Patterning of Arbitrary 3D Surfaces via Direct-Write Hybrid Lithography

Technology

The technology described in this invention patterns curved surfaces without using fixed masks by accurately projecting light onto the photoresist-coated surface. In a departure from existing laser-based approaches, this system has a light projection system made up of an array of MEMS mirrors, each of which can be tilted to control whether individual pixels get illuminated. The projection module is attached to a six degree-of-freedom robotic arm that positions it in relation to the object being patterned, which is itself mounted on a rotary axis.

Before a patterning operation, a 3D scan is carried out to characterize the geometry of the target surface. This scan data is used to construct a digital model of the surface made up of a large number of triangular facets. For each triangle, the system orients the projection module normal to its centroid and adjusts the mirror array to selectively direct light from an LED source onto the triangle. This procedure is repeated until the entire surface has been patterned. A camera mounted in-line with the projection module images previously patterned areas to provide data for feedback control of projection system position to maintain accuracy over large areas.

Preliminary tests by the Inventors have demonstrated that resolutions up to 5 µm are achievable using this system. Further performance improvements are expected from the use of thinner photoresist layers.

Problem Addressed

A number of approaches to patterning photosensitive materials on arbitrarily shaped surfaces have been attempted. For example, companies such as Panasonic and Aiscent Technologies have developed laser-based systems to pattern curved surfaces. These methods are limited by restrictions in material choice, patternable area, and throughput. Additionally, some of them are further restricted to patterning spherical surfaces. Alternative technologies for patterning 3D surfaces include direct printing using inkjet technology and adapting conventional stereolithographic techniques to print non-normally onto substrate surfaces. These approaches are unable to handle undercuts or concave areas, limiting their utility to surfaces viewable from a single axis. This invention proposes a novel method of patterning 3D surfaces that overcomes these limitations, enabling high-resolution patterning of arbitrarily shaped 3D surfaces over large areas.

Advantages

• Reduces substrate heating to enable patterning on biological materials
• 7-axis relative motion system allows the patterning of undercuts and concave surfaces
• Feedback control using inline machine vision improves patterning accuracy over large areas