Abstract As compared to the conventional smart-cut technology based on single H ion implantation, sequential implantation of H and He ions has been demonstrated to be effective in reducing the implantation fluence and the thermal budget needed for Si layer splitting process. However, the sequential implantation method involves complicated process parameters such as ion energy and implantation sequence. The purpose of this study is to clarify the dependence of He ion energy on Si blistering characteristics by sequential implantation of H and He ions into Si in various sequences. The accelerated energy of H ions was fixed at 40 keV, while that of He ions was changed to 30, 50, and 70 keV. Both the implantation fluences of H and He ions were 1 × 1016 cm−2. The non-isothermal and isothermal annealing methods in combination with an in-situ optical microscopy (OM) detection system were adopted to determine the threshold temperatures and the onset times for blister and crater formation as well as to examine the thermal evolution of blisters and craters. The results revealed that the threshold temperatures for blister and crater formation are highly correlative to the He ion energy and implantation sequence. Higher He ion energy is preferable to blistering for the specimens first implanted with He ions, but the opposite is true for the reverse implantation sequence. This statement can be also supported by the activation energy levels required for blister and crater formation obtained from kinetics analysis. In addition, the variation of hydrogenated complexes induced by sequential implantation and annealing can be evidently identified from the Raman spectra, showing a noticeable transformation of H-related defect complexes from VH 3 to Si(100):H bonding configuration due to the emergence of blisters and craters. Highlights • H/He sequential implantation is proved to be effective for smart-cut technology. • Two-step ion implantation process varied in sequence and He ion energy was done. • Blistering characteristics were assessed using quantitative and kinetics analysis. • Blistering effectiveness depends on implantation sequence and He ion energy. [ABSTRACT FROM AUTHOR]