the fine Al line structure fabricated by the new technique revealed that the Al line structure did not suffer severely from the size effect, which started to affect Cu damascene structures that were 50 nm wide.

We report on the improved light extraction efficiency of blue light-emitting diodes (LEDs) by SiO2-coated ZnO nanorods (NRs) grown on indium–tin oxide (ITO). The optical output power of the LEDs with SiO2-coated ZnO NRs, which are grown on the patterned sapphire substrates, increases by 5% at 20 mA, compared with that of LEDs with bare ZnO NRs. This increase is attributed to the improved light extraction efficiency of LEDs because the SiO2 layer with a refractive index lower than that of ZnO NRs further reduces the Fresnel reflection.

We investigate the effect of internal electric field in InGaN well layer of InGaN/GaN multiple quantum well light-emitting diodes (LEDs) on efficiency droop behavior. The simulation results show that the internal electric field in InGaN well layers of Ga-polar LEDs is same as the direction of external electric field by forward bias voltage, resulting in a strong efficiency droop. However, N-polar LEDs show that the efficiency droop is drastically improved due to an increase of internal quantum efficiency and carrier injection efficiency by weakening the internal electric field with increasing the forward bias voltage and decrease of electron overflow.

We investigated InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with trapezoidal wells to improve the efficiency droop. MQW LEDs with trapezoidal wells showed a lower operating voltage and an improved efficiency droop with a low crossover current density of 5 A cm−2, which was a significant improvement over conventional LEDs that use rectangular wells. The external quantum efficiency was increased by 20% at a current density of 70 A cm−2. The improvement in efficiency droop of the MQWs with trapezoidal wells can be attributed to an increased internal quantum efficiency due to the enhanced overlap of the electron and hole wave functions at high current densities.

The improved contact resistance was obtained by the new barrier metal scheme such as CVD-Co/Ti/TiN process in the level of about half of that from CVD-Ti/TiN process. And the mechanism of contact silicidation of CVD-Co/Ti/TiN was investigated. Because Co silicide may prohibit the Si diffusion into Ti silicide and Si recess during TiCl4-based CVD-Ti process, and the inertness of Co silicide to the dopants, the improved contact resistance with uniform silicide morphology was obtained. Therefore, CVD-Co/Ti/TiN contact silicide process can be regarded as the next generation contact silicidation process.

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.

Pb(Zr,Ti)O3 (PZT) films were deposited on Pt/Ti/SiO2/Si substrates by electron cyclotron resonance (ECR) plasma enhanced DC magnetron reactive sputtering. Various seed layers with different compositions were formed by varying the target power of each element at the initial stage of the deposition process, and the effects of the seed layers on the properties of the PZT films subsequently deposited on them were studied. The seed layers were fabricated in three ways: increasing Pb flux at a particular Zr/Ti flux ratio which is kept constant in the subsequent PZT film deposition process, increasing Pb flux with decreasing the Zr/Ti flux ratio to make the layer composition below the morphotrophic phase boundary (Zr/Ti=1.08) value and finally maintaing a Zr flux of zero for the PbTiOx seed layer. It was found that the PZT seed layer is more effective than a PbTiOx seed layer and the effectivity of the seed layer is increased not by just increasing the supply of Pb, but by increasing the Pb supplement in the presence of low Zr/Ti flux ratio. However, too much excess supplement of Pb element during the seed layer deposition degrades the crystallinity and capacitance properties of overlying PZT films.

Pb(Zr,Ti)O3 films were deposited by DC magnetron reactive sputtering on Pt/Ti/SiO2/Si and Pt/SiO2/Si substrates. The activation of oxygen by electron cyclotron resonance (ECR) plasma facilitated the incorporation of Pb. This enabled the fabrication of Pb(Zr,Ti)O3 films with stoichiometric composition and perovskite structure even at a high Zr/Ti film concentration ratio and high substrate temperature and on Pt/SiO2/Si substrates where the pyrochlore second phase was usually observed when the films were deposited without oxygen activation.

Interfacial phenomena in the O2-annealed multilayer systems of Pt/Ti/SiO2/Si and Pb(Zr, Ti)O3/Pt/Ti/SiO2/Si have been studied using Auger electron spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). Emphasis has been placed on the microstructural analysis of interfaces. The strong tendency of titanium diffusion into platinum appeared to be responsible for the formation of an isolated platinum layer when the samples were annealed in O2 for 4 h at 450° C or higher. The formation of a TiO2 phase was confirmed at the annealing temperature of 600° C or higher. TEM analysis of the 650° C annealed sample confirmed the presence of a Pt-containing layer sandwiched by TiO2 layers. Rapid thermal annealing is strongly recommended to suppress undesirable interdiffusions and the resultant chemical reactions.

We have investigated the structural and electrical properties of lead-zirconate-titanate (PZT) thin films prepared on Pt/Ti/SiO2/Si substrates by multitarget reactive DC magnetron cosputtering. Film composition has been controlled by independently varying the DC power applied to the Pb, Zr and Ti targets. A single perovskite phase with a pseudocubic structure has been obtained with postannealing at 550°C in oxygen. The structure, composition and chemical state have been examined as a function of annealing temperature. The 0.65 µm- and 2.1 µm-thick films annealed at 550°C have dielectric constants of 178 and 497 at 100 kHz, remanent polarizations of 1.7 µC/cm2 and 2.4 µC/cm2 and coercive fields of 7.8 kV/cm and 8.4 kV/cm, respectively.