International Business Machines Corporation

James Michael Hammond

Kenneth Gilbert Roessler

Dong Chen Chen

Edwin Flecha

Michael Servedio

Jiann-Chang Lo

James E Boyette, Jr

Yves Corfield Martin

Martin A Klos

Robert M Stowell

James Christopher Mahlbacher

Hans-George H Kolan

David William Abraham

Hemantha Kumar Wickramasinghe

Li-Cheng Richard Zai

Salvatore R Riggio, Jr

Ali Reza Taheri

The vibrating probe of a scanning force microscope is brought into engagement with a sample surface in an initial approach process moving the probe toward the sample surface until the amplitude of probe vibration at an excitation frequency is measurably affected by forces between the tip and the sample, an then in a final approach process in which a change in vibration amplitude caused by a dithering vibration superimposed on the excitation vibration exceeds a pre-determined threshold limit. The excitation frequency is reduced if the phase angle of vibrations exceeds another limit, and the amplitude of the excitation driving function is increased as the amplitude or tip vibration falls below a setpoint. During approach and scanning, vibration amplitude is measured through a demodulator having an intermediate reference signal locked in phase with the tip motion signal.

Scanning force microscope with automatic surface engagement

Controlling motion of a scanning force microscope probe tip moving into engagement with a sample surface

A scanning probe microscope operates in the manner of an atomic force microscope during intermittent periods of scanning motion, in which a sample surface is driven so that a scan line on the surface is moved past a probe tip being vibrated in engagement with the surface. Between these intermittent periods of scanning motion, the vibrating probe tip is moved out of engagement with the sample surface, so that the amplitude and phase shift of probe tip vibrations are determined by the gradient of a force field extending outward from the sample surface. Such a force field is established when the probe tip is attracted by, or repelled from, a magnetic or electric field at or near the sample surface. For each sample point, the system stores data representing the height of the sample surface and the force field.

Detecting fields with a single-pass, dual-amplitude-mode scanning force microscope

The probe tip of a scanning probe microscope is scanned either along an X- or Y-direction of the apparatus, or along a scan line forming an acute angle with both the X- and Y-directions. During scanning, an excitation vibration is applied in the Z-direction, perpendicular to the surface of the sample being scanned. In a first mode of operation, a dithering vibration is applied to the probe tip, along the scan line. In a second mode of operation, the probe tip is dithered in a circular motion, which is used to identify the direction in which a wall extends along the sample surface. Alternately, in a third mode of operation, the probe tip is dithered in X- and Y-directions at differing vibrational frequencies to identify this direction of a wall. When this direction is identified, the probe proceeds straight up or down the wall to obtain an accurate profile thereof.

Apparatus and method for determining side wall profiles using a scanning probe microscope having a probe dithered in lateral directions

A scanning probe microscope having a probe attachment fixture, to which a probe assembly is removably attached during measurements, driven in an engagement direction, and a sample stage driven in scanning directions perpendicular to the engagement direction includes a buffer with a number of buffer stations within the sample stage. When the stage is driven so that one of the buffer stations is in alignment with the attachment fixture, and when the attachment fixture is driven in the engagement direction to be in proximity to the buffer station, the probe assembly is selectively transferred in either direction between the attachment fixture and the buffer station. In a preferred embodiment, probe assemblies are transferred on transfer pallets, and a stationary magazine is provided for storing these pallets, which are transferred in either direction between the magazine and the buffer.

Automatic probe replacement in a scanning probe microscope

The vibrating probe of a scanning force microscope is brought into engagement with a sample surface in an initial approach process moving the probe toward the sample surface until the amplitude of probe vibration at an excitation frequency is measurably affected by forces between the tip and the sample, and then in a final approach process in which a change in vibration amplitude caused by a dithering vibration superimposed on the excitation vibration exceeds a pre-determined threshold limit. The excitation frequency is reduced if the phase angle of vibrations exceeds another limit, and the amplitude of the excitation driving function is increased as the amplitude or tip vibration falls below a setpoint. During approach and scanning, vibration amplitude is measured through a demodulator having an intermediate reference signal locked in phase with the tip motion signal.

Scanning force microscope with automatic surface engagement and improved

A scanning probe microscope operates in the manner of an atomic force microscope during intermittant periods of scanning motion, in which a sample surface is driven so that a scan line on the surface is moved past a probe tip being vibrated in engagement with the surface. Between these intermittant periods of scanning motion, the vibrating probe tip is moved out of engagement with the sample surface, so that the amplitude and phase shift of probe tip vibrations are determined by the gradient of a force field extending outward from the sample surface, Such a force field is established when the probe tip is attracted by, or repelled from, a magnetic or electric field at or near the sample surface. For each sample point, the system stores data representing the height of the sample surface and the force field.

Detecting fields with a single-pass, dual-amplitude-mode scanning force

A scanning probe microscope includes a segmented piezoelectric actuator having a course segment and a fine segment, the outputs of which are combined to determine the movement of a distal end of the actuator, to which the probe is mechanically coupled. Movement of the probe tip, or a change in the level of its engagement with a sample surface is sensed by a detector, which generates a feedback signal. A correction signal, which is used to determine how the actuator should be moved to maintain a constant level of such engagement, is generated in a comparison circuit, which compares the feedback signal with a control signal. The correction signal is used to drive the fine segment of the actuator, while an integral of the correction signal is used to drive the coarse segment.

