Abstract:
An electrostatic deflector that can be manufactured easily and very accurately without using a member for positioning is provided. After multiple slits  81   d  to  88   d  have been formed in the same direction as that of the bus bar of an approximately conical electrode material  100  whose large-diameter section is formed with flange portions  81   a  to  88   a  for installation on an insulator  90,  each of the flange portions is coupled with the insulator  90,  then the electrode material  100  is cut along extension lines of the slits  81   d  to  88   d , and thus, multiple electrode members electrically isolated from one another are formed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to deflectors for deflecting electron beams, ion beams, and other electrically charged beams. More specifically, the invention relates to an electrostatic deflector for use in electron beam exposure apparatuses, ion implantation apparatuses, electron microscopes, and the like.  
         [0002]     Some of traditionally known deflectors are outlined below. Japanese Patent Laid-open No. 2-100250 describes an electrostatic deflector having four sector-form electrodes arranged, with rod-shaped structures as their supporting columns, inside a cylindrical insulator. Also, Japanese Patent Laid-open No. 8-171881 describes an electrostatic deflector constructed by machining eight split electrode pieces integrally into flange form and mounting these electrode pieces in or on an electrode supporter.  
         [0003]     In addition, Japanese Patent Laid-open No. 4-174510 describes a method of manufacturing an electrostatic deflector for an electron beam exposure apparatus. The method described in Japanese Patent Laid-open No. 4-174510 includes the steps of: bonding a cylinder formed of an electrode material, onto the inner surface of a cylinder formed of an insulator; cutting the cylinder formed of the electrode material, into a plurality of segments in the axial direction of the cylinder so that the cylinder formed of the insulator is invisible from the path of an electron beam; and using the remaining cut pieces as electrode pieces.  
         [0004]     Furthermore, Japanese Patent Laid-open No. 2-123651 describes a method of manufacturing an electrostatic deflection electrode having the required number of pole pieces. In the method described in Japanese Patent Laid-open No. 2-123651, after an integrated first component constructed of an electroconductive semiconductor or metal and having a hollow symmetrical shape has been readied for use, a second component constructed of an insulator is embedded in the outer surface or inner surface of the first component, then a plurality of slits each extending from one end of the first component to the other end thereof and terminating at the second component are formed to segment the first component at the slits.  
         [0005]     Moreover, Japanese Patent Laid-open No. 10-261376 describes a method of manufacturing an electrostatic deflection electrode for an electron beam lithography apparatus. The method described in Japanese Patent Laid-open No. 10-261376 includes: a first step of obtaining a cylindrical material formed of an electroconductive metallic; a second step of providing slits of a required width in the cylindrical material, each of the slits extending from the top of an independent line for sectioning the outer peripheral surface of the cylindrical material circumferentially into eight equal segments, to a radial halfway position on the cylindrical material in the direction of its axial center line; a third step of securing an independent, ring-shaped insulating jig internally to each of the regions provided with the slits at both edges of the cylindrical material in the direction of its axial center line; and a fourth step of extending the inner end side of each slit in the direction of the axial center line under the conditions where the ring-shaped jigs are mounted, and separating the cylindrical material circumferentially into eight electrode elements.  
         [0006]     Besides, Japanese Patent Laid-open No. 5-29201 describes a method of manufacturing an electrostatic deflection electrode in the manner below. A plurality of outer insulating grooves each extending from the side face of a block towards an electron beam passage region are formed, then an independent insulator is fittingly inserted into each outer insulating groove and bonded onto the inner wall thereof, and a plurality of intermediate insulating grooves are formed. This causes the outer insulating grooves to communicate with associated inner insulating grooves and thus forms a plurality of electrodes each surrounding the electron beam passage region.  
         [0007]     Such an electrostatic deflector as described in Japanese Patent Laid-open No. 2-100250, however, has a problem in that since four sector-form electrodes must be arranged with rod-shaped structures as their supporting columns inside a cylindrical insulator, too great a deal of working labor is required for efficient manufacture of the electrostatic deflector. Also, such electrostatic deflectors as described in Japanese Patent Laid-open Nos. 8-171881, 4-174510, 2-123651, and 10-261376 have a problem in that since electrodes must be mounted in or on an electrode supporter by means of bonding or the like, a great deal of working labor is required and the electrodes are extremely difficult to arrange in equally spaced form with respect to an electron beam so as not to cause a disturbance of a magnetic field and so as not to bring the electrodes into contact with one another. In addition, such an electrostatic deflector as described in Japanese Patent No. 5-29201, however, has a problem in that since independent insulators are fittingly inserted into outer insulating grooves and then bonded onto the inner walls thereof, too great a deal of working labor is required for efficient manufacture of the electrostatic deflector.  
