This study systematically investigates the molecular design and photolithographic process optimization of positive photosensitive polyimide (p-PSPI) photoresists

aiming to advance their application in high-resolution microelectronic fabrication. A novel strategy is proposed to synergistically regulate the esterification ratio of polyimide precursor resins through isoimide pretreatment and controlled esterification. By optimizing the pretreatment conditions of polyisoimide and conducting kinetic analysis

the critical parameters governing the esterification reaction are identified. The optimal process conditions

including an esterification time of 2 h and a temperature of 50 °C

significantly enhance the structural regularity and photochemical reactivity of the precursor. Structural characterization reveals that the pretreatment facilitates the conversion of polyisoimide into linear amic acid structures

thereby increasing the accessibility of reactive carboxyl groups for esterification. To further optimize the lithographic performance

an orthogonal experimental design is employed to systematically evaluate the synergistic effects of key process variables

including developer concentration

photosensitizer content

and pre-baking conditions. This approach elucidates the interplay between development kinetics and photochemical crosslinking efficiency

enabling a balanced optimization of sensitivity and resolution. Experimental results demonstrate that the optimized p-PSPI exhibits excellent photosensitive under 365 nm ultraviolet irradiation

achieving a contrast ratio of 2.5 and sensitivity of 70 mJ/cm². High-resolution patterning capabilities are confirmed

with resolutions of 10 μm on glass substrates and 3 μm minimum feature size on silicon wafers. The cured p-PSPI films display outstanding mechanical properties and thermal stability

meeting the stringent requirements for high-density integrated circuit packaging. The mechanical robustness and thermal resistance are attributed to the well-controlled esterification and crosslinking networks formed during the photolithographic process. This study establishes a synergistic framework for tailoring both molecular architecture and processing parameters

providing a versatile platform for developing high-performance polyimide photoresists. The proposed p-PSPI demonstrates broad potential in advanced applications such as high-precision micro-nano fabrication

flexible electronics

and next-generation semiconductor packaging

offering a viable solution for emerging technological demands in the electronics industry.