Abstract
In recent years, the mobile, tablet and liquid-crystal monitors increase rapidly. The requirement of the driver IC becomes important and popular. The high-voltage DEMOSFETs are widely used in driver IC circuits including Op-Amp, Gate driver and Source driver. For Op-Amp application, the voltage gain and mismatch performance are important for the circuit operation due to color quality requirement of the panel displayers. In the thesis, the high-voltage DEMOSFETs are used for studying the electrical characteristics and physical mechanisms by simulation and experiments. Two major topics are under investigated. The first topic is drain saturation current after pinch-off situation. The drain current usually saturates and keeps a constant value after pinch-off for the ID-VD characteristics. However, in high-voltage device, the current often increases or decreases with the drain bias after entering the saturation region. The simulation depicts that the resistors distribution and Kirk effect are the major causes of the saturation current increase. In contrast, the self-heating and parasitic JFET are the root causes for the degradation of the saturation current. For the second topic, we discuss the reliability for the high-voltage DEMOSFETs. The hot-carrier effect becomes serious during high-voltage operation. The effect indeed degrades the device characteristics and causes the qualification fail. The simulation is used to predict the electrons trapped locations and show the corresponding characteristics after charges trap situation. We also discuss the substrate bias enhanced long channel device degradation phenomenon for the high-voltage DEMOSFETs.