We developed flexible liquid crystal devices using ultra-thin polyimide substrates and bonding polymer spacers, and discussed the effects of polymer spacer structure on the cell thickness uniformity of flexible LCDs. We clarified that the lattice-shaped polymer spacer is effective to stabilize the cell thickness by suppressing the flow of the liquid crystal during bending process.

We examined the novel aggregation control of the LC and monomer during formation of the polymer walls from a LC/monomer mixture in order to suppress the presence of the residual monomers and polymer networks in the pixel areas. The method is utilization of the differing wettabilities among LC and monomer molecules on a substrate surface. We patterned a substrate surface with a fluororesin and a polyimide film, and promoted phase separation of the LC and monomer by cooling process. This resulted in the LC and monomer aggregates primarily existing in the pixel areas and non-pixel areas, respectively. Moreover, the polymer-walls structure which was formed in this method partitioned into individual pixels in a lattice region and prevented the LC from flowing. This polymer-walls formation technique will be useful for developing high-quality flexible LCDs.

We developed flexible LC devices using coat-debond polyimide substrates with a low birefringence and etched post spacers, and clarified that flexible LCDs using post spacers with small spacer distance have a high flexibility without degradation of the image quality. This result ensured the feasibility of flexible LCDs using coat-debond method.

Polyimide thin films were prepared by vapor-deposition polymerization. Naphthalene carboxylic dianhydride (NTCDA) was coevaporated with either diamino naphthalene (DAN) or diamino benzophenone (DAB). Coevaporation of dianhydride and diamines yielded thin films of polyamic acids. A polyimide thin film was obtained by annealing the codeposited film of NTCDA-DAB. On the other hand, the codeposited film of NTCDA-DAN was not imidized by annealing. In both cases, chemical structures of the products were not largely influenced by the molar ratio of depositing monomers if sufficient amount of diamine molecules are supplied in the coevaporation process.

Thickness of crystalline layer induced by annealing after rubbing at surface of polyimide film for liquid crystal displays was estimated to be 3--5 nm by grazing-incidence X-ray diffractions with multi incident angles. Agreement of thickness of crystalline layer with that of initially oriented layer suggests polymer orientation induced by rubbing proceeds crystallization by annealing. Furthermore, no in-plane smectic ordering in bottom 20,nm region of polyimide film was suggested.

Grazing incidence X-ray diffraction experiment proved that the a- and c-axes of PMDA-ODA crystals preferentially aligned in normal and parallel directions to rubbing at surface of rubbed film, and that polymer chains of residual amorphous phase aligned in rubbing direction.

Depth profile of mass density of vertical alignment film was investigated by X-ray reflectivity, in order to characterize side chains at film surface for vertical alignment of liquid crystals. Existence thin and low density top layer at surface of polyimide film, which was considered to be side chains, was clearly detected. Furthermore, existence of high density layer just below side chain layer was also found, and it is suggested that backbone chain ordering at film surface. Effect of rubbing on VA film was not detected. However, density growth by annealing just below side chain layer of rubbed VA film suggests more ordered backbone chain alignment induced by rubbing.

We developed a new method for characterizing molecular distribution in very thin liquid crystal layer (5-40 nm) evaporated onto rubbed polyimide film used by grazing-incidence X-ray diffraction (GIXD). The diffraction peaks corresponding to intermolecular correlation perpendicular to longitudinal axis of liquid crystal molecule and the clear anisotropic distribution of liquid crystal molecules in a thin layer were successfully observed. We found that in the vicinity of the alignment film, the intermolecular spacing correlation perpendicular to longitudinal axis of the 5CB molecule was expanded by the alignment film, and that the ordering of the 5CB was not so high. As the distance from the alignment film the spacing came close to the intrinsic intermolecular spacing.

We investigated effect of annealing after rubbing by grazing incidence X-ray diffraction, since annealing process is performed in the actual process of liquid crystal display (LCD) fabrication. It was found that rubbed surface polymers were highly crystallized by annealing at 250 after rubbing, and that the crystallization of surface polymers by annealing occurred in the aligned polymer region induced by rubbing. Crystallization of surface polymers by annealing increasingly occurred as increasing of rubbing strength. Thus, it is considered that annealing process after rubbing should also play an important role to control liquid crystal alignment in LCD.

