Laser & Optoelectronics Progress, Volume. 59, Issue 9, 0922030(2022)
Evolution and Application of Digital Micromirror Device Based Maskless Photolithography
Fig. 1. Schematic diagram of DMD maskless projection lithography
Fig. 2. Principle of fly-eye lens and beam homogenizer
Fig. 3. Working principle of micromirror or micromirror array. (a) Structural diagram of single micromirror[17]; (b) scanning electron microscope image of micromirror array[17]; (c) photos of integrated DMD chips of different models[18]; (d) schematic diagram of micromirror controlling light exit direction in optical path[18]
Fig. 4. Development history of resolution of DMD maskless projection lithography. (a)~(b) 50 μm line width obtained by DMD maskless projection lithography experimentally in 2000[27]; (c)~(e) 1.5~1.8 μm horizontal scanning line width and 1 μm diagonal scanning line width obtained by point array technique projection in 2003[29]; (f) 600 nm line width obtained in 2005[38]; (g) line array of 0.67 μm width obtained in 2010[39]; (h)~(i) dot array with 900 nm period obtained in 2010[40]; (j)~(k) helix structures with 400 nm minimum linewidth in 2013[41]; (l) 357 nm feature line width obtained by introducing high NA and big magnification projection lens in 2020[42]
Fig. 5. Linewidth resolution obtained by femtosecond laser maskless surface projection exposure.(a) 150 nm feature linewidth obtained by introducing high NA objective lens and femtosecond laser[45]; (b) light field distribution diagram of single pixel width’s projection line[46]; (c) schematic diagram of chemical nonlinear effect, where left column and right column images correspond to high and low light field intensity regions in (b)[46], respectively; (d) objective lens with 100 × magnification and NA of 1.45[45], and obtained fine line array; (e) 32 nm linewidth structure which breaks through diffraction limit to λ/12[46]
Fig. 6. Photonics devices manufactured by DMD maskless projection lithography. (a)~(c) Arrayed waveguide grating pattern[46]; (d)~(e) micronanofluid device pattern[46]; (f)~(h) electrostatic comb micro-resonators[46]; (i) chromium Fresnel zone plate fabricated with single exposure[39]; (j)~(k) Fresnel zone plate with diameter of tens of micrometers, which has response at about 114 μm[45]; (l)~(m) large area structure with high precision obtained by single exposure[46]
Fig. 7. Biological scaffolds and bionic structures fabricated by DMD maskless projection lithography. (a) Process of 3D layer-by-layer sinking fabrication[26]; (b) kidney-shaped 3D scaffold[26]; (c) top view and side view photographs of hydrogel enhanced by scaffold[50]; (d) scaffold enhanced hydrogel’s mechanical capabilities and now it can ‘stand’ on surfaces[50]; (e) bionic tendon structure inspired from human calf, capable of lifting 1 kg weight[51]
Fig. 8. Introduction of femtosecond laser can realize exposure of special materials using DMD maskless projection lithography. (a) Processing hard material structure with layer-by-layer fabrication[52]; (b)~(c) micro metal woodpile structure and nano metal wire bridgefabricated by layer-by-layer process[52]; (d) schematic diagram of gray level represented by dot matrix density arranged uniformly in space, and simulated distribution of DMD reflected light field smoothed out by diffraction[53]; (e) graphene removed on catalysis substrate after exposure[53]; (f) graphene transferred to device substrate after exposure[53]
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Ziyi Zhou, Xianzi Dong, Meiling Zheng. Evolution and Application of Digital Micromirror Device Based Maskless Photolithography[J]. Laser & Optoelectronics Progress, 2022, 59(9): 0922030
Category: Optical Design and Fabrication
Received: Mar. 1, 2022
Accepted: Mar. 24, 2022
Published Online: May. 10, 2022
The Author Email: Dong Xianzi (dongxianzi@mail.ipc.ac.cn), Zheng Meiling (zhengmeiling@mail.ipc.ac.cn)