Papers by Author: Shen Dong

Abstract: Here a simple and direct method based on transfer printing has beep developed, in which rigid stamps transfer metal films deposited on the relief surface of the stamps onto patterned organic substrates. Ultra-precision machining technology is combined with conventional photolithography to fabricate patterned Si stamps and organic substrates by replica molding. Experiment results indicate that patterned metal films on Silicon stamps were successfully transferred onto PDMS substrates. Fabrication of patterned metal films on organic substrates by transfer printing may suit for fabricating sub-micrometer and nanometer scale features in a single process.

Abstract: This paper presents a novel, rapid and damage-free method to polish the ultra-smooth surface of the SiC optics. First, the basic philosophy of this method is introduced, which uses the active radicals got from CF4 in the atmospheric pressure plasma zone to react with the SiC material at the optics surface to generate the vaporization of SiF4. Then, the design of the atmospheric pressure plasma jet and the corresponding prototyping polishing facility are introduced. The theoretical analysis on the necessary conditions to generate the excited radicals is also presented in this part. To verify the effectiveness of this novel polishing method, experiments on the generation of atmospheric pressure plasma and the SiC optics polishing are carried out with our prototyping facility. The experiment results show that plasma discharge is stable at the atmospheric pressure and sub-nanometer roughness of the polished SiC surface can be obtained.

Abstract: Effects of the scratching feed on machined surface and scratching forces are studied by using AFM-based nanomachining process scratching along the long axis of the cantilever. Results show: A deeper structure and rougher surface can be obtained at a smaller feed. An increase in the feed results in increases in scratching forces and the resultant force and a decrease in the normal force. Finally, all forces reach to a saturation value. The ratio of the cutting force to the thrust force in the plane perpendicular to the cutting edge can reveal effects of ploughing and cutting between the tip and the sample in the nanomachining process. Correspondingly, different states (cutting or ploughing) play a key role in formation of the machined surface at different feeds.

Abstract: As a “bottom-up” approach to nanostructures for nanofabrication, self-assembled block copolymer thin films have received much attention not only thanks to the scale of the microdomains but also due to the convenient shape tunability. In order to realize applications of self-assembled block copolymer thin films in nanotechnologies, control over microdomain spatial and orientational order is paramount. In this paper, using atomic force microscopy (AFM), we studied systemically nanostructure transitions induced by post-solvent annealing in self-assembled block copolymer thin films. Furthermore, a variety of thin films with well-ordered nanostructures, which can be employed as templates for nanotechnologies, have been realized simply and at low cost.

Abstract: This paper presents a sophisticated trajectory tracking algorithm based on the utilization of the compound control and fuzzy contour control for the ultra precision machine tools. The main idea is to use the compound control to broaden the bandwidth of the servo system and, therefore, improve the tracking accuracy of the single axis. Then, FUZZY cross coupled contour control is introduced to compensate for the contour error caused by imperfect dynamics of the tracking axis and the mismatch of the control parameters of the servo systems. Experiments carried out on the HCM-1 ultra precision machine tool with a T-type layout show that the integration of the compound control with the fuzzy cross coupled contour control can effectively improve the contour tracking accuracy of the ultra precision machine tool.

Abstract: With the development of science and technology, Atomic Force Microscope is widely applied to the field of machining process in nanometer scale. Due to the limitation of the inventive purpose of AFM, only height mode and deflection mode can be applied in AFM-tip micromachining. It can’t control the machining depth during the micromachining process at present. In this paper, a new micromachining system is set up, which composed of a high precision three-dimensional stage, an AFM, a diamond probe and a special control device. By utilizing variation parameters PID algorithm and controlling the machining depth directly, the micromachining system can resolve the problem mentioned above.

Abstract: The measuring system was developed based on a reconstructed atomic force microscope (AFM) combined with the precision rotating air-bearing and assistant transform shaft. By this system the experiment was carried out according to the principle of three orthogonal orientations towards a micro sphere about 0.46 mm in diameter, and nine one-dimensional traces around the sphere were obtained. Analyses on roundness and sphericity are carried out from the measured data.The results show that the maximal roundness is 0.3895 μm, and the sphericity error is 0.3880 μm.These evaluations are significant references to evaluate its fabrication accuracy or to reform its machining processes.

Abstract: Ripples in the area of femtosecond laser irradiated discrete points and continuous lines were studied. The characteristics of interference-induced ripples (LSFL) in the area irradiated by single shot were investigated by AFM. During single point irradiation, morphology of the irradiated area changed with energy deposition. Morphologies of the irradiated continuous lines with and without ablated groove inside were both investigated. The intensity of interfered light waves varied in different positions of each energy stripes. Thus the characteristics of ripples in the irradiated area varied with different positions. Ripples much larger than LSFL were found perpendicular to laser polarization.

Abstract: In order to investigate nanoindentation data of polymer film-substrate systems and to learn more about the mechanical properties of polymer film-substrate systems, SEBS (styreneethylene/ butylene-styrene) triblock copolymer thin film on different substrate systems have been tested with a systematic variation in penetration depth and substrate characteristics. Nanoindentation experiments were performed using a Hysitron TriboIndenter with a Berkvoich tip. The resulting data were analyzed in terms of load-displacement curves and various comparative parameters, such as hardness and Young’s modulus. The results obtained by the Oliver and Pharr method show how the composite hardness and Young’s modulus are different for different substrates and different penetration depth.

Abstract: Atom Force Microscopy (AFM) can be employed to create surfaces in Si substrate with recessed features. The resulting patterns can serve as masters to make the required elastomeric stamps for soft lithography. Morphology analysis of patterned features on Si substrate and polydimethylsiloxane (PDMS) stamp by AFM imaging confirms that pattern can be successfully transferred from Si substrates to PDMS stamps. It is shown that this method for creating masters can be performed with an AFM, making this method particularly straightforward, economical and accessible to a large technical community that are provided with AFM for measurement.