Digital Instruments

Other

University of California

Veeco Instruments Inc.

Bruker Nano Gmbh

Virgil B Elings

John A Gurley

David F Nicoli

David A Grigg

Paul K Hansma

James Massie

Barney Drake

Craig B Prater

Peter Maivald

Dror Sarid

Dennis M Adderton

Lucien P Ghislain

Craig Prater

Kevin Kjoller

James M Young

David T Phillips

Charles R Meyer

Sergei Magonov

Jeffrey R Elings

Mark R Rodgers

Matthew J Longmire

William H Hertzog

Kenneth L Babcock

Christopher C Schmitt

A scanned-stylus atomic force microscope (AFM) employing the optical lever technique, and method of operating the same. The AFM of the invention includes a light source and a scanned optical assembly which guides light emitted from the light source onto a point on a cantilever during scanning thereof. A moving light beam is thus created which will automatically track the movement of the cantilever during scanning. The invention also allows the light beam to be used to measure, calibrate or correct the motion of the scanning mechanism, and further allows viewing of the sample and cantilever using an optical microscope.

Scanning stylus atomic force microscope with cantilever tracking and optical access

A method of scanning probe microscopy includes using a cantilever having a planar body, generally opposed first and second ends, and a tip disposed generally adjacent the second end and extending downwardly towards a surface of a sample. Preferably, the sample is disposed on a support surface. The method includes directing a beam of light onto the second end in a direction substantially parallel to the support surface. In operation, the second end directs the beam towards a detector apparatus at a particular angle. Then, the method monitors a change in the angle of deflection of the beam of light caused by deflection of the cantilever as the cantilever tip traverses the surface of the sample, the change being indicative of a characteristic of the surface. Preferably, the second end includes a flat reflective surface, with the flat reflective surface being generally non-planar with respect to the planar body of the cantilever. In addition, the flat reflective surface comprises a mirror fixed to the second end, while in another embodiment, the flat reflective surface is microfabricated integrally with the cantilever.

Method and apparatus for atomic force microscopy

A feedback control system for enhancing the feedback loop characteristics of a vertical axis control in a scanning tunneling microscope or the like, including a tip member for positioning relative to a surface for measuring the topography of the surface. A horizontal control coupled to the tip for providing a plurality of adjacent horizontal scans across the surface. A vertical control coupled to the tip for providing a vertical control of the tip during the plurality of adjacent horizontal scans. A local error signal produced in accordance with the vertical position of the tip relative to the surface in real time during the plurality of adjacent horizontal scans. A storage member responsive to the local error signal for storing the local error signal for producing a delayed error signal representing the vertical position of the tip relative to the surface at an earlier time, and a vertical tip control signal coupled to the vertical control and formed by combining the local error signal and the delayed error signal for enhancing the control of the vertical position of the tip.

Feedback control for scanning tunnel microscopes

A surface of the sample is scanned in intermittent contact mode with an the AFM. The probe tip is electrically conductive and is electrically connected to a capacitance sensing circuit. The oscillation of the AFM probe modulates capacitance between probe tip and sample surface. The modulated capacitance is demodulated to yield the capacitance properties of the sample.

Capacitance atomic force microscopes and methods of operating such microscopes

A scanned-stylus atomic force microscope (AFM) employing the optical lever technique, and method of operating the same. The AFM of the invention includes a light source and a scanned optical assembly which guides light emitted from the light source onto point on a cantilever during scanning thereof. A moving light beam is thus created which will automatically track the movement of the cantilever during scanning. The invention also allows the light beam to be used to measure, calibrate or correct the motion of the scanning mechanism, and further allows viewing of the sample and cantilever using an optical microscope.

