Abstract:
A cantilever unit comprises a substrate and a self-detecting type cantilever attached to the substrate. The self-detecting type cantilever has a cantilever portion extending from the substrate and a probe tip depending from the cantilever portion and detects a deflection of the cantilever portion when, for example, the probe tip is scanned over a surface of a sample. A visual identification portion of the cantilever unit permits the cantilever unit to be visually distinguished from other cantilever units.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a cantilever unit suitable for a scanning atomic force microscope (AFM) which is a typical scanning probe microscope, and more particularly to a cantilever unit having a self-detecting type cantilever outputting an electric signal in response to deflection of the cantilever itself. 
     In the scanning atomic force microscope (AFM), a cantilever having an exploring needle at a free end is used as a scanning probe. In the configuration, because attraction or repulsion based on interatomic force appears between surface of a sample and the exploring needle by scanning the exploring needle on the surface of the sample, a shape of the surface of the sample can be measured by detecting the interatomic force a as deflection of the cantilever. 
     Although deflection of said cantilever is measured by detecting an optically displacement quantity of a reflecting beam radiated to a back surface of the cantilever, there is a problem that the configuration is complex and adjusting is difficult in the way detecting optically deflection of the cantilever. Therefore, a self-detecting type cantilever is developed recently which directly outputs detected deflection as electric signal forming a detecting circuit for detecting deflection on the cantilever. 
     The self-detecting type cantilever having the above-mentioned configuration is installed on the main body of the microscope as a cantilever unit in the detachable state holding the cantilever on the surface of semiconductor substrate in cantilever type because it is difficult to handle alone. 
     In the scanning probe microscope, there are various modes except the above-mentioned AFM mode. They are a friction force microscope (FFM) mode detecting change of friction applied between surface of sample and cantilever as deflection of horizontal direction of the cantilever, a magnetic force microscope (MFM) mode measuring magnetic distribution of surface of sample detecting magnetic force by AC detecting method making an exploring needle magnetized and cantilever resonate, and a tunnel microscope mode measuring surface shape by applying voltage between surface of sample and cantilever, and by controlling and detecting tunnel current flowing through between them. 
     In any of operation modes, an exclusive cantilever unit can be selectively installed without changing the main body of the device. Therefore, an operator should selectively install a cantilever unit corresponding to the desired operation mode on the main body of the device. 
     Here, it is difficult to identify each cantilever unit with the naked eye because the cantilever units are not very small in size but also are little difference in their constructions though shape and size of the cantilever portion is different from each other depending on their kinds. Therefore, it has been difficult to identify the desired cantilever unit when the cantilever unit suitable for the desired operation mode is searched among the stock. It has been difficult to identify too the cantilever unit being installed now on the main body of the device. 
     An object of the present invention is to provide a cantilever unit enable to identify simply kinds of cantilever units with eyes solving the conventional above-mentioned problem. 
     SUMMARY OF THE INVENTION 
     To achieve the above-mentioned object, the present invention is characterized by that proper identification data is recorded for use of the concerned cantilever unit, namely each self-detecting type cantilever installed on the concerned cantilever unit. 
     According to the above-mentioned configuration, the types of the concerned cantilever units are identified so as to become easy to identify the cantilever unit by only confirming identification data without confirming the construction of the cantilever units. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plane view of a cantilever unit according to the present invention. 
     FIG. 2 is a side view of FIG.  1 . 
     FIG. 3 is a side view showing a cantilever unit holder with the cantilever unit of the present invention installed thereon. 
     FIG. 4 is a plane view showing a first embodiment (No. 1) of the present invention. 
     FIG. 5 is a plane view showing a first embodiment (No. 2) of the present invention. 
     FIG. 6 is a plane view showing a second embodiment (No. 1) of the present invention. 
     FIG. 7 is a plane view showing a second embodiment (No. 2) of the present invention. 
     FIG. 8 is a plane view showing a third embodiment (No. 1) of the present invention. 
     FIG. 9 is a plane view showing a third embodiment (No. 2) of the present invention. 
     FIG. 10 is a plane view showing a fourth embodiment (No. 1) of the present invention. 
     FIG. 11 is a plane view showing a fourth embodiment (No. 2) of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the figures, the present invention will be described in detail. A configuration of a cantilever unit installing a self-detecting type cantilever will be described first. FIG. 1 is a plane view showing a cantilever unit  10 , and FIG. 2 is a side view of FIG.  1 . 
     The cantilever unit  10  comprises a self-detecting cantilever  70  and a glass epoxy substrate  80 . The self-detecting cantilever  70  comprises thin plate shaped silicon substrate  71  and thick plate shaped silicon substrate  72  being layered as shown in FIG. 2, an exploring needle  10   a  is formed at free end of a cantilever beam portion  71   a  projecting from one end of the thin plate shaped silicon substrate  71 . The self-detecting type cantilever  70  is held by a glass epoxy substrate  80  so that at least the cantilever beam portion  71   a  projects from the end portion as shown in FIG.  1 . 
     A detecting circuit (not shown) an outputting electric signal in response to a to deflection quantity of the beam portion  71   a  and bonding pads  72   b  for power supply line and signal line of the detecting circuit are formed on main surface where the exploring needle  10   a  is on the silicon substrate  71 . On the glass epoxy substrate  80 , a plural of wiring patterns  82  are formed. At one end of each wiring pattern  82 , contact patterns  82   a  for external connecting are formed, and at other end, bonding pads  82   b  are formed. 
     The bonding pads  72   b  of the silicon substrate  71  and the bonding pads  82   b  of the glass epoxy substrate  80  are connected with bonding wires  83 , and a plastic mold  81  are performed on bonding wires  83  and each bonding pad  72   b  and  82   b.    
