Film Deposition Conditions Research Articles

Microscopic examination of rf-cavity-quality niobium films through local nonlinear microwave response

The performance of superconducting radio-frequency (SRF) cavities is sometimes limited by local defects. To investigate the rf properties of these local defects, especially those that nucleate rf magnetic vortices, a near-field magnetic microwave microscope is employed. Local third-harmonic response (P3f) and its temperature dependence and rf power dependence are measured for one Nb/Cu film grown by direct current magnetron sputtering (DCMS) and six Nb/Cu films grown by high-power impulse magnetron sputtering (HiPIMS) with systematic variation of deposition conditions. Five out of the six HiPIMS Nb/Cu films show a strong third-harmonic response that is likely coming from rf vortex nucleation due to a low-Tc surface defect with a transition temperature between 6.3 and 6.8 K, suggesting that this defect is a generic feature of air-exposed HiPIMS Nb/Cu films. A phenomenological model of surface-defect grain boundaries hosting a low-Tc impurity phase is introduced and studied with time-dependent Ginzburg-Landau (TDGL) simulations of probe-sample interaction to better understand the measured third-harmonic response. The simulation results show that the third-harmonic response of rf vortex nucleation caused by surface defects exhibits the same general features as the data, including peaks in third-harmonic response with temperature, and their shift and broadening with higher microwave amplitude. We find that the parameters of the phenomenological model (the density of surface defects that nucleate rf vortices and the depth an rf vortex travels through these surface defects) vary systematically with film deposition conditions. From the point of view of these two properties, the Nb/Cu film that is most effective at reducing the nucleation of rf vortices associated with surface defects can be identified. Published by the American Physical Society 2024

Key Sputtering Parameters for Precursor In2O3 Films to Achieve High Carrier Mobility.

Owing to their extremely high carrier mobility (μ) of >100 cm2/(V s) and suitable low carrier concentrations, transparent conducting films of solid-phase crystallized H-doped In2O3 (spc-IO:H) exhibit high conductivity with high optical transparency over a broad frequency range. These properties can be attributed to solid-phase crystallization of the amorphous precursor film. Therefore, the development of high-quality spc-IO:H films requires the deposition conditions of the precursor films to be optimized. This study systematically investigates the effects of three key sputtering parameters, namely, water vapor partial pressure (PH2O), radio frequency magnetron sputtering power (PRF), and flow ratio of O2 to total sputter gas (fO2) on the crystallographic texture evolution of spc-IO:H films during solid-phase crystallization. In addition, the carrier transport in the resulting films is examined. PH2O, PRF, and fO2 are found to be indispensable for producing high-mobility (>100 cm2/(V s)) spc-IO:H films. Furthermore, it is found that introducing a small amount of PH2O during deposition, a lower PRF, and a suitable fO2 facilitates the formation of precursor films having a lower crystallite density. Moreover, after annealing at a temperature of 200 °C, the IO:H precursor films with a lower crystallite density are found to have larger crystal grains. However, the μ values of the postannealed IO:H films are mainly correlated with the stoichiometric deviation.

Mathematical modeling study to optimize the production of molybdenum and silica absorbing thin films

Reducing costs in renewable energy technologies, such as solar energy, can be achieved by optimizing manufacturing processes to enhance the performance of solar absorbers. This study investigates the optical characteristics of molybdenum (Mo) films deposited on AISI 304 stainless steel substrates, both with and without a silicon dioxide (SiO2) anti-reflective layer. The work involves optimizing film thickness and deposition conditions to improve solar absorption and minimize thermal emission. A mathematical model was developed to determine the optimal film thickness for achieving high optical selectivity, and this model was validated through experimental deposition and characterization. The results show that a 53 nm Mo film achieved a selectivity factor of 10.35, with an emissivity of 9.30 % and an absorptivity of 96.28 %. The addition of an 18 nm SiO2 layer further increased the spectral selectivity to 13.95, with an absorptivity of 98.00 % and an emissivity of 7.02 %. These findings confirm that the theoretical predictions align with the experimental data, validating effectiveness of the optimized deposition parameters in enhancing the performance of solar absorbers.

