Modeling and simulation of chemical amplification photoresist to produce high-density cone-shaped micro bumps

The cone-shaped micro bump provides fine-pitch room-temperature flip-chip Bonding technology. It has been demonstrated to be able to connect $15 \mu \mathrm {m}$-pitch 640x512 array pixels of an image sensor composed of a compound semiconductor photodetector array and silicon readout integrated circuit. The cone-shaped micro bump is fabricated by utilizing the characteristic of the chemical amplification photoresist. For further shrinkage of the interconnection pitch below $10 \mu \mathrm {m}$, not only refining of process condition But also a new design of photoresist is required. In this work, we build a model and a simulation method to investigate how the property of the photoresist and process condition determine the final shape of the cone bump.