Rubbed polyimide films have been widely used as liquid crystal alignment films for liquid crystal displays. Washing after rubbing is essential to fabricate liquid crystal displays, and should affect alignment of liquid crystal as well as rubbing. We investigated the effects of rubbing condition and soaking in acetone on polyimide films by grazing incidence X-ray diffraction. It was found that soaking in acetone promoted crystallization of surface aligned polymers, and that the crystallization by acetone was dependent on the initial polymer alignment. The larger initial crystalline phase was, the more newly crystallization occurred by soaking. It was also revealed that the crystallization by soaking in acetone was completed within 1 min.

We report effects of washing rubbed polyimide film on the near surface. Especially we focused dependence of solvent. Rubbed polyimide films have been used as liquid crystal alignment films in Liquid crystal displays (LCDs), and in actual LCD panel fabrication washing on film surfaces after rubbing is essential process to remove dust and pollution. We investigated the effects of washing by grazing incidence X-ray diffraction (GIXD) measurements. In GIXD, the X-ray penetration into the polymer was changed from 8 nm (suface sensitive) to 4 nm (bulk sensitive) by variation of the X-ray incidence angle. It was found that crystallization near the surface induced by soaking was considerably dependent on solvent. However, in-plane distribution of the surface polymer chains of polyimide film was not found to be dependent on the solvents.

Rubbed polyimide films have been widely used as liquid crystal alignment films for liquid crystal displays (LCDs). We investigated the effect of rubbing on the surface molecules of polyimide films by using grazing incidence X-ray diffraction (GIXD) and reflection ellipsometry. We found that rubbing not only caused the polymer chains to align in the direction of rubbing but also to elongate near the film surface. However, the in-plane distribution of surface polymer chains of polyimide film was not found to be dependent on the rubbing conditions.

We have investigated the pretilt angle of liquid crystal (LC) molecules induced by photo-alignment films of polyimide (Azo-PI) containing azobenzene in the backbone structure. To generate finite pretilt angles, the Azo-PI film with inclined alignment of the backbone structure was prepared by a double light-exposure method. In this method the corresponding polyamic acid (Azo-PAA) film was first exposed to linearly polarized ultraviolet/visible (UV/VIS) light (LP-light) at normal incidence, and then oblique angle irradiation of unpolarized UV/VIS light (UP-light) was performed in the plane of incidence perpendicular to the polarization direction of the LP-light. Repeated photo-isomerization reactions of azobenzene induce the alignment of the Azo-PAA backbone structure. By thermally imidizing the photo-treated film we obtained a thermally and optically stable Azo-PI film. The orientational distribution of the Azo-PI backbone structure was determined by measuring the polarized infrared absorption spectra as a function of the sample rotation angle and the angle of incidence. The pretilt angle of LC molecules was determined by a crystal rotation method. We found that the average inclination angle of the Azo-PI backbone structure increased with the UP-light exposure. The pretilt angle of LC molecules, measured from the surface plane, also increased with the UP-light exposure. We succeeded in generating a pretilt angle of 3. The relation between the LC pretilt angle and the average inclination angle of the Azo-PI backbone structure is discussed.

The alignment of a nematic liquid crystal (LC) parallel to the polarization direction of the laser could be induced by three types of polyimide (PI) films, a PI based on aromatic dianhydride and two PIs on alicyclic dianhydride, exposed to polarized pulsed laser at 266 nm at high fluence in air. The UV-visible absorption spectra of the PI films showed that a remarkable chemical change occurred after exposure at the high fluence in air. In contrast, in argon atmosphere the PI based on aromatic dianhydride was radiation-resistant and the exposed PI film could induce alignment of the LC molecules parallel to laser polarization. We estimate that the mechanism of the parallel alignment observed in argon is not the photodegradation but the orientation of the PI molecules.

We examined the current-voltage (I-V) characteristic of metal/polyimide/rhodamine-dendorimer/polyimide/ metal junctions prepared by the Langmuir-Blodgett (LB) technique. At a temperature of 32.8 K, a step structure was observed in the I-V characteristic, whereas it was not observed for the junctions without rhodamine-dendorimer. The step structure was very similar to that seen in so-called Coulomb staircase. On the basis of the model of Coulomb blockade, the possibility of single electron tunneling via rhodamine-dendrimer (Rh-G2) molecule as a quantum dot was discussed.

