JP2006134798A - Sputter ion pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputter ion pump having a baking treatment mechanism which will not induce demagnetization, demagnetization, and leakage of magnetic lines of force or the like, and retains the intended magnetic field strength. <P>SOLUTION: The ion pump 1 comprises a pump cell 2b, constituted of an anode 7 and a pair of cathodes 6a, 6b in the inside of a pump case 2 and is installed with a pair of magnetets 8a, 8b in a direction facing both the cathodes 6a, 6b and a yoke 4 surrounding these magnets 8a, 8b on the outside of the pump case 2. A heating heater 9 of plate shape is installed at the side face portion of the pump cell 2b, from the outside of the pump case 2. Further, separate heating heaters 3a, 3b are installed from the outside of the pump case located in the space portion 2a. Furthermore, the pump case 2, installed with the magnets 8a, 8b, the yoke 4, and the heating heaters 9, 3a, 3b, is housed in a heat insulating box 11, and at that time, the contact portion between the pump case 2 and the heat insulating box 11 is limited to be only a fixing screw 12 of non-magnetism material quality. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sputter ion pump. The sputter ion pump has a high exhaust performance higher than the high vacuum or ultra-high vacuum region.

The sputter ion pump uses a Penning discharge generated under a strong magnetic field for a pair of cathodes facing each other in a pump case and an anode disposed between the cathodes in a non-contact state with each cathode. Is. That is, the gas molecules generated between the cathode and the anode are exhausted by the sputtering action (embedding of ionized gas molecules) and the getter action (sorption to the vapor deposition layer formed by the sputtered particles). In order to perform discharge sputtering continuously, a structure in which the outer sides of both cathodes are sandwiched between magnets or a structure in which the outer sides of the magnets are further covered with an iron yoke is often used. Thus, it is possible to reach a so-called high vacuum or ultra-high vacuum region in the range of 10 ⁻⁴ to 10 ⁻⁹ Pa without generating mechanical vibration.

  In order to maintain such high exhaust performance, baking processing to the pump body such as a pump case is indispensable. A conventional baking method is generally one in which a tape heater or a sheath heater is wound around a surface material such as a pump main body, a magnet, or a yoke, and this is energized and heated.

However, this baking method has various problems, for example,
1) Since the surface side of the winding heater is exposed to air, heat is exhausted to the air side, and sufficient heating efficiency cannot be obtained.
2) It is difficult to wind the heater around a bent part of the pump body or a complicated part of the piping.
3) Since the heater is exposed, safety management for workers is required.
4) Heating becomes uneven in the heater winding portion and other portions, or in the multiple winding portion and other portions.
5) When the heater is wound around the surface of the magnet or the yoke position, the heat conduction to the pump case is not sufficient, and especially when the heater is wound on the magnet, it tends to cause a decrease in magnetic characteristics.

And what is shown, for example in patent document 1 has coped with these problems by using the structure which interposes a heater between a pump case and a magnet.
JP-A-5-290791 (page 2)

  However, the sputter ion pump having the structure of Patent Document 1 also has a new problem. The biggest problem is that the distance between the magnets is increased by interposing a heater between the case and the magnet, which may greatly reduce the magnetic field strength and cause a decrease in exhaust performance. There is.

  Moreover, in the structure shown in patent document 1, since a heater and a magnet are adjacent, the above-mentioned demagnetization problem still remains. For this measure, it may be possible to adopt a structure in which a heat insulating material or the like is interposed between the heater and the magnet. It becomes difficult to ensure performance.

  Furthermore, the problem of magnetic field strength also arises from another aspect. That is, there is an increasing demand for a sputter ion pump that can handle an ultra-high vacuum region, and the volume of a magnet to be mounted tends to increase. For this reason, as before, it is difficult to converge the magnetic lines of force only by the facing structure of the magnet and the reinforcement of the yoke, which causes the divergence of the magnetic lines of force. As a result, a residual magnetic field is generated around the pump due to the leaked magnetic field lines, which may affect peripheral equipment.

  In view of the above problems, an object of the present invention is to provide a sputter ion pump having a baking processing mechanism that does not induce demagnetization, magnetic field reduction, or leakage of magnetic field lines, and can maintain a desired magnetic field strength. .

  In order to solve the above-described problems, the present invention includes a pump cell including one or more anodes and a pair of cathodes facing each other through the anodes inside the pump case, and both the cathodes facing each other outside the pump case. In an ion pump in which a pair of magnets that are overlapped in the direction and opposed to each other and a yoke that surrounds both magnets are attached, a heater for heating is attached to the outside of the pump case located on the side surface of the pump cell.