Engineering Thin Films of Silicon Phthalocyanines for Organic Thin Film Transistors

Metal phthalocyanines (MPc) show great promise as semiconductors due to their exceptional optoelectronic properties, high thermal and photochemical stability, and ability to be easily synthesized and functionalized for specific applications. The metal/metalloid ion in the center of the MPc ring can significantly influence the electronic, optical, and magnetic properties of the compound, as well as its solubility and stability. The majority of MPc, such as copper phthalocyanine (CuPc) are used as hole-transport materials (p-type) in organic electronics. Silicon phthalocyanines (R2-SiPc) are emerging semiconductors which predominantly moves electrons and have led to high performance n-type organic thin-film transistors (OTFTs). Their low synthetic complexity paired with their versatile axial group facilitates the finetuning of their chemical properties, solution properties and processing characteristics without significantly affecting their frontier orbital levels or their absorption properties. The crystal engineering and film forming characteristics of R2-SiPc semiconductors can be tuned through appropriate axial group functionalization, therefore facilitating their integration into both OTFTs and OPVs by solution processing or vapor deposition.Our group has developed families of R2-SiPc and integrated them into OTFTs with an emphasis on thin film processing and engineering of the interfaces for improved device performance. We have established structure property relationships of the final device performance as a function of 1) R2-SiPc axial groups and peripheral groups, 2) surface chemistry and composition and 3) thin film deposition conditions. I will also be discussing our recent work using advanced film characterization such as polarized Raman microscopy and synchrotron based scanning transmission x-ray microscopy to evaluate the resulting films and optimize the OTFT performance. Figure 1

Optimization of Electrospray Deposition Conditions of ZnO Thin Films for Ammonia Sensing.

This study focuses on the influence of electrospray deposition parameters on the morphology, topography, optical and sensing properties of ZnO films deposited on gold electrodes of quartz crystal resonators. The substrate temperature, precursor feed rate and emitter's voltage were varied. Zinc acetate dehydrate dissolved in a mixture of deionized water, ethanol and acetic acid was used as a precursor. The surface morphology and average roughness of the films were studied by scanning electron microscopy (SEM) and 3D optical profilometry, respectively, while the optical properties were investigated by diffuse reflectance and photoluminescence measurements. The sensing response toward ammonia was tested and verified by the quartz crystal microbalance (QCM) method. The studies demonstrated that electrospray deposition parameters strongly influence the surface morphology, roughness and gas sensing properties of the films. The deposition parameters were optimized in order for the highest sensitivity toward ammonia to be achieved. The successful implementation of the electrospray method as a simple, versatile and low-cost method for deposition of ammonia-sensitive and selective ZnO films used as a sensing medium in QCM sensors was demonstrated and discussed.

A study on the fabrication procedure for a high-D/Ti-ratio-deuterated-titanium film on the disk-type neutron generator target

This study aims to present thin film deposition and deuterium adsorption procedure to fabricate disk-type targets with high D/Ti values for a neutron generator and increase their lifespan. The neutron target consists of a titanium thin film with hydrogen loading, and a copper substrate for heat removal. We optimized the incident deuterium ion beam energy and thin film thickness using Geant4 simulations. Additionally, we calculated the expected neutron yield under the optimized conditions. The hydrogen adsorption conditions were optimized by comparing the H/Ti results as per hydrogen adsorption temperature and loading time using titanium foils of different thickness values. Hydrogen (or deuterium) adsorption ratio is strongly influenced by the surface condition and the deposition conditions of the thin film. A titanium film was deposited in various conditions of plasma DC power and substrate temperature. The quality of the thin film was evaluated through surface roughness evaluation and thin film sheet resistance for each deposition conditions. Subsequently, the hydrogen adsorption results were compared according to the quality of the thin titanium films, and the thin titanium film deposition conditions with the highest hydrogen adsorption ratio were confirmed. The selected conditions were applied to conduct deuterium adsorption. In conclusion, this study underscores the critical relationship between thin film quality and hydrogen (or deuterium) adsorption ratio, reinforcing the importance of optimizing thin film deposition parameters for the design of neutron generator disk-type targets with high quality of film and extended lifespan.