We fabricated a tunable and polarization-insensitive arrayed-waveguide grating (AWG) 1616 multiplexer that operates around the wavelength of 1. 55 µm using fluorinated polyimides. The wavelength channel spacing was 0. 8 nm, and the 3-dB passband width was 0. 26 nm. The insertion loss at each channel was from 8 to 12 dB, and the crosstalk was less than -28 dB. The transmission pass wavelength was tuned over a wide range of 6 nm by heating from 24 to 64. The slope of the temperature dependence of the pass wavelength was -0. 15 nm/, which is ten times that of a silica-based multiplexer. Polarization-insensitivity was achieved by fabricating a film AWG multiplexer, which was formed by removing the silicon substrate and annealing at 350. The polarization-dependent wavelength shift was smaller than the spectrum analyzers wavelength resolution of 0. 1 nm.

It is well known that the existence of electrically resistive film layers formed on contact surfaces increases contact resistance and it causes a nonlinear relationship between voltage and current observed in a contact layer. Nonlinear distortion voltages can be detected by our sensitive detection system based on the dual frequency method when a thin film exists on the surface. In this study, multilayer films of polyimide (PI) was used as an ideal material of ultra thin film, because of electrically good insulator with simple molecular structure, to study non-linearity through metal-insulator-metal contact. The number of deposited layers between one and twenty one were formed on three types of substrates; (a) evaporated gold on a glass plate, (b) gold plate and (c) evaporated gold on gold plate, to obtain good insulating film. Where each layer of PI film has 0. 4 nanometer thickness. A pin contact was made by pressing a bent gold wire on the PI film. It is concluded that [1]; the second-order distortion voltage increases exponentially as the film thickness increases, [2]; polarity of the surface potential of PI depends on the film thickness, and that I-V characteristic depends on the polarity of the surface potential.

I have examined factors for implementing a high-speed, low-power-consumption thermal head. In conventional thermal heads, a heat insulation layer is provided between the heating resistor and the radiator. I found it desirable to implement fast operation and low power consumption to lower the thermal conductivity of the heat insulation layer and to thin the heat insulation layer. I also found there is an optimum heat characteristic to the thickness of one heat insulation layer. I assumed polyimide as a material for the heat insulation layer which could materialize the hypothesis, and studied necessary items based on the thermal calculation. I manufactured a trial thermal head on the basis of this result and confirmed that our assumptions were correct. In addition, to confirm that the assumption is also ultimately correct, I fabricated a trial thermal head only consisting of a heating resistor and without a protective coat and a heat insulation layer. I confirmed that the structure with only the heating resistor exhibited excellent heat response and consumed less power necessary for heating.

A superconducting multichip module using Nb/Polyimide on a mullite multilayer ceramic substrate has been developed for Josephson LSI circuits. The Nb/Polyimide stacked layers on the mullite multilayer ceramic substrate makes it possible to fabricate superconducting off-chip wiring for control signal line. We named the MCM "SuperMCM". The superconducting transmission line is designed to have the characteristic impedance of 14 Ω to match with the Josephson devices. The superconducting critical temperature, critical current density and critical current at a via hole are 8.5 K, 8.2105 A/cm2 and 2.5 A, respectively. The SuperMCM also provides matching circuits employing quarter wavelength striplines for driving Josephson LSI circuits at a microwave frequency, and DC bias circuits in the mullite multilayer ceramic substrate. The characteristics of the matching circuit is measured in the frequency range up to 3.6 GHz and the microwave current gain of 20 dB is obtained at 1.2 GHz, which revealed that the SuperMCM has the ability to drive the Josephson LSI circuits at more than 1.2 GHz clock speed.

A film carrier with 48 peripheral-contacts, which is applicable to ultra-high speed GaAs digital integrated circuits (ICs) with a more than 10 Gbps operation, has been developed. The film carrier has been realized using the following newly developed techniques; (1) wave guides with a well-controlled characteristic impedance of 50 Ω, (2) precise vias of as small as 50 µm diameter conducting both sides of grounded metal planes on a polyimide film, and (3) a feed-through structure for high speed input signals with good impedance matching. The film carrier was molded by resin after ILB (inner lead bonding) to a chip with a copper plate heat spreader. As an application, the film carrier has been applied to a 3 Gbps operational 4-bit GaAs multiplexer IC, and has been proved to have excellent high-frequency characteristics.