Shigeru Koibuchi

FLUORINATED POLYIMIDES AND ITS APPLICATION TO OPTICAL WAVEGUIDES

The performance requirements of polymer waveguides used in optical telecommunication and their future opportunities are discussed. The polymer waveguide is suited for mass production and has an excellent cost performance ratio; therefore, it is to be utilized in the home terminals of FTTH. Fluorinated polyimides will be used for these terminals because they have good optical properties, high heat resistance, and long-term reliability. We have fabricated the fluorinated polyimide planar lightwave circuit integrated with V-groove contributing to high throughput assembly and automated manufacturing of high performance transceiver modules, and confirmed it accurate enough for optical network units.

Negative resists for i-line lithography utilizing acid-catalyzed intramolecular dehydration reaction

Chemical amplification negative resist system composed of a novolak resin, a carbinol and an acid generator is investigated for i-line phase-shift lithography. The reaction in this resist is based on an acid-catalyzed intramolecular dehydration reaction. The dehydration products act as aqueous-base dissolution inhibitors, and carbinol compounds in unexposed areas work as dissolution promoters. The resist composed of a novolak resin, 1,4-bis((alpha) -hydroxyisopropyl) benzene (DIOL-1) and 2- naphthoylmethyltetramethylenesulfonium triflate (PAG-2) gives the best lithographic performance in terms of sensitivity and resolution. Line-and-space patterns of 0.275 micrometers are obtained using an i-line stepper (NA:0.45) in conjunction with a phase shifting mask.

A Series Of Azide-Phenolic Resin Resists For The Range Of Deep UV To Visible Light

A series of new type of negative photoresists composed of a phenolic resin and azide sensitizers has been developed. RD-2000N is sensitive in the deep UV region, RU-1000N in the mid UV region and RG-3000N in the mid UV to visible region. These resists are non-swelling aqueous developable, and give higher resolution compared to conventional cyclic rubber based negative resists. Resolution in less than 1 μm can be obtained by 1 : 1 projection or 10 : 1 reduction projection aligning method. Adequate exposure doses to define submicron patterns are 50 mJ/cm4(at 254nm),70 mJ/cm° (at 365 nm) and 180 mJ/cm2(at 436nm) for RD-2000N, RU-1000N and RG-3000N, respectively. The resistance to dry etch gases is also superior to conventional negative resists, and comparable with novolak resin based positive resists. Intense absorption of irradiating light by these resists makes them insensitive to reflected light from the substrate, resulting in a high resolution on stepped substrates without any antireflective layers which are necessary in positive resist applications.