Multiple wavelength photolithography for preparing multilayer microstructures

A method for preparing a multilayer, high aspect ratio microstructure, comprising, in order, the steps of:

• (a) applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer;
• (b) exposing a portion of the first photodefinable composition to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer;
• (c) applying a second photodefinable composition having a second exposure wavelength directly on the first polymeric layer to form a second polymeric layer;
• (d) exposing a portion of the second photodefinable composition to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer;
• and
• (e) removing a portion of each layer according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portion removed from the layers, thereby forming the multilayer microstructure,
• wherein at least one of the first and second polymeric layers have a thickness of at least 10 micrometers and the first and second exposure wavelengths different.