Shao-Hui Shieh

Fabricating zinc oxide semiconductor device of flexible substrate by using the spin-coating method

In recent years, zinc oxide (ZnO) semiconductor have attracted much attention. Amorphous silicon thin film transistors are currently processed at a high temperature (>600 °C), with low mobility, but cannot be used in flexible electronics. Other organic thin film transistors were fabricated at a low temperature with middle mobility, but had a short life. This study used a bottom gate structure, low temperature (<400 °C) and spin-coating method to achieve the ZnO device with the on-off ratio = 107. The future study will focus on reducing channel width and length of devices, and the flexible substrate to make better flexible devices.

Fabrication of sol-gel-derived zinc oxide thin-film transistor

In this paper, a zinc oxide (ZnO) thin-film transistor (TFT) has been developed by using the sol-gel method with spin coating. Solution-processed thin-film deposition method is used to overcome the drawback of other vacuum deposition techniques in which process needs high temperature coating and expensive equipment. In order to analyze the characteristics of ZnO film, atomic force microscopy (AFM) is used to investigate the roughness of ZnO film. The experimental results show that the thickness of ZnO film is ranging from 5 nm to 10 nm with mean roughness 0.683 nm. The I–V characteristic of ZnO thin film transistor shows high current on-to-off ratio up to 106.

Low power self-checking two-rail code checker design

Totally self-checking (TSC) system can execute on-line testing in normal operation mode and immediately detect the fault existing in a system to enhance reliability. In this paper, a novel non-tree structure two-rail code self-checking checker (denoted by TCC-P) is proposed. Based on TSMC 0.18um process technology, the real chip is designed and verified. The experiment results show that the proposed checker has reduced 39.30% power dissipation with the penalty of little area overhead as compared with the best one previous work. The feature of both lower power and the capability to work in both clock phases confirm our design is valid and efficient.

The effect of X-ray irradiation on the novella type photoresist

As a result of the rapid development of lithography, it enables semiconductor technology to design more devices in the same area, which therefore makes electronic products faster, more functional, and hold more components. The photoresist, playing an important role in lithography, constantly develops with light wavelength used for exposure, from early entire wavelengths to present optical and non-optical lithography. The light sources of optical lithography have moved from the early 436nm and 365nm wavelength to short-wavelength light gradually. It is a big issue to find a suitable photoresist under the exposure of 0.578nm X-Ray light source. In this paper we first proposed to use DNQ / Novolak photoresist sold in the market for the 0.578nm X-Ray lithography. Due to the good resolution of NQ / Novolak photoresists, we obtained a 30nm line width as shown in Figure 1.In the experiment, it was discover that the exposure amount of X-Ray can determine if the photoresist is positive or negative; in low doses, when the photoresist film thickness is increased with the reduced exposure time, and a critical level is reached, the Novolak liquid will become positive photoresist after it is exposed in certain time. The high-dose X-Ray beam will make Novolak resin bond break and result in free radicals, which, through resin crosslinking, can improve the internal strength, and reduce developer solubility so the Novolak liquid can become to be a negative photoresist as shown in figure 2. By using synthesized DNQ / Novolak photoresist, under X-Ray exposure, we can reduce process line width, and explore principles of photoresist imaging analysis under the different exposure doses.