AP300

A lithography stepper projects a mask pattern onto photoresist-coated wafers in repeated exposure fields. A tool in this class is used to define patterned layers during semiconductor manufacturing. A stepper belongs to the photolithography stage of wafer fabrication and is used between resist coating and resist development.

A stepper exposes one field at a time and then moves the wafer to the next field for another exposure. A lithography tool of this class aligns the wafer to the reticle pattern before exposure so that successive patterned layers register with earlier layers. A stepper uses projection optics to transfer the reticle image onto photoresist on the wafer surface.

Photolithography follows wafer surface preparation and photoresist coating. Stepper exposure is typically followed by post-exposure processing and resist development. The patterned resist then serves as a mask for later etch, implant, plating, or deposition pattern-transfer steps.

Stepper lithography is used wherever repeated die or feature patterns must be transferred across a wafer. Tools in this class support front-end device fabrication as well as some packaging and interconnect patterning flows, depending on the process stack and reticle set. Patterned resist produced by a stepper can define regions for material removal, material addition, doping windows, and electrical interconnect formation.