Hydrogen Role on the Properties of Silicon Nitride for Flexible Thin Film Encapsulation

High transmittance, high density, and good mechanical properties of silicon nitride (SiNx) make it a potential candidate for barrier layers of flexible organic light emission diodes (FOLEDs). However, the overall characteristics and water oxygen barrier properties of the films are easily affected by the dangling bonds in the films. After adding hydrogen flow rate to the deposition conditions of SiNx films, the hydrogen content interacts with the dangling bonds in amorphous SiNx, which could reduce the number of dangling bonds and improve the density of the hydrogenated amorphous silicon nitride (SiNxHy) films. The high‐density film layer could effectively prevent the invasion of water vapor due to its smaller pinhole density. Therefore, the water oxygen barrier performance of SiNxHy is significantly improved, the maximum decrease in water vapor transmittance rate (WVTR) value is approximately 22.4%. In addition, the increase of hydrogen content also changed the overall properties of the films, including transmittance, elastic modulus, hardness, residual stress, and fracture strain. Therefore, compared with SiNx films, SiNxHy films have more excellent mechanical and optical properties. The SiNxHy films featuring a simplified preparation process with high efficiency, low cost, and superior barrier performance is of great potential for the commercial applications.

(Invited) Bonding Strength of Cu-Cu Hybrid Bonding for 3D Integration Process

Introduction Cu-Cu hybrid bonding is a significant technology in the manufacture of 3D stacked semiconductor devices and is indispensable for the integration of 3D heterogeneous stacked packages.1 A process is used to thin the bonded semiconductor during 3D stacking integration, but delamination can occur when the bonding strength of the bonded interface is insufficient.Therefore, the bonding strength is a key factor in the 3D stacked integration process, and mechanisms for improving the strength have been thoroughly investigated. Cu-Cu hybrid bonding strength During Cu-Cu hybrid bonding, the bonding strength between bonded wafers, which is a crucial factor, is complicated to describe because of the various materials contained in the bonding interface. Because the bonding interface includes not only Cu/Cu and dielectric/dielectric films, but also Cu/dielectrics as a result of the misalignment of Cu pads, the strength of the Cu-Cu hybrid bond needs to comprehensively account for these interfaces. We investigated the relationship between the bonding strength and amount of misalignment using patterned Si substrates that were bonded after intentionally being aligned with an offset and thermally annealed.Although the bonding strength before annealing was confirmed to decrease lineally depending on the amount of misalignment, the wafers showed a different behavior after annealing in the region where the amount of misalignment was low. Simulation calculations elucidated the behavior of the overall bonding strength. When a Cu pad with a large recess contacted the opposing Cu pad, an uneven amount of pressure was generated between their contact surfaces because of the thermal expansion produced by the annealing. An area with very low pressure was also found between the surfaces, and extremely little or no diffusion occurred in this area.2 This phenomenon was not observed in a case where the amount of recess was small in both the experiments and simulation calculations, which showed linear relationships dependent on the misalignment after annealing.This study determined the misalignment dependence of the bonding strength after annealing considering the recess of the Cu pad, and an integrated model of the comprehensive bonding strength that included three interfaces involved in the Cu-Cu hybrid bonding could be presented. Improvement of bonding strength between dielectric films We are also continuing to study ways to improve the bonding strength of the interface between the dielectrics films that exist in the interfaces of a Cu-Cu hybrid bond. Elucidating the mechanism of strength generation would offer a guideline to improve the bonding strength.The dielectric films are bonded using a dehydration condensation reaction on the plasma-activated surface by thermal annealing. This bonding process has been widely studied from the perspective of the amount of surface Si-OH by considering the activation method and condition, type of dielectrics, and flatness of the surface. Because few investigations have considered factors other than the bonding interfaces, we focused on the influence of the H2O contained in the dielectric film to be bonded and investigated the relationship between the amount of H2O in the film and the bonding strength.The deposition conditions of the dielectric films produced using Plasma Enhanced Chemical Vapor Deposition (PE-CVD) were varied to prepare five types of films that contained various amounts of H2O. After CMP treatment of each film, the surface roughness and amount of Si-OH were measured, and it was confirmed that there was no significant difference. When the bonding strength was obtained by bonding using these films and plotted against the amount of H2O, it was found that the bonding strength was dependent on the amount of H2O. In addition, after being bonded and annealed, it was confirmed that the expansion of the dielectric film depended on the amount of H2O, as seen in cross-sectional STEM images of the interface.An investigation of the mechanism for this phenomenon suggested that the bonding strength was increased by filling the gap in the bonding interface through the expansion of the film. This study suggested that filling up the gap in the interface would be one approach for improving the bonding strength.These results offer a deep understanding of the mechanism for the bonding strength of Cu-Cu hybrid bonds and will contribute to the development of 3D stacking technology in the future.

