Multiple Low-inductance Antenna Research Articles

Nanocrystalline Si:H films made by inductively coupled plasma using internal low inductance antenna

P-type hydrogenated nanocrystalline silicon (nc-Si:H) thin films are prepared on glass substrate by an inductively coupled plasma chemical vapor deposition system using multiple internal low inductance antenna units. The deposition rate as well as the microstructural and electrical properties of the nc-Si:H films are investigated systematically as functions of hydrogen dilution, discharge power and working distance. The effects of various process parameters are identified and rationalized. The applicability of this type of high density plasma to manufacture nc-Si:H films is critically assessed.

Low-damage plasma processing of polymers for development of organic-inorganic flexible devices

Plasma generation and control technologies for processing of polymers have been developed with multiple low-inductance antenna (LIA) units, as a promising candidate for next-generation processing of hybrid flexible devices. Properties of argon–oxygen mixture plasmas sustained with multiple LIA units have been investigated in terms of ion energies bombarding onto polymer surface. Ion energy distribution at the sheath edge of the argon–oxygen mixture plasmas showed considerable suppression of ion energies as small as or less than 10 eV. Effects of the plasma exposure onto polymers have been examined using hard x-ray photoelectron spectroscopy (HXPES) in terms of chemical bonding states of the polymer surface and the interface between polymer and silicon film.

Low-damage surface modification of polymethylmethacrylate with argon–oxygen mixture plasmas driven by multiple low-inductance antenna units

Surface modification of polymethylmethacrylate (PMMA) films has been investigated with argon–oxygen mixture plasmas sustained with multiple low-inductance antenna units. PMMA films were exposed to argon–oxygen mixture (20%) plasmas on a water-cooled substrate holder. Average ion energies bombarding onto the PMMA films was estimated to be as low as 6 eV, which was evaluated from the gap between plasma potential and floating potential. The etching depth of PMMA surface increased linearly with increasing plasma-exposure time and the etching rate was 170 nm/min. Surface roughness of PMMA slightly increased from 0.3 nm to 1.4 nm with increasing exposure time. Hard X-ray photoelectron spectroscopy (HXPES) was carried out to examine chemical bonding states of the PMMA surface in deeper regions (about 54 nm) as compared with those observed in shallower regions (27 nm).

X-ray photoelectron spectroscopy for analysis of plasma–polymer interactions in Ar plasmas sustained via RF inductive coupling with low-inductance antenna units

Plasma–polymer interactions have been investigated on the basis of hard X-ray photoelectron spectroscopy (HXPES) together with conventional X-ray photoelectron spectroscopy (XPS) for analysis of chemical bonding states in the surface nano-layers of polymethylmethacrylate (PMMA) films, which were exposed to argon plasmas sustained via RF inductive coupling with multiple low-inductance antenna units. The PMMA films were exposed to argon plasmas on a water-cooled substrate holder. Average ion energies bombarding onto PMMA films were varied in the range of 6–16 eV, which were evaluated as ion kinetic energies at the sheath edge to the ground potential using a mass-separated ion-energy analyzer. The etching of PMMA surface after Ar plasma exposure with an ion dose of 3.4 × 10 18 ions/cm 2 was measured to be insignificant (less than 20 nm). Surface roughness of PMMA slightly increased from 0.3 nm to 0.4 nm with increasing ion bombardment energy from 6 eV to 16 eV. HXPES was carried out together with conventional XPS to examine chemical bonding states of the PMMA surface in deeper regions (about 54 nm) with HXPES as compared to those observed in shallower regions (8 nm) with the conventional XPS.

Plasma surface treatment of polymers with inductivity-coupled RF plasmas driven by low-inductance antenna units

Plasma surface treatment of polymers has been carried out with argon/oxygen mixture plasmas driven by multiple low-inductance antenna units. Kinetic energy distribution of argon ions from the argon/oxygen mixture plasmas onto polymers showed considerable suppression of ion energies sufficiently less than 10 eV. Polyethyleneterephthalate (PET) films were exposed to argon/oxygen mixture plasma for 1–5 min on a water-cooled substrate holder. The etching depth of PET surface increased with increasing plasma-exposure time and the etching rate was 118 nm/min. Surface roughness of PET surface (root-mean-square value) increased from 0.5 nm to 2.7 nm with increasing plasma-exposure time from 0 min (original sample) to 5 min. Hard X-ray photoelectron spectroscopy (HXPES) was carried out for analysis of chemical bonding states of the PET surface. The HXPES analyses exhibited nano-surface modification of the PET surface without suffering degradation of molecular structures beneath.

