Journal of Surface. Roentgen, Synchrotron and Neutron Studies, number 1, pages 5-16, January 2010
Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, volume 4, number 1, pages 1-11, January-February 2010
Vacuum ultraviolet smoothing of nanometer-scale asperities of poly(methyl methacrylate) surface
R. V. Lapshin1, 2, A. P. Alekhin1, 2, A. G. Kirilenko1, S. L. Odintsov1, V. A. Krotkov1
1State Scientific Center of Russian Federation, Institute of Physical Problems named after F. V. Lukin, Zelenograd, Moscow, Russia 2Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
Smoothing of nanometer-scale asperities of poly(methyl methacrylate) (PMMA) film by using vacuum ultraviolet (VUV) with wavelength λ=123.6 nm is investigated. During the VUV-treatment, an exposure time and a residual air pressure in the working chamber are varied. A nanostructured surface of PMMA film is used as a sample to be exposed. The nanostructured surface is obtained by treating the initial spin-coated smooth PMMA film in oxygen radio-frequency plasma. The conclusion regarding to degree of VUV-exposure is based on the changes fixed in topography morphology and roughness of the nanostructured surface. Surface topography of the PMMA film is measured by the atomic-force microscopy (AFM). Recognition of morphological surface features and determination of their main geometrical characteristics on the AFM-images are performed by using the method of virtual feature-oriented scanning. The detailed investigation of morphology and Fourier spectra shows that the nanostructured surface of PMMA film is partially-ordered. The VUV-smoothing method developed can be used for treatment of electron-beam, UV or X-ray sensitive PMMA-resists, PMMA-elements of microelectromechanical systems, biomedical PMMA-implants, and for validation of nanotechnological equipment having UV sources.
Measurement Science and Technology, volume 18, issue 3, pages 907-927, March 2007
Automatic drift elimination in probe microscope images based on techniques of counter-scanning and topography feature recognition
Rostislav V. Lapshin
Solid Nanotechnology Laboratory, Institute of Physical Problems, Zelenograd, Moscow, 124460, Russian Federation
An experimentally proved method for the automatic correction of drift-distorted surface topography obtained with a scanning probe microscope (SPM) is suggested. Drift-produced distortions are described by linear transformations valid for the case of rather slow changing of the microscope drift velocity. One or two pairs of counter-scanned images (CSIs) of surface topography are used as initial data. To correct distortions, it is required to recognize the same surface feature within each CSI and to determine the feature lateral coordinates. Solving a system of linear equations, the linear transformation coefficients suitable for CSI correction in the lateral and the vertical planes are found. After matching the corrected CSIs, topography averaging is carried out in the overlap area. Recommendations are given that help both estimate the drift correction error and obtain the corrected images where the error does not exceed some preliminarily specified value. Two nonlinear correction approaches based on the linear one are suggested that provide a greater precision of drift elimination. Depending on the scale and the measurement conditions as well as the correction approach applied, the maximal error may be decreased from 8-25% to 0.6-3%, typical mean error within the area of corrected image is 0.07-1.5%. The method developed permits us to recover drift-distorted topography segments/apertures obtained by using feature-oriented scanning. The suggested method may be applied to any instrument of the SPM family.
Nanotechnology, volume 15, issue 9, pages 1135-1151, September 2004
Feature-oriented scanning methodology for probe microscopy and nanotechnology
Rostislav V. Lapshin
Solid Nanotechnology Laboratory, Institute of Physical Problems, Zelenograd, Moscow, 124460, Russia
A real-time scanning algorithm is suggested which uses features of the surface as reference points at relative movements. Generally defined hill- or pit-like topography elements are taken as the features. The operation of the algorithm is based upon local recognition of the features and their connection to each other. The permissible class of surfaces includes ordered, partially ordered, or disordered surfaces if their features have comparable extents in the scan plane. The method allows one to exclude the negative influence of thermodrift, creep, and hysteresis over the performance of a scanning probe microscope. Owing to the possibility of carrying out an unlimited number of averages, the precision of measurements can be considerably increased. The distinctive feature of the method is its ability of topography reconstruction when the ultimate details are smaller than those detectable by a conventional microscope scan. The suggested approach eliminates the restrictions on scan size. Nonlinearity, nonorthogonality, cross coupling of manipulators as well as the Abbé offset error are corrected with the use of scan-space-distributed calibration coefficients which are determined automatically in the course of measuring a standard surface by the given method. The ways of precise probe positioning by local surface features within the fine manipulator field and the coarse manipulator field, automatic probe return into the operational zone after sample dismounting, automatic determination of exact relative position of the probes in multiprobe instruments, as well as automatic successive application of the whole set of probes to the same object on the surface are proposed. The possibility of performing accurately localized low-noise spectroscopy is demonstrated. The developed methodology is applicable for any scanning probe devices.
