Mass-producible monolithic silicon probes for Scanning Probe Microscopes

This paper describes the design, fabrication, and characterization of monolithically micromachined silicon probes for Scanning Probe Microscopes (SPM) applications. Each probe contains three integral components: an atomically sharp tip, a supporting flexural beam and a handle for packaging. A new fabrication technology for producing highly uniform devices has been developed, in which robust processing steps such as oxidation sharpening and etch stop are utilised to replace steps that require critical timing. Improved device uniformity and mass-producibility include the following aspects: (1) wafer-as well as batch-scale uniformity of tip/beam geometry, (2) robust compensation of uncertainty and inaccuracy in process and materials, and (3) no requirement for post-process assembly (e.g. wafer-wafer bonding). The flexural beam exhibits good mechanical characteristics (high resonant frequency, zero intrinsic stress, low creep and fatigue) due to the monolithic single crystal silicon material used. Mechanical characteristics of the probes, including resonant frequencies and quality factor, have been experimentally determined using a laser Doppler vibrometer. The operation of probes has been successfully demonstrated in force feedback configuration (AFM mode).