Nanoimprint lithography is an advanced methodology that allows the creation of circuits by pressing the imprinting of a scale mask on the substrate. This technology is fully compatible for meeting the standard micro-fabrication needs such as etching, lift-off, diffusion or selective re-growth.
In this article, we will provide a complete overview of the most popular and effective Nanoimprinting techniques:
- Thermal Nanoimprint: Thermal Nanoimprint lithography means embossment of characters onto a thermoplastic material or thermoplastic coating. With this method, multiple layers of topography can be stacked on the imprint molds. In this, the substrate is typically heated up to 20-40 degrees above the glass transition temperature after which an external force is applied on the embossing roller to shape up the substrate into required features. Lastly, the material is cooled by decreasing the overall temperature and it is stripped from the thermal embossing roller.
- UV Nanoimprint: It is ideal for multi-level patterning, where high precision and quality is the priority. This process follows a straightforward approach and can be performed easily at room temperature without generating thermal gradients. Under this technique, a photo-curable resist is used to withstand the UV-light exposure. Due to the absence of heating and cooling cycles in this technique, the production time is shortened. In addition to this, stamps can be easily obtained through casting and curing a liquid precursor onto a silicon master.
- Hot Embossing: Hot embossing can be defined as the process of structuring and embossing stamps on polymer films. As compared to other techniques, hot embossing is less prone to defects and is cost-effective.
- µ-contact Printing: Micro-contact printing technique is used for transferring certain molecules onto the surfaces by using advanced elastomeric stamps. This technique creates relief patterns on master polydimethylsiloxane (PDMS) stamp to form self-assembled monolayers (SAMs) on the surface of the substrate. Also, this technique requires less energy and cost for fabrication than other conventional techniques.
- Polymer Bonding: It is a technique used to create patterns in synthetic polymers by co-polymerizing both functional and cross-linking monomer. This technique is based on the formation of binding sites (also called as ‘imprints’) in a macromolecular matrix by a molecular casting procedure. Few characteristics such as robust nature and wide flexibility make this technique ideal for numerous applications in affinity separation.
Each technique falling under NIL has its own pros and cons. Therefore, it’s important to consider various factors, features, and cost before choosing the most suitable one.