Object-oriented scanning for probe microscopy and nanotechnology
Rostislav V. Lapshin
Institute of Physical Problems, Zelenograd, Moscow, 124460, Russia
Object- or feature-oriented scanning (OOS) methodology is suggested, developed, and proved experimentally. While measuring or crossing topography, surface features are used as reference points. All probe movements are performed relatively from one feature to another placed nearby. Generally defined hill- or pit-like surface elements are used as features. Surface topography is measured by small parts called segments. Each segment is a square neighborhood of the surface feature. The segments are obtained during the conventional raster-like scanning. The resulting topography image is reconstructed by using the feature segments and the relative distances between the features. All types of surfaces (i. e., ordered, quasiordered, and disordered) may be scanned in feature-oriented manner if only their features have comparable extents in the lateral plane. The proposed OOS permits to eliminate the negative effect of thermodrift, creep, and hysteresis. As a result, an unlimited number of averagings may be carried out theoretically. Due to a large number of the averagings, precision of the scanning probe microscope can be considerably increased. It is possible also to improve resolution of the instrument under the stipulation that a tip of the probe is sharp enough. The suggested approach eliminates the restrictions on scan size. Nonlinearity, nonorthogonality, cross coupling of manipulators as well as the Abbé offset error are corrected with the use of scan-space-distributed calibration coefficients which are determined automatically in the course of measuring a standard surface by the given method. Proposed are the ways of precise probe positioning by local surface features within the fine manipulator field and the coarse manipulator field, automatic probe return into the operational zone after sample dismounting, automatic determination of exact relative position of the probes in multiprobe instruments, as well as automatic successive application of the whole set of probes to the same object on the surface. The possibility of performing accurately localized low-noise spectroscopy is demonstrated. The suggested methodology is applicable for any scanning probe instruments such as scanning tunneling microscope, atomic-force microscope, magnetic force microscope, electrostatic force microscope, near-field scanning optical microscope, and many others, including the scanning electron microscope.
Review of Scientific Instruments, volume 71, number 12, pages 4607-4610, December 2000
Digital data readback for a probe storage device
Rostislav V. Lapshin
Institute of Physical Problems, Moscow, Zelenograd 103460, Russia
An experimentally proved method is described for data readback from an information track using separate atoms on a crystal surface as memory elements. The key idea consists of local scanning and recognition of memory elements on the carrier surface followed by attaching the device probe to them so as to keep the probe position over the track.
Review of Scientific Instruments, volume 69, number 9, pages 3268-3276, September 1998
Automatic lateral calibration of tunneling microscope scanners
Rostislav V. Lapshin
Zelenograd Physical Problems Institute, Zelenograd, Moscow, 103460, Russia
A practical method is described to find automatically the calibration coefficients and residual nonorthogonality of a tunneling microscope scanner. As initial data, the coordinates of three atoms were used forming a triangle in a highly oriented pyrolytic graphite surface appearing in the form of a spatially geometrical measure. A recognition procedure is described which can be applied to determine the lateral coordinates of the atoms. Length and orientation distortions were calculated, estimates of calibration errors were given and the requirement on the nonorthogonality limit was formulated for manipulator a given that ensures measurements of the predetermined accuracy. The sensitivity of the method to a noise in atom coordinates was determined. Experimental data showing the practical suitability of the method developed are presented.
Review of Scientific Instruments, volume 66, number 9, pages 4718-4730, September 1995
Analytical model for the approximation of hysteresis loop and its application to the scanning tunneling microscope
Rostislav V. Lapshin
“Delta”, Microelectronics and Nanotechnology Research Institute, 2 Schelkovskoye Shosse, Moscow 105122, Russia
A new model description and type classification carried out on its base of a wide variety of practical hysteresis loops are suggested. An analysis of the loop approximating function was carried out; the parameters and characteristics of the model were defined – coersitivity, remanent polarization, value of hysteresis, spontaneous polarization, induced piezocoefficients, value of saturation, hysteresis losses of energy per cycle. It was shown that with piezomanipulators of certain hysteresis loop types, there is no difference in heat production. The harmonic linearization coefficients were calculated, and the harmonically linearized transfer function of a nonlinear hysteresis element was deduced. The hysteresis loop type was defined that possesses minimum phase shift. The average relative approximation error of the model has been evaluated as 1.5%-6% for real hysteresis loops. A procedure for definition of the model parameters by experimental data is introduced. Examples of using the results in a scan unit of a scanning tunneling microscope for compensation of raster distortion are given.
