Abstract.Considered the task of reducing the thickness of the contact lines of the pattern masks used in the formation of the microrelief of diffractive optical elements (DOE) and produced by laser ablation of thin films of refractory metals. For contact mask of DOEs on molybdenum films with thickness of 40 nm using a laser ablation patterns recorded with elements of the picture width 0.25-0.3 µm. This is approximately 3 times smaller than the characteristic dimensions, obtained by thermochemical recording chromium films of the same thickness in the standard process. Reactive ion etching in an inductively coupled plasma through a mask was formed micro-relief height up to 300 nm in a quartz substrate. We have shown promising applications of thin films of molybdenum as a metallic mask in the formation of microrelief of DOEs. ─ The creation of metallic liquid etching mask film of chromium areas not exposed to laser radiation; ─ Plasma etching the substrate through the resulting metallic mask (the formation of microrelief in the substrate).The disadvantage of this technology is pretty low resolution. Standard achievable feature size structures in this case -the order of the wavelength, i.e. about 0.8 μm [10]. In this regard, the actual task is the development of technological methods for creating elements with high spatial resolution.On the basis of the above-described process sequence, for example, in [11], there has been an element size of 0.5 μm on the structure of the chromium films 50 nm thick inflicted thermal vacuum process substrates of optical glass.Patent [12] describes how to increase the resolution of the method of laser thermochemical oxidation film of titanium thickness of 3 -60 nm, deposited on the glass substrate.A characteristic feature of the studies described in [1][2][3][4][5][6][7][8][9][10][11], is that the resistance to the subsequent chemical resistance increases for portions of film exposed to the laser radiation. In contrast to [1][2][3][4][5][6][7][8][9][10][11], we propose an approach based on evaporation (ablation) portions of the film exposed to laser radiation.The purpose of this paper is the experimental investigation of the possibility of further increasing the spatial resolution diffraction microrelief formed by using the contact masks using laser recording. It is proposed to achieve this total rejection of liquid chemical processes of lithography through the use of new materials and other physical effects of producing binary microstructures.
Problem statement and proposed approachIn [13] have demonstrated the possibility of ablation of molybdenum films picosecond laser beam with a wavelength of 1064 nm, deposited on a sublayer of silicon nitride thickness of about 140 nm. The grounds were glass substrate of a thickness of 3 mm. Ablation of the films of molybdenum with a thickness of about 0.5 μm was carried out by laser beam with a maximum energy flux density of 260 W/cm 2 , and it was suggested that the molybdenum is removed from the substrate surface without chemical transformati...