Design And Reliability Of High Voltage Insulated Gate Bipolar Transistor (IGBT)

Insulated Gate Bipolar Transistor (IGBT) is a new kind of power electric device. Since coming into the world, it has gradually become the core of modern power devices because of its excellent performances. IGBTs are widely used in household electrical appliances, induction heating, industrial frequency converter, solar power generation, wind power generation, motor drive and so on. This thesis covers the study of the fundamental principles of different IGBTs and the development of a planar non-punch through25A/1200V IGBT. During the development, the key parameters were first determined based on the simulation results and then optimized following the comparisons of final test. In addition, a series of reliability assessments, such as Temperature Cycle (TC), High Temperature Gate Bias (HTGB), Temperature and Humidity Bias (H3TRB) and High Temperature Reverse Bias (HTRB), were carried out on the packaged devices. Failure analyses were also performed on the failed devices during the reliability assessments to identify the root causes. The main results of this thesis are as follows:1) Study the principles and structures of different IGBTs, analyze the current status and future trend of domestic and international IGBT research, and illustrate the wide application of IGBT as modern power device.2) Develop a25A/1200V IGBT. This non-punch-through IGBT is fabricated on a monocrystalline silicon wafer based on process and device simulations using Sentaurus. The key parameters were optimized by comparing simulation results and actual measurement data and then modifying design and process accordingly. The device characteristics from the final design and process have met the target specifications.3) For the above25A/1200V IGBT, a series of reliability assessments were carried out according to industry standards, which include Temperature Cycle, High Temperature Gate Bias, Temperature and Humidity Bias and High Temperature Reverse Bias. The results before and after the tests have been carefully studied. 4) For the failed devices, a series of failure analyses were conducted, such as repeated test, LC hot spot detecting and EMMI. Through these methods, mobile impurities were found to be the essential factor leading to failure. Additional protections in the process were introduced to prevent the penetration of mole impurities. With the modified process, the product passed all the assessments listed above.