In this work, effects of structural parameter scaling on IGBT performance were systematically studied for both 1200 V non-scaled (k = 1) and scaled (k = 3) IGBTs. Relatively small area IGBT test devices with varied device parameters were fabricated on 3 inch wafers simultaneously with full size IGBTs. Mesa width, trench depth, p-base depth (MOS channel length) and gate oxide thickness were varied to clarify the contribution of each scaling parameter. P-collector dose was also varied for both k = 1 and k = 3 IGBTs to control the on-sate voltage. Clear on-state voltage improvement was verified in scaled IGBTs, in agreement with TCAD simulations. The origin of the performance improvement and the possibility of further improvement by scaling are discussed.