In Micro/Nano Direct-Write Lithography Systems, the Stage's Exceptional Dynamic Performance Enhances Lithography Accuracy and Efficiency

Direct-write lithography and projection lithography are two distinct classes of lithography technologies with clearly defined roles in the current industry. In lithography applications involving substrate warpage or substrate deformation—such as Fan-Out, COF, and other advanced packaging developments—packaging lithography technology requires smaller line widths, larger format sizes, and enhanced pattern alignment and overlay adaptation capabilities. The adaptive adjustment capability of direct-write lithography provides advantages such as high yield and excellent consistency.

The key technical challenges faced by direct-write lithography equipment not only include lithography light sources and line-width quality, but also encompass technical issues unique to direct-write lithography: high-speed, high-precision motion stages and position accuracy; pattern stitching; and large-volume pattern data generation along with high-speed, real-time, distortion-free data transmission—all of which are critical points in equipment integration and manufacturing.

The high-precision, wide-dynamic-range lithographic optical imaging system projects patterns reflected by the digital micromirror device through optical lenses with high precision onto the photosensitive material-coated substrate. This system is one of the critical modules of lithography equipment. It must not only have a sufficiently large numerical aperture to ensure resolution that meets line-width accuracy requirements, but also maintain image quality close to the ideal, with distortion controlled within 0.001%. To ensure consistency in parallel operation of multiple imaging systems, the lens magnification needs to have a certain fine-tuning capability.

The high-precision, high-speed real-time autofocus system is another key technical aspect of the equipment, ensuring that patterns are consistently exposed at the optimal focal plane during the lithography process, thereby maintaining line-width accuracy. Due to variations in substrate thickness, differences in surface flatness, fluctuations in vacuum chuck flatness, and the limited depth of focus of the projection imaging system, each lens must be equipped with a high-precision real-time focusing system to ensure uniformity of the overall exposure effect across the substrate. This system measures substrate surface flatness differences in real time through a measurement system, and a nano-actuator adjusts the distance between the lens and the substrate to keep the substrate constantly at the optimal imaging position of the lens.

In addition to the classic CFT-200XY XY integrated motion platform, Coretech also offers the higher-end Surface series planar air-bearing stages, which are frequently used in direct-write lithography applications.

The Surface series is Coretech's high-precision, high-dynamic-performance planar air-bearing stage. It features an XY dual air-bearing positive/negative pressure design with air-cushion preloading, using negative air pressure to balance the upward floatation and downward preload forces of the air-bearing guides, ensuring proper air gap clearance. Its geometric performance is exceptional, with an effective travel of 350 mm × 350 mm. Pitch and yaw angles are both less than 2 arc seconds, with resolution of 1 nm, repeatability of ±100 nm, and positioning accuracy of ±250 nm. Maximum speed reaches 2 m/s, and maximum acceleration is 2 g.