JPH0740478B2 - Electrode short-circuit mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode short-circuit mechanism, and more particularly to a mechanism for short-circuiting multi-stage acceleration electrodes in an electron microscope or the like.

[Prior Art] When using an apparatus, such as an electron microscope, which generates an electron beam and accelerates the electron beam to irradiate a sample or the like, prior to use, the surface of the acceleration electrode is used. It is common to work to short-circuit the accelerating electrode for the purpose of removing the adhering substances and the like adhering to the accelerating electrode and keeping the electrostatic lens action constant in the accelerating electrode. , An electrode short circuit mechanism is provided.

An example of the configuration is shown in FIG. FIG. 6 is a view showing an example of a vertical cross section of an electrode short circuit mechanism of an accelerating electrode to which an accelerating voltage of 120 kV is applied. A Wehnelt 81 having a built-in emitter is arranged at the uppermost part of the electron gun chamber 80. Below the Wehnelt 81, a plurality of acceleration electrodes 82, 83, 84, 85, 86 are arranged,
Further, an electron gun alignment coil (not shown) is arranged below the acceleration electrode. Each of the accelerating electrodes 82 to 86 is provided with an opening for passing an electron beam in the central portion thereof, and an electrode formed of a ring having a circular cross section through an insulator 88 on the outer periphery thereof. A ring 87 is provided.

Then, in the electron gun chamber 80, a seat 89 is provided at a position corresponding to the position of the second electrode, that is, the electrode of the accelerating electrode, which is the second electrode from the top as indicated by 83 in the drawing, which is arranged from the top. , The electrode short-circuit mechanism 90 is attached to the seat 89,
The second electrode can be short-circuited by the electrode short-circuit mechanism 90.

A conductive rod 91 is housed inside the electrode short-circuit mechanism 90,
A spring 94 is built into one end of the conductive rod 91, and a contactor 94 capable of contacting the electrode ring 87 is provided.The other end of the conductive rod 91 is connected with an electric wire 95 by welding or the like. The other end of the electric wire 95 is connected to a part of the electrode short-circuit mechanism 90 by welding or the like and short-circuited to the electron gun chamber 80.

In such a structure, when the second electrode 83 is short-circuited, the lever 93 fixed to the conducting rod 91 at right angles with a screw or the like is provided in the electrode short-circuiting mechanism 90 as shown in FIG. It is stored in the crank-shaped guide groove 92 at a position indicated by a.
As a result, the short circuit switch 96 is turned on, the short circuit release switch 97 is turned off, and the second electrode 83 is short-circuited.

When a predetermined acceleration voltage is applied to the second electrode 83 after the short circuit ends, the lever 93 is moved from the position a to the position b, the short circuit switch is turned off, and the short circuit release switch 97 is turned on. After that, a power source (not shown) is connected to apply a predetermined acceleration voltage.

[Problems to be Solved by the Invention] However, the conventional electrode short-circuit mechanism has a problem because only one electrode, for example, the second electrode, can be short-circuited. That is, in recent years, in electron microscopes and the like, the acceleration electrodes tend to have multiple stages, and it has become very difficult to make the electrostatic lens action constant by simply shorting one electrode, as shown in FIG. It was found that such a conventional configuration cannot cope with the multi-stage acceleration electrode. Of course, it is possible to provide an electrode short-circuit mechanism as shown in FIG. 6 for a plurality of electrodes. However, if the electrode short-circuit mechanism is simply provided for each electrode, each electrode short-circuit mechanism is independent of each other. Therefore, forgetting to pull out the conductive rod when applying the accelerating voltage, and applying a high accelerating voltage with the electrodes still short-circuited, a situation in which the prescribed accelerating voltage cannot be applied occurs. There is a risk that

