Hybrid application of laser-focused atomic deposition and extreme ultraviolet interference lithography methods for manufacturing of self-traceable nanogratings

A novel hybrid method that combines the laser-focused atomic deposition (LFAD) and extreme ultraviolet (EUV) interference lithography has been introduced. The Cr grating manufactured by LFAD has advantages of excellent uniformity, low line edge roughness and its pitch value determined directly by nature constants (i.e. self-traceable). To further enhance the density of the Cr grating, the EUV interference lithography with 13.4 nm wavelength was employed, which replicated the master Cr grating onto a Si wafer with its pitch reduced to half. In order to verify the performance of the gratings manufactured by this novel method, both mask grating (Cr grating) and replicated grating (silicon grating) were calibrated by the metrological large range scanning probe microscope (Met.LR-SPM) at Physikalisch-Technische Bundesanstalt (PTB). The calibrated results show that both gratings have excellent short-term and long-term uniformity: (i) the calibrated position deviation (i.e. nonlinearity) of the grating is below ±1 nm; (ii) the deviation of mean pitch values of 6 randomly selected measurement locations is below 0.003 nm. In addition, the mean pitch value of the Cr grating is calibrated as 212.781 ± 0.008 nm (k = 2). It well agrees with its theoretical value of 212.7787 ± 0.0049 nm, confirming the self-traceability of the manufactured grating by the LFAD. The mean pitch value of the Si grating is calibrated as 106.460 ± 0.012 nm (k = 2). It corresponds to the shrinking factor of 0.500 33 of the applied EUV interference lithographic technique. This factor is very close to its theoretical value of 0.5. The uniform, self-traceable gratings fabricated using this novel approach can be well applied as reference materials in calibrating, e.g. the magnification and uniformity of almost all kinds of high resolution microscopes for nanotechnology.