1. Field of the Invention
The present invention relates to a fine movement mechanism unit and a scanning probe microscope, and more particularly, to a fine movement mechanism unit suitable for measuring a large-sized sample by moving a section including a cantilever when observing the sample, and a scanning probe microscope provided with the fine movement mechanism unit, in which a spot to be measured can be observed by an optical microscope or an electron microscope and the like in advance and the spot is measured by detecting flexural deformation (bending) of the cantilever by means of an optical detecting system.
2. Description of the Related Art
As literatures on the conventional scanning probe microscope (SPM), for example, two literatures such as "Evaluation on electronic and magnetic materials by using STM/AFM/MFM and its applications", Journal Vol.16, No.3, 1992 (511 page) of Application Magnetism Society of Japan, and "Force microscope of optical lever system with AFM and MFM functions", Papers (277 page) in Autumn Academic Lecture Meeting of Precision Technology Society, 1992, can be cited. As described in the literatures, a "SPM" means a general term as to a scanning tunnel microscope (STM), an atomic force microscope (AFM) and a magnetic force microscope (MFM) and the like. The SPM operates to obtain information as to a surface structure or a leakage magnetic distribution on a sample by making use of a tunnel current, an atomic force and a pressing force (hereinafter these are called "mutual operative force" as a general term) which are generated by approaching extremely or touching a solid probe tip to the sample. The resolution of the SPM is higher than that of the microscopes with an optical lens system by one figure or two figures.
The above-mentioned SPM has the probe tip arranged to be directed to the sample when carrying out measurement. The shapes of the probe tip are various and a shape like a rod or a pole, a cone, a prism, or a beak is used in response to objects to be measured by the SPM.
Further, as a concrete example of the SPM, there is a probe-tip movement type atomic force microscope which is configured so that the part including a cantilever with the probe tip can be moved when measuring the sample by the probe tip. As literatures on the atomic force microscope of the probe-tip movement type, JP-A-6-82249 and JP-A-8-278317 can be cited, for example.
The atomic force microscope described in JP-A-6-82249 has a configuration that the part including a spring element (equivalent to the cantilever) with a detecting tip (equivalent the probe tip) at its point and an optical detecting system relevant to the spring element are movable by a fine movement mechanism and the part including the sample stands still. This configuration enables the atomic force microscope to measure a large-sized sample or a heavy sample.
The atomic force microscope described in JP-A-8-278317 is equipped with two layered-piezoelectric-element rods arranged respectively in an X-axis direction and a Y-axis direction so as to connect their pointed ends, and a cantilever with a probe tip, which is attached to the connected part of the two pointed ends through a Z-axis direction piezoelectric actuating member. Further, this atomic force microscope has an optical detecting system in which optical routes are formed by using optical route converting members so that the flexural deformation (bending) of the cantilever can be sure to be detected optically even if the position of the probe tip is changed in the X-axis and Y-axis directions based on the expansion and contraction of the respective piezoelectric-element rods for the X-axis and Y-axis directions. In addition, an open space is formed above the cantilever so that the optical detecting system can be placed at an optional position in the upper region above the cantilever. In accordance with the structure, even if the probe tip is relatively moved in relation to the sample, a ray of light from a light source always strikes the same spot on the rear of the cantilever and further strikes the same point on a light receiving surface of a light receiving element after the reflection on the rear of the cantilever.
The above-mentioned first conventional atomic force microscope is capable of measuring a large-sized sample by moving the part including the probe tip by means of the fine movement mechanism. However, the structure of the first conventional microscope poses a problem that an optical microscope used for observing the place to be measured can not be added, since the members forming the optical detecting system are arranged above the cantilever. On the other hand, the second conventional atomic force microscope does not pose the above problem. However, since the piezoelectric actuating member used for the X direction (corresponding to an X fine movement mechanism) and the piezoelectric actuating member used for the Y direction (corresponding to a Y fine movement mechanism) are fixed to the body of the microscope through a block member and a hinge member, when performing scanning operation in an XY rectangular coordinates system, an interference effect happens between X and Y movements and therefore it poses another problem that independent precise motions in each of the X and Y directions cannot be generated.