Batch fabrication of atomic force microscopy probes with recessed integrated ring microelectrodes at a wafer level

A batch fabrication process at the wafer-level integrating ring microelectrodes into atomic force microscopy (AFM) tips is presented. The fabrication process results in bifunctional scanning probes combining atomic force microscopy with scanning electrochemical microscopy (AFM-SECM) with a ring microelectrode integrated at a defined distance above the apex of the AFM tip. Silicon carbide is used as AFM tip material, resulting in reduced mechanical tip wear for extended usage. The presented approach for the probe fabrication is based on batch processing using standard microfabrication techniques, which provides bifunctional scanning probes at a wafer scale and at low cost. Additional benefits of batch fabrication include the high processing reproducibility, uniformity, and tuning of the physical properties of the cantilever for optimized AFM dynamic mode operation. The performance of batch-fabricated bifunctional probes was demonstrated by simultaneous imaging micropatterned platinum structures at a silicon dioxide substrate in intermittent (dynamic) and contact mode, respectively, and feedback mode SECM. In both, intermittent and contact mode, the bifunctional probes provided reliable correlated electrochemical and topographical data. In addition, simulations of the diffusion-limited steady-state currents at the integrated electrode using finite element methods were performed for characterizing the developed probes.