A Study on Film Properties Control of Atomic Layer Deposition Amorphous Carbon for PRAM Electrode Application

As the amount of data usage increases with the development of technologies such as artificial intelligence, Internet of Things (IoT), and big data, the need for development of high-performance memory devices and improvement of density is increasing. Phase change memory is a next-generation memory device that stores and erases information by the resistance difference generated by reversibly and rapidly changing the crystal structure of the memory cell. Recently, research on the material engineering aspect to increase thermal efficiency by using various electrode materials and the structural aspect to increase the degree of integration by making a 3D structure is attracting attention. As an electrode material to increase the thermal efficiency of PRAM devices, carbon, which has various resistances (conductor (graphite, sp2 bond) – insulator (diamond, sp3 bond)) depending on the state of atomic bonding is an attractive material. Therefore, research using carbon as an electrode by using PVD and CVD processes has been conducted, but there is a problem that it is difficult to use it for devices with a complex 3D structure with the existing process. Therefore, in this study, an a-C ALD process that can be uniformly deposited in a 3D structure was developed using the CBr4 precursor. And by analyzing the bonding state and physical properties of the deposited thin film, the mechanism of how the a-C thin film grows according to the thin film deposition conditions is studied.

Reactive Magnetron Sputtering Control Based on an Analytical Condition of Stoichiometry

Abstract The conditions for stoichiometric thin film deposition by reactive magnetron sputtering include the existence of a given ratio between the flux of the sputtered metallic atoms and the flux of the reactive gas molecules on the surface of the substrate. To meet this condition, a relationship based on the Berg model is formulated between the partial pressure of the reactive gas, the target coverage, and the sputtering current density. Given that the target coverage can be estimated online from the sputtering voltage, it is possible to create a control structure where the reactive gas partial pressure is controlled to obtain stoichiometric thin film deposition. Simulation results are presented based on the dynamic model of the sputtering process.

Prediction by a hybrid machine learning model for high-mobility amorphous In2O3: Sn films fabricated by RF plasma sputtering deposition using a nitrogen-mediated amorphization method

In this study, we developed a hybrid machine learning technique by combining appropriate classification and regression models to address challenges in producing high-mobility amorphous In2O3:Sn (a-ITO) films, which were fabricated by radio-frequency magnetron sputtering with a nitrogen-mediated amorphization method. To overcome this challenge, this hybrid model that was consisted of a support vector machine as a classification model and a gradient boosting regression tree as a regression model predicted the boundary conditions of crystallinity and experimental conditions with high mobility for a-ITO films. Based on this model, we were able to identify the boundary conditions between amorphous and crystalline crystallinity and thin film deposition conditions that resulted in a-ITO films with 27% higher mobility near the boundary than previous research results. Thus, this prediction model identified key parameters and optimal sputtering conditions necessary for producing high-mobility a-ITO films. The identification of such boundary conditions through machine learning is crucial in the exploration of thin film properties and enables the development of high-throughput experimental designs.

Optimizing Sputter Deposition Conditions of Silver Thin Films Used in Low-Emissivity Coatings in an In-Line Deposition System

This research sought to determine the optimal conditions for depositing thin silver layers in the fabrication of low-emissivity coatings. The study utilized an in-line semi-industrial high-vacuum magnetron sputtering system with rectangular targets, closely resembling those used in industrial settings. Trilayer AZO/Ag/AZO structures were deposited to enhance the wetting properties of the silver, and to protect it from the atmosphere. The effects of the power and argon flow on the sample properties were analyzed, along with variations in the silver thickness. The results demonstrate that a lower power (200 W) and higher argon flows (1000 sccm) lead to a higher transmittance and a lower sheet resistance, resulting in a reduced emissivity (up to 0.015 for 24 nm of silver). The identified optimal conditions offer valuable recommendations for producing more efficient and optically superior coatings. This study also reveals the importance of the silver thickness to the properties of the coatings, in accordance with previous research findings. These findings provide insights for improving the performance of low-emissivity coatings in various applications.

