We used an on-wafer UV photon monitor to measure the amount of UV photon irradiation on the substrate surface of a thin film transistor (TFT) device in N2/O2 atmospheric plasma. We found that the amount of UV photon irradiation on the surface strongly depended on the ratio of N 2 to O2 in the plasma. On the other hand, no irradiation of charged particles was observed by using this method. Additionally, we used TFTs with a single drain (SD) and lightly doped drain (LDD) structures as well as UV filters of slide glass (transparent above 280 nm) and synthetic quarts (transparent above 170 nm) to investigate the degradation of the TFTs. We found that UV photon irradiation significantly degraded TFT electrical characteristics in atmospheric plasma. An on-current decrease was observed only for LDD TFT when UV wavelength below 280nm was irradiated. On the other hand, we observed an off-current increase for both types of TFT when UV light with a wavelength of less than 170nm was irradiated. We will discuss a possible mechanism of the degradation.
ASJC Scopus subject areas
- Physics and Astronomy(all)