Study On Black Coating And Lift-Off Lithography Process In Multichannel Filter Manufacture

Multi-channel filters are widely used in modern optical information technology, such like remote sensing, chromatic display, image acquiring, etc. In some of its applications, miniaturized and integratable multi-channel filters are urgently needed, however, it is difficult to make such filters via traditional process based on metal mask. Therefore how to make highly precise multi-channel filters is a tricky problem. Key processes of multi-channel filter making are discussed in this paper as following:Design and manufacture of metal-dielectric based black coatings. Black coatings are of great importance in stray light suppression, infrared thermal detection, and solar energy harvest. A Cr/SiO2 stacked black coating optimized by simplex combined simulated annealing method is proposed, and its optical properties and layer sensitivities are analyzed by using Monte Carol simulation. Test shows that the average reflectance of actual production is 2.14%, which meets the practical requirements.Study on thick photoresist lift-off lithography process. The total thickness of complex thin films and infrared coatings is generally up to tens of microns, therefore the thickness of photoresist pattern shall be at least 100μm if lithography process is adopted. On the other hand, the pattern thickness of current lithography process for making multi-channel filters is less than 10μm, which does not satisfy aforementioned needs. Double spin coating method is proposed to making 200μm high photoresist pattern in this paper, which could hopefully be applied in multi-channel filter manufacture.Parameters optimization of lithography process. For NR9-8000 photoresist and NR21-20000P photoresist, the impact of process parameters on edge profile quality of photoresist pattern is investigated in detail, and the development rate and transmittance with different process parameters are also tested. Finally, optimized process parameters are determined by orthogonal experiments. AFM shows that the slope length of film edge is less than 6μm.