How to grow single-crystalline and epitaxial NiTi films in (100)- and (111)-orientation

Understanding the martensitic microstructure in nickel–titanium (NiTi) thin films helps to optimize their properties for applications in microsystems. Epitaxial and single-crystalline films can serve as model systems to understand the microstructure, as well as to exploit the anisotropic mechanical properties of NiTi. Here, we analyze the growth of NiTi on single-crystalline MgO(100) and Al2O3(0001) substrates and optimize film and buffer deposition conditions to achieve epitaxial films in (100)- and (111)-orientation. On MgO(100), we compare the transformation behavior and crystal quality of (100)-oriented NiTi films on different buffer layers. We demonstrate that a vanadium buffer layer helps to decrease the low-angle grain boundary density in the NiTi film, which inhibits undesired growth twins and leads to higher transformation temperatures. On Al2O3(0001), we analyze the orientation of a chromium buffer layer and find that it grows (111)-oriented only in a narrow temperature range around 500 ∘C. By depositing the Cr buffer below the NiTi film, we can prepare (111)-oriented, epitaxial films with transformation temperatures above room temperature. Transmission electron microscopy confirms a martensitic microstructure with Guinier Preston-zone precipitates at room temperature. We identify the deposition conditions to approach the ideal single crystalline state, which is beneficial for the analysis of the martensitic microstructure and anisotropic mechanical properties in different film orientations.

Deposition of GeSn film on Si substrate by plasma-enhanced chemical vapor deposition using GeCl4 and SnCl4 in H2 for developing short-wave infrared Si photonics

The deposition of a GeSn film on Si substrate with GeCl4 and SnCl4 in H2 as precursors was demonstrated by using plasma-enhanced chemical vapor deposition (PECVD). A partially strain-relaxed, impurity-free, monocrystalline GeSn film with a surface roughness of 6 nm and a threading-dislocation density of 1 × 107 cm−2 could be directly grown at a rate of ca. 15 nm/min at a substrate temperature of 180 °C without the need of a buffer layer or post-annealing. A Sn atomic percentage exceeding 9% was achieved, providing a light absorption beyond 2.4μm for the deposited 260-nm-thick film. The same deposition process for Ge and Sn enabled easier control of film deposition conditions and better clarification of the underlying mechanisms. The low deposition temperature renders this method compatible with complementary metal–oxide–semiconductor (CMOS) technology, suitable for developing short-wave infrared Si photonics.

Characteristics of Hf0.5Zr0.5O2 Thin Films Prepared by Direct and Remote Plasma Atomic Layer Deposition for Application to Ferroelectric Memory.

Hf0.5Zr0.5O2 (HZO) thin film exhibits ferroelectric properties and is presumed to be suitable for use in next-generation memory devices because of its compatibility with the complementary metal-oxide-semiconductor (CMOS) process. This study examined the physical and electrical properties of HZO thin films deposited by two plasma-enhanced atomic layer deposition (PEALD) methods- direct plasma atomic layer deposition (DPALD) and remote plasma atomic layer deposition (RPALD)-and the effects of plasma application on the properties of HZO thin films. The initial conditions for HZO thin film deposition, depending on the RPALD deposition temperature, were established based on previous research on HZO thin films deposited by the DPALD method. The results show that as the measurement temperature increases, the electric properties of DPALD HZO quickly deteriorate; however, the RPALD HZO thin film exhibited excellent fatigue endurance at a measurement temperature of 60 °C or less. HZO thin films deposited by the DPALD and RPALD methods exhibited relatively good remanent polarization and fatigue endurance, respectively. These results confirm the applicability of the HZO thin films deposited by the RPALD method as ferroelectric memory devices.

Quasi-normally off AlGaN/GaN high-electron-mobility transistors with p-type CuOx gate synthesized through magnetron reactive sputtering

In this study, magnetron reactive sputtering using a copper oxide target was performed to obtain a series of high-quality CuOx films with high hole concentration. The results of X-ray photoelectron spectroscopy and Hall measurements revealed that the hole concentration exhibited a negative correlation to the Cu + to Cu2+ ratio in the p-type CuOx film. This phenomenon indicated that the hole concentration can be modulated by adjusting film deposition conditions. Considering the high hole concentration and fine surface quality, these CuOx films were used as p-type gates without gate etching and positively shifted the threshold voltage (Vth) of AlGaN/GaN high-electron-mobility transistors (HEMTs). This study is the first to achieve quasi-normally off GaN HEMTs using CuOx gates, in which Vth positively shifted approximately 2.5 V and reached 0.5 V. Because of the excellent surface quality of the CuOx gate, the off-state current and gate leakage current of GaN HEMTs improved considerably. This study verified that CuOx is a promising gate candidate for fabricating low-cost, normally off AlGaN/GaN HEMTs.

