Passivation and packaging of positive bevelled edge termination and related electrical stability

Low cost high power diodes usually use a MESA structure as an edge termination, filled with resin or glass. This paper provides an extensive analysis of the power diodes voltage capability as a function of the main geometrical and technological parameters. The effect of the fixed charge density inherent to the MESA groove filling material is also considered. Technological and electrical 2D simulations have been carried out to monitor the dependence on each parameter and to determine the location of the breakdown point. Fagor commercial MESA power diodes have been used to corroborate experimentally the optimisation of the voltage capability. Finally, a new axial package design which significantly enhances the device reliability has been developed, successfully tested and transferred into the Fagor production line.