     FIG. 3 is a side view showing a cantilever unit holder  50  for holding said cantilever unit wherein the cantilever unit  10  is installed. The cantilever unit holder  50  is fixed at the main body  40  of the device through a piezoelectric plate  58 . The piezoelectric plate  58  is formed in order to make the cantilever resonate during observation of a soft sample such as biological molecule. 
     At one side of the holder  50 , a plural of grooves  55  in which U-shaped portion of each S-shaped elastic body electrode  54  is inserted. Under the holder  50 , pectination-shaped electrode guide  53  is supported like cantilever so as to face to the main body keeping predetermined gap. The pectination of the electrode guide  53  is constructed so as to lack a part thereof at the position corresponding to said each groove  55 . 
     One U-shaped portion of each elastic electrode  54  is inserted in each groove  55 , and a bending portion  57  of a part from the other U-shaped portion to end elastically projects from pectination of the electrode guide  53  into the gap as shown in the figure. At other side of the holder, a prism  59  is fixed, and at under thereof, a cantilever table  52  is formed. 
     A cantilever unit  10  is inserted into the gap portion between the cantilever table  52  and the electrode guide  53  diagonally upward from the down part. The cantilever unit  10  is pushed to the cantilever  52  side by elastic force thereof after being inserted into the gap so as to be put between the electrode  54  and the cantilever table  52  because the cantilever unit  10  is inserted resisting elastic force of the electrode  54  elastically projecting toward the gap. Each electrode  54  is previously positioned so that the bending portion  57  contacts with each contact pattern  82   a  of the glass epoxy substrate  80  when the cantilever unit  10  is inserted to the correct position. 
     FIGS. 4 and 5 are plane views of a cantilever unit  10  of a first embodiment of the present invention. The same symbols show the same or similar parts as above-mentioned. The present embodiment, is characterized by that a dummy pattern for a mark is formed at differ position of surface of a substrate from others depending on kinds of the cantilever. 
     If the cantilever unit  10  is used for AFM for example, a circular dummy pattern  91   a  is formed at upper right corner of the glass epoxy substrate  80  as shown in FIG.  4 . If the cantilever unit  10  is used for MFM, a circular dummy pattern  91   b  is formed at down right corner of the glass epoxy substrate  80  as shown in FIG.  5 . It is desirable that the above-mentioned dummy pattern mark  91  is formed at the same time with the same process as forming wiring patterns  82 . 
     According to the present embodiment, kinds of cantilevers can be easily identified based on the position formed at the surface of the glass epoxy substrate  80  without confirming the structure of the self-detecting cantilever  70 . 
     FIGS. 6 and 7 are plane views of cantilever units  10  of a second embodiment of the present invention. The same symbols show the same or similar parts as above-mentioned. The present embodiment is characterized by that any of four corners of a glass epoxy substrate  80  is cut down depending on kinds of the cantilever units  10 . 
     If the cantilever unit  10  is for AFM for example, an upper right corner  92   a  of the glass epoxy substrate  80  is cut down as shown in FIG.  6 . If the cantilever unit  10  is for MFM, a down right corner  92   b  of the glass epoxy substrate  80  is cut down as shown in FIG.  5 . 
     According to the present embodiment, kinds of cantilevers can be easily identified based on the cut down position of the glass epoxy substrate  80  without confirming the structure of the self-detecting type cantilever  70 . 
     FIGS. 8 and 9 are plane views of cantilever units  10  of a third embodiment of the present invention. The same symbols show the same or similar parts as above-mentioned. The present embodiment is characterized by that different pattern  93  from others is formed at side of a glass epoxy substrate  80  depending on kinds of the cantilever units  10 . 
     If the cantilever unit  10  is used for AFM for example, a pattern  93   a  having two lines is formed at side of the glass epoxy substrate  80  as shown in FIG.  8 . If the cantilever unit  10  is used for MFM, a pattern  93   b  having three lines is formed as shown in FIG.  9 . 
     According to the present embodiment, kinds of cantilevers can be easily identified based on the pattern  93  marked at side of the glass epoxy substrate  80  without confirming the structure of the self-detecting cantilever  70 . Moreover, in the present invention, kinds of the cantilever units  10  can be identified even if the cantilever unit  10  is installed at the cantilever holder because the pattern  93  for identification is marked at side of the glass epoxy substrate  80 . 
     FIGS. 10 and 11 are plane views of cantilever units  10  of a fourth embodiment of the present invention. The same symbols show the same or similar parts as above-mentioned. The present embodiment, is characterized by that character, number or the like expressing concretely kinds of the cantilever units  10 . 
     If the cantilever unit  10  is used for AFM for example, characters “AFM” are marked at surface of the glass epoxy substrate  80  as shown in FIG.  10 . If the cantilever unit  10  is used for MFM, characters “MFM” are marked as shown in FIG.  11 . 
     According to the present embodiment, kinds of cantilevers can be easily identified based on the symbols marked at surface of the glass epoxy substrate  80  without confirming the structure of the self-detecting cantilever  70 . 
     Although in each embodiment, the substrates forming newly a mark on surface thereof and being newly cut down at a part thereof are described, the substrate may be identified by, for example, color of the plastic mold  81  depending on kinds of the cantilever units  10 . 
     Combination of the above-mentioned embodiments can be used so as to become possible to distinguish more kinds of the cantilever units. 
     According to the present invention, kinds of cantilevers can be easily identified only by confirming identification data without confirming the structure of the self-detecting cantilever.