International Business Machines Corporation

Edwin Flecha

Kenneth Gilbert Roessler

Dong Chen Chen

James Michael Hammond

Robert Marshall Stowell

Yves Corfield Martin

James Christopher Mahlbacher

Michael Servedio

Kenneth S Weinaug

Martin A Klos

Kelvin D Henry

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

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

A scanning probe microscope includes a detection mechanism producing a feedback signal indicating a condition of engagement between the scanning probe and the surface of a sample being examined. When this engagement is above a threshold level, the lateral scanning movement between the probe and sample is stopped. The scanning movement occurs in incremental movements, and a feedback signal above the threshold level indicates that, if the scanning movement were to continue, the probe could not be moved upward fast enough to prevent a crash condition between the probe and the sample surface. The scanning movement is not re-started until the feedback signal indicates that the probe has been moved far enough away from the sample surface that such a crash condition can be avoided during the next incremental movement.

Method for protecting a probe tip using active lateral scanning control

A scanning probe microscope includes probe moved into and out of engagement with a sample surface by a combination of deflections occurring within a fast actuator, having a relatively small range of motion, and a slow actuator, having a relatively large range of motion. When the deflection of the fast actuator is moved outside a predetermined range, in which such deflection is a linear function of applied voltage, the slow actuator is operated so that subsequent operation of the fast actuator can return the fast actuator to its predetermined range, Furthermore, when it is necessary to operate the slow actuator in this way, a scanning motion moving the sample surface past the probe is stopped until the probe is brought into a correct level of engagement with the sample surface, with the fast actuator deflected within the predetermined range.

Method for improving measurement accuracy using active lateral scanning

A method and apparatus for testing circuit boards uses a pair of probes to contact the various nodes on the circuit board. A single one of the pair of probes may be used to deposit a charge at a being tested net and checking for the presence of a charge at subsequent nets to determine whether a short condition exists. Moreover, the pair of probes is used to contact two nodes of a network being tested to measure the resistance within the network being tested; the measured resistance being compared to a nominal resistance, to determine whether an open condition exists. In addition, the pair of probes may be used to measure the resistance between networks in order to verify or determine whether a short condition exists between networks.

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Boca Raton, FL, United States of America

Edwin Flecha