  According to this, in the hollow cylindrical pump cell, the heater is attached from the outside of the pump case to the side surface portion corresponding to the body portion when both sides sandwiched between the two magnets are the upper and lower bottom surfaces. Heating for baking can be performed without increasing or decreasing. Further, unlike the conventional heater mounting structure in which the heater and the magnet overlap in a planar manner, the heater and the magnet do not directly come into surface contact. As a result, it is possible to suppress a decrease in magnetic field strength and a problem of demagnetization during the baking process, and the high exhaust performance inherent to the sputter ion pump can be obtained.

  In addition, as a heater for heating, in order to maximize the contact area with respect to the pump case, it is desirable to use a plate-shaped one or a sheath heater-shaped one.

  By the way, the pump case of the sputter ion pump may be formed with a structure having a space portion communicating with the pump cell. In this case, a heater for heating may be further attached to the outside of the pump case located in the space portion with respect to the space portion connected to the pump cell portion inside the pump case. This space portion is located away from the magnetic flux of the magnetic field lines by both magnets and the yoke, so that the heater attached to this portion does not affect the magnetic field strength of the pump cell portion.

  In addition, it is desirable to use nonmagnetic materials, such as mica (mica), rubber | gum, a silicon | silicone, and a ceramic fiber, for the constituent material of these heaters.

  Further, as described above, the pump main body to which the magnet, the yoke and the heater are attached is accommodated in the heat insulation casing, and at that time, the contact portion between the pump main body and the casing is limited to the position fixing jig. . Since the pump main body is accommodated in the housing in a state where the contact portion between the heat retaining housing and the pump main body is held only by the position fixing jig, a space is secured around the internal pump main body. Therefore, the entire pump case is efficiently and uniformly heated by the internal radiant heat. Moreover, since the heating part with respect to a pump is not exposed, the advantage on safety management is also acquired.

  It is desirable to use a nonmagnetic material (stainless steel, aluminum, ceramics, etc.) for the position fixing jig between the pump body and the housing so that the suppression of the residual magnetic field can function more effectively.

  On the other hand, it is desirable to use a magnetic material (metallic iron, iron-nickel alloy, etc.) as the material of the heat insulation casing. Thereby, the residual magnetic field which leaks from the pump main body accommodated in the inside and can generate | occur | produce can be suppressed.

  Further, in order to reliably obtain the heat retaining effect inside the housing, it is desirable to form at least one surface inside the housing with a heat retaining material, or to fill the gap between the pump body and the housing with the heat retaining material.

  In the sputter ion pump of the present invention, a heater is attached to the side surface portion of the pump cell from the outside of the pump case, so that it is possible to suppress a decrease in magnetic field strength and a problem of demagnetization during the baking process. High exhaust performance can be obtained.

  Further, by housing the pump body with the heater for heating in the heat retaining casing, the entire pump case is efficiently and uniformly heated by the internal radiant heat, and further, there is an advantage in safety management.

  FIG. 1 is a conceptual diagram of a sputter ion pump 1 according to the present invention. A space portion 2a of a pump case 2 is covered with plate heaters 3a and 3b, and a pump cell portion 2b connected to the space portion 2a is covered with a yoke 4. ing. The upper portion of the space portion 2a is connected to the intake hole 5.

  The internal structure of the ion pump 1 configured as described above is constituted by the space portion 2a of the pump case 2 and the pump cell 2b. As shown in FIG. 1, the pump cell 2 b is formed as a box-shaped protrusion in the pump case 2. A pair of cathodes 6a and 6b and a plurality of anodes 7 are disposed between the cathodes 6a and 6b. Magnets 8a and 8b are arranged at positions outside the pump case 2 so as to further sandwich the pair of cathodes 6a and 6b. Further, the magnets 8 a and 8 b and the pump cells 2 b and 2 b arranged in such a sandwich structure are surrounded by the iron yoke 4.

  In order to maintain the exhaust performance of the ion pump 1, a paking process is indispensable. However, as shown in FIG. 1, in the ion pump of the present invention, a plate heater 9 is used. That is, in the pump cell 2b having a hollow cylinder structure, for example, the plate heater 9 is attached from the outside of the case so as to cover the side surface portion corresponding to the body portion when both surfaces on the magnets 8a and 8b side are the upper and lower bottom surfaces. By doing so, the distance between the magnets 8a and 8b is not affected, and the heater 9 does not directly come into surface contact with each of the magnets 8a and 8b. Therefore, it is difficult for magnetic field intensity to decrease due to an increase in the interval between the magnets 8a and 8b, and to decrease magnetic characteristics (demagnetization) due to the heater 9 coming into direct contact with the magnets 8a and 8b.

  By the way, for the baking process of the whole pump case 2, it is desirable to heat also the space part 2a. Therefore, in the ion pump 1 of the present invention, the plate heaters 3a and 3b are attached to the side surface portion of the space portion 2a from the outside of the case.

