Large Area Stepper

Critical applications such as manufacturing small, high density multi-layer interconnects using relatively unstable substrates create a need for extremely accurate registration. For these applications, global alignment methods such as those used by traditional contact and proximity printers may no longer be sufficient. Contact printing has the additional disadvantage of high defect counts. Laser direct imaging (LDI) has an inherent tradeoff as well, with limitations in resolution and throughput.

Large area projection lithography steppers offer an optimum solution, minimizing defects, maximizing resolution and overlay accuracy, while maintaining high throughput using standard photoresists. Tamarack’s steppers literally expose one die or area at a time, then step to the next die or set of die until they have exposed the entire substrate/wafer. This provides the ability to align and expose each site individually and compensate for material dimensional changes that may have occurred.

A large field, 6 um resolution projection lens adds flexibility, allowing imaging of sites sized up to 6”x6” in one exposure, with no need for stitching of adjacent fields. Any variation in substrate sizes due to expansion and contraction can be corrected through automatic or preset lens magnification changes. The large depth of focus allows imaging of thick photoresists as required by many process applications. This means one exposure tool can be used for many applications, ranging from very small micro BGA and flip chip substrates, to much larger interconnect boards.

The following platforms are available:

• Model 401 for up to 12” x 12” panels

• Model 400 for up to 24” x 24” panels