Abstract
Femtosecond laser-induced backward transfer of transparent photopolymers is demonstrated in the solid state, assisted by a digital micromirror spatial light modulator for producing shaped deposits. Through use of an absorbing silicon carrier substrate, we have been able to successfully transfer solid-phase material, with lateral dimensions as small as ~6 microns. In addition, a carrier of silicon incorporating a photonic waveguide relief structure enables the transfer of imprinted deposits that have been accomplished with surface features exactly complementing those present on the substrate, with an observed minimum feature size of 140 nm.
Highlights
Laser-induced transfer, which relies on the energy of an incident laser pulse to transfer a deposit of material from a carrier substrate towards a receiver substrate, encompasses a range of techniques for rapid microfabrication of electronic, photonic and biomedical devices [1,2,3,4,5]
Recent results have shown the lateral shaping of deposits in a dynamic fashion for laser-induced forward transfer (LIFT), via the use of a digital micromirror device (DMD) acting as a spatial light modulator [6, 7], enabling the rapid prototyping of complex shapes with micron-scale fabrication resolution
We present the results from a different approach whereby the intact transfer of solid deposits has been achieved via laser-induced backward transfer (LIBT), where the deposits produced can have feature sizes well below the diffraction limit
Summary
Laser-induced transfer, which relies on the energy of an incident laser pulse to transfer a deposit (or variously termed voxel) of material (the donor) from a carrier substrate towards a receiver substrate, encompasses a range of techniques for rapid microfabrication of electronic, photonic and biomedical devices [1,2,3,4,5]. We present the results from a different approach whereby the intact transfer of solid deposits has been achieved via laser-induced backward transfer (LIBT), where the deposits produced can have feature sizes well below the diffraction limit This was achieved via use of a silicon carrier substrate that incorporated a prefabricated photonic waveguide relief structure, so that the donor material was imprinted with the complementary waveguide relief features before the LIBT process. This imprint transfer is a process allowing the fabrication of nanostructures which has not been demonstrated on such a small deposit scale with a direct-write laser technique [14], and such pre-structuring of a voxel prior to transfer could increase the complexity and functionality of the printed device. There is a very strong thermal gradient originating at the carrier–donor interface, and this interfacial region of the carrier experiences the largest change in its physical properties which is likely responsible for the subsequent detachment and backward propagation of the donor deposit
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