Development of a combined interference microscope objective and scanning probe microscope

Abstract

A compact sensor head combining optical interference and scanning probe microscopy in a single instrument has been developed. This instrument is able to perform complementary quantitative measurements, combining fast nondestructive three-dimensional surface analysis with high lateral resolution imaging. A custom interference microscope sensor head has been designed as the optical microscope objective and integrated within the architecture of a commercial interference microscope. The combined instrument makes available both the acquisition software and the hardware interface of the commercial microscope. The latter is able to function as a phase-shift interferometer or white light interferometer. Furthermore, the use of an optical fiber to transmit light from an external laser: (i) removes a major heat source from the measurement environment and (ii) makes aperture correction unnecessary. The lateral resolution of the instrument has been extended by the addition of a previously developed compact scanning probe microscope (SPM) module to the custom interference microscope objective. This SPM unit is based upon piezoresistive cantilever technology. The “piezolevers” are self-sensing and therefore require no additional systems, such as optical beam deflection or fiber interferometry, to monitor their displacement. The mechanical simplicity of the piezolever SPM unit allows for a small physical size and can thus be added to the custom optical sensor head without violating constraints on the working distance defined by the optics. A major benefit of the system, in terms of a quantitative nanometrology, is the possibility to perform a traceable and direct calibration of the SPM module. This calibration is achieved practically by measuring an appropriate sample at a common location using both techniques. Results are presented here for the measurement of two calibration standards and a test sample to demonstrate the increased lateral resolution of the instrument.

Useful surface parameters for biomaterial discrimination

“…The few and weak correlations encountered among nano and microroughness (Table ) suggest that both techniques give complementary information and thus it is of paramount concern to include two different scales. These results are in agreement with previous authors’ recommendations of using optical measuring methods such as white light interferometry to expand the AFM measuring range and to improve roughness measuring efficiency (Tyrrell et al ., ; Guo et al ., ). Therefore, in general S a ‐S ku ‐S mid at the nanoscale and S a ‐S z at the microscale are not correlated being confirmed the complementarity of both groups of parameters.…”

“…This method has been shown to be fast, non‐destructive and accurate. The combination of both techniques has been proposed to improve the measuring efficiency of AFM for the surface characterization of biomaterials (Tyrrell et al ., ; Guo et al ., ).…”

Dimensionelle Nanometrologie in der PTB – eine Übersicht (Dimensional Nanometrology at PTB – a Survey)

“…Hierbei konnte die Über-A B C I I I I I I I I I EOMS 213 176 293 276 967 964 SFM 205 180 281 270 960 961 Tabelle 1: Ergebnisse der Messung der Kopflinienbreite von einzelnen (II) und mehrfachen (dichten) Si-Linien (I) mit unterschiedlichen nominellen Linienbreiten (A, B, C) unter Verwendung eines Niedervoltelektronenmikroskops (EOMS) und eines Rasterkraftmikroskops (SFM), entnommen aus [26]. in der PTB das Konzept eines multiskaligen Instrumentes realisiert, das den Millimeterbereich mit dem Nanometerbereich verknüpft [32].…”

Phase control of ellipsometric interferometer for nanometric positioning system

“…Producers of CD-masters and DVD-masters as well as integrated circuit manufacturers are using laser interferometers in the nanometer region. In national metrology institutes laser interferometers are popular in use as calibration aids to calibrate other sensors, or to develop new traceable measurement devices, such as atomic force microscopes [1,2]. In such institutes laser interferometers are also used as high precision scales in coordinate measuring machines (CMM's) [3].…”