Techniken der Oberflächenphysik (Techniques of Surface Physics) Prof. Yong Lei & Dr. Yang Xu (& Liying Liang) Fachgebiet 3D-Nanostrukturierung, Institut für Physik Contact: yong.lei@tu-ilmenau.de; yang.xu@tu-ilmenau.de; liying.liang@tu-ilmenau.de Office: Heliosbau 1102, Prof. Schmidt-Straße 26 (tel: 3748) www.tu-ilmenau.de/nanostruk Vorlesung: Mittwochs (G), 9 10:30, C 108 Übung: Mittwochs (U), 9 10:30, C 108
What is nanofabrication? How many methods can be used for nanofabrication?
"Nanofabrication" refers to the fabrication of structures with feature sizes measured in the nanometers, especially below 20 nanometers on a side. How to fabricate surfaces especially in nano-sized range? 1. Template-based processes, PVD, ALD, CVD 2. Nanofabrication: Lithography, soft lithography, nano-impringting
What are the two principles of nanofabrication? Please give one or two nanofabrication examples by using the two principles.
Nanofabrication-two principles Top down: Using techniques to remove, add or distribute atoms or molecules in a bulk material to create a final structure. The top-down approach often uses the traditional workshop or microfabrication methods where externally controlled tools are used to cut, mill, and shape materials into the desired shape and order. Micropatterning techniques, such as photolithography and inkjet printing belong to this category. Vapor treatment can be regarded as a new top-down secondary approaches to engineer nanostructures.
Bottom up: This approach seeks to have smaller components (usually atoms or moleculars) direted assembly to create larger scale structures. e.g., chemical self-assembly Bottom-up approaches use the chemical properties of single molecules to cause single-molecule components to (a) self-assemble into some useful conformation, or (b) rely on positional assembly. These approaches utilize the concepts of molecular self-assembly and/or molecular recognition. Such bottom-up approaches should be able to produce devices in parallel and much cheaper than topdown methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases.
Chem. Soc. Rev. 2013, 42, 6006.
How many types does lithography have?
What is photolithography? Please describe its basic steps.
It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate.
compound Substrate (Si) Cleaning & Pre-baking Priming Substrate (Si) Spin-on PR coating Substrate (Si) Hydrophobicity adhesion Even, smooth Soft Baking Exposure Development Positive Photoresist Removing solvent Mask plate UV light Substrate (Si) Substrate (Si) Negative Photoresist Substrate (Si)
The resist becomes crosslinked/polymerized and difficult to dissolve in the developer. The resist becomes more The resist becomes more soluble in the developer. soluble in the developer.
What is X-ray lithography?
Please introduce the two types of charged beam based lithography.
EBL is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electronsensitive film called a resist ( exposing ). The e-beam changes the solubility of the resist, enabling selective removal of either the exposed or non-exposed regions of the resist by immersing it in a solvent ( developing ).
FIB deposition FIB etching
What are soft lithography and nanoimprint lithography?
It is called "soft" because it uses elastomeric materials, most notably PDMS.
It is a simple nanolithography process with low cost, high throughput and high resolution. NIL is based on the principle of mechanically modifying a thin polymer film using a template containing the micro/nanopattern, in a thermo-mechanical or UV curing process. In other words, NIL uses the direct contact between the mold (template) and the thermoplastic or UV-curable resist to imprint (or replicate) the pattern, unlike optical lithography, does not require expensive and complex optics and light sources for creating images. As a result, distinct features for NIL involve two points: (1) the contact nature of the process; (2) direct mechanical deformation of the resist. thermal nanoimprint lithography (T-NIL), UV-based Nanoimprint Lithography (UV-NIL)
That s all. Thank you!