The present invention is to solve the above problems and is mainly adopted in a field emission electron gun (hereinafter, referred to as FEG), and keeps the electrostatic lens action of the first-stage electrode in the multi-stage acceleration electrode constant. It is an object of the present invention to provide an electrode short-circuiting mechanism that can be used.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the electrode short-circuit mechanism of the present invention is provided for a plurality of predetermined acceleration electrodes, and a tip is provided with a contactor that contacts the acceleration electrodes. Electrode short-circuit shafts, slide pulleys fixed at predetermined positions on the respective electrode short-circuit shafts, and moving means for moving the corresponding electrode short-circuit shafts in the axial direction. , A fixed pulley provided for each electrode short-circuit shaft, and both ends are fixed at predetermined positions, respectively, through slide pulleys and fixed pulleys of all electrode short-circuit shafts,
It is characterized in that the slide pulley and the fixed pulley are provided with wires alternately hung on the pulley.

[Operation and Effect of Invention] In the present invention, since the electrode short-circuit mechanism is provided for a predetermined plurality of electrodes, it is of course possible to keep the electrostatic lens function of the first-stage electrode constant. The operation of each electrode short-circuit mechanism is linked electrically and mechanically,
Since it is performed only for one electrode at a time, when applying a predetermined voltage to each electrode, avoiding the situation that a high acceleration voltage is applied while the electrodes are short-circuited. In addition, the acceleration voltage applied to the electrodes can be set arbitrarily.

Examples Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention,
FIG. 3 is a vertical cross-sectional view of an electrode short-circuit mechanism arranged in an electron gun chamber provided with G, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, showing a state in which the accelerating electrodes are short-circuited, and FIG. FIG. 4 is a diagram showing a mutual relationship between the detection switch and the cam at the time of short circuit,
FIG. 5 is a diagram showing a circuit state at the time of short circuit, and FIG. 5 is a diagram for explaining the operation of the conductive rod.

In FIGS. 1 and 2, a bearing box 3 formed into a cylinder via an O-ring 2 is fixed to the electron gun chamber 1 with screws 4 at right angles to the Z-axis (optical axis) direction. Brackets 5 and 6 are fixed to the inner bottom of 3 by screws 9a and 9b symmetrically with respect to the Y-axis. Between the tips of the brackets 5 and 6, there is a bearing 10 with screws 11a and 11b.
It is fixed at. The bearing 10 is provided with five through holes at equal intervals in the direction perpendicular to the Z axis. In the figure, the terminal labeled -HT is a terminal to which a negative high voltage is applied, and this terminal can be connected to the emitter 54. The through-holes, in order from the bottom, are electrodes 62, 61, 61, 5 respectively.
Electrode short-circuiting shafts 12, 13, 14, 15 for short-circuiting 9 and high-voltage applying shaft 16 are inserted. These electrodes are short-circuited to the ground when a voltage of 200 kV, 160 kV, 120 kV, 100 kV is applied between the emitter 54 and the ground. Also, on the inner bottom of the bearing box 3, each electrode short-circuit shaft 12 to 15 and a high voltage applying shaft are provided.
A hole into which 16 is inserted is formed. Each electrode short-circuit shaft 12-
Racks 12a to 16a are embedded in the lower part of 15 and the high-voltage applying shaft 16, and slide pulleys 17, 18, 19, 20, 21 each having a V-shaped groove are fixed by screws. The bearing 10 and the bracket 6 are provided with elongated holes 10b and 6a, respectively.
21 is movable in the range of L in the figure.

In addition, each rack 12a-16a, pinion 22,23,
It meshes with 24, 25 and 26 and is supported by bearings 27 and 28. The bearings 27, 28 are fixed to the brackets 5, 6 with screws 29, 30. The shafts of the pinions 22 to 26 are fixed by a vacuum flange 31 vacuum-sealed with an O-ring. A drive means 32 for driving a pinion shaft such as a motor or a manual knob is attached to the ends of the pinions 22 to 26 via a bracket 33 screwed to the bearing housing 3. Between the bracket 33 and the vacuum flange 31, as shown in FIG. 3, cams 34, 35, 36 and 37 are respectively provided on the pinion 22.
It is attached to ~ 26. Micro switches 38, 39, 40, 41 are mounted on the bearing housing 3 via switch mounting plates 42 near the cams 34-37. Fixed pulleys 43, 44, 45, 46 having V-shaped grooves are fixed to the bracket 6 by screws between the pinions 22 to 26 and the slide pulleys 17 to 21. Wires 47 are alternately hung on the V-shaped grooves of the slide pulleys 17 to 21 and the fixed pulleys 43 to 46,
One end of 47 is fixed to a metal fitting 48 provided on the upper part of the bracket 6, and the other end is a metal fitting 49 provided on the lower part of the bracket 6.
It is fixed to.

