EV-420

Mask aligners transfer patterns from a photomask into photoresist on a substrate by optically aligning the mask to features on the substrate and then exposing the resist. Mask aligners are core pattern-transfer tools in photolithography for research and production work that does not require projection-stepper architecture.

Mask aligners position a mask relative to a resist-coated substrate, use alignment optics to register the pattern to existing features, and then expose the resist through the mask. Frontside alignment uses marks viewed from the patterned side, while backside alignment is used when the new pattern must register to features on the opposite side of the substrate.

Mask aligners are typically used after substrate preparation, adhesion promotion, resist coating, and soft bake. Mask aligners are typically followed by resist development and then by pattern transfer steps such as etch, deposition with lift-off, or plating, depending on the process module.

Mask aligners are used for patterned resist exposure in microsystems fabrication, sensor fabrication, microfluidics, and general thin-film structuring. Backside alignment capability is especially relevant when patterns on opposite faces of a substrate must be registered for through-substrate features, membranes, cavities, or bonded-device layouts.