Characterization of latent three-dimensional exposure patterns in photoresists

We report on the imaging of latent 3D features exposed in photoresist during Direct Laser Write micro-/nanofabrication. The imaging method is based on monitoring of photoluminescence emitted by photonitiator in the photoresist, and exploits photoluminescence quenching and its dependence on the dose of the previous optical exposure. By spatially scanning focus of a low-intensity laser beam over the previously recorded latent features, spatial PL intensity maps reveal negative image of the latent pattern, and allows determination of feature size and shape prior to development. The imaging can be carried in situ, immediately after the fabrication, and does not require extensive modification to the existing equipment.

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