Fig. 3

a FTIR spectra of as-cast (0 μC/cm²) and e-beam-exposed (50 μC/cm²) HSQ films for the range of Si–O–Si vibration. b Optical microscope image of e-beam patterned and developed HSQ. 100, 200, 300, and 500 nm periods with 1:1 line and space patterns can be seen. The imaging results of the s-SNOM phase (\({\varphi }_{2}\)) correspond to specific chemical structures. Images were taken at c 1125 cm⁻¹ and d 1067 cm⁻¹, and these respectively represent the cage-like and network structure. The red color indicates higher infrared absorption. The scale bar is 10 μm