JP2011082152A - Ion gun and grid used for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion gun having a half-pipe grid which is superior in reproducibility of output characteristics at the time of grid exchange, shape stability accompanying temperature change, and storage performance. <P>SOLUTION: The ion gun is provided with a body to generate plasma inside, a grid for extracting plasma from the inside of the body, and a frame-shaped accelerating electrode which interposes the grid between it and the body. The end face opposed to the grid of the body has a valley-like curved surface, and the grid is made of a flat-plate grid and is installed so that it makes a curved face to coincide with the curved surface at the contact interface of the body and the grid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ion gun, and more particularly to an acceleration grid for extracting an ion beam from plasma and an ion gun using the same.

  FIG. 11 shows a configuration of a conventional ion gun 100. The ion gun 100 includes a main body 110 for generating plasma therein, a shielding grid 121 provided with a number of grid holes and an acceleration grid 122 (collectively referred to as a grid 120), a support 112 attached to the main body 110, and an acceleration grid. A screw 140 for fixing 122 to the support 112 is provided. The acceleration grid 122 to which a voltage is applied from a power source (not shown) draws ions from the plasma inside the main body 110, whereby an ion beam (arrow) is emitted. This ion beam is applied to a piezoelectric element (not shown) or the like and used for frequency adjustment of the piezoelectric element (for example, Patent Document 1).

  Although the grid 120 shown in FIG. 11 is planar, a configuration is known in which the grid 120 is curved in order to increase the convergence of the ion beam for the purpose of increasing the rate. For example, Patent Document 2 discloses a grid (electrode 8) that is curved so as to be recessed toward the main body (ion source 5) side, and Patent Document 3 also discloses a plurality of grids that are curved so as to be recessed toward the main body (reference numeral 5). The plate 7) is disclosed. These grids are called half-pipe grids.

Japanese Patent No. 4048254 Japanese Patent Laid-Open No. 4-6272 Japanese Utility Model Publication No. 63-18746

However, the conventional ion gun using a half-pipe grid has the following problems.
First, in both Patent Documents 2 and 3, a flat grid plate is curved in one direction at the time of grid manufacture, and then attached to the main body. However, it is difficult to ensure the accuracy of this bending process, and the degree of curvature varies depending on the degree of curvature. Is likely to occur. In the ion gun, the grid is a consumable item and is replaced relatively frequently. However, due to the variation in the bending process, there is a problem that the characteristics of the emitted ion beam change each time the grid is replaced. Therefore, the conventional half-pipe grid has a problem that the reproducibility of the emitted ion beam is poor due to the variation in the bending process.

  Secondly, in the conventional ion gun configuration (regardless of whether it is a half-pipe type of Patent Documents 2 and 3 or a flat type of Patent Document 1), the shape stability of the acceleration grid is poor, and the output characteristics after the start of ion beam extraction are low. It took time to stabilize. That is, if the temperature of the acceleration grid rises after the start of ion beam extraction, the position of the grid hole with respect to other members changes due to deformation due to thermal expansion, but the use of the ion gun starts (for example, piezoelectric) until this change stabilizes. It was necessary to wait for the start of the frequency adjustment of the element (for example, about 15 minutes in the case of Patent Document 1). Therefore, there is a problem in that power and waiting time until the ion beam is stabilized after being emitted from the low shape stability is wasted.

  Third, since the grid is a consumable item as described above, it is necessary for the ion gun user to store a large number of stocks. However, the curved grids as in Patent Documents 2 and 3 have a large volume, and furthermore, it is not preferable to load a large number of grids so that the curved state is not impaired during storage. It took storage and storage space. Therefore, the conventional half-pipe type grid also has a problem of poor storage.

  Therefore, an object of the present invention is to provide a half-pipe grid excellent in reproducibility of output characteristics at the time of grid replacement, shape stability accompanying temperature change, and storage, and an ion gun including the same.

  The first aspect of the present invention is an ion gun, comprising a main body for generating plasma inside, a grid for extracting plasma from the inside of the main body, and a frame-like acceleration electrode that sandwiches the grid between the main body, The ion gun is an ion gun that is a flat plate grid that is mounted so that the end surface facing the grid of the main body has a curved surface having a valley fold, and the grid forms a curved surface that coincides with the curved surface at the contact surface between the main body and the grid.