Scanning stylus atomic force microscope with cantilever tracking and

The oscillation parameters of a probe of an atomic force microscope (AFM) typically vary over time. This variation can cause problems during either 1) scanning or measurement functions in which the probe's operative state is one in which oscillatory measurements are taken or 2) the process of bringing the tip to the sample to begin measurement, commonly referred to as engaging the probe, in which the probe's operative state is one in which the probe is about to move into its measuring position. These problems can be eliminated during either process by measuring changes in a parameter or parameters of probe oscillation, determining what changes are not due to probe-sample interaction, and correcting the oscillation parameters accordingly. This may be accomplished in two ways, the first with the probe out of intermittent contact with the sample, and the second during scanning. The first comprises placing the probe in a reference or free oscillation state in which the probe tip oscillates at a free oscillation amplitude A.sub.o, measuring A.sub.o and adjusting it if necessary, and then returning the probe to its operative state. The probe can be placed in its reference state by varying the spacing between the probe and the sample, by altering probe drive parameters, or by any other suitable technique. The second comprises measuring the phase of the probe oscillation during scanning and adjusting the phase to a desired range.

Method for improving the operation of oscillating mode atomic force

A scanning probe microscope uses a high refractive index solid immersion lens (SIL) probe to provide optical images with a resolution better than the diffraction limit in air. The SIL probe has a spherical upper surface and a conical (or pyramidal) lower surface with a sharp tip. The SIL reduces the focused spot size because the spherical surface increases the angle of the marginal rays and the high refractive index material shortens the wavelength. The focused spot generates an evanescent wave having an amplitude that decays exponentially with distance from the SIL. The sharp tip on the lower surface reduces the tip-sample contact area and the tip-sample separation so that sample is within the near-field of the SIL probe. The sample perturbs the evanescent wave and a photodetector monitors characteristics of the light. A cantilever carries the SIL probe and a cantilever deflection sensor permits precise control of tip-sample forces and separation. The cantilever deflection sensor operates in a force feedback loop to maintain the tip-sample gap within the near-field as the SIL probe scans over the sample in a raster pattern to generate optical data.

Scanning probe optical microscope using a solid immersion lens

A probe-based surface characterization or metrology instrument such as a scanning probe microscope (SPM) or a profilometer is controlled to account for errors in the vertical positioning of its probe and errors in detecting the vertical position of its probe while scanning over relatively large lateral distances. Accounting for these errors significantly improves the measurement of vertical dimensions. These errors are accounted for by subtracting reference scan data acquired from the scanned sample from measurement scan data. The measurement scan data is obtained from an area that includes the feature of interest as well as a portion of a reference area which is preferably located near to the feature of interest and which is preferably featureless. The reference scan data is obtained from an area that includes the reference area and that preferably excludes the features of interest. Subtracting the reference such data from the measurement scan data obtains corrected measurement scan data that accounts for scanning errors and for errors in detecting the probe idiosyncrasies. In order to facilitate process automation, the features of interest can be identified automatically or semi-automatically by operating the instrument in a feature-locating mode to identify distinguishing characteristics of the features of interest such as differences in magnetic or electrical properties between the features of interest and the adjacent features. This procedure is particularly wellsuited for measuring pole tip recession in a magnetic head.

Method and apparatus for obtaining improved vertical metrology

An atomic force microscope that has an electrically-conductive probe and tip includes a feedback control circuit for generating a substantially constant, desired Fowler-Nordheim current between the probe tip and the surface of an electrically-conductive sample having a thin dielectric or insulating film thereon. The feedback circuit maintains the desired Fowler-Nordheim current flow between the probe tip and the sample by adjusting the bias voltage applied to the probe tip, and by tracking and using the changes in the applied bias voltage to provide a measure of the thickness, electrical conductivity or other electrical property of the film.

Atomic force microscope for measuring properties of dielectric and

The mechanical properties of a surface are measured by using a pointed tip on the end of a bendable cantilever such that with force on the other end of the cantilever the tip can be pushed into the surface using the bending of the cantilever as the measure of the constant force. The indentation, scratch, or wear created by the application of forces between the tip and sample is then measured with the same tip and cantilever by raising the cantilever off the surface and putting it into oscillation. The tip is then scanned over the area where the indentation was made with the tip tapping on the surface in order to image the surface.