Radial‐Profile Control of Cylindrical Plasma Source With Multiple Low‐Inductance Antenna Units

AbstractRadial‐profile control of cylindrical plasma source with 500 mm in diameter has been carried out using multiple low‐inductance antenna (LIA) units. Measurements of ion saturation current in the cylindrical chamber demonstrated an excellent control capability of radial distribution by adjusting the power‐deposition profile. The non‐uniformity of radial distributions was improved from 8.3% to 5.4% with the plasma control technologies. The results indicate that the plasma control technologies with multiple LIA units are quite attractive as a plasma source for large‐area wafer processes over 450 mm in diameter, which inherently require excellent profile control capabilities.

Large-area and low-damage processes for hybrid flexible device fabrications with reactive high-density plasmas driven by multiple low-inductance antenna modules

Plasma generation and control technologies for meters-scale ultra-large-area plasma sources have been developed with multiple low-inductance antenna (LIA) modules, as a promising candidate of ultra-large-area and high-density plasma sources for next-generation processing of hybrid flexible devices. Properties of argon-oxygen mixture plasmas sustained with multiple LIA units have been investigated and surface modifications of polymer substrates using the plasmas have been performed. Ion energy distribution at the sheath edge of the argon-oxygen mixture plasmas showed considerable suppression of ion energies as small as or less than 10 eV. We have examined effect of plasma exposure on surface modification and/or degradation of polymer. Surface analysis of polytetrafluoroethylene (PTFE) exhibited nano-surface modification of the polymer surface without suffering degradation of molecular structures beneath the nano- surface layer.

Simulation-Aided Designing of Meter-Scale Large-Area Plasma Source with Multiple Low-Inductance Antenna Modules

The plasma profiles in a 300 cm rectangular plasma source sustained with multiple low-inductance antenna (LIA) modules were investigated using a fluid-simulation code. The profiles of argon plasmas sustained with two LIA modules were investigated in order to evaluate the appropriate spacing between LIA modules for obtaining uniform plasmas in multiple antenna configurations. For designing meter-scale large-area plasma sources, the simulation in the rectangular chamber with multiple LIA modules was carried out. Argon ion (Ar+) and metastable radical neutral (Ar*) distributions with a nonuniformity of <6.0% in a 220 cm rectangular area were obtained with the proper arrangement of antenna modules.

Uniformity of 500-mm cylindrical plasma source sustained with multiple low-inductance antenna units

Uniformity of plasma density and 4s excited Ar (Ar⁎) density profiles in a 500-mm cylindrical plasma source sustained with eight LIA units have been investigated with a fluid-simulation code. Uniformity of the simulated radial profiles of plasma density on the substrate holder located at a distance of 300 mm from a top flange became better with increasing Ar pressure from 1.3 Pa to 6.7 Pa. The radial uniformity of plasma density in the central 300 mm region was evaluated to be approximately 4.0% at 6.7 Pa. Uniformity of the radial profiles of Ar⁎ density became better with increasing distance of the substrate holder to the down-stream region. In the present antenna configuration, fairly uniform radial profiles of Ar⁎ density can be obtained at a distance of 300 mm from the top flange.

Large-area low-damage plasma sources driven by multiple low-inductance-antenna modules for next-generation flat-panel display processes

Plasma-generation and profile-control technologies for ultra-large-area processing of flat-panel displays have been developed by employing multiple low-inductance antenna (LIA) modules to sustain meter-scale inductively-coupled plasmas, as a promising candidate for high-density (1011–1012 cm−3) plasma sources as well as high-quality (low-damage) plasma processing. Our proposal of the unique source configuration is based on the principle of multiple operation and integrated control of LIA modules. Each of the LIA modules consists of a U-shaped internal antenna with a scale-length much smaller than 1/4 wavelength of the high-frequency power transmission to avoid problems associated with standing-wave effects. Furthermore, for active control of power-deposition profiles to attain desired plasma distributions, each of the LIA modules is equipped with an independent RF power amplifier. Experiments with a meter-scale reactor demonstrated achievements of high plasma densities above 1011 cm−3 in argon and uniformity control capabilities. The results indicated that the plasma production and/or control technologies with the LIA modules are promising for a variety of FPD processes.

