Patent Publication Number: US-2007109636-A1

Title: Specimen stage array for scanning probe microscope

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This is a Continuation Application of PCT Application No. PCT/JP2006/310137, filed May 22, 2006, which was published under PCT Article 21(2) in Japanese. 
    
    
      This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-171269, filed Jun. 10, 2005, the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a specimen stage for a scanning probe microscope.  
      2. Description of the Related Art  
      An atomic force microscope (AFM) is one typical device of scanning probe microscopes. The atomic force microscope is an instrument that detects the influence of a force that acts when a distance between a probe and a specimen changes from the sub nm order to the nm order as a displacement or a change in resonance characteristics of a cantilever connecting to the probe, so as to measure the three-dimensional image of the specimen. In a high-speed AFM, the cantilever is changed from one having a response speed of several kHz to several 100 kHz, which is used in the conventional AFMs, to one having a response speed of 500 kMz or more. This enables scanning of 100 lines or more per second. To scan a specimen stage at a high speed, the lighter the specimen stage, the better.  
      The specimen stage of a high-speed AFM, such as one obtained by cutting glass or one obtained by cutting a resin, is fabricated separately. The specimen stage has a surface to which the specimen is adsorbed and a surface in contact with a scanner. The specimen fixing surface that adsorbs the specimen is used after adhering mica to it or subjecting it to surface treatment to form an underlying layer that adsorbs the specimen.  
      Regarding the surface treatment of the specimen fixing surface, the surface treatment conditions must be constant to improve the reproducibility and allow comparison of differences among specimens. Conventional specimen stages, however, are separate from each other. Accordingly, conditions such as the activity of the specimen as the result of the surface treatment of the specimen stage and the adsorbing density of the specimen largely vary among the individual specimens. Also, as the specimen stage is small, handling of the specimen stage to perform uniform treatment is difficult.  
     BRIEF SUMMARY OF THE INVENTION  
      For example, the high-speed AFM is used for measurement to check the motion and reactivity of specimen molecules.  
      To control the fixing strength for the specimen, the charged state, hydrophilic nature, and hydrophobic nature of the specimen stage surface must be controlled. To hold the specimen by utilizing specific adsorption among molecules, surface treatment is preferably performed so that the surface density of the molecules that adsorb the specimen in a specific manner becomes constant.  
      A specimen stage array according to the present invention includes specimen stages to hold specimens as observation targets of a scanning probe microscope, respectively, the specimen stages include specimen fixing surfaces to which the specimens are fixed, respectively, and all the specimen stages are arrayed so that the specimen fixing surfaces of all the specimen stages are included in a common plane.  
      Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.  
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
       FIG. 1  shows the first step in the process of fabricating a specimen stage array according to the first embodiment of the present invention;  
       FIG. 2  shows a step that follows the step shown in  FIG. 1  of the process of fabricating the specimen stage array according to the first embodiment of the present invention;  
       FIG. 3  shows a step that follows the step shown in  FIG. 2  of the process of fabricating the specimen stage array according to the first embodiment of the present invention;  
       FIG. 4  shows a step that follows the step shown in  FIG. 3  of the process of fabricating the specimen stage array according to the first embodiment of the present invention;  
       FIG. 5  shows a finished product of the specimen stage array according to the first embodiment of the present invention;  
       FIG. 6  shows a state wherein a specimen stage obtained from the specimen stage array of  FIG. 5  is attached to the Z scanner of a high-speed AFM;  
       FIG. 7  shows a specimen stage array according to the second embodiment of the present invention;  
       FIG. 8  shows a state wherein a specimen stage obtained from the specimen stage array of  FIG. 7  is attached to the Z scanner of a high-speed AFM; and  
       FIG. 9  shows a specimen stage array according to the third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The embodiments of the present invention will be described hereinafter with reference to the drawings.  
     FIRST EMBODIMENT  
      The first embodiment is directed to a specimen stage array fabricated by machining a glass plate. Machining of the glass plate employs a dicing saw, a diamond cutter, or the like. The specimen stage array according to this embodiment is fabricated in accordance with the following processing procedure.  
      First, as shown in  FIG. 1 , a glass plate GP is cut down in the surface that will be specimen fixing surfaces except for the left end part with a constant width and a constant depth in the direction of a section C and at intervals in the direction of a section B.  
      As shown in  FIG. 2 , the surface that will be specimen fixing surfaces is cut down with a constant width and a constant depth in the direction of the section B and at intervals in the direction of the section C.  
      Subsequently, as shown in  FIG. 3 , an inner part of each portion that has been cut in the process of  FIG. 2  is cut down with a constant width and a constant depth in the direction of the section B and at intervals in the direction of the section C, leaving a thickness corresponding to the thickness of bridge portions, which are to be broken when obtaining specimen stages.  
      Furthermore, as shown in  FIG. 4 , an inner part of each portion that has been cut in the process of  FIG. 1  is cut away with a constant width and a constant depth in the direction of the section C and at intervals in the direction of the section B.  
