In recent years a new device concept appeared in the IGBT technology. It is a structure between a PT and an NPT device, with a low-doped emitter, where the fundamental role is played by the Field-Stop layer. In this paper we fixed some considerations about a proper design of this layer. Some simulated and real electrical characteristics of a trench-gate emitter-implanted IGBT will be shown and correlated to the Field-Stop layer process parameters.