  However, as the magnet volume increases in recent years, it is necessary to take measures against leakage magnetic field lines. Therefore, it is desirable to use a nonmagnetic material such as mica, rubber, silicon, or ceramic fiber as the material of the heaters 3a, 3b, and 9. By using a non-magnetic material, magnetic field line leakage does not spread unintentionally, so that the influence on the formation of magnetic field lines between the magnets 8a and 8b is minimized, and the desired magnetic field strength can be obtained. For the same reason, it is desirable to use a non-magnetic material for a fixing screw or the like when attaching the heaters 3 a, 3 b, 9 to the pump case 2 or a position fixing jig such as the spacer 10.

  By the way, in the baking process, it is necessary to heat the pump case 2 uniformly and efficiently under strict safety management. Therefore, as shown in FIG. 1, the sputter ion pump 1 of the present invention has a structure in which the pump case 2 with a heater or the like attached is further accommodated in a heat insulation box 11.

  As shown in FIG. 2, the heat insulation box 11 is composed of a pair of divided boxes 11a and 11b, and is connected to the internal pump case 2 only by a fixing screw 12 for position fixing. The internal pump case 2 (including accessories such as the attached heater) is disposed with a gap from the inner surface of the heat insulating box 11. Therefore, the entire pump case 2 is efficiently and uniformly heated by the radiant heat inside the heat insulating box 11. Of course, there is an advantage in safety management because the heated portion is not exposed to the outside of the apparatus.

  Alternatively, by applying or applying a heat insulating material such as mica to the inner surface of the heat insulating box 11, the heat insulating effect in the heat insulating box 11 is ensured. Further, the heat insulation effect is increased by filling the gap between the pump case 2 and the heat insulation box 11 arranged inside the heat insulation box 11 with the gap space and filling the gap with a heat insulation material such as mica.

  By the way, the countermeasure against the leakage magnetic field lines accompanying the enlargement of the magnet volume is also important in the heat insulating box 11. That is, by taking measures against leakage magnetic field lines on the heat insulating box 11, it can be used as a magnetic shield. In the present invention, a magnetic material such as metallic iron or iron-nickel alloy is used as the material of the heat insulation box 11, so that the residual magnetic field is absorbed by this, and leakage to the outside is kept to a minimum. A non-magnetic material (SUS or aluminum material) is also used for a fixing screw 12 for connecting and fixing the heat insulating box 11 and the pump case 2 and a fixing screw (not shown) for connecting the heat insulating boxes 11a and 11b in a divided state. ) Is desirable.

  In forming the members of the heat insulation box 11, it is common to use a method of bending, drawing, welding or the like. In this case, each part of FIG. The structure shown in is used. The purpose of this is to maximize the contact area of the member A and the member B in each of FIGS. 3A to 3F, and to obtain a sufficient shielding effect, and from the processing restrictions, the member A and the member B. Even if a gap occurs between them, the two are overlapped to prevent leakage of the residual magnetic field.

  The attachment of the heater used in the present invention and the shield by the heat insulation box can be used not only for the sputter ion pump but also for a high-performance pump that requires baking.

Conceptual diagram of the sputter ion pump of the present invention Conceptual diagram of the sputter ion pump of the present invention when a heat insulation box is installed (A)-(f) Schematic sectional drawing which shows the joining structural example of the division member of a heat insulation box

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sputter ion pump 2 Pump case 2a Space part 2b Pump cell part 3a, 3b Plate heater 4 Yoke 6a, 6b Cathode 7 Anode 8a, 8b Magnet 9 Plate heater 10 Spacer (position fixing jig)
11 Insulation box (insulation case)
12 Fixing screw (position fixing jig)

Claims (7)

 A pump cell comprising one or more anodes and a pair of cathodes facing each other through the anodes is provided inside the pump case, and a pair of magnets facing each other in the facing direction of the cathodes on the outside of the pump case; An ion pump having a yoke surrounding both magnets, wherein a heater for heating is attached to the outside of the pump case located on the side surface of the pump cell.  The sputter ion pump according to claim 1, wherein a heater for heating is further attached to the outside of the pump case located in the space portion with respect to the space portion connected to the pump cell portion inside the pump case.   The pump main body to which the magnet, the yoke, and the heater for heating are attached is housed in a heat insulating casing, and a contact portion between the pump main body and the casing is limited to a position fixing jig. The sputter ion pump according to 1 or 2.   The sputter ion pump according to any one of claims 1 to 3, wherein a nonmagnetic material is used for a position fixing jig between the pump body and the casing.   The sputter ion pump according to any one of claims 1 to 4, wherein a magnetic material is used for the casing.   The sputter ion pump according to any one of claims 1 to 5, wherein at least one surface inside the casing is formed of a heat insulating material. The sputter ion pump according to any one of claims 1 to 6, wherein a gap between the pump body and the housing is filled with a heat insulating material.

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