Hiroto Sato

16.4: Low‐Temperature Fabrication of Flexible AMOLED Displays Using Oxide TFTs with Polymer Gate Insulators

We have developed InGaZnO4 TFTs with polymer gate insulators that can be formed by spin-coating on plastic substrates at temperatures below 130 °C. A 5-inch QVGA flexible OLED display has been fabricated by means of ink-jet printing on a TFT backplane, and it has successfully displayed clear color video images while in a bent state.

Development of Xe‑and Sn‑fueled high‑power Z‑pinch EUV source aiming at HVM

Discharge-produced plasma (DPP) based EUV source is being developed at Gotenba Branch of EUVA Hiratsuka R&D Center. Among the several kinds of discharge scheme, Z-pinch is employed in our source. An all-solid-state magnetic pulse compression (MPC) generator is used to create a Z-pinch plasma. Low inductance MPC generator is capable of producing a pulsed current with over 50 kA of peak amplitude and about 100 ns of pulse duration at 7 kHz of pulse repetition frequency. In order to obtain sufficient output radiation power, tin-containing gas is being used as well as xenon. Due to the high spectral efficiency of tin, demonstrated EUV output power reached 645 W/2πsr within 2% bandwidth around 13.5 nm. A novel scheme of fuel gas supply led to as good output energy stability as xenon can achieve. Using a nested grazing-incidence collector, EUV power at intermediate focus point which is defined as an interface to the exposure tool reached 42 W with 3.3 mm2sr of etendue.

Development of Sn-fueled high-power DPP EUV source for enabling HVM

Discharge-produced plasma (DPP)-based EUV source is being developed at Gotenba Branch of EUVA Hiratsuka R&D Center. A high-repetition-rate high voltage power supply (HVPS) was developed and put into operation on the magnetic pulse compression (MPC)-driven DPP source, enabling 8-kHz operation with 15 J/pulse of maximum charging energy and 0.11 % of stability. SnH4 gas was used as a fuel gas in order to obtain high conversion efficiency. SnH4-fueled Z-pinch source demonstrated EUV power of 700 W/2&pgr;sr within 2 % bandwidth around 13.5 nm. Using a nested grazing-incidence collector, EUV power at the intermediate focus which is defined as an interface to the exposure tool reached 62 W with 3.3 mm2sr of etendue. Tin deposition rate on the collector surface, which is the concern in any tin-fueled EUV sources, was decreased by four orders of magnitude as a result of debris-shield development. Cleaning processes were also developed to enhance total lifetime of the collector. A sequence of intentional deposition and cleaning process for the ruthenium grazing-incidence mirror sample was repeated 13 times. By measuring reflectivity of the mirror, it was confirmed that halogen cleaning process worked very effectively and did not get the mirror damaged after such a long-term cleaning experiment.

High-repetition-rate MPC generator-driven capillary Z-pinch EUV source

Discharge-produced plasma (DPP) based EUV source have been studied and developed at EUVA/Gotenba Branch. Among the several kinds of discharge scheme, a capillary Z-pinch has been employed in our source. An all-solid-state magnetic pulse compression (MPC) generator was used to create a Z-pinch plasma. Low inductance MPC generator provides a pulsed current with about 17 kA of peak amplitude and 350 ns of pulse duration, and allows 2-kHz continuous operation. A water-cooled discharge head was coupled with the MPC generator. In order to evaluate the source performance, electrical energy input to the discharge, EUV radiation power, radiation spatial profile, pinhole image and spectra were observed. 54.4 W/2%BW of 13.5-nm EUV output was achieved at 2-kHz operation. Through the radiation profile measurement and pinhole-camera observation, spatial image of EUV radiation was understood.