      Finally, as shown in  FIG. 5 , incisions to facilitate separation of the specimen stage array into rows are formed to complete a specimen stage array  10  of this embodiment.  
      In the specimen stage array of this embodiment, specimen stages are arrayed in rows. Alternatively, in the step of  FIG. 4 , the glass plate GP may be cut through in the direction of the section C to form a specimen stage array in which specimen stages are arrayed linearly.  
      As shown in  FIG. 5 , the specimen stage array  10  includes ten specimen stages  12 , which are integrally held by bridge portions  14  and the left end portion of the glass plate GP. The specimen stage array  10  of this embodiment is fabricated by cutting the glass plate GP, which is a flat plate member of the same material. Thus, all the specimen stages  12  are arrayed so that specimen fixing surfaces  12   a  are included in a common plane. This readily allows uniform surface treatment of the specimen fixing surfaces  12   a  of all the specimen stages  12  of the specimen stage array  10 . The surface treatment may include dipping the entire specimen stage array in a processing solution, depositing a metal such as gold on the specimen fixing surfaces  12   a , uniformly spraying a processing solution to the specimen fixing surfaces  12   a , plasma-ashing the specimen fixing surfaces  12   a  to incinerate organic contamination, and the like.  
      Conventionally, the specimen stages cannot but be surface-treated separately. The specimen stage array  10  of this embodiment enables simultaneous surface treatment of the specimen stages  12 . For example, the surface treatment includes forming a film, from which a gold surface  111  is exposed, as a specimen fixing surface to adsorb a specimen, and bonding a functional group such as an SH group, an amino group, a carboxyl group, a sulfone group, or the like to the specimen fixing surface with a constant density by using a silane coupler.  
      The specimen stage  12  cut out from the specimen stage array is directly adsorbed to a Z scanner  18  of the high-speed AFM by using an adhesive material, as shown in  FIG. 6 .  
     SECOND EMBODIMENT  
      The second embodiment is directed to a specimen stage array that is fabricated using a silicon process. As shown in  FIG. 7 , a specimen stage array  20  according to this embodiment has specimen stages  22 , a frame  24  surrounding the specimen stages  22 , and bridge portions  26  connecting the specimen stages  22  and the frame  24 . This specimen stage array is fabricated from a semiconductor substrate such as a silicon substrate using the MEMS technique such as a masking process, isotropic and anisotropic etching, and the like. As is apparent from a section A, the specimen stages  22  to the frame  24  are integrally connected by the bridge portions  26 .  
      Since specimen stage  22  of the second embodiment is thinner than the specimen stage  12  of the first embodiment, when the specimen stage  22  is applied to a high-speed AFM that is installed to match the height of the specimen stages  12  of glass of the first embodiment, the specimen stage  22  is not directly adhered to a Z scanner  18 , but through a spacer  28 , as shown in  FIG. 8 .  
      Since the specimen stage array  20  of this embodiment is fabricated by cutting the semiconductor substrate, which is a flat plate member of the same material, using the MEMS technique, all the specimen stages  22  are arrayed so that specimen fixing surfaces  22   a  are included in a common plane. This accordingly readily allows uniform surface treatment of specimen fixing surfaces  22   a  of all the specimen stages  22  of the specimen stage array  20 , like the first embodiment.  
      In the specimen stage array of the second embodiment, the frame  24  and the bridge portions  26  hold the specimen stages  22  independently of each other. This enables cutting out a specimen stage  22  at an arbitrary position and using it.  
     THIRD EMBODIMENT  
      The third embodiment is directed to a specimen stage array that is fabricated by arraying specimen stages on a holding member. As shown in  FIG. 9 , a specimen stage array  30  according to this embodiment comprises specimen stages  32  and a holding member  34  to hold the specimen stages  32 . The holding member  34  comprises a film having an adhesive surface. The specimen stages  32  are arranged on the holding member  34  at constant intervals, and their scanner contact surfaces are adhered to the adhesive surface of the holding member  34 . All the specimen stages  32  are held on the holding member  34  so that they have the same height. As a result, the specimen fixing surfaces of all the specimen stages  32  are included in a common plane. The holding member  34  may comprise a plate member coated with an adhesive material in place of the film having the adhesive surface.  
      In the specimen stage array  30  according to the third embodiment, the holding member  34  holds all the specimen stages  32  so that the specimen fixing surfaces are included in a common plane. Thus, this embodiment readily allows uniform surface treatment of the specimen fixing surfaces  32   a  of all the specimen stages  32  of the specimen stage array  30 , like the first embodiment.  
      In the specimen stage array  30  of the third embodiment, the film having the adhesive surface is pulled to strip off the scanner contact surfaces of the specimen stages  32  from it, so that the specimen stages  32  are separated one by one. Since this separation does not produce dust such as glass pieces or silicon pieces, impurities are hardly to present on the specimen surfaces.  
      So far the embodiments of the present invention have been described with reference to the drawings. Note that the present invention is not limited to these embodiments. Various changes and modifications may be made without departing from the spirit and scope of the invention.  
      For example, mica or isinglass may be adhered to the specimen fixing surfaces of the specimen stage arrays respectively formed in accordance with the first and second embodiments, and then cleaved to subject the specimen stage arrays to surface treatment.  
      Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.