Papers by Keyword: Nano Metrology

Abstract: This paper proposes a methodology method for line edge roughness (LER) measurement and characterization using atomic force microscope. The definition and origins of LER are discussed firstly. A LER quantificational method using image processing and threshold method is presented, which is used to analyze AFM images of Silicon lines and extract LER characteristics. Then the energy distribution of LER is determined by the multi-scale analysis based on wavelet transform and the parameters of multi-scale characterization were given. The experiment data shows that this method can offer an effective quantitative analysis of LER.

Abstract: An innovative two-dimensional (2D) grating was designed for precision pitch measurement using an atomic force microscope with laser interferometers (DLI-AFM). Two kinds of 2D gratings, cylindrical and octagonal pattern, were investigated and compared. In pitch analyses of these patterns, the latter octagonal pattern showed smaller fluctuation of pitch values, less than 0.1 nm. Therefore, one of the major uncertainty components, filtering parameter, was reduced dramatically. We propose the octagonal pattern is probably the most preferable pattern for accurate calibration on 2D gratings.

Abstract: The today’s nanometrology limits the accuracy of the precision engineering. These limits are based on the meter definition as redefined in 1983. It is proposed to define precision mechatronics as the science and engineering of high level precision systems and machines. The paper describes a precision mechatronic machine. This device represents a long range positioning machine having a resolution of 0.1 nm over the range of 25 mm x 25 mm x 5 mm. The integration of several optical and tactile nanoprobes makes the 3D-nanopositioning suitable for various tasks. New developed nanoprobes (optical focus probe, nanoindenter, metrological scanning force microscope) and results of measurement will be presented.

Abstract: The paper presents metrology of the growth and characterization of 3d metal monolayer films on silicon. EELS analysis of plasmon peaks during the layer-by-layer growth of Co films on Si(111) demonstrate that thickness measurement of the monolayer films is possible on base of spectra decomposition with interface and film plasmon peak extracting. Results of the resistivity measurement of Co films on Si(111) with different state of the surface correlate with growth mechanism of the films on AES data. AFM-pictures show replication of step surface relief versus the thickness demonstrating growth of the smooth Fe nanofilm on Si(100).

Abstract: To meet the demand of large displacement measurement instrument with nanometer precision, this paper introduces the metrological grating with the nanometer measurement precision and large displacement, based on two times' Moiré fringe principle. Its basic principle is that two indicated gratings are fixed on the same measuring base scale, when they move relatively to the scale grating, two groups of one time Moiré fringe will be produced, then two groups of lens are adopted to make the fringe move oppositely, at last the two times Moiré fringe will be produced through interference on the photoelectronic receive element. By subdivision of the two times Moiré fringe, this system can achieve 2.70×10-10m measurement resolution. In addition, this paper also analyse the optics system and light source.

Abstract: In this paper, we applied the contact constant-height mode together with the pre-compensation technique which can realize the capability of high speed as well as faithful topographical image. Before scanning, the slope variation of the micro-structured surface was measured by the capacitance sensor and then stored in a PC. During the surface profile scanning, a piezoelectric actuator is applied which can provide the inconsecutive motion that corresponds to the pre-measured slope variation. As a result, the precision measurement can also be achieved. The validity of the proposed method and its performance are verified by compare the topographical images that were gained by the contact constant-force mode with feedback control. However, the scanning speed of our method is obviously high.

Abstract: This paper presents an efficient computation method to evaluate scattered light intensity distributions, generated by a nanostructured surface which is illuminated with a monochromatic laser beam of several millimeters in diameter. The new simulation approach based on a modified Huygens-Fresnel approximation enables to improve measuring methods without expensive and time consuming experiments. The qualitative verification of the model results in a roughness measuring principle based on double scattering of coherent light.

Abstract: For functional properties such as gliding, sealing, assembling, adhering etc. the outer layer of the surface is the functional related surface. For the functional assessment of the surface this outer layer should be used as the reference for any functional characteristic. With the existing mean line system for the assessment of roughness and waviness, the standardized characteristics do not follow this logic. However there are valid historical reasons for the acceptance of the shortcomings of the mean line system. They are e.g. the alignment of the profile, the removal of form, the assumption of a sinusoidal structure of the waviness on the surface, and the distortion of the surface by the application of the mean line filtering process. To overcome these shortcomings morphological operations have been used to establish a new developed envelope system. In order to define new parameters to characterize and specify functional properties of surfaces, a common datum is necessary. The presented method for the alignment of datums is consistent with the algorithms used to establish datums and datum systems for workpieces, where the datum is established by the location of a tangent geometrical element such as a line, plane, cylinder etc. The orientation is usually derived by the application of the minimum zone algorithm. The benefit of the assessment of the functional properties of surfaces with morphological operations will be presented for two examples.

Abstract: The implementation of the basic physical principle of Chromatic Confocal Microscopy in the field of Phase stepping interferometry (PSI) opens new opportunities for the development of an innovative surface metrology method specially dedicated to 3D nanotopography with subnanometric z axis resolution altogether with a very large measuring range: typically up to one hundred micrometers. The basic property of optical sectioning inherent to (chromatic) Confocal imaging is particularly well adapted to Phase stepping Interferometry since it automatically solves the critical and time consuming problem of phase unwrapping computation. The axial chromatic extension of the chromatic confocal setup offers a very fast and easy way to determine the height of the different elementary surfaces forming the measured object. It is then easy to carry out, for each one of those elementary surfaces, a measurement in phase shifting interferometry, at the wavelength corresponding to the altitude indicated by the confocal chromatic, in order to reach subnanometric axial resolutions. The four phases needed for implementing the phase stepping interferometric measuring procedure can be successively realized by adequate spectral shifts instead of the classical axial displacements of the reference mirror which then stands in a fixed position. Consequently this chromatic confocal phase stepping interferometer (CCPSI) has definitely no moving part, the spectral shifts being done by electrooptical means. Typical applications are MEMS and microoptics surface topography and/or roughness metrology. For this purpose we designed a new system incorporating confocal chromatic imaging and phase stepping interferometry. As a direct consequence of the optical sectioning property, this system allows measuring through any type of optical window (for example a cover glass).

Abstract: A new signal-denoising approach based on DT-CWT (Dual-Tree Complex Wavelet Transform) is presented in this paper to extract feature information from microstructure profile. It takes advantage of shift invariance of DT-CWT, non-Gaussian probability distribution for the wavelet coefficients and the statistical dependencies between a coefficient and its parent. This approach substantially improved the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts. A simulated MEMS microstructure signal is analyzed.