Automated optimization of grayscale masks for 3D micro-structuring

Automated optimization of grayscale masks for 3D micro-structuring

Van Kempen, F.C.M.

Van Keulen, A. (mentor)

Mechanical, Maritime and Materials Engineering

Precision and Microsystems Engineering

2012-10-31

Photolithography is the engineering field where micro-chips are made by creating minuscule patterns on a plate of silicon using light. The patterns are made in a photoactive polymer layer, called a photoresist which was applied to the substrate. These dissolve easily when they are irradiated with light, but resist dissolution during the development process if they were in the shadow. Traditionally, these layers were only a few micrometers thick and only used to create planar patterns. However, recently thick photoresists are getting more attention. In addition, it has also become possible to control the local irradiation accurately enough, such that we can create complex relief-typee3D structures, using grayscale exposure techniques. The potential applications in the field of micro-mechanical devices include micro-sensors and actuators, microoptics and micro-fluidics. Unfortunately, designing the proper light exposure profile and choosing the development time for a specific 3D micro pattern is complicated by the non-linear nature of the processes at hand. Therefore, the most widely used approach is based on trial-and-error designed exposure conditions and manual repair of the design by an engineer. In this research a systematic design approach is developed, based on computational process simulation, associated adjoint sensitivity analysis and optimization techniques. The computationally created designs were fabricated and compared to the desired shape to show the power of this approach.

automated optimization
grayscale masks
3D micro-structuring

http://resolver.tudelft.nl/uuid:0048c755-704a-4be9-8b81-67456e507c9b

2013-04-24

Student theses

master thesis

(c) 2012 Van Kempen, F.C.M.