A contact 50 is attached by a pin 52 to one end of each of the electrode short-circuit shafts 12 to 15. On the outer circumference of the contact 50,
A long hole is provided in the axial direction, and a spring is provided in the long hole.
51 are stored. An electric wire 53 is connected to the bearing housing 3 at the other ends of the electrode short-circuit shafts 12 to 15.

In the electron gun chamber 1, an exhaust chamber including an emitter 54, a bias electrode 55, and an extraction electrode 56, and a first electrode 57, a second electrode 58, a third electrode 59, and a fourth electrode 57, which are provided with a ring around the exhaust chamber, are provided. Electrode 60, fifth electrode 61, sixth electrode 62, and each electrode 57-
The accelerating tube that becomes the insulator 63 joined between 62 is joined,
The accelerating pipe and the exhaust chamber are integrally formed and fixed with screws via an O-ring seal.

Next, regarding the operation of the configuration shown in FIG. 1 and FIG.
A description will be given with reference to FIG. 4, FIG. 5 and FIG.

Figure 3 is shows the relationship between the cam 34 to 37 and the microswitch 38 to 41 at the time of electrode short-circuit, FIG. Fig. 4 shows the relationship between the electrodes short circuit and conditioning switch 64 _{1-64 5} However, when the contact 50 is in contact with the electrode ring, the cam is in the state of the cam 34 in FIG.
When the contact 50 is not in contact with the electrode ring, the cam is in the state of the cams 35 to 37 shown in FIG. At this time, the COM terminal of the micro switch 38 is connected to the NC terminal as shown in FIG. 4, and the contact 50 is in contact with the electrode ring. Therefore, the sixth electrode 62 is connected to the electron gun chamber 1 set to the ground potential, and is short-circuited. On the other hand, the contact 50 of the other electrode short-circuit shaft is not in contact with the electrode ring, so that the microswitch 39-
The COM terminal of 41 is connected to the NO terminal, and the electrodes corresponding to these electrode short-circuit shafts are not connected to the electron gun chamber 1, so that no short circuit is performed. COM is an abbreviation for COMMON, which means a common terminal, NO is an abbreviation for normally open, which means that normally it is in an open state and is closed only during operation, and NC is normally closed. It is an abbreviation and means that it is normally in a closed state and is opened only during operation.

Moreover, conditioning and closed all the conditioning switch 64 _{1-64 5,} the emitter 54, the bias electrode 55, the extraction electrode 56 and the first electrode 57 (hereinafter, these are collectively referred to as FEG) accelerate the conducting state Acceleration voltage applied from the acceleration voltage source (not shown) to the top of the tube −HT
And FEG are set to the same potential. This makes it possible to prevent discharge from the accelerator tube side to the FEG side and protect the emitter 54. Further, normally, an extraction voltage source and an acceleration voltage source are connected to the FEG, but it is clear that the electron gun does not operate at all because these voltage sources are not connected during conditioning.

Fig. 5 shows the electrode short-circuit shaft 12 when the electrodes are short-circuited and when high voltage is applied.
FIG. 5 (a) is a view for explaining the movement of the electrode, and FIG. 5 (a) is a view showing the movement of the electrode short-circuiting axis when the electrode is short-circuited. Ten
Taking 0kV as an example, it is as follows.