         [0008]     An object of the present invention is therefore to provide an electrostatic deflector that can be manufactured easily, efficiently, and very accurately, without using a member for positioning.  
       SUMMARY OF THE INVENTION  
       [0009]     In an electrostatic deflector manufacturing method and electrostatic deflector according to the present invention, an electrode material formed with slits is connected to an insulator and then the electrode material is cut along the slits, whereby a plurality of electrode members are constructed.  
         [0010]     More specifically, the method of manufacturing an electrostatic deflector according to the present invention includes: forming a plurality of slits in an essentially conical electrode material to extend in the same direction as that of a bus bar of the electrode material, which has a large-diameter section formed with a flange section for installation on an insulator; and coupling the flange section with the insulator, and then cutting the electrode material to communicate with the slits for manufacture of an integrated electrode formed up of a plurality of electrode members electrically isolated from one another.  
         [0011]     Also, the electrostatic deflector according to the present invention is outlined below. The electrostatic deflector includes a plurality of electrode members arranged to put slits, extending along a bus bar, therebetween and to be formed into an essentially conical shape. The electrode members are installed on an insulator through a flange portion formed on a large-diameter side of the electrode members. Inn addition, the electrode members are manufactured by forming a plurality of slits in an essentially conical electrode material to extend in the same direction as that of a bus bar of the electrode material, coupling the flange section with the insulator, and then cutting the electrode material along extension lines of the slits for electrical isolation.  
         [0012]     The slits in the electrode material may be continuously formed spanning from the flange section to the conical section. The electrode material of the approximately conical shape can also be cut from a small-diameter section thereof. Additionally, electrical discharge machining can be employed to perform the above cutting operations. Furthermore, each of the electrode members can be an approximately conical member with required thickness.  
         [0013]     In the present invention, therefore, first assembling the electrode material into an insulating member integrally without separating the electrode material into each electrode member and by forming slits therein, and then splitting the electrode material allows an electrostatic deflector to be manufactured easily and very accurately without using a member for positioning the electrostatic deflector. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a diagram showing a schematic construction of a scanning electron microscope that uses an electrostatic deflector according to an embodiment of the present invention;  
         [0015]      FIG. 2  is a sectional view showing installation of the electrostatic deflector of  FIG. 1  in a scanning electron microscope;  
         [0016]      FIG. 3  is a perspective view of the electrostatic deflector of  FIG. 2  as viewed from below;  
         [0017]      FIG. 4  is a plan view of the electrostatic deflector shown in  FIG. 2 ;  
         [0018]      FIG. 5  is a perspective view showing the electrostatic deflector of  FIG. 2  as viewed from below to describe its manufacturing process steps;  
         [0019]      FIG. 6  is a sectional view of an electrode material of the electrostatic deflector shown in  FIG. 2 ; and  
         [0020]      FIGS. 7A and 7B  are a plan view and a front view, respectively, showing an installation member for the electrostatic deflector of  FIG. 2 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     A method of manufacturing an electrostatic deflector according to an embodiment of the present invention will be described below. The electrostatic deflector according to the invention is used in, for example, the scanning electron microscope shown in  FIG. 1 . This scanning electron microscope, after generating an electron beam  41  from an electron beam generator  11  provided in an upper section of a lens barrel  10 , first deflects the electron beam via alignment coils  12  (a first deflector) and stigmatic coils  13  (a second deflector). Next, the scanning electron microscope adjusts a magnification using objective lens coils  14  (a magnification controller), and scans a sample  21 . After this, the scanning electron microscope activates a detector  30  to detect an electrically charged particle  42  generated from the sample  21 , such as a secondary electron or backscattered electron, and displays an image of the sample at an image display device not shown, such as a monitor. The image of the sample can thus be viewed.  
         [0022]     A detailed structure of this electrostatic deflector is shown in  FIG. 2 . In the present embodiment, inside the lens barrel  10 , the electrostatic deflector  40  according to the embodiment is disposed spanning from a position internal to objective lens coils  50  equivalent to the objective lens coils  40  shown in enlarged view, to a position above the objective lens coils  50 . In the present embodiment, electrodes  80  of the electrostatic deflector  40  are each attached to an annular installation member  70  with a screw  71 , with an annular insulator  90  sandwiched between the electrode  80  and the annular installation member  70 .  
