JP3428303B2 - Ion irradiation equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of deflecting an ion beam by a deflecting magnet having a structure in which a tip of a magnetic pole penetrates a vacuum vessel, and irradiating the ion beam to a substrate. The present invention relates to an ion irradiation apparatus for performing a process such as ion implantation on the substrate, and more specifically, to a means for preventing metal contamination from occurring on the substrate due to a magnetic pole being sputtered by scattering particles. FIG. 4 is a cross-sectional view showing an example of an ion irradiation apparatus. This apparatus is an example of a so-called hybrid parallel scan type ion implantation apparatus that performs magnetically parallel scanning of the ion beam 2 and mechanically scans the substrate 12. [0003] This apparatus includes an energy analysis magnet 4 which is extracted from an ion source (not shown), and which separates and derives ions having a specific energy from an ion beam 2 which has been subjected to mass separation, acceleration, and the like as necessary. A scanning magnet 6 that is provided downstream of the energy analysis magnet 4 and that reciprocally scans the ion beam 2 derived from the energy analysis magnet 4 in one dimension magnetically (along the paper surface in the illustrated example); The ion beam 2, which is provided downstream of the scanning magnet 6 and is bent back from the scanning magnet 6 so as to be parallel to the reference axis 7 and cooperates with the scanning magnet 6.
And a substrate (for example, a silicon wafer) in the irradiation area of the ion beam 2 provided downstream of the beam collimating magnet 8 and derived from the beam collimating magnet 8. ) 12
And a substrate scanning mechanism 14 for mechanically scanning the scanning magnet 6 in a direction substantially perpendicular to the scanning direction of the ion beam 2 by the scanning magnet 6 (in the illustrated example, in the direction of the front and back of the paper). Reference numerals 16 to 19 are vacuum containers. The substrate 12 is irradiated with the ion beam 2 to perform processing such as ion implantation. The energy analysis magnet 4, the scanning magnet 6, and the beam collimating magnet 8 all deflect the ion beam 2 magnetically.
It is a kind of deflection magnet. These are, in this example,
A penetrating structure in which the tip of the magnetic pole penetrates into the vacuum vessels 16 to 18 is employed. [0005] This will be described with reference to the most downstream beam collimating magnet 8 as an example.
Has, for example, as shown in FIG. 5, two upper and lower magnetic poles 20 whose tips penetrate into the vacuum vessel 18, a yoke 22 connecting them, and an exciting coil 24 for exciting the magnetic poles 20. . The reason why the tip of the magnetic pole 20 is penetrated into the vacuum vessel 18 is that the distance between the magnetic poles can be reduced to increase the magnetic flux density between the magnetic poles. This is because downsizing can be achieved. In this example, the magnetic pole 20 and the yoke 22 are separate from each other in order to facilitate disassembly and assembly, but may be integrated. [0006] In the case of the beam collimating magnet 8 having the above-described penetrating structure, the tip of the magnetic pole 20 is in a state where it can be seen from the ion beam 2. Although the ion beam 2 does not normally directly hit the tip of the magnetic pole 20, the residual gas particles scattered by colliding with the ion beam 2, or conversely, are scattered by the residual gas. Scattering particles 26 such as beam particles (that is, particles of ions, electrons, etc. constituting the ion beam 2) may collide with the tip of the magnetic pole 20, though the amount is usually not so large. When this occurs, the particles constituting the magnetic pole, typically iron, are sputtered from the surface of the magnetic pole 20, and a part of the sputtered particles 28 is directed toward the substrate 12 (see FIG. 4) on the downstream side. To cause so-called metal contamination (contamination by metal) on the substrate 12. When this occurs, problems such as disturbing the characteristics of the device on the substrate surface occur. Such a problem becomes more serious as the deflection magnet is closer to the substrate 12, that is, the largest in the case of the beam collimating magnet 8 in this example, but other deflection magnets, that is, the energy analysis magnet 4 in this example. And the scanning magnet 6 is present to a greater or lesser extent. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent a metal contamination from occurring on a substrate due to the fact that the tip of the magnetic pole of a deflection magnet having the above-described penetrating structure is sputtered by scattering particles. In the ion irradiation apparatus according to the present invention, the surface of the non-magnetic plate is made of the element constituting the substrate at the tip of the magnetic pole of the deflection magnet having the penetrating structure as described above. Cover with a removable shielding plate covered with a coating film
It is characterized in that it is attached and the tip of the magnetic pole is covered with the shielding plate. According to the above configuration, since the tip of the magnetic pole penetrating into the vacuum vessel is covered with the shielding plate, the tip of the magnetic pole is not sputtered by scattering particles. Alternatively, a coating film covering the surface of the shielding plate may be sputtered by the scattering particles. However, since the coating film is composed of the elements constituting the substrate, the sputtered particles from the coating film may be sputtered. , Metal particles do not occur because only the particles of the constituent elements enter the substrate. As a result, metal contamination on the substrate can be significantly reduced. FIG. 1 is a longitudinal sectional view showing an example of the periphery of a beam collimating magnet of an ion irradiation apparatus according to the present invention, and corresponds to a section taken along line AA of FIG. Parts that are the same as or correspond to those in the conventional example of FIG. 5 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below. In this embodiment, shielding plates 30 are respectively placed on the top ends of the upper and lower magnetic poles 20 of the above-mentioned beam collimating magnet 8, which is an example of a deflection magnet, and cover the front ends of the respective magnetic poles 20. . This shielding plate 30
