||With the development of integrated circuits, the transistors dimension has been scaling. In order to maintain the electrical behavior of transistors, miniature engineering faced many challenges. For example, reduced of gate control ability and increased of subthreshold swing. There are many ways to keep the transistors performance. One of the option is using high dielectric constant material instead of the traditional gate oxide layer.|
In the thesis, LTPS-TFTs are fabricated with Hafnia oxide gate dielectric and the impact of oxygen plasma induced interfacial layer on electrical behavior of P-type Poly-Si thin film transistors were investigated. First discuss the electrical behavior at room temperature. The transistors with oxygen plasma have less dangling bonds and more strain bonds, leading to smaller subthreshold swing and lower transconductance. The oxygen plasma will grow plasma-induced interfacial layer, it contains negative fix oxide charges, resulting in smaller threshold voltage.
To study the effect of reliability, it was divided into negative bias stress, negative bias temperature instability and temperature effects. In the experiment, the traditional transistors have serious degradation in subthreshold swing. Since the dangling bonds generated on the surface of channel. The transistors with oxygen plasma occurred hole injection in HfO2, producing positive fix oxide charges.