title: Electron beam lithographically-defined scanning electrochemical-atomic force microscopy probes: fabrication method and application to high resolution imaging on heterogeneously active surfaces.
abstract: This paper describes in detail the use of electron beam lithography (EBL) to successfully batch microfabricate combined scanning electrochemical-atomic force microscopy (SECM-AFM) probes. At present, the process produces sixty probes at a time, on a 1/4 of a three-inch wafer. Using EBL, gold triangular-shaped electrodes can be defined at the tip apex, with plasma enhanced chemical vapor deposited silicon nitride serving as an effective insulating layer, at a thickness of 75 nm. The key features of the fabrication technique and the critical steps are discussed. The capability of these probes for SECM-AFM imaging in both tapping and constant distance mode is illustrated with dual topographical-electrochemical scans over an array of closely-spaced 1 microm diameter Pt disc electrodes, held at a suitable potential to generate an electroactive species at a transport-limited rate. As highlighted herein, understanding diffusion to heterogeneous electrode surfaces, including array electrodes, is currently topical and we present preliminary data highlighting the use of SECM-AFM as a valuable tool for the investigation of diffusion and reactivity at high spatial resolution.
authors.affiliation: Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow, UK.
authors.forename: Phillip S
authors.initials: PS
authors.lastname: Dobson
authors.forename: John M R
authors.initials: JM
authors.lastname: Weaver
authors.forename: David P
authors.initials: DP
authors.lastname: Burt
authors.forename: Mark N
authors.initials: MN
authors.lastname: Holder
authors.forename: Neil R
authors.initials: NR
authors.lastname: Wilson
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Unwin
authors.forename: Julie V
authors.initials: JV
authors.lastname: Macpherson
mesh_terms: D002516:Ceramics; D004563:Electrochemistry / Q000379:methods; D007089:Image Enhancement; D038101:Insulator Elements; D018625:Microscopy, Atomic Force / Q000379:methods*; D017655:Silicon Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D017655:Silicon Compounds; C032734:silicon nitride