2500V, 600A gate turn-off thyristor (GTO)

The vital point for 2500V, 600A GTO design is to establish a principle for increasing maximum gate turn-off current (IATO), while keeping overall thyristor characteristics in reasonable balance. High IATOwas attained by decreasing p-base surface resistance to below a certain limit, as well as decreasing n-emitter finger width. Excellent thyristor characteristics were obtained by adopting thick p-base layer with as low as possible acceptor concentration. From a device process point of view, introducing a new annealing process of phosphorus redeposition increased carrier lifetime in the p-base to a sufficiently high level. This process contributed most strikingly to improving the off-state voltage.