Hyung Choi

Bio: Hyung Choi is an academic researcher from Samsung. The author has contributed to research in topics: Layer (electronics) & Optical switch. The author has an hindex of 12, co-authored 80 publications receiving 459 citations.

Method for manufacturing metal structure having different heights

Abstract: Disclosed is a method for forming a plurality of metal structures having different heights on a semiconductor substrate. The disclosed method for manufacturing a metal structure having different heights includes: forming a plurality of seed layers, to have heights corresponding to the metal structure to be formed, on a semiconductor substrate so that those layers can be electrically separated, performing a plating process using a plating mold, and applying different currents to the respective seed layers so that the plating thickness can be adjusted for each of the seed layers. Accordingly, a plurality of metal structures having different heights can be obtained by a plating mold forming process and a plating process that are performed just once, respectively.

Magnetic MEMS device and method of forming thereof

Abstract: A microelectromechanical system (MEMS) sensor and method for measuring the motion of an intermediate member and a method for making the MEMS sensor. The MEMS sensor includes a substrate, a lower magnetic member disposed on the substrate, a layer disposed over the substrate, an upper magnetic member disposed at a side of the layer facing the lower magnetic member, an intermediate magnetic member magnetically levitated between the lower magnetic member and upper magnetic member; and a component measuring at least one of motion, forces acting on, and a displacement of the intermediate magnetic member.

Impact of transparent electrode on photoresponse of ZnO-based phototransistor

Abstract: ZnO-based photo-thin film transistors with enhanced photoresponse were developed using transparent conductive oxide contacts. Changing the electrode from opaque Mo to transparent In-Zn-O increases the photocurrent by five orders of magnitude. By changing the opacity of each source and drain electrode, we could observe how the photoresponse is affected. We deduce that the photocurrent generation mechanism is based on an energy band change due to the photon irradiation. More importantly, we reveal that the photocurrent is determined by the energy barrier of injected electrons at the interface between the source electrode and the active layer.

Light emitting device package

Abstract: A light-emitting device package including: a package main body including a cavity and a lead frame including a mounting portion disposed in the cavity and a plurality of terminal portions; a light-emitting device chip mounted on the mounting portion; a plurality of bonding wires for electrically connecting the plurality of terminal portions and the light-emitting device chip; a light-transmitting encapsulation layer filled in the cavity; and a light-transmitting cap member disposed in the cavity and blocking the encapsulation layer to contact the plurality of bonding wires.

Review of On-Chip Inductor Structures With Magnetic Films

Abstract: A comparison of on-chip inductors with magnetic materials from previous studies is presented and examined. Results from on-chip inductors with magnetic material integrated into a 90 nm CMOS processes are presented. The inductors use copper metallization and amorphous Co-Zr-Ta magnetic material. Inductance densities of up to 1700 nH/mm2 were obtained thanks to inductance increases of up to 31 times, significantly greater than previously published on-chip inductors. With such improvements, the effects of eddy currents, skin effect, and proximity effect become clearly visible at higher frequencies. Co-Zr-Ta was chosen for its good combination of high permeability, good stability at high temperature (> 250degC), high saturation magnetization, low magnetostriction, high resistivity, minimal hysteretic loss, and compatibility with silicon technology. The Co-Zr-Ta alloy can operate at frequencies up to 9.8 GHz, but trade-offs exist between frequency, inductance, and quality factor. Our inductors with thick copper and thicker magnetic films have dc resistances as low as 0.04 Omega, and quality factors of up to 8 at frequencies as low as 40 MHz.

Light Emitting Device

Abstract: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

Flexible display device and method of manufacturing the same

Abstract: A flexible display device and a method of manufacturing the same are provided. The flexible display device comprises a first flexible substrate including a display area including an organic light emitting layer, and a peripheral circuit area, and a second flexible substrate coming in contact with the first flexible substrate and including a pattern for facilitating bending thereof, wherein the second flexible substrate has a certain shape according to the pattern, and the first flexible substrate has a shape corresponding to the certain shape. Various embodiments of the present invention provide a flexible display device capable of realizing a narrow bezel-type or bezel-free display device and simultaneously realizing improved types of design, facilitating bending of a bezel area so as to realize a narrow bezel-type or bezel-free display device, and minimizing damage to an area to be bent.

Methods of fabricating electronic and mechanical structures

Abstract: The present invention relates to the fabrication of complicated electronic and/or mechanical structures and devices and components using homogeneous or heterogeneous 3D additive build processes. In particular the invention relates to selective metallization processes including electroless and/or electrolytic metallization.