Novel Monolayer-enhanced Non-Conductive Film (NCF) for Ultra-Fine Pitch High Performance Interconnect in Lead-free Electronics

With the aim of improving electrical properties of non-conductive film (NCF), two thiol (-SH) terminated -conjugated molecular wires are introduced into the interface of NCF. The conjugated molecular wires can be well assembled on the Au electrodes and improve the interfacial properties of the NCF joints. Biphenyldithiol (BPD) exhibits higher thermal stability after curing condition (150degC) than 1,4-benezenedithiol (BDT) due to the higher aromaticity (more aromatic rings) and thus more rigid structure. Formation of self-assembled monolayer on Au electrodes can tune the effective work function (Phi) of Au electrodes and reduce the tunnel resistivity. Therefore, the joint resistance of NCF joints, which is the sum of tunnel resistance and constriction resistance, can be significantly reduced from 0.15 times 10^-3 Omega to 0.1 times 10^-3 Omega and 0.05 times 10^-3 Phi with BDT and BPD, respectively. The improved electrical conduction and current carrying capability enables the application of NCF in fine pitch and high performance interconnects in microelectronics.