For fast flexible electronics,transferrable mono-crystalline Si (c-Si) nanomembranes (NMs) become the most attractive candidate,owing to their material uniformity,mechanical flexibility and durability,electrical properties similar to the bulk Si,easy handling and processing,and low cost.Unfortunately,c-Si cant directly be grown on a flexible polyimide (PI) substrate due to its high crystalline temperature.For sub-ten micrometers free-standing c-Si membranes,it can be obtained by immersing the Si wafers in KOH solution with a concentration of 50 wt% at 90℃ for different duration of time to obtain different thickness (etching rate ~ 1.3 μm/min).However,the way for obtaining c-Si nanomembranes (c-SiNMs) is still quite limited.Currently,the main method for obtaining c-SiNMs is selectively to remove the tiny sandwiched SiO2 layer of the SOI (Silicon on Insulator) by using high concentrated hydrofluoric (HF) acid-called epitaxial lift-off process (ELO).It exists many limitations,including low lateral etching rate (LER) as well in liquid the lift-off thin-film wrinkling and cracking problems (i.e.c-SiNMs maintained issues).Looking into the bottleneck of traditional ELO technology by wet etching method,people found its LER is mainly dominant by diffusion-limited instead of reaction-rate-limited.In other words,the primal reason for manipulating etching rate is dependent on the solubility of reaction residues and the exchanging rate of fresh etchant solution in the etching tunnel.Hence,as sample dimension is getting larger and the thickness of sacrifice layer becomes narrower (i.e.higher gap-aspect-ratio),it has been expected the etching rate will be much slowing down.