Jae-joon Choi

Electromagnetic micro x-y stage with very thick Cu coil for probe-based mass data storage device

We fabricated electromagnetic micro x-y stage for application to probe based mass data storage (PDS) devices. The stage consists of Si body containing planar copper coils, glass substrate bonded to the body, and 8 permanent magnets. The dimensions of springs and copper coils were determined so that a current of 100 mA would provide 50 μm motion in x and y. For application to PDS device, electromagnetic stage should have a flat top surface and coils of low resistance. So conducting planar copper coils have been electroplated within silicon trench of high aspect ratio (5 μm in width and 30 μm in depth). As insulating layer, polyimide was used. Silicon flexures with the height of 250 μm were fabricated by using ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching). The characteristics of the fabricated electromagnetic stage were measured by LDV (Laser Doppler Vibrometer) and DSA (Dynamic Signal Analyzer). DC gain was 0.16 μm/mA and the maximum displacement was 42 μm at a current of 180 mA. The natural frequency was 325 Hz.

Fabrication of Micro XY-Stage with Large-Area Rectangular Shuttle using Anodic Bonding Process

The Micro XY-stage with the large area rectangular shuttle (5 mm×5 mm) is fabricated using an anodically bonded fixture. The large area of a stage is prepared for the integration of a large number of nano-structure array or data-recording media with high density. No etching hole on the central stage is preferred to maximize effective area. The novel release process, μ -CARP (Micro Channel Assisted Release Process) is developed to release a large plate structure without etching hole and to resist a downward sticking. The mechanical characteristics of a fabricated device is measured and discussed.

Optimal Shape Design for Electrodes of a Rotary Microactuator

The electrostatic rotary microactuators integrating optimally curved electrodes are proposed to enhance the actuating force-generation capability. In most of conventional type of electrostatic microactiators using rotary mode, the electrodes have not been rigorously evaluated in terms of optimality for the shape and simply have adopted a straight shape. As a result, two neighboring electrodes should be spaced in the way of leading to relative large clearance at the far region from the center of rotation, hence the force generation capability is inherently limited. To overcome the limitation, the optimally curved electrode shape is introduced by tilting the electrodes in a continuous manner along with the radius.