Preparation And Research Of A Thick Film Photoresist For Mini LED

Photoresist is a photosensitive mixed liquid that can undergo chemical changes under light conditions,so that its solubility in certain specific solutions will change significantly.Photoresist is an indispensable processing material for large-scale etching of micro-patterns in industrial production.In recent years,under the rapid development of the chip industry,especially the mobile phone chip industry,the research,development and application of photoresist have made significant progress.In this paper,a thick film photoresist with high acidolysis activity is designed and synthesized.The photo-etched pattern of this photoresist has a high aspect ratio,which is suitable for the Mini LED display field and which has attracted much attention in recent years.First,using poly(p-hydroxystyrene)resin monomer as raw material,two kinds of resins with poly(p-hydroxystyrene)as the main chain structure were designed and synthesized,and the synthetic process route was developed.Then,the structure of the above-mentioned resin was characterized by nuclear magnetic resonance,Fourier Infrared spectrometer and other instruments,and it was proved that the above-mentioned resin had an acetal structure.Secondly,the physical and chemical properties of these poly(phydroxystyrene)resins containing acetal structure were studied.Including molecular weight and its distribution,optical properties,heat resistance properties and decomposition properties under acidic conditions.Studies have shown that under acidic conditions,the synthesized resin can undergo a deprotection reaction at a lower temperature or even at room temperature,and has high acidolysis activity.Through the exploration of the synthesis process,poly(p-hydroxystyrene)resin with ethyl vinyl ether as the protective group was selected as the film-forming resin of the photoresist.The resin and solvent propylene glycol methyl ether acetate(PGMEA),sulfonic acid photoacid generator,alkaline quencher and other additives are mixed in a certain proportion to prepare a photoresist.Finally,apply the designed photoresist to the actual photolithography experiment.Studies have shown that when the spin coating speed is 1000 rpm,the thickness of the photoresist layer exceeds 15μm,which is a thick film photoresist.Through continuous attempts on the photolithography process,finally came to the conclusion:when the grafting rate of the film-forming resin is 45%,i-line is used for exposur,exposure energy is 30mJ/cm~2,baking temperature after development is 110℃ and baking time is 60s,a pattern with a resolution of 6μm and an aspect ratio of 2 can be obtained by photolithography.