Preferential growth of (001)-oriented Bi2SiO5 thin films deposited on (101)-oriented rutile substrates and their ferroelectric and dielectric properties

Ferroelectric thin films are important because of their great potential for use in various electric devices such as ferroelectric random-access memory. It was expected that Bi2SiO5, a Si-containing ferroelectric material, would show improved ferroelectricity by targeting a film with the (001)-orientation (polar-axis) on the substrate. Although there was a narrow process window for the deposition of the (010)/(001)-oriented Bi2SiO5 thin film, it was successfully prepared on a (101)-oriented TiO2 single substrate using the pulsed layer deposition technique. The optimum film deposition conditions and film thickness were found, and in this material, the volume fraction of the (001)-oriented domain reached about 70%. By controlling film orientation to the polar axis, the remanent polarization value of this film was 4.8 μC cm−2, which is the highest value among reported Bi2SiO5.

Substrate temperature dependence of GaN film deposited on sapphire substrate by high-density convergent plasma sputtering device

Substrate temperature dependence of GaN films deposited on a sapphire substrate was studied by the high-density convergent plasma sputtering device (CPSD). The crystal structure, surface morphology, and film stress of the GaN films were evaluated at 80–800 °C without changing plasma discharge conditions. The deposited GaN films tend to be preferentially oriented on the (0002) plane at all substrate temperature ranges. The in-plane φ-scans of x-ray diffraction measurements showed sixfold symmetric diffraction patterns of GaN(10−10) above 200 °C. At 800 °C, the film stress was down to one tenth compared with 80 °C and the full width at half maximum of the rocking curve at a GaN(0002) diffraction angle reached down to 1.1°. The GaN film deposition condition of 200 °C by CPSD suffices for the alignment of the twist angle of the c axis of GaN.

Tailoring Ordered Wrinkle Arrays for Tunable Surface Performances by Template-Modulated Gradient Films.

Complex wrinkled microstructures are ubiquitous in natural systems and living bodies. Although homogeneous wrinkles in film-substrate bilayers have been extensively investigated in the past 2 decades, tailoring heterogeneous wrinkles by a facile method is still a challenge. Here, we report on the controllable heterogeneous wrinkles in template-modulated thickness-gradient metal films sputter-deposited on polydimethylsiloxane substrates. It is found that the stress of the gradient film is strongly position-dependent and the wrinkles are always restricted in thinner film regions. The morphological characteristic and formation mechanism of the heterogeneous wrinkles are analyzed and discussed in detail based on the stress theory. Ordered wrinkle arrays are achieved by adjusting the deposition time, copper grid period, template shape, and lifting height. The surface performances (e.g., the friction property) are well controlled by the wrinkle arrays. This work could promote better understanding of the spontaneously heterogeneous wrinkles in template-modulated gradient films and controllable fabrication of various wrinkle arrays by independently tuning film deposition conditions and template parameters.

Deposition phenomena of diamond-like carbon coating on inner surface of circular metal tube by nanopulse plasma chemical vapor deposition

A method of depositing a diamond-like carbon (DLC) film on the inner surface of a circular metal tube by chemical vapor deposition using a nanopulse power source was developed. Because the nanopulse power source can supply rapidly rising and falling high-voltage nanopulses of nanosecond order, a stable plasma can be obtained even in small-diameter tubes by applying a high gas pressure of more than 100 Pa. DLC films were successfully deposited on the inner surfaces of metal tubes of 14 mm diameter and 300 mm length (21% aspect ratio), and of 40 mm diameter and 300 mm length. To understand the plasma state inside the tubes to determine appropriate DLC film deposition conditions, wavelength- and time-resolved optical emission spectroscopy of the plasma generated inside the tubes and numerical simulation were performed. Results of these investigations and characterization clarified that one nanopulse power source introduced to tubes generates glow and after-glow discharges at μs time intervals. It was further clarified that these discharges in combination with high-repetition pulses, suggested together contribute to the effective ionization of gas. Thus, the high speed and high source gas yield of DLC film deposition inside the tubes were confirmed.