  The second aspect of the present invention is an ion gun comprising a main body that generates plasma inside, a grid for drawing plasma from the inside of the main body, and a frame-like acceleration electrode that sandwiches the grid between the main body, The ion gun is a flat plate grid that is mounted so that the end face of the acceleration electrode facing the grid has a mountain-shaped curved surface, and the grid forms a curved surface that matches the curved surface at the contact surface between the acceleration electrode and the grid. .

  A third aspect of the present invention is an ion gun, comprising a main body that generates plasma inside, a grid for extracting plasma from the inside of the main body, and a fixture that fixes the grid to the main body, and faces the grid of the main body. The ion gun is a flat plate grid that is mounted so that the end surface has a curved surface having a valley-like shape and the grid forms a curved surface that coincides with the curved surface at the contact surface between the main body and the grid.

  A fourth aspect of the present invention is an ion gun in which a grid hole is continuously formed from one end of a grid to the other opposite end, and the grid is curved in a direction perpendicular to the continuously formed grid hole. The ion gun grid on the fourth side is preferably used in combination with a shielding plate that opens only the ion beam effective area. The grid may be curved in the row direction.

  The ion guns on the first to fourth side surfaces have grid holes arranged in parallel to the column direction of the piezoelectric elements arranged in a matrix, and irradiate the piezoelectric elements conveyed in the row direction with an ion beam in units of columns. The resonance frequency of the piezoelectric element can be ion etched.

  The grid used in the first to fourth side surfaces is made of molybdenum and preferably has a thickness of 200 μm to 20 μm, more preferably 150 μm to 50 μm.

It is a bird's-eye view which shows the 1st Example of this invention. It is a side view which shows the 1st Example of this invention. It is a top view which shows the 1st Example of this invention. It is a figure which shows the grid used in the 1st Example of this invention. It is a side view which shows the 2nd Example of this invention. It is a side view which shows the 2nd Example of this invention. It is a side view which shows the 2nd Example of this invention. It is a figure which shows the 3rd Example of this invention. It is a side view which shows the 4th Example of this invention. It is a front view which shows the 4th Example of this invention. It is a top view which shows the 4th Example of this invention. It is a bird's-eye view which shows the 4th Example of this invention. It is a bird's-eye view which shows the 4th Example of this invention. It is a bird's-eye view which shows the 4th Example of this invention. It is a top view which shows the 4th Example of this invention. It is sectional drawing which shows the 4th Example of this invention. It is sectional drawing which shows the conventional ion gun. It is a figure which shows the structure of the conventional ion gun.

Example 1.
1 and 2A and 2B show an ion gun 1 of a first embodiment of the present invention. 1 is a bird's-eye view of the ion gun 1, FIG. 2A is a side view, and FIG. 2B is a top view. In addition, each drawing and the drawings shown in the following examples are not drawn to scale, but are shown in an emphasized manner for explanation.
The ion gun 1 includes a main body 10 that generates plasma therein, a grid 20 for extracting plasma from the inside of the main body 10, and a frame-shaped (annular) acceleration electrode 30 that sandwiches the grid 20 between the main body 10 and the main body 10. The end surface facing the 10 grids 20 has a valley-like curved surface. A voltage is applied to the acceleration grid 22 from the power source 50 via the acceleration electrode 30, and ions are extracted from the plasma through the many grid holes. Thereby, an ion beam (arrow) is emitted. This ion beam is applied to a piezoelectric element (not shown) and used for frequency adjustment of the piezoelectric element, but the application is not limited to this.

