The atomic force microscope as a mechano–electrochemical pen

Abstract

SummaryWe demonstrate a method that allows the controlled writing of metallic patterns on the nanometer scale using the tip of an atomic force microscope (AFM) as a “mechano–electrochemical pen”. In contrast to previous experiments, no voltage is applied between the AFM tip and the sample surface. Instead, a passivated sample surface is activated locally due to lateral forces between the AFM tip and the sample surface. In this way, the area of tip–sample interaction is narrowly limited by the mechanical contact between tip and sample, and well-defined metallic patterns can be written reproducibly. Nanoscale structures and lines of copper were deposited, and the line widths ranged between 5 nm and 80 nm, depending on the deposition parameters. A procedure for the sequential writing of metallic nanostructures is introduced, based on the understanding of the passivation process. The mechanism of this mechano–electrochemical writing technique is investigated, and the processes of site-selective surface depassivation, deposition, dissolution and repassivation of electrochemically deposited nanoscale metallic islands are studied in detail.

Reversible mechano-electrochemical writing of metallic nanostructures with the tip of an atomic force microscope

“…Writing of metallic structures with the tip of an atomic force microscope as a “nano-electrochemical pen” was performed as described in our previous work [12]. A glass substrate covered with a polycrystalline gold film is used as a substrate.…”

“…The results of previously reported [12] already showed that once an area or line along the surface is activated with the AFM tip, the passivation layer starts to regrow within a certain time, which was typically on the order of seconds (depending on the chemical parameters of the system such as concentrations, pH value), requiring a continuous reactivation of the active area of the surface with the tip of the AFM to allow for the nucleation of further islands. Assuming this, a repeated scanning of the same line or trace with the AFM tip is needed during the structuring process to prevent repassivation of the tip-activated areas before the deposition process is completed.…”

“…Examples of recent work can be found in the literature [30–40]. At the same time, the scanning tips of the atomic force microscope, the scanning tunneling microscope (STM) and related instruments can be used as tools for surface modification and nanolithography [9–12 41–48], even down to the atomic scale [41–45]. The great advantage of these instruments for nanoelectrochemistry is the fact that they also allow the in situ and real-time observation of the processes within the electrochemical cell [49–53], making them a valuable tool for studying electrochemical processes on the nanometer scale.…”

“…Recently, we demonstrated the local electrochemical deposition of metallic nanostructures and nanowires mechanically induced with the tip of an AFM [12]. In the semiconductor industry, mechano-electrochemical processes are frequently used in the form of mechano-electrochemical polishing.…”

Site-selective growth of surface-anchored metal-organic frameworks on self-assembled monolayer patterns prepared by AFM nanografting

“…The feature sizes that can be achieved with this method, however, are limited and the preparation of sub-micrometer sized patterns is challenging or even impossible for µCP. The fabrication of structures within SAMs [26] of higher resolution can be obtained by nanoshaving and nanografting [27] or other methods based on scanning probe microscopy techniques, e.g., atomic force microscopy (AFM) [28–29]. Both lithography methods allow for lateral structuring with resolutions down to several nanometers.…”