A new punch through IGBT having a new N-buffer layer

IGBTs based on the NPT (nonpunch through) design approach exhibit excellent safe operating area and short circuit endurance, a positive temperature coefficient of on-state voltage over the operating current range, and low silicon cost. These merits have supported the development and commercialization of NPT IGBTs above the 1200 Volt class. However, the need for quite thin silicon to obtain competitive on-state losses at 1200 volt and below classes has hindered the use of the NPT approach in this area. A new punch through (PT) IGBT has been developed which exhibits the merits of the NPT approach, rugged SOA and short circuit endurance, while also having a better trade-off relation between on-state voltage and turn-off loss than either existing NPT or third generation PT IGBT.