UV Alignment Research Articles

High transmittance in-plane switching liquid crystal mode using double-exposed UV alignment method

In general, the super in-plane switching (S-IPS) liquid crystal (LC) mode is widely used for LCD applications because of its wide-viewing properties. However, it can also diminish the aperture ratio in active areas due to the zigzag pattern. In this paper, we proposed an IPS LC mode that has wide-viewing properties even if the stripe-patterned electrodes, which can provide a high transmittance property, are applied using the double-exposed UV alignment method to the upper/lower domain of the active area. The initial alignment direction of the upper/lower domain was optimized with simple experiments and we achieved both the superior dark level in the initial mode and wide-viewing properties in the applied voltage mode. As a result, we obtained an increased aperture ratio of about 10% and a higher optical transmittance of 15% compared to the conventional S-IPS LC cell because of the high aperture ratio without any optical loss of the initial dark state and viewing angle property.

P‐98: UV Aligned IPS‐LCD for High Resolution Smart Displays

Abstract: For high resolution mobile display, UV alignment technology has been getting the technical spotlight at LCD industries. Our IPS‐LCD panels with UV alignment technology showed higher contrast ratio since it would prevent rubbing scratch and light leakage in pixel area. And UV aligned IPS sample showed wider viewing angle performance because of their very symmetrical luminance distribution. Especially, our samples showed low gray scale inversion and color shift in a diagonal direction so that one could get more vivid images than rubbed IPS‐LCD panel.

A thick photoresist process for advanced wafer level packaging applications using JSR THB-151N negative tone UV photoresist

The development of thick photoresist molds using JSR THB-151N negative tone UV photoresist for the electroplating of interconnects in advanced packaging technologies has been demonstrated. Two different thick photoresist molds 65 and 130 µm high with aspect ratios of up to 2.6 have been fabricated with good reproducibility using single and double coating processes. Optimized lithography parameters using a UV aligner to achieve straight and near-vertical side-wall profiles are also reported. Near-vertical side walls similar to that obtained using SU-8 photoresist have been obtained. JSR photoresist has been found to be easily striped with no residues in solvent stripper solutions, making it suitable for wafer bumping applications and the processing of MEMS devices. Through-mold electroplating of copper and solder is also demonstrated. The simultaneous fabrication of 1167 000 high density interconnects on 8 inch wafers, using lithography and electroplating technologies, is also reported.

Electro-Optical Characteristics of Photoaligned TN Cell Using UV Alignment on the a-C:H Thin Film

ABSTRACT We studied the nematic liquid crystal (NLC) alignment capability by the UV alignment method on a a-C:H thin-film surface, and investigated electro-optical performances of the UV aligned twisted nematic (TN)- liquid crystal display (LCD) with the UV exposure on a-C:H thin film surface. A good LC alignment by UV irradiation on a a-C:H thin-film surface at a layer thickness of 200 Å was achieved. Also, a good LC alignment by the UV alignment method on the a-C:H thin film surface was observed at an annealing temperature of 180°C. However, the alignment defect of the NLC was observed at an annealing temperature above 200°C. Monodomain alignment of the UV aligned TN-LCD can be observed. The best electro-optical (EO) characteristics of the UV aligned TN-LCD in the photoaligned TN-LCDs was observed with oblique ion beam exposure on the a-C:H thin film surface for 1 min.

Diamond-Like-Carbon 박막표면에 UV 배향법을 이용한 액정 배향 효과에 관한 연구

Diamond-Like-Carbon 박막표면에 UV 배향법을 이용한 액정 배향 효과에 관한 연구

LP‐5: Late‐News Poster: Thin Retardation Film for Parallax Free Reflective Guest‐Host Liquid Crystal Display

AbstractVery thin quarter lambda plate was fabricated using liquid crystal polymer, aiming to use for parallax free high contrast G‐H reflective displays. UV curable LC polymer was aligned by either by rubbed polyimide or UV alignment process. The film was thin enough by optimization of monomer composition, so that the voltage loss was small enough when the film is placed between two electrodes inside cell. Contrast ratio of the G‐H cell using this film was almost comparable to that using commercially available dispersion compensated multiplayer film.

A method for liquid crystal alignment using in situ ultraviolet exposure during imidization of polyimide

Homogeneous alignment of liquid crystals can be achieved by a technique using polyimide films and in situ exposure to linearly polarized ultraviolet (LPUV) light during imidization. The alignment layers prepared by this method exhibit higher thermal stability while requiring shorter processing time than the conventional UV alignment method which employs UV exposure after the imidization of polyimide is complete. Multidomain cells can be easily fabricated with the use of a photomask and multistep in situ LPUV exposure during hard bake.

Mechanical characterization of a new high-aspect-ratio near UV-photoresist

Characterization of the mechanical and thermal properties of the high-aspect-ratio, negative, UV resist, SU-8 has been carried out. This resist allows for a broad range of thicknesses to be obtained with a single spin process. Standard exposure with a UV aligner has produced outstanding aspect ratios, 15 for lines and trenches. This type of performance lends itself well to MEMS applications, packaging, micromolds, spacers, etc. Because of the simplicity of use of the resist in addition to the large range of possible applications, the process dependent mechanical and thermal properties must be understood in order to completely exploit the potential of the resist.

SU-8: a low-cost negative resist for MEMS

This paper describes the characterization of a home-made negative photoresist developed by IBM. This resist, called SU-8, can be produced with commercially available materials. Three blends were prepared for this article and some of its optical and mechanical properties are presented. One of its numerous advantages is the broad range of thicknesses which can be obtained in one spin: from 750 nm to with a conventional spin coater. The resist is exposed with a standard UV aligner and has an outstanding aspect ratio near 15 for lines and 10 for trenches. These ratios combined with the electroplating of copper allow the fabrication of highly integrated electromagnetic coils.

Is the UV Alignment Effect Present in Low Redshift Radio Galaxies?

When a FRII radio galaxy at z > 0.7 is observed in the optical, its continuum appears extended and aligned with the radio axis. This phenomenon occurs actually when the optical bands start to sample the rest-frame UV, and it was called alignment effect (McCarthy et al. 1987). The UV continuum of high z radio galaxies shows also strong linear polarization due to scattering of anisotropic radiation escaping from the obscured quasar nucleus (di Serego Alighieri, Cimatti & Fosbury 1994). However, the observations of the UV continuum have been concentrated mostly on high z radio galaxies, leaving open a main question : is the alignment effect an evolutionary phenomenon present only at high z, or is it simply a selection effect due to the K-correction ? In order to investigate the origin and evolution of the UV alignment effect, we have started a ground-based imaging and polarimetric survey for studying the UV continuum in FR II radio galaxies with 0.1 < z < 0.5. Depending on the redshift, the filters U and B can be used to sample the UV continuum free from strong emission lines, and in the same rest-frame spectral region observed in radio galaxies at higher redshift. The survey is in progress and here we present only our first results.

The UV alignment effect in a low-redshift radio galaxy

The UV alignment effect in a low-redshift radio galaxy

A Highly-Sensitive Dry Developable Resist

A highly-sensitive dry developable resist for a deep UV aligner is described. The exposure time required is 1–2 sec, and the resist thickness remaining after dry development is 80–90%. The mechanism giving the high sensitivity was elucidated theoretically.