Cheng-Yao Lo

Investigation of transparent and conductive undoped Zn2In2O5−x films deposited on n-type GaN layers

Transparent, conductive, multicomponent oxide films composed of undoped Zn2In2O5−x were deposited on n-type GaN layer using rf sputtering. We investigated the dependence of the surface, electrical, and optical properties on the sputtering parameters, including rf power, total pressure, and the post-deposition annealing process. We obtained high transparency (>80% in the visible and near-infrared ranges) and low electrical resistivity (2.58×10−4 Ω cm). Atomic force microscopy and optical transmittance measurements of Zn2In2O5−x films were used to investigate the mechanisms of resistivity variation in the films. The ohmic performances of Zn2In2O5−x contacts to the n-type GaN layer are also demonstrated.

Micro Roll-to-Roll Patterning Process and Its Application on Flexible Display

Novel electrode patterning techniques on thin polymer substrates were developed on a roll-to-roll (reel-to-reel, R2R) printing system. Hot embossing, laser ablation, and lift-off processes were evaluated for mass production for active-matrix display arrays with 1000 µm display pixels by using the concept of micro electro mechanical system (MEMS) Fabry–Perot etalon. Among which, the newly developed lift-off flexography process provided the best pattern integrity with 100 µm resolution. The demonstrator of display array proved R2R printing systems possibility and capability under 1 m/s speed. A complete multilayer stack demonstration with alignment process also indicated its variable application. Further actuation for the MEMS display proved the robustness of device made by printing techniques.

MEMS Fabry-Pérot Pixels

Novel Coulomb force controlled color display pixels of tunable MEMS (Micro Electro Mechanical System) Fabry-Pérot interferometer structure on flexible PEN (polyethylene naphthalate) substrate have been demonstrated with optical, electrical, and mechanical characteristics.

CoSix thermal stability on narrow-width polysilicon resistors

In this study, the thermal stability of polysilicon lines with various widths and different dopant types in 90-nm processes is investigated. The thermal behavior of silicides formed on N+ polyresistors and P+ polyresistors is very different. The worst thermal stability is found on the narrower N+ polyresistors, while an abnormal thermal behavior is observed on P+ polyresistors. This anomalous thermal-stability change with different drawn linewidths of P+ polyresistors is related to the grain-size distribution and the actual polyresistor linewidth. Also, it is interesting to find that the voids formed in P+ polyresistors lead to a stepped increase in sheet resistance.

Reverse CoSi2 thermal stability and digitized sheet resistance increase of sub-90 nm polysilicon lines

An equation for quantifying the CoSi2 thermal stability of polysilicon lines ranging from 50 nm to 2 µm is proposed for the first time. In contrast to the intuitive thinking of narrower lines having a worse thermal stability, the equation predicts the weakest thermal stability occurring at the super nominal line in 90 nm technology. An interesting phenomenon of digitized resistance increase is also reported for the first time.

A test structure to verify the robustness of silicided N+/P+ interface

We propose a new test structure that provides a single current path for silicide robustness detection at N+/P+ butted well tap interface with good sensitivity. Two reference test structures suspected with more than one current path and consequently give false results are also compared for structure and electrical performances.