Real Time Monitoring Of Exposure Controlled Projection Lithography

• Main Authors: Zhao, Changxuan, Jariwala, Amit S., Rosen, David W.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2016
• Online Access: https://hdl.handle.net/10356/84379; http://hdl.handle.net/10220/41771
• Institution: Nanyang Technological University

Exposure Controlled Projection Lithography (ECPL) is a stereolithographic process in which lens shaped features are fabricated from Photopolymer resin. During the fabrication process, a dynamic mask is used to control and project radiation patterns through a transparent substrate onto the photopolymer resin to grow the features progressively from the substrate surface. We present a novel method to monitor the photopolymerization process in real-time with spatial resolution in a plane perpendicular to the growth of polymerization. A transparent Spatial Light Modulator (SLM) was incorporated into our Interferometric Cure Monitoring (ICM) system, an interferometric monitoring system which is used to measure the cured part height. The introduction of SLM enabled multiple point which could not be achieved by the traditional manually operated iris. This improved ICM system fulfilled the need of selectively scanning the curing area and estimating the height and width of the cured part at a specific region of interest. This multiple-point-selective monitoring approach is experimentally validated to measure the height at different locations of the cured part in real time, and also the lateral dimensions of the cured part at the substrate level by a scanning process controlled by the SLM.