  As shown in FIG. 2A, the end surface 11 on the grid 20 side of the main body 10 is curved in one direction in a valley shape, and the end surface 31 on the grid 20 side of the acceleration electrode 30 is in one direction in a mountain shape with the same curvature as the end surface 11. Is curved. That is, the end surface 11 and the end surface 31 are curved in the same direction with the grid 20 in between. In the drawing, for convenience of explanation, the end surface 11 and the shielding grid 21 and the acceleration grid 22 and the end surface 31 are illustrated with a gap therebetween, but in actuality, these are closely attached. The shielding grid 21 and the main body 10 are maintained at the shielding potential, the acceleration grid 22 and the acceleration electrode 30 are maintained at the acceleration potential, and the shielding grid 21 and the acceleration grid 22 are disposed at a predetermined interval.

As shown in FIG. 2B, the acceleration electrode 30 has a frame-like (annular) shape so that the center part (grid hole 22a) of the acceleration grid 22 is exposed and the grid 20 is fixed at the peripheral part.
Further, since the acceleration electrode 30 is configured to surround the ion beam, the acceleration electrode 30 acts as an electrostatic lens, and the ion beam convergence can be improved.

  The grid 20 is composed of a plurality of grids, the one on the main body 10 side is called a shielding grid 21, and the one on the acceleration electrode 30 side is called an acceleration grid 22. Here, two grids 21 and 22 are shown for simplicity of explanation, but more grids may be superimposed. In any case, these grids are collectively referred to as a grid 20.

  FIG. 3 shows one of the grids 20 (before mounting). In FIG. 2A, the grid 20 is curved in one direction, whereas the grid 20 before mounting is flat as shown in FIG. That is, the grid 20 is flat at the time of manufacture, but is bent in one direction according to the end face 11 and is pressed by the acceleration electrode 30 when mounted on the main body 10. Therefore, even if the grid 20 is the same material (for example, molybdenum) as the grid shown in each patent document, it is a flat plate thinner than them. For example, the thickness is preferably 200 μm to 20 μm, and more preferably 150 μm to 50 μm. desirable. In addition, the planar grid before mounting means a substantially flat grid, and includes a case where a small part of the grid is not flat or slightly bent as a whole.

  In the above configuration, the grid 20 is manufactured as a flat grid, and the grid 20 is curved by fitting the grid 20 to the end surface 11 of the main body 10 when mounted on the main body 10 (for example, during replacement). The reproducibility reduction factor of variation can be eliminated. Therefore, even if the grid, which is a consumable item, is replaced, the reproducibility of the emitted ion beam can be ensured before and after that.

  In the above configuration, since the acceleration grid 22 is in contact with the acceleration electrode 30, the deformation of the grid 20 due to thermal expansion after the start of ion beam extraction is only deformation along the end surface 31 of the acceleration electrode 30. Similarly, since the shielding grid 21 is in contact with the main body 10, the deformation of the grid 21 due to thermal expansion after the start of ion beam extraction is only in the direction along the end surface 11 of the main body 10. Accordingly, the shape stability against temperature rise is excellent, and the time required for the output to stabilize after the start of ion beam extraction is shortened compared to the conventional one. Specifically, even with the same output power, it was confirmed that the time required for output stabilization was about 15 minutes in the example of Patent Document 1, whereas it was about 3 minutes in the present invention.

  Furthermore, since the grid 20 of the present invention is manufactured and stored as a flat plate instead of a curved plate, it is easy to handle the grid 20 before mounting. In particular, since the flat grid 20 can be loaded at the time of storage, the storage space is saved and the storage property is excellent.

Example 2
4A and 4B show an ion gun 2 according to a second embodiment of the present invention according to a manufacturing process. In this embodiment, as in the first embodiment, all the grids 20 to be used are flat grids, but the positions of the holes for passing the respective fixtures described later are different.

  In FIG. 4A, the shielding grid 21 is fixed to the end surface 11 of the main body 10 by a fixture (for example, a screw) 41, and the acceleration grid 22 is fixed to the end surface 31 of the acceleration electrode 30 by a fixture (for example, a screw) 42. Here, the configuration of the main body 10 is basically the same as that of the first embodiment, except that the electrode support 12 is provided in a part of the main body 10 and the configuration of the screw holes. The acceleration electrode 30 is basically the same as that of the first embodiment, but is different in that a recess 32 for the electrode support 12 is provided and the screw hole is different. The electrode support 12 is electrically insulated from the main body 10, and a voltage is applied from the power supply 50. Although omitted in the figure, a plurality of electrode supports 12 are arranged on the periphery of the main body 10 and support the acceleration electrode 30 at the upper end. By the electrode support 12, the shielding grid 21 and the acceleration grid 22 are arranged with a potential difference while maintaining the distance between the grids. The distance between the grids may be adjusted according to the height of the electrode support 12 and the shape of the recess 32.