Discharge profiles of internal-antenna-driven inductively-coupled plasmas

In this work radio frequency inductively-coupled plasmas (ICPs) sustained with a single low-inductance antenna (LIA) have been characterized in an attempt to clarify profiles of plasma parameters in the near-antenna region. The present investigations have been carried out for the purpose of understanding the local discharge features with a single LIA unit, which are regarded as one of the elements for sustaining large-area plasma source with multiple LIA configurations. The ion-saturation current profiles had a peak at a distance of 10–20 mm from the outer surface of the antenna insulator and then decreased with increasing distance from the antenna, while the electron temperature peaked in the vicinity of the outer surface of the antenna insulator. These results suggest that the discharge sustained with a single LIA is mainly excited via the induction electric field, which is inherent in near-field nature of the induction electric fields peaking in the vicinity of the antenna and attenuating with a depth of penetration (skin depth) in the plasma. Distribution of the RF fluctuation of the floating potential was also measured to evaluate the electrostatic coupling of the antenna to the plasma.

21406 マルチアンテナ型RFプラズマによるメートル級大面積での低ダメージプロセスと制御(基調講演,デバイス&配線技術2,OS.1 機械工学が支援する微細加工技術(半導体・MEMS・NEMS),学術講演)

21406 マルチアンテナ型RFプラズマによるメートル級大面積での低ダメージプロセスと制御(基調講演,デバイス&配線技術2,OS.1 機械工学が支援する微細加工技術(半導体・MEMS・NEMS),学術講演)

Ultra-Large Area RF Plasma Sources Employing Multiple Low-Inductance Internal-Antenna Modules for Flat Panel Display Processing

Plasma-generation and control technologies for meters-scale ultra-large-area RF plasma sources have been developed with multiple low-inductance antenna (LIA) modules, as a promising candidate of ultra-large area and high-density (1011-1012 cm-3) plasma sources for next-generation large-area processing. The present technologies are based on principle of multiple operation and integrated control of LIA modules, which enables effective control of power deposition profiles and hence the plasma uniformity over meters-scale large area for processing. This paper presents issues in designing ultra-large-area plasma sources to demonstrate feasibility of the uniform sources with 3m x 3m scales to meet requirements in the next-generation processes.

Development of Large Area Plasma Reactor Using Multiple Low-Inductance Antenna Modules for Flat Panel Display Processing

This article reports characteristics of plasmas sustained with LIA modules and profile control capabilities. Experiments with a meter-scale reactor demonstrated uniform plasma production to attain densities as high as 5x1011 cm-3 at an argon pressure of 1.3 Pa and an RF power of 4 kW. Design issues for large-area plasma sources with a scale-size of 3 m were also presented to exhibit the feasibility of novel large-area plasma sources to meet the requirements of the next-generation meters-scale processing.

Production and Control of Large-Area Plasmas for Meters-Scale Flat-Panel-Display Processing with Multiple Low-Inductance Antenna Modules

Plasma technologies for meters-scale flat-panel-display (FPD) processing have been developed using multiple low-inductance antenna (LIA) modules to drive inductively coupled plasmas (ICPs), in which RF-power-deposition profiles can be controlled in plasma reactors with a scale as large as meters. The LIA module consisted of a U-shaped internal antenna with dielectric isolation, each of which was coupled to an RF power system for independent power control of driving ICP. Our new proposal of the unique source configuration is based on the principle of multiple operation and integrated control of LIA modules, which allow low-voltage high-density plasma production with active control of power deposition profiles. Multiple LIA modules mounted on the wall of a discharge chamber were independently controlled to attain the desired plasma profiles. Experiments with a meter-scale rectangular reactor resulted in stable source operation to attain high densities >1011 cm−3. Plasma-enhanced chemical vapor deposition of amorphous hydrogenated carbon films showed an excellent control capability of film-thickness distributions to achieve the film-thickness uniformity of 8.6%, which was defined as the value of (maximum thickness − minimum thickness) divided by the average thickness over the substrate area of 410 mm × 520 mm. The obtained results indicate that the plasma production and/or control technologies with the LIA modules are quite attractive as a high-density low-potential plasma source for a variety of FPD processes.

Properties of Inductively-Coupled Plasmas Driven by Multiple Low-Inductance Internal-Antenna Units

We have developed cylindrical RF plasma sources sustained with multiple low-inductance antenna (LIA) units and have measured plasma parameters for argon plasmas. The plasma source could be operated at 2 000 W RF powers to attain plasma densities as high as 1012 cm−3. The plasma potential as low as 13–14 V in high-density plasmas has been achieved and the potential drop from plasma potential to floating potential was almost constant at 10 V. Kinetic energy distributions of Ar ions were measured at argon pressures around 1.3 Pa in an RF power range of 200–2 000 W, which have peaks which almost correspond to the magnitude of the plasma potential.

