Yukio Ogura

Eye-position tracking stereoscopic display using image-shifting optics

We have developed an eye-position tracking stereoscopic projector which employs image shifting optics. The display allows 3D images to be viewed without special glasses from any position along a lateral axis. Its image shifting device contains a plane parallel glass plate and is installed in a liquid crystal projector. Refraction produced by inclination of the glass plate shifts the optical axis of the projected image. Since the only moving part in the optics is the lightweight glass plate, the response of the image shifting device is both fast and precise enough for interactive 3D-CAD and virtual reality applications. To improve the systems interactive response, we have widened the stereoscopic viewing area by adding a device which causes the image to vibrate laterally. Also we use a new tracking algorithm which reduces the tracking error that would ordinarily be created by delay time. Experimental results confirm the success of these improvements.

Monolayer Halftone Phase-Shifting Mask for KrF Excimer Laser Lithography

A new monolayer halftone phase-shifting mask has been developed. The phase-shifting film consists of the compounds SiO 2 and Cr 2 O 3 . The transmittance of the film is controlled by changing the mixing ratio of the two materials. Our mask can be easily fabricated because the structure of the mask is very simple and the film is considerably thicker than the Cr layer of the original double-layer halftone phase-shifting mask. Experimental results using a KrF excimer laser stepper confirm the effect of increasing the depth of focus of hole patterns

Transparent photoacid generator (ALS) for ArF excimer laser lithography and chemically amplified resist

A novel photoacid generator, ALS (alkylsulfonium salt; cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane- sulfonate) for ArF excimer laser ((lambda) equals193 nm) lithography and a single-layer resist have been developed. ALS shows high transparency at 193 nm and photoacid generating capability on irradiation by ArF excimer laser. A novel methacrylate terpolymer, poly(tricyclo[5.2.1.02,6]decanylmethacrylate-co-2- tetrahydropyranylmethacrylate-co-methacrylic acid), is synthesized as a base resin. The resist, consisting of ALS and the polymer, shows chemical amplification and good resolution. A 0.2-micrometers line and space negative-tone image is observed at 15 mJ/cm2 dose using an ArF excimer laser.

Precise Measurement of Pipe Wall Thickness in Noncontact Manner Using a Circumferential Lamb Wave Generated and Detected by a Pair of Air-Coupled Transducers

In this paper, we present a novel method of accurately estimating pipe wall thickness by detecting the minute difference in the angular wave number of a circumferential (C-) Lamb wave. A C-Lamb wave circling along a circumference of a pipe is transmitted and received by a pair of noncontact air-coupled ultrasonic transducers. For the accurate detection of the angular wave number, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This method is very useful to monitor the integrity of piping in high-temperature environments because of its noncontact nature. The principle of the method and experimental verification are shown.

Polarization Dependence of Electric Field Intensity Distributions in Photoresist Films

The polarization dependence of the electric field intensity distributions in photoresist films has been studied by simulation. S-polarized illumination produces higher image contrast than P-polarized illumination in air. However, due to the high refractive indices of photoresist films, the difference of the image contrasts formed by S- and P-polarized illuminations almost disappears in the photoresist films. The reflectivities from nonplanar substrates strongly depend on the polarization of illumination. The reflection from nonplanar substrates can be strongly suppressed by using P-polarized illumination.

Monochromatic Projection Optical System for ArF Excimer Laser Lithography

We have developed an ArF excimer laser exposure system that combines a monochromatic quartz projection lens system and a spectrally-narrowed ArF excimer laser. The bandwidth of the laser was narrowed to 0.7 pm by using three prisms and an etalon. We delineated 0.2 µm lines-and-spaces using a chemically amplified resist and 0.16 µm lines-and-spaces using a top surface imaging resist.

ArF excimer laser lithography using monochromatic projection lens coupled with narrowed-bandwidth laser

We have developed an ArF excimer laser exposure system that combines a monochromatic quartz projection lens system and a spectrally-narrowed ArF excimer laser. The bandwidth of the laser was narrowed to 0.7 pm by using three prisms and an etalon. We fabricated 0.12 micrometers lines-and-spaces using an alternating phase shifting mask and a top surface imaging resist.

Xe2 excimer lamp (172 nm) for optical lithography

A Xe2 excimer lamp (172 nm) has been used for submicrometer patterning of photoresist films. We resolved 0.35 micrometers lines and spaces using a contact printing system. We exposed a chemically amplified photoresist customized for ArF. The sensitivity of the photoresist was 130 mJ/cm

Sub 0.1 μm ArF excimer laser lithography with alternating phase-shifting masks

=2) or about ten times smaller than the sensitivity for ArF.

Optical illumination instrument

We delineated 0.088 micrometers line and space patterns by using an etched-in phase-shifting mask. The etched area of the mask had good morphology and high transmittance for deep UV light. The phase-shifting angle of the etched area was well controlled within 180 +/- 5 degrees.