The controlled punch through (CPT) IGBT buffer is discussed as a mean for the reduction of wafer thickness down to the theoretical limit of the next generation 1200 V IGBT. The CPT buffer occupies a small fraction of the silicon and at the same time provides a high degree of freedom in the design of the anode doping profile to maintain all relevant electrical parameters within a given specification. While presented for 1200 V IGBTs, the new buffer concept can also be applied with advantages to any voltage class. Beside the reduced ON-State losses, the IGBT maintains good blocking, soft turn-off, wide SO A and very good short circuit capability. This is shown theoretically and proved experimentally.