  In FIG. 4B, the main body 10 and the shielding grid 21, the acceleration electrode 30 and the acceleration grid 22 are attached so that the electrode support 12 is converged in the recess 32, and these are fixed by a fixture (for example, a screw) 43. In the figure, the fixtures 41 and 42 are omitted for clarity. As shown in FIG. 4C, the grid 20 may be directly fixed to the acceleration electrode 30 by using the fixing tool 42, and the acceleration electrode 30 and the main body 10 may be fixed by the fixing tool 43. A spacer made of an insulating material is disposed between the shielding grid 21 and the acceleration grid 22.

Example 3 FIG.
The third embodiment shows a configuration in which the acceleration electrode 30 is not used as a modification of the first embodiment.
FIG. 5 shows a side view of the ion gun 3 of this embodiment. As shown in the figure, the grid 20 is directly fixed to the main body 10 using a fixing tool 44. By appropriately disposing the fixing tool 44, the grid 20 can be fixed in accordance with the curvature of the main body 10 without using the acceleration electrode.
In this case, a voltage is directly applied from the power source 50 to the acceleration grid 22.

  In the above configuration, although it is difficult to obtain the effect (that is, excellent shape stability, electrostatic lens action, etc.) due to the acceleration grid, even if the grid which is a consumable is replaced as in the first and second embodiments, The reproducibility of the emitted ion beam is ensured before and after, and the grid is easily stored.

Example 4
6 to 9 show an ion gun 4 according to a fourth embodiment of the present invention. 6A is a side view, FIG. 6B is a front view, and FIG. 6C is a top view.
The ion gun 4 is the ion gun shown in the first embodiment, and is characterized in that the main body 60, the grid 70, and the frame-like acceleration electrode 80 are rectangular. Except for the shape and the grid 70, the other configurations are the same as those of the first embodiment, and thus the description thereof is omitted. Further, the ion gun 4 may use the grid fixing means shown in the second embodiment, or the acceleration electrode 80 may be omitted as shown in the third embodiment. The rectangular ion gun is effective when the frequency of a plurality of linearly arranged piezoelectric elements is adjusted simultaneously, but the application is not limited to this.

  As shown in FIG. 6A, the end surface 61 of the main body 60 on the grid 70 side is bent in one direction (in the same figure, the rectangular short side direction) in a valley shape, and the end surface 81 of the acceleration electrode 80 on the grid 70 side is the end surface It is curved in the same direction as the end face 61 in a mountain shape with the same curvature as 61. The shielding grid 71 and the acceleration grid 72 are formed with a plurality of grid holes 71a and 72a along one side of the rectangle. In the figure, a plurality of grid holes 71a and 72a are formed along the long side at the central portion of the rectangular short side direction, and a band-shaped ion beam irradiation area parallel to the long side is obtained. In the embodiment, since the hole is formed not only in the whole grid but in the central part in the short side direction, both ends in the short side direction having high strength can be brought into close contact with the main body and the acceleration electrode, and the curvature of the main body and the acceleration electrode can be set to the grid plate. Easy to match. Moreover, since both ends in the short side direction having a large area are in close contact with the main body and the acceleration electrode, heat transfer is large and deformation due to thermal expansion hardly occurs.

  FIG. 7 shows a bird's eye view of the acceleration electrode 80 and the acceleration grid 72. Since the grid 70 is fixed by the curved main body 60 and the peripheral edge of the acceleration electrode 80, the reproducibility and shape stability are excellent, and the acceleration electrode 80 surrounding the ion beam acts as an electrostatic lens to converge the ion beam. It is the same as in the first embodiment that it has the effect of improving the properties.

