Long-range AFM profiler used for accurate pitch measurements

Abstract

A long-range atomic force microscope (AFM) profiler system was built based on a commercial metrology AFM and a home-made linear sample displacement stage. The AFM head includes a parallelogram-type scanner with capacitive position sensors for all three axes. A reference cube located close to the tip acts as the counter electrode for the capacitive sensors. Below this metrology AFM head we placed a linear sample displacement stage, consisting of monolithic flexures forming a double parallelogram. This piezo actuated stage provides a highly linear motion over 380 µm. Its displacement is simultaneously measured by a capacitive position sensor and a differential double-pass plane mirror interferometer; both measuring systems have subnanometre resolution capability.For the measurement of periodical structures two operating modes are possible: a direct scanning mode, in which the position of the displacement stage is increased point by point while the AFM head measures the height, and a combined scanning mode where the displacement stage produces offsets which are multiples of the pitch to be measured while the AFM head is simultaneously scanning to locate an edge or a line centre position. Construction details, system characteristics and results from first pitch measurements are presented. The estimated relative combined uncertainties for pitch values on different standards are in the range 2 × 10 −5 to 8 × 10 −5 . Laser diffraction measurements of comparable uncertainty were performed on the same standards and show a very good agreement.

Signal Transformation Approach to Tracking Control With Arbitrary References

“…Equations (9) and (10) reveal that the closed-loop system dynamics are nonlinear in a monotonic time interval. Since the nonlinear functions change when one monotonic interval is switched to the next, the system has a time-varying nature as well.…”

“…Such applications include scanning probe microscopy [3]- [5], nanometrology [6]- [9], nanolithography [10], [11], material science [12], [13], high-density data storage systems [14]- [16], and nano-fabrication [17]. Capacitive and inductive sensors are commonly used in nanopositioning systems due to their capability of providing simple solution for non-contact, high-resolution measurement.…”

The Design and Characterization of a Piezo-Driven Inchworm Linear Motor with a Reduction-Lever Mechanism

“…All elements are connected to each other through flexure hinges. Lever mechanisms have been widely applied to amplify the input motion of the piezoelectric actuators (15) - (17) . Unlike those, reduction flexure levers are utilized in the push-pull device.…”

Deep atomic force microscopy

“…[5][6][7][8][9] We are interested in using long range AFM to study fractured bone, a sample with rough topography and deep features exceeding the actuation range of conventional AFM. Since the development of the Reference Point Indenter (RPI), [10][11][12][13][14][15] an instrument which directly quantifies bone fracture resistance by creating an indent in bone and measuring the depth of the indent produced, we have been eager to image these indents with long range AFM.…”