Eine Nanopositioniervorrichtung mit integrierten piezoresistiven Sensoren für Hochgeschwindigkeits-Rastersondenmikroskopie-Anwendungen

Der Fokus dieser Arbeit liegt auf der Entwicklung einer quasi-monolithischen Nanopositioniervorrichtung für die Anwendung in Hochgeschwindigkeits-Rastersondenmikroskopie-Systemen. Das Konzept der in dieser Arbeit entwickelten neuen Nanopositioniervorrichtung stellt die quasi-monolithische Integration der kinematischen Konstruktion aus monokristallinem Silizium, der piezoelektrischen Aktoren und der piezoresistiven Sensoren dar. Eine monolithische Integration der Piezowiderstände in die Verformungselemente der kinematischen Konstruktion aus Silizium ermöglicht eine Kompensation von möglichen Nichtlinearitäten. Die entwickelte Positioniervorrichtung wurde als Prototyp implementiert und die Funktionsfähigkeit experimentell bestätigt. In einem Rasterkraftmikroskopiesystem wurden Kalibrierung und Probemessungen erfolgreich durchgeführt.

This work focuses on the development of a quasi-monolithic scanning stage for high scanning probe microscopy (SPM) applications. Conventional positioning stages are characterized by a low resonance frequency (usually lower than 3 kHz). Therefore they posses decreased operating frequency ranges. In order to increase the resonance frequency, it is necessary to use materials with a high elasticity module and small mass density. However, the increase of stiffness is limited by material properties as well as by driving forces. Multilayer piezoelectric actuators, which can realize high force and extension, cannot support high-dynamic processes. Furthermore, the hysteresis and the creep are critical properties of piezoelectric actuators and they have to be compensated in order to raise the positioning precision. In this work, a developed concept of the nanopositioning stage presents a quasi monolithic integration of the kinematical construction from mono- crystalline silicon, piezoelectric actua-tors and piezoresistive sensors. The novel design and concept has been protected by the patent specifications DE102007005293 and EP2126925. The high E-module and a small density of the silicon open a possibility for the rise of the resonance frequency of the construction. A monolithic integration of the piezoresistors in the flexures of the kinematical construction from silicon allows a compensation of possible non-linearities. The design of the novel nanopositioning stage is based on parallel kinematics. Thereby, a transmission of the drive force and the decoupling between orthogonal movements has been realized by Ω-shaped elements. In a quasi-static operation these elements scale down the ex-tension of the actuator. This increases the resolution of the stage. The piezoelectric actuators are driven pair wise in a push-pull-mode. Thus, overshoots can be suppressed to some large extend. The concept for the operating frequency range expansion is explained in detail as a part of the thesis. A prototype of the new positioning stage has been implemented and its functional abilities have been evaluated. The exact movement of the sample holder in the x-y-direction has been measured by the developed combination of piezoresistive sensors, which are embedded in the construction’s flexures. Calibration and successful test measurements have been performed by using an atomic force microscope system. The nanopositioning stage posses a resonance fre-quency of 27 kHz and a scanning range 5 μm x 5 μm. Experimental and application oriented re-sults have proven the theoretically developed concept.

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