In this paper, an extensive investigation on high dv/dt of High Voltage Silicon Carbide (SiC) Insulated Gate Bipolar Transistor (IGBT) is conducted by the use of accurate two-dimensional (2D) numerical simulations and fundamental physical modeling. The root cause of high dv/dt is identified and revealed, and the physical mechanism behind is analyzed and clarified. It is found that the punch-through (PT) phenomenon is the leading reason that accounts for high dv/dt of SiC IGBT, however, taking measures to eliminate the occurrence of this phenomenon is not appropriate. To overcome this issue, a simple design method is recommended in this work, and verification by 2D simulation results shows that it is capable of achieving suppressing dv/dt and lowering turn-off energy loss simultaneously.