The basic principle behind Nanoimprint and Nanoimprint Lithography (NIL) has been known for centuries if not millennia. In 1995, Stephen Chou coined the term Nanoimprint Lithography and demonstrated its ability to perform sub-100 nm parallel lithography by physically deforming a thermoplastic material in a temperature and pressure-controlled printing process. It was achieved using a silicon stamp patterned by Electron Beam Lithography and Dry Etching. The beauty of this technique is that it can take a silicon “master” with nano-patterns made using time-consuming and expensive processes and use it to make tens of thousands of replications, thus reducing the cost and increasing the throughput.
How to perform nanoimprinting
In thermal nanoimprinting, a thin thermoplastic or thermosetting polymer layer is applied onto a substrate. The layer is deformed by pressing a stamp into the polymer at a temperature above the polymer's glass-transition temperature. Thereafter, the polymer is cooled down below its glass-transition temperature and the stamp is removed. This leaves the relief of the master in the polymer on the substrate. There will always be a thin residual polymer layer on the substrate, which can be removed in a plasma process. The substrate is now ready for further processing using the polymer layer as a mask.
Today, we have several variants of NILNanoimprint Lithography. The most important of these are:
- Thermal wafer scale NIL
- UV wafer scale NIL
- UV step and
- Repeat NIL
Additionally, there are replication techniques that build on the same technology. These are often referred to as “Nanoimprint”, and they include:
- Roll-2-Roll printing
- UV replication
- Micro Contact Printing (µCP)
- Hot embossing
- Roll-2-Plate printing
All nanoimprint techniques require a stamp/mold/master/template/shim to transfer a pattern design to a polymer. NIL Technology specializes in delivering world-class masters for all mentioned technologies.
In UV nanoimprint, transparent masters, often referred to as templates, are imprinted into UV curable polymers at room temperature or slightly above. When the stamp is filled with liquid polymer, the polymer is exposed to UV radiation which that cures the polymer into a solid. Subsequently, the stamp is removed.
NIL differs from the other nanoimprint techniques by the thickness of the polymer layer. In NIL, the polymer layer thickness is comparable to the master structure height. In other techniques, the polymer thickness is much larger than the master structure height. This property completely changes the physics of the polymer flow, and from a more practical standpoint, the other nanoimprint techniques are often faster and are less prone to defects. On the other hand, NIL can be used for semiconductor processing, where the other nanoimprint techniques are rarely applicable.
Typical substrate materials are Silicon, Fused Silica, III-V materials and polymer sheets and typical imprint polymers are PMMA, COC, COP, PC and PET.
NIL Technology and imprint services
NIL Technology offers masters for all techniques mentioned above.
NIL Technology offers lab-scale tools for Nanoimprint lithography (Thermal and UV), UV replication, Hot Embossing, and Roll-2-Plate replication.
NIL Technology offers processing service and prototyping within Nanoimprint Lithography (all variants), Hot Embossing, and UV replication.