When applying 100 kV to the third electrode 59, it is necessary to short-circuit the third electrode 59. For that purpose, first, the pinion 25
The driving means 32 such as a motor for driving the motor is rotated in the direction of the arrow in FIG. 5 (a). As described above, the electrode short-circuit mechanism is provided with the four fixed pulleys 43 to 46 and the five slide pulleys 17 to 21, and both ends have a predetermined length fixed to the metal fittings 48, 49. Since the wire 47 with a pin is alternately hung on the slide pulley and the fixed pulley,
When 25 is rotated, as shown in FIG. 5 (a), the slide pulley 20 projects and only the contact of the electrode short-circuit shaft 15 abuts on the electrode ring, whereby the third electrode 59 is short-circuited.
At this time, the high voltage applying shaft 16 and other electrode short-circuit shafts 12, 13,
Since 14 moves in the right direction of FIG. 5 (a) in conjunction with the movement of the electrode short-circuit shaft 15, the electrodes corresponding to these electrode short-circuit shafts 12-14 are not short-circuited. It is obvious that the short-circuiting of the other electrodes can be similarly performed by rotating the pinion of the electrode-shorting shaft corresponding to the electrode to be short-circuited.

Next, when applying a desired accelerating voltage to the electrodes, all the electrode short-circuiting shafts must be separated from the electrode ring. For that purpose, as shown in FIG.
The drive means 32 may rotate the 26 in the direction of the arrow in the figure. As a result, the slide pulley 21 projects, only the high-voltage applying shaft 16 moves to the left in the figure, and the electrode short-circuit shafts 12 to 15 move to the right in the figure, so that all the contacts are separated from the electrode ring. Be done.

Although one embodiment of the present invention has been described above, it will be apparent to those skilled in the art that the present invention is not limited to the above embodiment and various modifications can be made.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention,
FIG. 2 is a longitudinal sectional view of an electrode short-circuit mechanism arranged in an electron gun chamber equipped with G, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, showing a state in which the accelerating electrodes are short-circuited, and FIG. FIG. 4 is a diagram showing a mutual relation between the detection switch and the cam at the time, FIG. 4 is a diagram showing a relation between the electrode short circuit and the conditioning switch,
FIG. 5 is a diagram for explaining the operation of the conductive rod, and FIG. 6 is a diagram showing a configuration example of a conventional electrode short-circuit mechanism. 1 ... Electron gun chamber, 2 ... O-ring, 3 ... Bearing box, 4 ...
… Screws, 5,6… Brackets, 9a, 9b… Screws, 10…
… Bearing, 11a, 11b …… Screw, 12,13,14,15 …… Electrode short-circuit shaft, 16 …… High-voltage applying shaft, 17,18,19,20,21 …… Slide pulley, 22,23,24 , 25,26 …… pinion, 27,28 …… bearing, 29,30 …… screw, 31 …… vacuum flange, 32 …… driving means, 33 …… bracket, 34,35,36,37 …… cam, 38,3
9,40,41 …… Micro switch, 42 …… Switch mounting plate, 43,44,45,46 …… Fixed pulley, 47 …… Wire, 48,
49 …… metal fittings, 50 …… contacts, 51 …… springs, 52 ……
Pin, 53 ... Electric wire, 54 ... Emitter, 55 ... Bias electrode, 56 ... Extraction electrode, 57 ... First electrode, 58 ... Second
Electrode, 59 ... Third electrode, 60 ... Fourth electrode, 61 ... Fifth electrode, 62 ... Sixth electrode, 63 ... Insulator, 64 ... Conditioning switch.

Claims (1)

[Claims] 1. A plurality of accelerating electrodes provided for a predetermined number,
An electrode short-circuit shaft having a contactor attached to the accelerating electrode at its tip, a slide pulley fixed at a predetermined position of each electrode short-circuit shaft, and each electrode short-circuit shaft are provided respectively. Moving means for moving the electrode short-circuit shaft in the axial direction, fixed pulleys provided for each electrode short-circuit shaft, both ends fixed at predetermined positions, slide pulleys and fixed pulleys for all electrode short-circuit shafts An electrode short-circuit mechanism comprising: a slide pulley and a wire alternately hooked around a fixed pulley.