Microlens formation using heavily dyed photoresist in a single step

The work described here produced a new method of forming microlenses which requires fewer processing steps, eliminates the need for reflow or photoresist etching steps, and can be used with an inexpensive mask to form arrays. In this new method, a strongly absorbing dye is added in high percentage to a normal positive i-line photoresist. This photoresist is then processed at a much higher exposure dose than the normal photoresist. This paper describes simulated microlens structures as predicted by PROLITH as well as actual lens structures that were produced with the new method. This newly developed method is designed to enable the formation of microlenses at significant cost savings and with increased process control.