Meters-Scale Large-Area Plasma Sources with Multiple Low-Inductance Antenna Units for Next-Generation Flat-Panel Display Processing

Profiles of argon plasma sustained with multiple low-inductance antenna (LIA) units in a 300-cm rectangular plasma source have been investigated by a three-dimensional plasma simulation using fluid model. Profile of 4s excited Ar (Ar*) density was investigated as well as plasma density profile. It is found that FWHM of the profile for Ar* density is larger than 2 factors compared to that for density of Ar plasma sustained with two LIA units were installed at the center of top plate. This difference is caused by the different diffusion for particles; i.e., Ar ions diffuse along the electric field gradient while 4s excited Ar particles follow the diffusion of neutral argon. With multiple LIA units, the nonuniformity of the plasma density was 5.5% while that of Ar* density was 4.9% in 230-cm rectangular area, which is equivalent to the substrate size required for next generation flat-panel display processes.

Characterization of Inductively-Coupled RF Plasma Sources with Multiple Low-Inductance Antenna Units

We have developed a cylindrical RF plasma source by the inductive coupling of multiple low-inductance antenna (LIA) units and analyzed the plasma density profile of this source using fluid simulation. Experiments using four LIA units showed a stable source operation even at 2000 W RF power, attaining plasma densities as high as 1011–1012 cm-3 in an argon pressure range of 0.67–2.6 Pa. The amplitude of antenna RF voltage was measured to be less than 600 V, which is considerably smaller than those obtained using conventional ICP antennas. The radial distribution of plasma density sustained using four LIA units showed excellent agreement with profiles numerically predicted using a fluid-simulation code.

Effects of Antenna Size and Configurations in Large-Area RF Plasma Production with Internal Low-Inductance Antenna Units

Recent trends of liquid crystal display (LCD) fabrication toward a significant enlargement of glass substrates require large-area plasma sources with a scale length exceeding 1 m. To meet this requirement, large-area plasma sources with internal low-inductance antenna (LIA) units have been developed for uniform processes, in which design principles for selecting antenna size and configurations in the multiple installation of the LIA units are established. In this study, the effects of antenna size were examined in terms of plasma production characteristics indicating small increase in plasma density with a decrease in antenna size (or antenna impedance). Furthermore, plasma density distributions with the LIA units were investigated to understand the nature of plasma diffusion, which can be utilized for designing plasma profiles with multiple LIA units. First, it was shown that the plasma density distributions followed exponential decay as a function of distance from the antenna. Secondly, the measured plasma density profiles with multiple LIA units were shown to agree well with those obtained by superposing those described by exponential functions, which can be utilized for prediction.

Characterization of Amorphous Hydrogenated Carbon Formed by Low-Pressure Inductively Coupled Plasma Enhanced Chemical Vapor Deposition Using Multiple Low-Inductance Antenna Units

Three-dimensional plasma enhanced chemical vapor deposition (CVD) of hydrogenated amorphous carbon (a-C:H) has been demonstrated using a new type high-density volumetric plasma source with multiple low-inductance antenna system. The plasma density in the volume of phi 200 mm x 100 mm is 5.1 x 10(10) cm(-3) within +/-5% in the lateral directions and 5.2 x 10(10)cm(-3) within +/-10% in the axial direction for argon plasma under the pressure of 0.1 Pa and the total power as low as 400 W. The uniformity of the thickness and refractive index is within +/-3.5% and +/-1%, respectively, for the a-C:H films deposited on the substrates placed on the six side walls, the top of the phi 60 mm x 80 mm hexagonal substrate holder in the pure toluene plasma under the pressure is as low as 0.04 Pa, and the total power is as low as 300 W. It is also found that precisely controlled ion bombardment by pulse biasing led to the explicit observation in Raman and IR spectra of the transition from polymer-like structure to diamond-like structure accompanied by dehydrogenation due to ion bombardment. Moreover, it is also concluded that the pulse biasing technique is effective for stress reduction without a significant degradation of hardness. The stress of 0.6 GPa and the hardness of 15 GPa have been obtained for 2.0 microm thick films deposited with the optimized deposition conditions. The films are durable for the tribology test with a high load of 20 N up to more than 20,000 cycles, showing the specific wear rate and the friction coefficient were 1.2 x 10(-7) mm3/Nm and 0.04, respectively.