Structural Design of Low‐Temperature Curable, Alkaline‐Developable Photosensitive Polyimides With High Resolution and Mechanical Properties

ABSTRACT Low‐temperature curing photosensitive polyimide (PSPI) has attracted significant attention in the field of advanced packaging. As a key material for the passivation layer of multi‐layer structures in microelectronic manufacturing, it not only needs to cure at a lower temperature but also should have low corrosiveness to devices and no harm to the environment. However, current research on PSPI that can be water‐soluble and cured at low temperatures is relatively limited. Therefore, a structural design method for water‐soluble and low‐temperature curing PSPI was proposed. This involves introducing amide groups and phenolic hydroxyl groups into the polymer main chain to achieve the water solubility of polyimide. Combined with DNQ, this method achieves a high‐resolution water‐based development pattern of 2 μm. During the curing stage, only the solvent needs to be removed at 180°C without sacrificing performance. The glass transition temperature ( T g ) of the prepared PSPI is 301.7°C, and the elongation at break reaches 21.3%. The proposed PSPI structural design method has good solubility in alkaline aqueous solutions, highlighting the impact of introducing hydrophilic groups in the main chain to prepare soluble polyimide for water‐soluble patterning and low‐temperature curing. It provides a feasible strategy for the structural design of water‐soluble and low‐temperature curing PSPI.