Development Of The Atomic Force Microscope Scanning Head Based On The QPlus Technology And Its Calibration Method

Atomic force microscope as a member of its family, with advantages of multi-subject detection, high adaptability to circumstance, and the ultra high resolution, has become a very important tool in nanoscience research and nanotechnology manufacture field, widely applied in various areas such as physical, electrochemical, material science, biomedicine etal. With the development of science and technology, qPlus technology has become the hot technology of the current in the scanning probe microscope field.In this paper, the development of atomic force microscope measuring head based on qPlus technology mainly includes the following aspects of content:First, the physical design of atomic force microscope scanning head, whose force sensor is a combination of quartz tuning fork as piezoelectric micro cantilever and probe made by the method of mechanical cutting platinum-iridium wire, then providing external mechanical stimulation by piezoelectric ceramics. Second, the design of the preamplifier, includes current voltage conversion unit and parasitic capacitance compensation unit, which can extract the weak current signal from the piezoelectric tuning fork successfully. Third, the research on demodulation of detection signal and the realization of the excitation signal, selecting integrated digital phase-locked amplifier solve both problems, improving the integration of the system. Fourth, system performance test, verified the linear working distance of developed qPlus AFM scanning head is about 50 nm and resolution is better than 2.4 nm by Frequency Range Sweep, Force-Distance and the Resolution Test. In addition, to achieve the calibration of atomic force microscopy, studied a group of one dimensional grid standard method of fixed value, having written the program of gravity method for calculating the grating period.Through the design, setting up a small scanning head of atomic force microscope based on qPlus technology, verified the feasibility of the scanning head. This lay the foundation for later research, and has the vital significance for the comprehensive research and development of nanometer measurement instrument at the same time. In addition, established a set of grid micro-nano standards, what is perfect for the nanometer metrology.