Nanofabrication, nanoscale devices, nano‑objects in fluids
Nanoscale patterning is being explored to create unique and novel devices and concepts. We are examining novel fabrication schemes and using their capabilities to create unique functional devices. Applications range from the fabrication of nanoscale electronic devices, (nano-)fluidic concepts for particle placement, transport and separation, to novel devices for studying graphitic interfaces.
Thermal scanning probe lithography
A hot tip is used to produce patterns with sub‑10‑nm lateral and sub‑1‑nm vertical accuracy.
Being able to create nanometer accurate patterns and structures is at the heart of nanoscale science and technology. We use a heated scanning probe tip to trigger locally the decomposition reaction of a thermally sensitive resist material. With each contact of the hot tip, a well-defined void is created, resulting in a pattern with high accuracy of its lateral and vertical dimensions. For 2D fabrication, we achieve <10 nm lateral resolution in the resist without it suffering from proximity effects. Linear speeds of up to 20 mm/s and pixel rates of up to 500 kHz have been demonstrated.
In t-SPL, the pattern is created and imaged on the fly, providing direct feedback of the lithography result to the user. The nanometer-precise imaging of the surface prior to patterning enables a sub-5-nanometer precise overlay to existing structures on the sample. Using a dedicated transfer stack, we obtained high-resolution patterns with feature sizes down to 11 nm half pitch in substrate etching, metal lift-off or ion milling. A unique feature of t‑SPL is the capability to write 3D profiles with nanometer accuracy in a single patterning run. We exploit this feature to gain control over objects in nanofluidic confinement.
“A unique feature of t‑SPL is the capability to write 3D profiles with nanometer accuracy in a single patterning run.”
—IBM scientist Armin Knoll
Fabrication of high-performance solid-state silicon quantum devices
High-resolution patterning with minimal substrate damage
Particle–surface interactions in nanofluidic confinement depend strongly on the separation between the surfaces. Accordingly, by shaping the topography of the surfaces, the interaction can be modulated and the particles experience an energy landscape designed by the topography. We strive to use this method to explore novel concepts for the control, transport, separation and positioning of particles.
Current reversal in a rocking Brownian motor
Experimental verification of a longstanding theory
We aim to control the positioning and deposition of colloidal objects that range from several tens of nanometers to a few micrometers in size. Capillary forces at the edge of a moving meniscus are very suitable to position large numbers of colloidal objects in parallel into predefined trapping sites on a template. In a sequential assembly process, new colloidal materials—called “colloidal molecules”—can be produced with an unprecedented freedom of composition and shape. Such colloidal molecules are very promising model systems for molecular assembly processes, and they are building blocks for actively and autonomously moving colloidal objects that can mimic active living matter.