Controlling engagement of a scanning microscope probe with a segmented

Disclosed is a Mini Probe Positioning Actuator which is low in cost and mass, capable of high accelerations, relatively long stroke and compact packaging. The probe positioning actuator is composed of a pair of substantially parallel cantilevered beams, each beam being comprised of flexible, signal carrying cable formed of a polyimide composition which allows for the probe tip to be suspended from and form part of the armature of the actuator. The armature also includes a pair of oppositely wound coils intermediate the beams, which coils coact electromagnetically with a pair of spaced apart but fixedly positioned (relative to the coils/armature) magnets forming a motor for effecting armature and thus probe tip movement. The light mass of the coils and armature and the dual functional purpose of the suspension beams serves to make the probe actuator highly accurate and sensitive while allowing for reliable operation.

Miniature probe positioning actuator

A digital and analog controller for controlling a high-speed probe actuator is disclosed. This method and system provide the probe actuator system with improved damping ratio and reduced impact force, so the throughput of the tester is increased with fast settling actuator armature. With this method and system, the steady-state probe force is less sensitive to the servo system, test probe and variation in the probing distance d. An electronic circuit, which consists of analog operational amplifiers, monostable multivibrators, and D flip-flops, is presented for low-cost applications.

Method and system for controlling high-speed probe actuators

Disclosed is a Probe Positioning Actuator which is low in cost and mass, capable of high accelerations, relatively long stroke and compact packaging, as well as high in efficiency. The actuator assembly comprises a frame, and at least one pair of spaced apart, laterally extending, conductor carrying, flexible beams attached to the frame. A non-magnetic armature, substantially U-shaped in cross section, is attached adjacent or approximate the extended terminal ends of the beams, and a probe is attached to the base of the 'U' of the armature for contacting selected points in the electrical circuit associated with the device being tested. The heart of the actuator includes a coil mounted on the upstanding legs of the U-shaped armature and arranged so that the axis of the coil is perpendicular to the base of the armature but substantially parallel to the probe tip. This arrangement places the `motor` portion of the actuator adjacent the probe and permits accurate and repeatable, fast control of not only probe tip position but probe tip movement. To complete the motor portion of the actuator, means, carried by the frame create a magnetic field across the coil, whereby upon energization of the coil, deflection of the armature (and thus the beams) occurs, effecting movement of the probe tip into contact with selected portions of the device being tested.

Probing system performance is improved by dynamically positioning a test probe at a test site during the gantry settling interval using a high performance secondary positioner to compensate for the inherent moving mass oscillational displacements. A primary positioner positions the gantry and its associated test probe to within a predetermined axis distance of the test site and a secondary positioner dynamically maintains the test probe at a target position corresponding to the test site during the settling interval by imparting compensating displacements to the test probe to counteract the displacement errors incurred as the primary positioner attempts to settle the gantry at the test site. Similarly, automatic machine tool performance is improved by dynamically positioning a work tool at a work site during the gantry settling interval using a high performance secondary positioner to compensate for the inherent moving mass oscillational displacements. A primary positioner positions the gantry and its associated work tool to within a predetermined axis distance of the work site and a secondary positioner dynamically maintains the work tool at a target position corresponding to the work site during the settling interval by imparting compensating displacements to the work tool to counteract the displacement errors incurred as the primary positioner attempts to settle the gantry at the work site.

High speed test probe positioning system

Disclosed is a Probe Positioning Actuator which is low in cost and mass, capable of high accelerations, relatively long stroke and compact packaging, as well as high in efficiency. The actuator assembly comprises a frame, and at least one pair of spaced apart, laterally extending, conductor carrying, flexible beams attached to the frame. A non-magnetic armature, substantially U-shaped in cross section, is attached adjacent or approximate the extended terminal ends of the beams, and a probe is attached to the base of the 'U' of the armature for contacting selected points in the electrical circuit associated with the device being tested. The heart of the actuator includes a coil mounted on the upstanding legs of the U-shaped armature and arranged so that the axis of the coil is perpendicular to the base of the armature but substantially parallel to the probe tip. This arrangement places the `motor` portion of the actuator adjacent the probe and permits accurate and repeatable, fast control of not only probe tip position but probe tip movement. To complete the motor portion of the actuator, means, carried by the frame create a magnetic field across the coil, whereby upon energization of the coil, deflection of the armature (and thus the beams) occurs, effecting movement of the prob into contact with selected portions of the device being tested.

A dual quad flexure carriage and assembly, for receiving a sensing probe, is used for scanning the sensing probe across a target surface. The flexure carriage is a unitary structure providing flat motion for the sensing probe during the scanning procedure, while further compensating for thermal creep. The dual quad flexure assembly comprises the dual quad flexure carriage along with piezo actuators and control systems to provide highly linear orthogonal motion.

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Boca Raton, FL, United States of America

James Michael Hammond