Thermal scanning probe lithography—a review

Abstract

Fundamental aspects and state-of-the-art results of thermal scanning probe lithography (t-SPL) are reviewed here. t-SPL is an emerging direct-write nanolithography method with many unique properties which enable original or improved nano-patterning in application fields ranging from quantum technologies to material science. In particular, ultrafast and highly localized thermal processing of surfaces can be achieved through the sharp heated tip in t-SPL to generate high-resolution patterns. We investigate t-SPL as a means of generating three types of material interaction: removal, conversion, and addition. Each of these categories is illustrated with process parameters and application examples, as well as their respective opportunities and challenges. Our intention is to provide a knowledge base of t-SPL capabilities and current limitations and to guide nanoengineers to the best-fitting approach of t-SPL for their challenges in nanofabrication or material science. Many potential applications of nanoscale modifications with thermal probes still wait to be explored, in particular when one can utilize the inherently ultrahigh heating and cooling rates.

Thermomechanical Nanocutting of 2D Materials

“…[ 5 ] Specifically, thermal scanning probe lithography (t‐SPL) is an emerging direct‐write method that uses a heated nanotip for 2D and 3D subtractive/additive manufacturing. [ 20–22 ] The creation of patterns by t‐SPL is accomplished by consecutive indentation of the sample with the heated nanotip while simultaneously scanning the sample. In addition to ultrafast writing, the sample can be imaged with the cold tip similar to conventional atomic force microscopy (AFM), enabling closed‐loop lithography and pattern overlay.…”

Tuning Surface Morphology of Fluorescent Hydrogels Using a Vortex Fluidic Device

“…Our results demonstrate a novel technique, facilitating a one-step fabrication of PVA hydrogels with different surface morphologies. However, more studies are required to examine the effectiveness of the proposed method for the fabrication of a series of hydrogels, with their creation relying on the formation of hydrogen bonds including, but not limited to, PVA, gelatin, starch, cellulose, guar gum, and their composites [27][28][29]. Another direction for future studies is to develop an understanding of the mechanism of the formation of hydrogels.…”

“…The creation of micropatterned hydrogels is also achieved by soft lithography using elastomers [26]. Although this approach has been used for the fabrication of both physically and chemically crosslinkable hydrogels, detachment of hydrogels from the mold is a major drawback, affecting the quality of the patterns [27].…”

Residue analysis of thermally depolymerized phthalaldehyde‐based polymer thin films

“…Pragmatic considerations of shelf life and deposition of volatile monomers onto exposure and metrology tools prevented its commercialization 1,2 . More recently, pPHA has become one of the choice resist systems for thermal scanning probe lithography due to its ability to cleanly degrade and vaporize in response to heat 3,4 . The patterning process involves bringing a heated probe tip, at a temperature up to ~1000°C, in contact with the resist for 1 to 100 μs to vaporize the polymer to form a topographical pattern.…”

“…The patterning process involves bringing a heated probe tip, at a temperature up to ~1000°C, in contact with the resist for 1 to 100 μs to vaporize the polymer to form a topographical pattern. The ability to directly pattern features on nanometer length scales without the need for photomasks or vacuum systems makes this a promising technology to rapidly prototype and manufacture structures for applications in sensors, imprint molds, and other nanodevices 4‐6 . The clean degradation of pPHA is due to the fact that it is a metastable polymer that can spontaneously depolymerize to its constituent monomers at ambient conditions in response to specific stimuli.…”