Patent of Russian Federation, no. 2,295,783, January 25, 2005
Method for automatic distributed calibration of probe microscope scanner
Rostislav V. Lapshin
The patented invention relates to scanning probe microscopy (SPM), in particular, to methods intended for SPM-scanner calibration. The invention may be applied for calibration of any instrument of SPM family, for example, for a scanning tunneling microscope, for a scanning atomic force microscope, for a scanning near-field optical microscope, etc. The suggested method may also be used for calibration of the scanning electron microscope. First, a space of scanner displacements is “partitioned” on some domains by a net, which nodes correspond to absolute integer coordinates of the scanner. Then, the microscope scanner moves from one net node to other neighbor node using a raster-like law. The displacements in the raster are carried out in such a way that the movements in the adjacent lines/columns and the movements in the adjacent planes occur in the opposite directions. Position of the fine Z manipulator of the scanner while moving by the net nodes in the vertical plane is set with a coarse Z manipulator. Within a vicinity of each net node a local aperture scanning, search and capture of the nearest local calibration structure (LCS) are carried out. Once approximate relative coordinates of LCS features have been determined, a skipping operation is implemented aimed for precision determination of relative coordinates of the LCS features. The skipping operation permits to measure precisely the feature relative coordinates despite a continuous thermal drift and creep of a microscope probe relative to a standard surface. The most generally defined hill- or pit-like topography elements may be used as standard surface features. Local calibration coefficients (LCC) are calculated by the relative coordinates of the LCS features. The obtained LCC correspond to the absolute real coordinate of the LCS. The LCS “gravity center” is used as the LCS coordinate. Constructing regression surfaces through the obtained LCC, it is possible to find sought for LCC, which correspond to the integer absolute coordinates of the scanner. If sizes of the features of the standard surface are known in addition to the information on distances between them, another set of LCC can be determined as follows: a counter scanning of topography segments is carried out during the skipping operation; then, linear transformation coefficients are calculated; finally, drift-induced topography distortions in the segments are corrected by using these transformation coefficients. In order to increase precision of the calibration method both LCC sets are averaged out. An additional growth of calibration precision is realized by repetitive calibrations which number is practically unlimited. The slower velocity change of the drift of the microscope probe relative to the standard surface during a skipping operation, the more precisely the suggested calibration method is. The most accurate calibration is achieved with stable single crystal surfaces as a standard. An increased precision of topography measurements is the technical result of the invention.
Patent of Russian Federation, no. 2,181,212, September 7, 1999
Procedure of movement of sonde of scanning microscope-nanolithograph in field of coarse X-Y positioner
Rostislav V. Lapshin
Institute of Physical Problems, Zelenograd, Moscow, 124460, Russian Federation
The patented invention relates to precision measuring instruments and nanotechnology. The invention may be utilized in a scanning probe microscope, probe nanolithograph or high capacity probe storage device. First, the movement is being carried out with a fine positioner until it will reach the boundary of the displacement range. Then, a nearest feature is searched out and a microscope probe catches that feature by using the attachment procedure. After that, a coarse positioner makes step displacements in such direction that the fine positioner that is forced to follow the coarse positioner due to the ceaseless attachments is moving to the opposite boundary of its range. After reaching the boundary, the described above sequence of operations is repeated cyclically until the probe will reach the terminal movement point located at the preset distance from the initial point. The technical result of the invention consists in increasing precision of probe movement over a large area of a sample under investigation.
Patent of Russian Federation, no. 2,175,761, June 8, 1999
Method for measuring surface relief by means of scanning probe type microscope
Rostislav V. Lapshin
Institute of Physical Problems, Zelenograd, Moscow, 124460, Russian Federation
The patented invention relates to an electronic measuring equipment. The invention is designed for use in a probe scanning device. The key idea of the method consists in employing surface features as reference points while implementing any movements. The movements are carried out from one feature to another located in vicinity. As a result, a connected chain of features is composed where these features are allocated relatively to each other. Feature search and detection as well as calculation of feature position coordinates are carried out by a recognition program. By scanning a small area around each feature, and then, lying the obtained surface segments on the respective positions determined at recognition, it is possible to reconstruct the real surface topography. Since coordinates of the feature positions are known, one may implement precision probe positioning by using the attachment mechanism. The technical result consists in increasing precision of surface topography measurements and improvement of instrument resolution.
Patent of Russian Federation, no. 2,181,218, November 2, 1998
Method for reading digital information in probe memory device
Rostislav V. Lapshin
Institute of Physical Problems, Zelenograd, Moscow, 124460, Russian Federation
The patented invention relates to a computer equipment. The invention is intended for use in a high capacity probe storage device (PSD). In the high capacity PSD, by means of a servo system in the vertical plane, a constant gap between a probe and a data carrier surface is provided while reading back digital information. By scanning a rectangle neighborhood of the current attachment element (i. e., an auxiliary synchronizing element or a memory element itself) in the raster-like manner, one may carry out a program recognition of the next attachment element within the mentioned neighborhood, then determine its relative position on the information track and the bits of the stored data. Further, the described above operations are repeated considering the next element as the current one. The technical result consists in increased tracking reliability as well as device design simplification.