Akiko Mizushima

Alkali-Developable Organosilicon Positive Photoresist(OSPR)

A new alkali-developable organosilicon positive photoresist for a bi-layer resist system has been developed. Novel alkali-soluble organosilicon polymers, polysilsesquioxane, polysiloxane, and polysil-methylene, were prepared as the matrix polymers. Among these polymers, poly(p-hydroxybenzylsilsesquioxane) ( I) exhibited the highest 09RIE resistance. A composite (OSPR-1334)prepared from I and naphEho-quinone diazide becomes an alkali-developable positive photoresist which is sensitive to i - g line light. The sensitivity and the resolution of OSPR-1334 are almost the same as those of conventional novolac-based resists when aqueous tetra(2-hydroxyethyl)ammonium hydroxide is used as the developer. Also, OSPR-1334 has excellent resistance to O2RIE. The etch rate is 3.6 nm/min, while that of polyimide or novolac-based resists is 100 nm/min. Thus, OSPR-1334 is suitable for use as the top layer of a bi-layer resist system. Submicron patterns with high aspect ratio can be easily obtained with this new bi-layer resist system.

Bilayer resist system utilizing alkali-developable organosilicon positive photoresist

A bi-layer resist system utilizing an alkali-developable organosilicon positive photoresist (OSPR) has been developed. The composite prepared from an alkali-soluble organosilicon polymer, poly(p- hydroxybenzylsilsesquioxane) and naphthoquinone diazide becomes a alkali-developable positive photoresist which is sensitive to UV (i line - g line) region, and exhibited high oxygen reactive ion etching (O2 RIE) resistance. The sensitivity and the resolution of OSPR are almost the same as those of conventional novolac-based positive photoresists. The bi-layer resist system utilizing OSPR as the top imaging layer gave fine patterns of underlayers with high aspect ratio easily.

10 Tb/s scale optical interconnection system using high-density optical wiring

The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach 10 Tb/s and over. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose a high-density optical backplane, which consists of a fiber cassette and eleven optical backplane connectors. The fiber cassette accommodates 768 optical fibers. The backplane connector housing can mount eight 48-fiber mechanically transferable (MT)-ferrules. Optical backplane is 89 mm wide and 13 mm thick; therefore, equipment can secure a sufficient area for cooling while achieving a 9.6-Tb/s aggregate bandwidth. It also eases assembly and testing. The insertion loss of the backplane including the two connectors results in 1 dB or less. We demonstrated an optical interconnection system using the optical backplane, which exhibited error-free transmission between boards up to 25.8 Gb/s. We also propose an optical connector using lensed ferrules instead of MT-ferrules. Due to the introduction of the lensed ferrules, the spring force of the connector can be reduced to 1/5 that with an MT-ferrule. The optical connector can be mounted in the front panel of ICT system equipment. These optical wiring components enable the development of ICT systems with bandwidth exceeding 10 Tb/s.

Optical interconnect technologies for high-bandwidth ICT systems

The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

3.3-Tb/s compact optical fiber package using pre-formed optical fiber

We developed a compact optical fiber package for rack-to-rack transmission in information communication technology. Using pre-formed optical fiber instead of optical fiber strands and ribbon fiber, we achieved a reduction in the routing area and protection of the optical fiber. We fabricated a prototype mock-up board with optical modules and achieved a bandwidth of 3.3 Tb/s and an area of 4500 mm2. We confirmed a good transmission performance board-to-board with 5 m of optical cable at 25 Gb/s (PRBS: 231-1).