The Research Into Hot Carrier Degradation Mechanism And Lifetime Model Of 550V Thick Film SOI-LIGBT

Lateral insulated gate bipolar transistor based on thick film silicon on insulator substrate (SOI-LIGBT) is the ideal power semiconductor output device by virtue of its high breakdown voltage, strong output capability and easy integration. As a result, it has been widely used in the field of power integrated circuit. Nevertheless, the SOI-LIGBT usually works under the conditions of high voltage and large current, and it suffers from serious hot carrier injection (HCI) effect, making the electrical parameters degrade gradually, and the lifetime of device and chip will be affected eventually. Therefore, the investigations of HCI degradation mechanism and lifetime model for thick film SOI-LIGBT are of great significance.Firstly, this thesis identifies that the worst gate voltage stress for the SOI-LIGBT is 15V, and it reveals that the HCI degradation mechanism of the device under the worst stress is the generation of interface states and the hot electron injection at the channel region. Then, the influence of anode voltage(Vac) for the HCI degradation is investigated. The study shows that the HCI degradation will increase with the increment of Vac when the Vac is low. When the Vac is high, because of the electric field shielding effects of the gate field plate and the cathode metal plate as well as the influence of the Kirk effect, the HCI degradation is independent of the Vac. The influences of structure parameters upon the electrical parameters are also investigated. The results show that the HCI degradation can be decreased by increasing the channel length, drift region length or N-buffer length. Finally, two kinds of high HCI reliability structure are proposed:the anode N+/P+ interval structure and the channel electric field shielding structure. The tests results show that these two structures could improve the HCI reliability.In addition, according to the degradation mechanism, the HCI degradation lifetime models for the saturation current and threshold voltage are established. The test results show that the deviations of both models are less than 7%. The proposed models could give theoretical guidance for the reliability optimization and lifetime evaluation of thick film SOI-LIGBT.