Fabrication of elastic bumps and narrow metal patterning for Si-based flexible electronics

Organic based materials and devices for flexible electronics have many disadvantages such as low charge transport, process temperature limitation, and etc. Those limitations, based on material itself, make the flexible electronic device difficult to compete with Si-based hard electronics that have excellent electric properties and much advanced design rule. Thus, as an effort to overcome the known weakness of conventional flexible electronics, a new processing method, selective transfer of integrated circuits (ICs) on plastic substrate, is widely suggested in many different research groups. However, before transferring ICs on flexible substrates, pre-electrical contacts should be formed to distribute the electrical signal, efficiently. In order to make the electrical contact for the ICs, we fabricated elastic bumps using a dispensing method that is creating a controllable elastic PR (photo resist) bump with a radius of 260 μm and a height of 19.6 μm by optimizing several factors (velocity, acceleration, pressure, and time of dispensing). After forming the elastic bumps, we also created an Ag metal line using an ElectroHydroDynamic (EHD) micro-patterning system for the electrical contact with the Si-based hard ICs.