1/1 µm Line and Space Cu Wiring with Organic Dielectric Through High Electrical Reliability

An electrical reliability of fine copper RDL with 1/1 µm line and space fabricated by using positive photosensitive polyimide (PSPI) has been demonstrated. The polyimide containing flexible molecular units in PSPI was introduced, which is assumed to increase the entanglement of each polymer chain with a design concept of polymer backbone to enhance mechanical and thermal reliability. To conduct a series of tests, test vehicles with semi-additive RDL with 1/1 µm line and space were fabricated with Toray’s PSPI for electrical reliability test. Through a series of electrical reliability tests utilizing our test vehicles, PSPI out-performed the phenol-based resin, which is assumed to have excellent mechanical and thermal stabilities when compared with other resins. 1/1 µm line and space electrodes after electrical reliability tests were also observed and cross-sectioned. This observation of electrodes clearly showed oxidation-reduction of the electrodes on anode and cathode, respectively.