  FIG. 8 is a bird's eye view showing another embodiment of the grid 70. The acceleration grid 73 is characterized in that grid holes are continuously formed from one end of the grid to the other opposite end, and the grid is curved in a direction parallel to the one end and the other end of the grid. In FIG. 7, since the strength of the plate is different between where the grid hole is present and where it is not, there may be a case where the curvature is not uniform, but in FIG. The strength of the plates is equal and it is easy to obtain a uniform curvature. Since the effective area of the ion beam is determined by the opening shape of the shielding plate 75, the opening may be formed so as to expose only a desired area. The opening of the shielding plate 75 is smaller than the opening of the acceleration electrode 80, and ions are extracted only from the grid holes exposed from the opening of the shielding plate 75. By using a grid plate and a shielding plate with holes formed on the outer edge as a set, it is possible to prevent the ion beam from being drawn out of the effective area while obtaining a uniform curvature.

  The shielding plate 75 is attached to the main body 60 side of the acceleration grid 73, but may be attached to the acceleration grid 80 in close contact with the acceleration grid 80 side. Further, the shielding plate 75 may not be a separate member and may be integrated with the ion gun body 60. Since the opening is formed at the center of the grid bending direction at any position on the grid, the curvature of the grid can be aligned at each position in the direction perpendicular to the bending direction. Thereby, compared with the acceleration grid 72 shown in FIG. 7, the acceleration grid 73 has the advantage that plate | board thickness can be thickened. If the grid is thick, the life of the grid can be extended. In the embodiment, a square grid is used. However, it is effective to form a hole up to the outer edge of the grid plate even in a circular, elliptical or other shape grid. In particular, when a circular or elliptical grid plate is formed with a hole only at the center, a strong force is required for bending at the end, but by forming a hole at the end, the end and the center A uniform curvature can be obtained. Whatever the shape, a grid hole may be continuously formed from one end of the grid to the other opposite end, and the grid may be curved in a direction perpendicular to the continuously formed grid hole.

  FIG. 9 is a bird's eye view showing another embodiment of the grid 70. The acceleration grid 74 forms a portion that is shielded by the shielding plate 75 in a slit shape. The effect of obtaining a uniform curvature is the same as that shown in FIG. 8, but by separating the ion extraction hole and the slit, the boundary between the effective area of the ion beam and the shielding area becomes clear and easy to distinguish.

  When the rectangular ion gun 4 shown in FIG. 6 is used, the frequency of the piezoelectric elements 200 in the row direction (arrow direction in the figure) arranged in a matrix as shown in FIG. 10 can be sequentially adjusted in units of columns. 10A is a plan view, and FIG. 10B is a cross-sectional view. The ion gun 4 is arranged so that the long side is parallel to the column direction with respect to the matrix-shaped piezoelectric element 200. The grid 70 of the ion gun 4 is curved in the short side direction. The width in the long side direction and the width in the short side direction of the grid hole group (when the grid shown in FIGS. 8 and 9 is used, the vertical width and the horizontal width of the opening of the shielding plate 75) are simultaneously adjusted. What is necessary is just to adjust according to the matrix number of the element 200. FIG. In FIG. 10, it is assumed that a uniform ion beam is applied to all the rows of piezoelectric elements.

  When the grid of the ion gun is a plane as shown in FIG. 10C, the etching rate is decreased because the ion beam diverges and the etching rate decreases as the distance d1 between the workpiece (piezoelectric element 200) to be irradiated and the ion gun increases. In order to ensure it, it is necessary to reduce the distance d1 between the piezoelectric element 200 and the ion gun 100. However, if the distance is small, the sputtered material of the mask 202 and the shutter 201 is deposited and separated on the ion gun and its surroundings, causing problems such as a short circuit between the grids due to the sputtered material.

  On the other hand, since the ion gun of the present invention curves the grid and converges the ion beam, an equivalent rate can be obtained while increasing the distance d2 between the piezoelectric element 200 and the ion gun 4. As the distance d2 is increased, the deposition rate of the sputtered material on the ion gun main body is decreased, so that the average failure interval (MTBF) of the apparatus can be increased. By mounting the ion gun 4 on the frequency adjustment device shown in FIGS. 10A and 10B, it is possible to perform frequency adjustment with excellent reproducibility. Furthermore, the frequency adjustment accuracy is further improved by using the grid 70 shown in FIGS.

