- News (bipolar transistor)

- IGBT laser annealing

The Insulated Gate Bipolar Transistor (IGBT) market is constantly growing because of significant advantages IGBTs offer compared to other transistor devices such as high voltage capability, low ON-resistance, ease of drive, fast switching speeds, robustness, etc.
One of the key factors contributing to this market growth is the increasing demand in automotive and industrial applications, including renewable energy, communications, medical, lighting and transportation.
IGBTs are manufactured on mechanically thinned wafers with a typical thickness of 100 µm or less. In order to establish a field stop and/or emitter layer on the rear side of the wafer, deep-implanted doping elements (like phosphorous or boron) have to be activated through a high-temperature annealing process towards the end of the FEOL process chain. Very often, the sensitive devices on the wafer front side are protected by an attached tape. Due to low damage temperatures of the tape, the heat-sensitivity of the front side devices, as well as a non-uniform heat distribution in the processing chamber, conventional oven activation is characterized by low activation levels and rates. ROFIN’s laser annealing process has been developed to overcome these issues and to provide significantly higher process stability and yield at competitive costs/wafer levels. Laser annealing deep-activates the dopants and simultaneously prevents damage to the wafer front side and the protection tape. The laser allows for precise depth control of the field stop and/or emitter layer activation in the range of up to 2 µm. With activation rates exceeding 90%, ROFIN’s IGBT laser annealing solution is far superior to conventional methods.