Monolithic double-grating phase mask for large-period highly coherent grating printing

Abstract

A monolithic double-grating phase mask comprising three short-pitch grating sections of spatial frequencies k(1) and k(2) collocated at one side of a substrate produces a large-period interferogram without higher harmonics to print in a photoresist film a latent grating of small spatial frequency equal to twice k(2)-k(1). When incorporated in a write-on-the-fly scheme, the elements permit the fabrication of unlimitedly long gratings.

DUV Interferometry for Micro and Nanopatterned Surfaces

“…Since then, this technique has been used by several research teams. Recently, Bourgin et al (Bourgin et al, 2009) have proposed an integrated solution providing the 2 gratings on the same substrate, which simplifies the alignments. Significant progresses in resolution have also been achieved using immersion technique.…”

Three-grating monolithic phase-mask for the single-order writing of large-period gratings

“…The functionality of such monolithic phase-mask was demonstrated by using photoresist gratings defined at the incidence side of a thick glass substrate [1]. Despite its poor efficiency, the principle was demonstrated of splitting an incident beam with a transmission grating G 1 of period  1 directing its + and -1 st diffracted orders to two reflection gratings G 2 of period  2 that redirect both incoming beams via their -1 st diffraction order below the substrate where they overlap and interfere.…”

“…The objective of the work presented here was to find out and to design the optimum configuration permitting to print a grating of 2 µm period. Such period is not printable by means of a standard phase mask because of the complexity of the multi-order generated interferogram and it was shown to be achievable by means of a Mach-Zehnder interferometer configuration [1]. Periods  1 = 420 nm and  2 = 380 nm do generate an interferogram of 2 µm period according to Eq.…”

“…The spatial frequency of the generated interferogram is equal to twice the difference between the spatial frequencies of the central and lateral gratings. After the functionality of this dual-grating phase mask has been demonstrated with a laboratory prototype based on a simple photoresist technology [1], we will report here on its optimization and implementation in hard materials by means of e-beam writing and reactive ion etching. depth of the fused silica lines to have the maximum power distributed in the + and -1 st orders and minimizing the 0 th reflected order.…”

Laser interference ablation by ultrashort UV laser pulses via diffractive beam management

“…Besides imaging of a grating in order to recombine the diffracted beams, also diffractive recombination by a second grating is possible. Such a totally diffractive beam management with a so-called two-grating interferometer has the particular advantage of combining a large patterning field with dramatically reduced requirements concerning beam coherence [20][21][22].…”