Table 1.

Comparison of the three concepts for thermal scanning probe lithography: removal, conversion and addition of material

	Removal	Conversion	Addition
Resolution
Demonstrated	8 nm half-pitch29,128	10 nm feature size81	35 nm110 10 nm117 (with particles)
Typical	20–50 nm	50–100 nm	100–500 nm
Limitation	Tip shape, temperature	Tip shape, temperature	Large effective tip radius due to loaded material, substrate wettability, temperature, contact duration
Speed
Demonstrated	20 mm/s7	1.4 mm/s78	40 µm/s110
Typical	0.1–1 mm/s	1–200 µm/s	0.1–5 µm/s
Limitation	Actuation frequency, and trade-off between scan speed and position accuracy	Reaction kinetics, heat diffusion	Mass flow, diffusion
Features and challenges	Closed-loop lithography permits 3D (grayscale) lithography with 1 nm vertical resolution Sub-10 nm marker-less overlay and field stitching Long tip lifetime possible (few days patterning), despite potential challenges with tip contamination	New material systems can be experimentally tested very quickly if suitable for conversion Strong temperature/force dependence can limit the reproducibility Patterning on hard surfaces can cause severe tip wear	Resolution depends on various parameters that need to be controlled well Risk of contaminating sample with ink during imaging Ink supply limited by tip capacity (might require reload of tip)
Applications	Prototyping of all kind of nanodevices and 3D masters Wide selection of etch transfer, lift-off and other processes for almost any material Compatible with mix-and-match lithography with integrated laser for increased throughput	Large potential for biological applications that require specific chemical binding Unique capability to produce nanoscale chemical gradients Nanodevices that require local change of physical properties like magnetization, ferroelectricity or conductivity	Deposition of various polymers, composites and metals Direct deposition of polymeric masks for further standard nanodevice processing Suitable for devices with topographies where negative resist patterns are required
Maturity	Technologically advanced (dedicated machines, cantilevers, softwares, resists, and processes) Alternative and extension to standard electron beam lithography in particular for materials/devices sensitive to damage from charged particle beams	Wide range of materials that can be thermally modified Few established processes beyond the individual research groups who developed it Good calibration and understanding might be required	Exploratory status Few people with experience Tip loading, good calibration and understanding of the deposition process are required

Note that the values for resolution and speed need to be interpreted with great care. Best demonstrated values often mean that experiments are pushed to the extreme and at the expense of other criteria, while best values also don’t necessarily mean that these values are already the physical limits. We quote the best demonstrated and typical values found in literature and used for real applications and add an interpretation based on our own experience and assumptions