Laser annealing of Semiconductors

Laser annealing is a constantly growing new technology, especially increasingly applied in the automotive, renewable energy, communications, lighting and medical and above all, the semiconductor market.

IGBTs (Insulated Gate Bipolar Transistor) 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 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.