         [0023]     As shown in FIGS.  2  to  4 , each electrode  80  in the present embodiment is constructed of eight electrode members  81  to  88 , and the electrode  80  has its entirety tapered as it goes downward, and is installed so as to form a conical shape having an electron beam penetration hole  89  at a front end.  FIG. 4  is a view looking from installation flange portions  81   a  to  88   a  of  FIG. 3 . In the present embodiment, the eight electrode members  81  to  88  are of the same shape and as shown in  FIG. 4 , each of the members is formed symmetrical to an optical axis O and has a clearance  81   b  to  88   b . Also, the flange portion  81   a  to  88   a  for installation through the insulator  90  is formed on a large-diameter side of each electrode member  81  to  88  of the conical shape, and the electrode member  81  to  88  provided extending downward from the flange portion  81   a  to  88   a , along the conical shape. In addition, a slit  81   d  to  88   d  contiguous to the clearance  81   b  to  88   b  is formed spanning from the installation flange portion  81   a  to  88   a  to an electrode portion  81   c  to  88   c . In the present embodiment, the installation flange portion  81   a  to  88   a  is installed on the insulator  90  by metallization.  
         [0024]     Next, a method of manufacturing the electrostatic deflector according to the present embodiment is described below. The electrostatic deflector  40  according to the present embodiment is manufactured by assembling into the insulator  90  an electrode material  100  which is an integrated body of the electrode members  81  to  88  and the installation flange portions  81   a  to  88   a , and then cutting the electrode material  100  by electrical discharge machining.  
         [0025]     In the present embodiment, the electrode material  100  includes, as shown in  FIGS. 5 and 6 , eight installation flange portions  81   a  to  88   a , a conical section  110  suspended in downward tapered form from a lower position of the installation flange portions  81   a  to  88   a , and a cylindrical section  120  provided at a front end of the conical section  110 . The electrode material  100  in the present embodiment is a metallic member and forms a spatial portion  111  inside the conical section  110 , and the spatial portion  111  communicates with the electron beam penetration hole  89 .  
         [0026]     Between the installation flange portions  81   a  to  88   a  in the present embodiment are also formed the slits  81   d  to  88   d , each of which extends to a required section below, along a bus bar of the conical section  110 .  
         [0027]     The insulator  90  is an annular member as shown in  FIGS. 7A and 7B , and is formed with grooves  91  on its connection surfaces with respect to the installation flange portions  81   a  to  88   a . Respective installation positions are set to achieve engagement with the above-mentioned slits  81   d  to  88   d . In addition, through-holes  92  adapted for bolt insertion into the installation member  70  are provided in required portions of the insulator  90 .  
         [0028]     Next, a description is given of manufacturing steps for the electrostatic deflector according to the present embodiment. First, the installation flange portions  81   a  to  88   a  of the electrode material  100  are installed on the insulator  90  by metallization. The insulator  90  can be of a material such as ceramics or resin. Also, an adhesive can be used to couple the insulator  90  with the installation flange portions  81   a  to  88   a.    
         [0029]     After coupling between the electrode material  100  and the insulator  90 , the electrode material  100  is divided into eight equal segments. This is accomplished by cutting the electrode material  100  from the cylindrical section  120  thereof, along the cylindrical section  120  and the bus bar of the conical section  110 , by use of electrical discharge machining. The clearances  81   b  to  88   b  are formed as a result of the cutting operations. The clearances  81   b  to  88   b  are thus formed so that they lead to the slits  81   d  to  88   d.    
         [0030]     In the method of manufacturing the electrostatic deflector according to the present embodiment, since each electrode member  81  is formed by cutting the electrode material  100  with each installation flange portion  81   a  to  88   a  and the insulator  90  remaining coupled with one another, a member for positioning is unnecessary and none of the electrode members requires assembly labor, either. The electrostatic deflector can therefore be manufactured easily and accurately.  
         [0031]     The electrostatic deflector manufactured is mounted in a required disposition section of an electron beam apparatus such as an electron beam exposure apparatus, ion implantation apparatus, or electron microscope.  
         [0032]     An insulator charge-up preventing component can also be installed internally to the disposition section in which the electrostatic deflector manufactured is mounted. In that case, since charge-up of the insulator can be prevented, this electrostatic deflector, unlike conventional types, makes it possible to avoid increasing the number of components required and complicating the shape of the electrodes.  
         [0033]     While an electrostatic deflector divided into eight equal segments has been described in the above embodiment, the deflector is not limited to such a structure and may be equally divided into a plurality of segments, such as two, three, or four segments. Also, the shape of the flange of the electrodes and the shape of the slits and clearances provided in the conical structure are not limited to a linear form and can be, for example, a zigzag form. Forming these sections into a zigzag shape makes it possible to prevent charge-up of the insulator, since the electron beam emitted is directly invisible from the insulator.