Review of Scientific Instruments, volume 64, number 10, pages 2883-2887, October 1993
Fast-acting piezoactuator and digital feedback loop for scanning tunneling microscopes
Rostislav V. Lapshin, Oleg V. Obyedkov
“Microelectronica”, R&D and Production Corporation, Schelkovskoye Shosse 2, 105122, Moscow, Russia
The design of a sectional piezoactuator is described, and the principle of operation of a tunnel junction digital stabilization system is given. The total settling time of the system while the least significant section is in operation is 1 µs at 0.01-nm resolution (in the Z direction). The application of the sectional piezoactuator permitted an increase in operating frequency and also eliminated errors caused by the piezoceramics hysteresis. Introduction of a fast-acting ALU as a digital accumulator of regulation errors made it possible to achieve high stability of the loop operation at high operating frequencies. The system suggested can adapt the speed of the loop operation depending on the relief steepness values. The blunting of the tip and sample destruction is avoided because there is a mechanism of smooth approach of the tip to the nominal scanning height.
R. V. Lapshin, Drift-insensitive distributed calibration of probe microscope scanner in nanometer range, Measurement Science and Technology, 2013 (submitted)
R. V. Lapshin, R. Z. Khafizov, E. A. Fetisov, Intelligent processing of the output optical image of a focal plane array of uncooled bimaterial IR-detectors, Instruments and Experimental Techniques, 2013 (submitted)
R. V. Lapshin, Hysteresis compensation model for STM scanning unit, Proceedings of the Second International Conference on Nanometer-Scale Science and Technology (NANO-II), Herald of Russian Academy of Technological Sciences, vol. 1, no. 7, part B, pp. 511-529, Moscow, Russia, 1994
R. V. Lapshin, Observation of a hexagonal superstructure on pyrolytic graphite by method of feature-oriented scanning tunneling microscopy, 25th Russian Conference on Electron Microscopy (SEM-2014), Chernogolovka, Russian Federation, June 2-7, 2014 (in Russian)
S. A. Gavrilov, V. M. Roschin, A. V. Zheleznyakova, S. V. Lemeshko, B. N. Medvedev, R. V. Lapshin, E. A. Poltoratsky, G. S. Rychkov, N. N. Dzbanovsky, N. N. Suetin, AFM investigation of highly ordered nanorelief formation by anodic treatment of aluminum surface, International Conference “Nanomeeting-2003”, Minsk, Belarus, May 20-23, 2003
R. V. Lapshin, Feature-oriented scanning for spacecraft-borne remote SPM-investigations, Workshop on Micro-Nano Technology for Aerospace Applications, Montreal, Canada, August 25-30, 2002
A. P. Alekhin, A. G. Kirilenko, R. V. Lapshin, A. A. Sigarev, AFM studies of the morphology of the carbon layers deposited on medical low-density polyethylene films by the method of pulsed plasma-arc sputtering of graphite, SPIE International Conference on Nanotechnology and MEMS, Galway, Ireland, September 5-6, 2002
S. A. Gavrilov, A. V. Emelyanov, E. A. Ilyichev, R. V. Lapshin, V. M. Roschin, Fabrication technique and characteristic investigation of field-controlled nanotransistors, All-Russian Scientific and Technical Conference “Micro- and Nano-electronics 2001”, vol. 2, p. P1-1, Zvenigorod, Moscow, Russian Federation, October 1-5, 2001 (in Russian)
R. V. Lapshin, Correction of drift-distorted SPM-images, The Third International Scientific and Technical Conference “Electronics and Informatics – XXI Century”, pp. 76-77, Zelenograd, Moscow, Russian Federation, November 22-24, 2000 (in Russian)
R. V. Lapshin, Procedure for atom recognition in STM-images, The Third International Scientific and Technical Conference “Microelectronics and Informatics”, pp. 222-223, Zelenograd, Moscow, Russian Federation, November 11-12, 1997 (in Russian)
S. A. Gavrilov, A. V. Emelyanov, R. V. Lapshin, V. N. Ryabokony, O. I. Chegnova, Electrochemical nanometer-scale structuring of silicon surface, The Third International Scientific and Technical Conference “Microelectronics and Informatics”, pp. 155-156, Zelenograd, Moscow, Russian Federation, November 11-12, 1997 (in Russian)
R. V. Lapshin, V. N. Ryabokon, A. V. Denisov, Scanning tunneling microscope measurements of the spatial characteristics of ordered surface nanostructures, The Fourth International Conference on Nanometer-Scale Science and Technology (NANO-IV), Beijing, P. R. China, September 8-12, 1996