D. Strathearn

A 0.25mm 3 Atomic Force Microscope on-a-chip

This paper reports the highest resolution achieved with a single-chip Atomic Force Microscope (sc-AFM). Images of a 20nm AFM calibration standard were obtained to show, for the first time, that single-chip instruments may obtain a vertical resolution comparable to state-of-the-art instruments at a minuscule fraction of the size (volume=1/1,000,000) and cost (1/1000). A maskless, 2-step release process is performed on CMOS chips in order to obtain devices that can image a sample without the need for any off-chip scanning or sensing components. We report a four-fold improvement in resolution when compared to previously reported sc-AFMs, enabling metrology for nanoscale manufacturing using MEMS AFM technology.

A distortion-free single-chip atomic force microscope with 2DOF isothermal scanning

A distortion free single-chip scanning probe microscope (sc-SPM) has been developed. The reported design integrates the 3 DOF scanner, sensors, and tip that are required for nanometer-scale measurements onto a single chip. This low-cost instrument has achieved imaging resolution comparable to conventional tools without the image distortion that was present in prior single-chip SPMs, arising from thermal coupling between electrothermal actuators. A single chip atomic force microscope is used with a novel 2D isothermal scanning algorithm to obtain a 5 μm × 3 μm rectangular topographical map, free from image distortion.

A multimode single-chip scanning probe microscope for simultaneous topographical and thermal metrology at the nanometer scale

This paper reports the first single-chip scanning probe microscope (sc-SPM) that is capable of simultaneously performing atomic force microscopy (AFM) and scanning thermal microscopy (SThM) without requiring any off-chip scanning or sensing components. A thermal-piezoresistive resonant sensor is used to hold the tip-sample interaction force constant, while a bolometer-style probe measures local heat transfer effects. The reported instrument obtains local thermal measurements of powered electrothermal MEMS devices and also achieves the first patterning results with a single-chip scanning probe instrument. Importantly, subsurface features on a 22nm CMOS chip are revealed by thermal phase imaging with the present device.

Optical MEMS index finger microgesture input sensor for mobile and wearable devices

We report the first optical microsystem that captures index finger microgestures with the precision, bandwidth, power consumption and form-factor required for close-range handwriting and gesture keyboarding (e.g. Swipe) on smart watches and mobile handsets. Finger position is measured with 30μm resolution (at a 5cm distance) at a bandwidth of up to 550Hz while consuming less than 15mW with the reported prototype system. A VCSEL, scanning diffractive optic element (DOE), and photodiode may be packaged in a 2×2×1mm package to fit unobtrusively in a wearable device. This component may enable the first information-rich touch-less gesture inputs to wearables.

A platform technology for metrology, manipulation and automation at the nanoscale

We present a platform technology for nanometer-scale metrology, manipulation, automation and robotics that consists of ultra-precise actuators, sensors, and electronics on a single CMOS chip. A conventional CMOS process is adopted to manufacture MEMS devices that can position payloads with sub-nanometer resolution and dynamically detect forces in the piconewton range. One example of an aggressively scaled device that has been designed, fabricated, characterized and commercialized in the present platform is a single-chip atomic force microscope (sc-AFM) that achieves atomic lattice resolution in the vertical direction. The modeling and design of sc-AFMs to optimize their distortion-free scan range, speed of operation, and robustness to ambient fluctuations are presented as example applications of the CMOS-MEMS technology platform.

High Speed, Large Scan Area, Distortion Free Operation of a Single-Chip Scanning Probe Microscope

Despite the exquisite resolution that may be obtained with AFMs, the industrial nanometrology enterprise has been reluctant to include them in their suite of inspection tools. The single-chip AFM [1] was introduced to overcome several shortcomings of conventional AFMs by replacing bulky piezoelectric scanners with 3 degree-of-freedom electrothermal (ET) MEMS actuators and by replacing laser detection with thermal-piezoresistive resonant sensing. These single-chip instruments are wellsuited to high-speed operation and may also be implemented as arrays, as they include all of the components that are required for an AFM to obtain an image on a single chip.

A large angle, low voltage, small footprint micromirror for eye tracking and near-eye display applications

This paper introduces a micromirror device that enables a compact, low-power, high-speed, high resolution eye-tracking system that may be integrated within eyeglasses or heads-up-displays. We report a CMOS-MEMS that achieves a scan range of 65 degrees (optical) in one axis and 25 degrees in another axis. The device operates at CMOS-compatible voltages (0-3.3V) and currents (<;15 mA), and employs isothermal scanning to suppress thermal excursions arising from electrothermal (ET) actuation. The footprint of the device is 40× smaller than commercially available micromirrors, at a mere 750μm × 750μm. Although the eye-tracking system is intended to operate under quasi-static conditions, its 5kHz resonant frequency may also enable QVGA resolution in near eye display applications.