The Development Of New Methods And Systems Of Large Scan Range Atomic Force Microscope

At the end of 20th century, the development trend of the electronic component, mechanism etc. is microminiaturization. Many component which is in nanometer order has been used in the science research and the industrial manufactory, the nano-technology is being more and more attentional.In the field of nano-technology, One of the most important tools used for observation and research is Scanning Probe Microscopy(SPM). Among the great varieties of SPMs, Atomic Force Microscope (AFM) is most widely used. AFM can be use to observe and research many kinds of materials including conductors, semiconductors, nonconductors. And the sample can be put in air, liquid or vacuum. It performances well, and its applicability is better.The most important performance indexes are the scanning range and the resolution. Commonly, The scanning range is from micron order to submillimetre order. This can't meet the requirement of the research in some certain occasion. In the study of the surface of some materials, for the sake of observe the characters of the sample surface(such as profile, disfigurement and so on), the scanning range is needed to be extended to several microns. When the non-contact mode AFM is use for biology, biomedicine study to research the biologic big molecule(including molecule of proteide etc.) or polymer of several molecules, the scanning range needed is more large. The sizes of a single molecule of proteide are various. The big one may be several millions angstroms, and the small one is at least several ten thousands angstroms. In this occasion, the micron order, even the submillimetre order, is far from the requirement. Toward the sample images of one single molecule of proteide or several molecule, the researchers can get only a little informations. The researchers always want see more area of the sample at the same high scanning resolution. Base on this requirement, we put forward the subject of atomic force microscope of large scanning range. The whole system has been developed. The scanning range is enlarged in the case of no decrease of scanning resolution.The thesis has 6 chapters. Chapter 1 and Chapter 2 introduce the nano-technology, the backdrop of this project; Chapter 3 presents the project's innovation in the controlling and detecting methods. Chapter 4 presents the research findings, namely, the AFM with large scanning range we developed; Chapter 5 presents the application of the AFM we developed, including the images obtained by AFM of some different kinds of sample; Chapter 6 is the expectation.This project's innovation including:We bring forward a new method to control the PZT tube. Formerly, the voltage signal connect with the PZT tube is mostly single, viz. one side of the PZT tube is put on the signal, and the other side connect with the GND. Now, we bring forward the new method to control the PZT tube. Connect two sides of the PZT tube with two signal which has a 180° phasic difference, making the direction of the electrical field added to the PZT tube changing alternately, so that the direction of polarization of the PZT changes alternately. By doing this, the range the PZT tube can expend to can be made longer, and then the scanning scale is enlarged.The driving circuit of the PZT scanner is improved. Using a phase displacement method. Output a control signal from the PC, and then we can get another control signal by using a circuit with phase displacement. The new signal has a 180° phasic difference. This circuit is a fast analog circuit, so that the response time can be ignored. The two signals' phasic difference can be accurately preserved.We also bring forward an image splicing method based on the micro drive stage. By adding a stage to the system, we can further improve the scanning scale. After scanning a sample image by the PZT scanner, move the sample for a certain distance by using the micro drive stage (can both in the X or Y direction), and then scan the sample for the next image. After all the image scanning, we can splice the image series into a large image. Because the stage...