High-power and high-repetition-rate EUV source based on Xe discharge-produced plasma

Discharge-produced plasma (DPP) based EUV source have been studied and developed at EUVA/Gotenba Branch. Among the several kinds of discharge scheme, a capillary Z-pinch has been employed in our source. An all-solid-state magnetic pulse compression (MPC) generator was used to create a Z-pinch plasma. Low inductance MPC generator provides a pulsed current with about 52 kA of peak amplitude and 120 ns of pulse duration, and allows 7-kHz operation. A water-cooled discharge head was coupled with the MPC generator. In order to evaluate the source performance, electrical energy input to the discharge, EUV radiation power, radiation spatial profile, plasma image and spectra were observed. In-band EUV power into usable solid angle obtained at 7 kHz was 93 W/2%BW. By using nested grazing-incidence collector, EUV power at intermediate focus obtained was 19 W/2%BW.

Development of Xe-filled capillary discharge extreme-ultraviolet radiation source for semiconductor lithography

An EUV radiation source development with discharge-produced plasma (DPP) has been started in Gotenba branch of EUVA Hiratsuka R&D center. For the early stage of the development, fundamental characteristics of DPP including current, voltage, EUV energy and spectrum in EUV region were studied. A capillary of which the inner diameter was 2.3 mm, and Xe gas were used as a source to be expected in-band EUV radiation from magnetically-compressed Z-pinch plasma. An all-solid-state magnetic pulse compression generator was employed, which can deliver the current of 14 kA into the capillary load with the rise time of approximately 500 ns. In-band EUV energy and spectroscopic measurements were carried out. It was found that the in-band EUV energy increased with increasing the current amplitude and/or pressure of filled Xe gas. The highest in-band EUV energy obtained was 8 mJ per unit solid angle.

10.4: Fast‐Response Flexible LCD Panel Driven by a Low ‐Voltage Organic TFT

A fast-response flexible ferroelectric liquid crystal (FLC) display panel driven by organic TFT (OTFT) was successfully developed. The fabricated OTFT with Ta2O5 gate insulator showed a mobility of 0.3 cm2/Vs and a current on/off ratio of 107 with a low operating drain voltage of −5 V. We obtained fast responses of less than 1 msec and contrast ratio of 14:1 with gray-scale display capability from a 16×16 pixel FLC panel.

23.3: Flexible Field‐Sequential‐Color FLCD Panels Driven by poly‐Si TFTs

A novel flexible field-sequential-color FLCD panel driven by poly-Si TFTs has been developed. A 16×16 active matrix panel was fabricated using polymer stabilized FLC and poly-Si TFTs fabricated onto plastic substrate below 150°C, and colored moving images were demonstrated on the panel with frame frequency of 60Hz.

Tin-Fueled High-Repetition-Rate Z-pinch EUV Source for Semiconductor Lithography

Summary form only given. Extreme ultraviolet (EUV) is the potential candidate for the light source used in next generation semiconductor lithography. In EUV lithography (EUVL), IC pattern as small as 32-nm pitch or below will be realized by using 13.5-nm radiation. There are two major schemes to obtain high-power EUV; laser-produced plasma (LPP) and discharge-produced plasma (DPP). DPP seems to provide more cost-effective source and easier way to obtain necessary EUV power than LPP. EUV is not a coherent radiation so that emitted radiation is collected by optics and transferred to an exposure tool. In volume production, significant amount of IC chip should be yielded. From these points of view, EUV radiation must be emitted from very small volume but have sufficient average power. In our development, Z-pinch plasma is employed to achieve such a high temperature and density micro plasma. It is very important to increase conversion efficiency (CE) of electrical energy input to 13.5-nm radiation. Xe used to be used as fuel material because of its easiness of handling and cleanliness. However, Sn is the best choice from the view point of CE. Despite its handling difficulties, Sn is now being commonly used in many EUV researches. In case of gas-discharge-produced plasma, it is necessary to feed the gas into the discharge region between the electrodes. For this purpose, we utilize SnH4 gas, which is in gaseous state at room temperature and able to be controlled like Xe. EUV source for semiconductor lithography is also required to work at pulse repetition frequency more than 7 kHz. By using high rep-rate (8 kHz) and high-average-power (120 kW) pulsed power driver, and low-inductance Z-pinch load, radiation characteristics of SnH4-fueled Z-pinch were investigated. Radiation energy, radiation stability, plasma image, temporal radiation behavior of Z-pinch were investigated. As a result, EUV power within 2 % bandwidth at 13.5 nm reached 700 W/2 pisr.