Each of the above embodiments shows the most preferable mode of the present invention, but the above can be modified as follows.
(1) In each of the above embodiments, the grid 20 is a circular plate or a rectangular plate, but it is sufficient that the grid 20 can be curved in one direction along the end surface 11 of the main body 10 or the end surface 31 of the acceleration electrode 30 and fixed to them. , Ellipse, square, etc.
(2) In the present invention, the “frame shape” expressing the form of the acceleration electrode has a shape having at least an outer edge and an inner edge, and the outer edge or the inner edge is a circle, an ellipse, a rectangle, another polygon, or the like. Shall be included.
(3) In Examples 1 and 4, the fixtures 40 and 90 were used as means for fixing the acceleration electrodes 30 and 80 and the grids 20 and 70 to the main bodies 10 and 60. Case) It is also possible to omit the fixture 40 by increasing the weight of the acceleration electrodes 30 and 80 themselves, or placing a weight on the upper part thereof.
(4) In the first, second and fourth embodiments, the acceleration electrodes 30 and 80 are shown as members for sandwiching the grid 20 between the main body 10, but the members have the same shape as the acceleration electrodes 30 and 80. If it exists, it may not be an electrode. In this case, a configuration in which a voltage is directly applied to the acceleration grid 22 as in the case of FIG. 5 is required.
(5) Although the distance between the grids is maintained using the electrode support in the second embodiment, a spacer or the like made of an insulating material may be inserted and fixed between the electrodes.

1, 2, 3, 4,. Ion gun 10, 60. Main body 11, 61. End face 12. Electrode support 20, 70. Grids 21, 71. Shielding grid 22, 72-74. Acceleration grid 75. Shield plates 30, 80. Acceleration electrodes 31, 81. End face 32,82. Recesses 40-44, 90. Fixture

Claims (10)

An ion gun comprising a main body for generating plasma therein and a grid for extracting plasma from the inside of the main body,
A frame-like acceleration electrode that sandwiches the grid between the main body and the grid,
The end surface of the main body facing the grid has a valley-like curved surface,
An ion gun, wherein the grid is a flat grid mounted so as to form a curved surface that coincides with the curved surface at a contact surface between the main body and the grid. An ion gun comprising a main body for generating plasma therein and a grid for extracting plasma from the inside of the main body,
A frame-like acceleration electrode that sandwiches the grid between the main body and the grid,
The end surface of the acceleration electrode facing the grid has a mountain-shaped curved surface,
An ion gun, wherein the grid is a flat grid mounted so as to form a curved surface that coincides with the curved surface at a contact surface between the acceleration electrode and the grid. An ion gun comprising a main body for generating plasma therein and a grid for extracting plasma from the inside of the main body,
A fixture for fixing the grid to the body;
The end surface of the main body facing the grid has a valley-like curved surface,
An ion gun, wherein the grid is a flat grid mounted so as to form a curved surface that coincides with the curved surface at a contact surface between the main body and the grid. An ion gun according to any one of claims 1 to 3,
A grid hole is continuously formed from one end of the grid to the other opposite end,
An ion gun in which the grid is curved in a direction perpendicular to the continuously formed grid holes.   5. The ion gun according to claim 4, wherein a shielding plate that opens only an effective area of the ion beam is attached to the grid.   The ion gun according to claim 1, wherein the grid is formed in a square shape. An ion gun according to any one of claims 1 to 5,
Grid holes of the grid are arranged parallel to the column direction of the piezoelectric elements arranged in a matrix,
An ion gun configured to irradiate the piezoelectric elements conveyed in the row direction with an ion beam in units of columns and ion-etch the resonance frequency of the piezoelectric elements.   The ion gun according to claim 7, wherein the grid is curved in the row direction.   A grid used in the ion gun according to claim 1, wherein the grid is made of molybdenum (material) and has a thickness of 200 μm to 20 μm.   The grid according to claim 9, wherein the thickness is 150 μm to 50 μm.

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