A Miniature Piezoresistive Transducer and a New Temperature Compensation Method for New Developed SEM-Based Nanoindentation Instrument Integrated With AFM Function

Instrumented indentation test inside SEM has become a versatile method for nanomechanical characterization and studying of deformation and failure mechanisms of coating materials at nano-to micro-scale thickness. However, the existing SEM-based nanoindentation instrument cannot acquire surface roughness of coating materials at nano-to micro-scale thickness before nanoindentation and the morphology of residual imprints in real-time inside SEM after nanoindentation. To overcome those two limitations, a new SEM-based nanoindentation instrument integrated with AFM function has been developed. This paper presents a miniature piezoresistive transducer capable of measuring force up to ±2.5N with a resolution of 0.5μN, and measuring displacement up to ±36μm with a resolution of 0.01nm for new developed SEM-based nanoindentation instrument. The transducer design, optimization, readout electronics and characterization are described. Cross-shape compliant mechanism is adopted considering the influence of the lateral force during nanoindentation process. Moreover, four piezoresistive bar-type semiconductor strain gauges (SCSG) have been glued on the cross-shape compliant mechanism enabling the transducer has a compact structure. A new temperature compensation method for SCSG sensors is proposed and solves the problem of amplifier saturation compared with traditional temperature compensation method. Compared with the existing widely used capacitive-based transducer for instrumented indentation test inside SEM, cross-shape piezoresistive transducer shows larger measured ranges. Compared with the existing piezoresistive-based transducer for instrumented indentation test inside SEM, cross-shape piezoresistive transducer shows better resolutions. In the end, the validation test of AFM imaging inside HITACHI SU5000 using standard AFM calibration chip SiC/0.75 is tested.