Tag Archives: NEMS

Direct, Low Frequency Capacitance Measurement for Scanning Capacitance Microscopy

Posted on by

Summary:

Scanning capacitance microscopy (SCM) circuits, used for such applications as semiconductor characterization (including dopant profiling, device characterization, and surface defect characterization), are typically not adapted for calibrated, low frequency measurements of absolute capacitance. In fact, these implementations of SCM generally do not measure capacitance directly. Rather, they measure the change in capacitance versus the change in voltage (dC/dV) by varying the probe-sample voltage V at frequencies greater than 10 kHz. This is due to a voltage dependant capacitance resulting from a voltage-dependant space change layer in the semiconductor substrate. The Ohio State University has developed a system and method for performing scanning capacitance microscopy using an atomic force microscope (AFM) that measures direct capacitance at a frequency less then 10 kHz. The system exhibits high sensitivity with very low noise. Recent advancements to this technology have resulted in even higher sensitivity by enabling direct measurements of absolute capacitance at higher frequencies. The design of the circuit has also been simplified, enabling the use of off-the-shelf components such as function generators. This straightforward design will shorten the investment of time and money needed to commercialize this powerful system.

Potential Applications:

This system is an ideal tool for semiconductor characterization. It is also useful for measuring a wide variety of dielectric films such as SiO2 grown on Si, or for dielectric films on other semiconductor substrates such as Si3N4, Al2O3, TiO2, and ZrO2. It may also be used to measure thin lubricant films such as perfluoropolyethers, a widely used class of compounds for MEMS and hard disk drive lubrication. Other suitable types of samples include self-assembled monolayers.

Advantages:

  • Enables direct capacitance measurements at low frequencies
  • Low noise
  • High sensitivity
  • Straightforward yet powerful design
  • Can also determine stray capacitance

Super hydrophobic surface profiles

Posted on by

Summary:

Engineers at The Ohio State University have developed super-slick, water-repellent surfaces that mimic the texture of lotus leaves. Scientists have long known that the lotus, or water lily, provides a good model for studying water-repellent surfaces. In studying this leaf, which is covered with microscopic bumps, OSU’s inventors realized that its texture could be exploited in applications where reduced friction is desired, as water-repellent surfaces generally exhibit a low coefficient of friction. The challenge is in optimizing the surface for specific materials and applications, so the researchers developed the first computer model that calculates the optimal distribution of "bumps" on the surface for a particular application. Among the wide range of potential applications, this technology could lead to self-cleaning glass, and could also reduce friction between the tiny moving parts inside micro-electrical-mechanical systems (MEMS), which can’t be lubricated by traditional means.

Potential Applications:

  • Self-cleaning glass for automotive and building applications
  • Water-repellent textiles/clothing
  • Lubrication of individual parts in MEMS/NEMS devices
  • Replacement of traditional lubrication techniques for a wide class of machine components
  • May reduce aerodynamic drag for automotive/aerospace applications
  • Self-cleaning solar panels

Advantages:

  • Overcomes limitations of traditional lubrication techniques for MEMS/NEMS devices
  • Can be optimized for a particular application
  • Achieves a lower coefficient of friction than the lotus leaf itself

Multi-Degree-of-Freedom Nano-Probes: Design, Actuation, and Measurement

Posted on by

Summary:

In applications such as scanning probe microscopy (e.g. AFM), nano-metrology, and micro/nano manipulation, traditional nano-probes are limited in that their tips have a fixed orientation. As a result, they are useful primarily for near-planar samples. Complex geometrical features or features with large changes in topography can either not be imaged at all or are imaged at greatly reduced lateral resolution with increased artifacts. Researchers at the Ohio State University have developed a novel multi-axis nano-probe that enables high-resolution imaging of 3-D surfaces on arbitrarily complex geometric features and nano-manipulation of 3-D samples. For these applications, the probe enables fast and precise co-located control of tip orientation by several tens of degrees and multi-axis control of probe-sample interaction forces. Together, they allow for controlled 3-D manipulation of soft, sensitive specimens and imaging samples with complex geometry (like re-entrant features and steep side-walls).

Potential Applications:

  • AFM equipment manufacturers
  • Nanometrology instrument manufacturers
  • Nanomanipulation system manufacturers
  • NEMS/MEMS manufacturers

Advantages:

  • Enables control of probe-orientation along two independent axes by several tens of degrees while retaining the probe-stiffness along the Z-axis
  • Compact, high-bandwidth, high-gain actuation for fast, large-angle tip-positioning
  • Enables the measurement of tip orientation angles that are possibly over a hundred times larger than the measurement range of the optical detectors used in scanning probe microscopy while retaining the high resolution of the detectors
  • Enables multi-axis co-located control of probe-sample interaction forces
  • Enables real-time tracking of surface orientation by the probe-tip during 3-D imaging of sample surfaces

Methods and Systems for Ultra-Precise Measurement and Control of Object Motion in Six Degrees of Freedom

Posted on by

Summary:

In microelectromechanical systems (MEMS), microelectronic fabrication techniques have led to mostly planar parts having dimensions in the vertical direction of only a few micrometers. Multi-scale 3-D devices, whose components range in size from several millimeters down to nanometers, are believed by many researchers and practitioners to potentially have a much greater range of applications than MEMS in a wide range of industries including medicine, communications, defense, aerospace, and consumer products. Metrology, manipulation, and testing of these devices have proven to be a significant barrier to their further development. To overcome this barrier, researchers at The Ohio State University have developed a visual sensing method and system that provides the full pose of multiple 3-D micro objects with under 10 nanometer precision in x-y-z. Furthermore, the system can automatically perform positioning and alignment of micro objects in real time using measurements derived from a single image, so that no scanning is necessary to obtain ‘out-of-plane’ motion parameters. Applications include dynamic alignment of micro parts, assembly of micro-optical and micro-mechanical components, and assembly of micro sensors, among others.

Potential Applications:

  • Micro-assembly and manipulation station developers
  • Sensor and measurement system manufacturers
  • R&D workstation developers

Advantages:

  • Provides the full pose of multiple 3-D objects with under 10nm precision in x-y-z
  • The six-degree-of-freedom motion of each micro object is measured from a single image so that no scanning is necessary to obtain ‘out-of-plane’ motion parameters
  • Allows automatic real-time positioning and alignment of micro-objects
  • Can serve as a compact motion sensor and can be employed to achieve direct metrology and direct visual servo control in the object space with nanometer resolution