No abstract

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.

A novel inductively-coupled RF plasma source with internal low-inductance antenna (LIA) units was developed to synthesize microcrystalline silicon (mc-Si) film on a large glass substrate. A film thickness profile on a 600 Â 720 mm 2 glass substrate was achieved with high plasma uniformity and a variation of less than AE5% without a standing-wave effect. Raman and transmission electron microscope (TEM) analysis revealed that highly crystallized mc-Si films, which were directly deposited on a glass substrate, were synthesized without an amorphous-phase incubation layer at the substrate interface. A bottom-gate thin-film transistor (BG-TFT) was fabricated employing an optimized mc-Si layer and exhibited a field-effect mobility of 3 cm 2 /(VÁs), which is one order higher than that of a typical amorphous silicon TFT.

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.

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.