Defect height estimation via model-less TSOM under optical resolution.

We propose a new method of through-focus scanning optical microscopy (TSOM) without a reference database, i.e., a model-less TSOM method. Building a TSOM reference database is time-consuming or even impractical in some TSOM applications that involve complex structures, such as 3D NAND, or irregular shapes such as defects. The proposed model-less TSOM method was used to determine just the height of defect particles, for the first time as far as we are aware. Defect height is the only relevant dimension for the display panel application. Specifically, we analyzed 40 organic light-emitting diode (OLED) surface defects using a lab-developed motion-free TSOM tool consisting of a 50× objective lens (numerical aperture (NA) 0.55), a 532-nm light source, an imaging detector with a 7.5-µm pitch, and a deformable mirror. The tool is in-line and capable of achieving high throughput non-destructively, both relevant features for industrial applications. We investigated linear regression relations between newly defined TSOM parameters (TSOM height, TSOM area and TSOM volume) and the defect heights, which were first measured by atomic force microscopy (AFM). Following defect classification based on in-focus images, we successfully found that the AFM height has a linear correlation with 50% TSOM height (H50%) within ± 20.3 nm (1σ) error over the range of 140 to 950 nm. The one-sigma error, i.e., 20.3 nm, was approximately λ/26 or 1/43 of the depth of focus (DOF) of the applied microscope.

Tunable binary retarder using self-aligned liquid crystal on anisotropic polymer film by photo-assisted imprinting.

We demonstrate an electrically tunable binary retarder (ETBR) with a self-aligned liquid crystal (LC) on an anisotropic polymer film produced by photo-assisted imprinting. The ETBR has two parts: a tunable optical layer of an LC and a static optical layer of an imprinted anisotropic polymer film possessing two different in-plane optic axes. The anisotropic polymer film was produced using reactive mesogens spontaneously aligned along the topographic microgrooves by imprinting under the exposure of ultraviolet light. An electrically tunable hybrid wave plate, whose phase retardation varies from a quarter to a half-wave, is constructed using the self-aligned LC layer on the imprinted polymer film that behaves as a quarter wave plate with two alternating optic axes. This approach can be used to design a new class of tunable optical devices with multiple in-plane optic axes.

Multi-functional nanopatterned optical films fabricated using capillary force lithography.

We demonstrate anisotropic optical films based on liquid crystalline polymer (LCP) using a capillary force lithography (CFL). The fabricated optical films can be used as both an optical component and a self-aligning capability of liquid crystal molecules introduced on the film. Additionally, HA or PA LC can be induced on same material by controlling the water repellency of LCP surface. Moreover, surface anchoring transitions could be controlled by variation of pattern sizes and surface treatment. In this point of view, one thin optical film can act both retarder and alignment layer and then shows good retardation, LC alignment, and transmittance at the same time.

Anisotropic nano-imprinting technique for fabricating a patterned optical film of a liquid crystalline polymer.

We developed an anisotropic nano-imprinting technique, which combines the exposure of ultraviolet light, to fabricate a patterned optical film of a liquid crystalline polymer (LCP). The nano-imprinted LCP film has two-fold functionality of an in-cell retarder and an alignment layer of liquid crystal (LC) molecules. In addition to the geometrically generated microgrooves, the anisotropic surface interactions of the LCP acquired at a nano-scale level during the imprinting process results in the LC alignment on the patterned LCP film without any surface treatment. The nano-imprinted, quarter wave LCP was implemented into a LC cell which produces half-wave retardation under crossed polarizers.