Nikon Engineering Co. Ltd. released the first NES PrA Mini Stepper lithography systems more than a decade ago. These simplified, small scale steppers have evolved over time for use in Research and Development applications and to address the specific manufacturing requirements of Air Bearing Surface (ABS) fabrication for magnetic heads. The enhanced NES1 Mini Stepper platform was subsequently launched in 2007. After achieving market leadership in this area, in 2009 Nikon expanded the NES product line to also satisfy the unique process challenges of Micro Electro Mechanical Systems (MEMS), while delivering maximum stepper yield at the lowest possible cost. Most recently, Nikon has begun shipping the NES2 line of Mini Steppers, which support 200 mm wafer capabilities to further increase customer productivity and efficiency.
Although MEMS do not have the same aggressive requirements for imaging or overlay capabilities that are demanded by semiconductors, they necessitate that the lithography systems are able to handle extremely warped wafers and very thick films, and accommodate significant step heights. In addition, bulk MEMS applications often need precise alignment to marks located on the backside of the wafer surface. Nikon NES Mini Steppers fully satisfy the critical requirements of these markets as well as those of Light Emitting Diodes (LED), optoelectronics, discrete semiconductors and crystal oscillator manufacturing, and well over 100 Mini Steppers are being used around the world today.
Nikon Mini Steppers use h-line illumination coupled with low lens numerical apertures specially optimized for MEMS-type applications and die-to-die autofocus, enabling these steppers to deliver the necessary resolution performance with tremendous depth of focus. Proven stepper technology ensures optimal CD uniformity across the wafer and the projection lens design eliminates costly mask contamination/defectivity issues experienced with contact or proximity printing methods. In addition, all of the Nikon Mini Steppers utilize Enhanced Global Alignment (EGA) that has long been employed on traditional Nikon Step and Repeat Systems to provide optimal overlay accuracy. They also provide Pattern Matching Alignment capabilities that enable alignment to structures other than the NES specific alignment marks. These critical functions are delivered on user-friendly, high productivity stepper platforms, with dramatically reduced system footprints to minimize equipment cost and cleanroom floor space usage.
Nikon continues to focus on expanding system capabilities and reducing cost to customers. Newly developed Mini Steppers support larger wafer sizes, provide enhanced imaging, and maximize productivity. Additionally, a multitude of add-on functions further boost Mini Stepper performance and yield.