Method and apparatus for measuring mechanical properties on a small scale

A scanned-stylus atomic force microscope (AFM) employing the optical lever technique, and method of operating the same. The AFM of the invention includes a light source and a scanned optical assembly which quides light emitted from the light source onto a point on a cantilever during scanning thereof. A moving light beam is thus created which will automatically track the movement of the cantilever during scanning. The invention also allows the light beam to be used to measure, calibrate or correct the motion of the scanning mechanism, and further allows viewing of the sample and cantilever using an optical microscope.

A scanning probe microscope and method having automated exchange and precise alignment of probes, wherein one or more additional stored probes for installation onto a probe mount are stored in a storage cassette or a wafer, a selected probe is aligned to a detection system, and the aligned probe is then clamped against the probe mount. Clamping is performed using a clamp which is disabled when removing a replacement probe from the storage cassette, enabled when installing the probe on the probe mount and disabled when releasing the probe at a later time for subsequent probe exchange. Probe alignment is automated using signals from the probe detection system or by forming an optical image of the probe using a camera or similar technique and determining probe positioning using pattern recognition processing of the probe image to allow probe removal and exchange without operator intervention. Techniques for error checking are employed to ensure proper probe installation and operation.

Scanning probe microscope having automatic probe exchange and alignment

A scanned-stylus atomic force microscope (AFM) employing the optical lever technique, and method of operating the same. The AFM of the invention includes a light source and a scanned optical assembly which guides a light beam emitted from the laser source onto a point on said cantilever during scanning thereof. A moving laser beam is thus created which will automatically track the movement of the cantilever during scanning. The invention also allows the laser beam to be used to measure, calibrate or correct the motion of the scanning mechanism, and further allows viewing of the sample and cantilever using an optical microscope.

A method of controlling a scanner, particularly a scanner for use in scanning probe microscopes such as an atomic force microscope, including the steps of generating a scan voltage which varies as a parametric function of time, applying the scan voltage to the scanner, sensing plural positions of the scanner upon application of the scan voltage, fitting a parametric function to the sensed scanner positions, and controlling at least one parameter of the scan voltage function based on the parametric function fitted to the sensed scanner positions in the fitting step. In a preferred embodiment, the scan voltage is a polynomial parametric function of time and the order of terms of the polynomial is set in relation to the size of the scan being controlled, with small scans having at least one order term and relatively larger scans having plural order terms. Thus, the sensed position data are used, not to control the motion of the scanner directly in a closed loop system, but instead to optimize the transducer calibration parameters for subsequent open looped scan control of a portion of a total scan, with the calibration of the transducer scan voltage parameters periodically occurring.

Scan control for scanning probe microscopes

A method of operating an atomic force microscope having a probe tip attached to a free end of a lever which is fixed at its other, wherein the probe tip is scanned in forward and reverse directions in a common scanline across the surface of a sample and either the deflection of the lever or the height of the sample is detected during the forward and reverse scans. The difference between the deflection of the lever or the sample height in the forward and reverse scans is determined as a relative measure of friction. A signal relating to the normal force applied to the sample, can be determined and based thereon, a coefficient of friction of the sample is determined. The signal relating to normal force is derived either from a force curve, or by scanning the probe at different force setpoints. To enhance accuracy of topographical data, the scanning angle is varied in order to minimize differences between the probe deflection (or sample height) during scanning in the forward and reverse directions. Once it is determined which angle results in minimum difference in data obtained during scanning in the forward and reverse directions in a common scanline, topographical data is obtained by scanning the sample at that angle. Frictional data is obtained by scanning at that angle which maximizes the difference between data obtained in forward and reverse scanning directions in a common scanline.

Growing community of inventors

Santa Barbara, CA, United States of America

Virgil B Elings