Process development and proton implanted n-type buffer optimization for 1700V rated thin wafer fast recovery diodes

Developing suitable processes for thin wafer fast recovery power diodes is important for modern production plants as the substrate dimension increases. A set of emerging technologies has been employed here in order to fabricate 1700V rated fast recovery diodes from standard Si IGBT substrates without pre-diffused backside n-type buffer. Wafer grinding, n⁺ back surface contact implant, laser annealing and multiple proton implantations were all employed here for the diode fabrication. Detailed processing parameters for each step were carefully selected and optimized for the fabrication. Both SRIM and Silvaco simulations were carried out to initially provide theoretical guide for experimental design and later compared with measured results. The fabricated diodes were tested under both static and dynamic recovery conditions. The results demonstrate that the processing technologies used here are capable of making fast recovery diodes from standard IGBT substrates.