Is detachably attached to the tip of the magnetic pole 20 by a plurality of screws 34 in this example. As shown in FIG. 2, the shielding plate 30 is formed by coating the surface of the non-magnetic plate 31 with an element similar to the above-described substrate 12 (see FIG. 4), more specifically, an element constituting the substrate 12. This is covered with a coating film 32 made of. Non-magnetic plate 3
The reason for using 1 is to not disturb the magnetic field entering and exiting the magnetic pole 20. The material of the non-magnetic plate 31 is preferably a non-magnetic metal such as aluminum or stainless steel (SUS), for example, because it is easy to process and has a small outgassing (outgassing), but may be other than metal. Among them, aluminum is more preferable because it is light and easy to process. If the thickness of the non-magnetic plate 31 is too thin, the strength becomes weak, and if it is too thick, the workability deteriorates.
It is preferable to set it to about 2 mm to 2 mm. The coating film 32 is a silicon layer when the substrate 12 is, for example, a silicon substrate. In the case of another semiconductor substrate, a film made of an element constituting the semiconductor is used.
If the thickness of the coating film 32 is too thin, the life is shortened, and if it is too thick, it becomes difficult to form the film. Therefore, it is preferable that the thickness is, for example, about several μm to several tens μm. The shield plate 30 is attached to the tip of the magnetic pole 20, for example, when a screw 34 is used as in this example, in order to prevent the screw 34 from being sputtered by the scattering particles 26, as in this example. It is preferable to perform it on the side surface of the magnetic pole 20. However, for example, as shown in FIG.
Protrusions 36 and recesses 38 to be fitted to each other are provided on the shield plate 30 side and the magnetic pole 20 side, or vice versa, and these fittings allow the shield plate 30 to be detachably attached to the tip of the magnetic pole 20. May be covered. Further, the pins to be fitted to each other and the receiving portions thereof may be provided on the shield plate 30 side and the magnetic pole 20 side, or vice versa.
In the case of the latter example, the shield plate 30 can be attached at the tip end surface of the magnetic pole 20. In any of these cases, the shield plate 30 can be easily attached and detached with a single touch. Further, unlike the case of the screw, there is no possibility that the mounting member is sputtered by the scattering particles 26. According to the above configuration, since the tip of the magnetic pole 20 penetrating into the vacuum vessel 18 is covered with the shielding plate 30,
The tip of the magnetic pole 20 will not be sputtered by the scattering particles 26 as described above. Alternatively, a coating film 32 covering the surface of the shielding plate 30 can be sputtered by the scattering particles 26,
Since the coating film 32 is made of the element constituting the substrate 12, even if the sputtered particles 28 from the coating film 32 reach the substrate 12, only particles of the element constituting the substrate 12 enter the substrate 12. Therefore, there is almost no adverse effect on the substrate 12. That is, no metal contamination occurs. As a result, metal contamination on the substrate can be significantly reduced, and problems such as disturbing the characteristics of devices on the substrate surface due to the metal contamination can be prevented. In addition, the surface of the shielding plate 30 is
Although it is necessary to clean the shield plate 30 occasionally because it is contaminated by the incident light of 6, for example, the shield plate 30 is detachable so that it can be easily replaced, thereby shortening the downtime of the ion irradiation apparatus associated with the cleaning. can do. The technique of covering the shielding plate 30 as described above is applied to a deflection magnet close to the substrate 12 side, for example, as the beam paralleling magnet 8 is applied as in this example.
Although the effect of preventing metal contamination on the substrate 12 is great, the present invention can be applied to other deflection magnets, for example, the above-described energy analysis magnet 4 and scanning magnet 6, and in this case, the beam collimating magnet 8 is also used for the same reason. Even if not so much, the effect of preventing metal contamination on the substrate 12 can be obtained. As described above, according to the present invention, since the tip of the magnetic pole penetrating into the vacuum vessel is covered with the shielding plate, the tip of the magnetic pole is sputtered by scattering particles. Is gone. Instead, the coating film covering the surface of the shielding plate can be sputtered by the scattering particles, but since the coating film is composed of the elements constituting the substrate, the sputtered particles from the coating film reach the substrate. However, even if only the particles of the elements constituting the substrate enter the substrate, no metal contamination occurs. As a result, metal contamination on the substrate can be significantly reduced. Moreover, since the surface of the shielding plate is contaminated by scattering particles or the like, it is necessary to clean it occasionally.
Since the shield plate is detachable, the shield plate can be easily replaced, thereby shortening the downtime of the ion irradiation apparatus associated with the cleaning.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an example around a beam collimating magnet of an ion irradiation apparatus according to the present invention, and FIG.
-A section. FIG. 2 is a cross-sectional view of the shielding plate in FIG. FIG. 3 is a cross-sectional view showing another example of the mounting structure of the shield plate. FIG. 4 is a cross-sectional view showing an example of an ion irradiation device. FIG. 5 is a longitudinal sectional view showing an example around a beam collimating magnet of the conventional ion irradiation apparatus, and corresponds to an AA section in FIG. [Description of Signs] 2 Ion beam 4 Energy analysis magnet (deflection magnet) 6 Scanning magnet (deflection magnet) 8 Beam collimation magnet (deflection magnet) 12 Substrates 16 to 19 Vacuum container 20 Magnetic pole 30 Shielding plate 31 Non-magnetic plate 32 Cover Coating

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-153406 (JP, A) JP-A-4-319238 (JP, A) JP-A-9-82268 (JP, A) JP-A-6-82268 60844 (JP, A) JP-A-5-325873 (JP, A) JP-A-9-259779 (JP, A) JP-A-6-223771 (JP, A) JP-A-61-161713 (JP, A) 1-85645 (JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) H01J 37/317 H01J 37/141

Claims (1)

(57) [Claim 1] In an ion irradiation apparatus configured to deflect an ion beam by a deflecting magnet having a structure in which a tip portion of a magnetic pole penetrates into a vacuum vessel and irradiate the ion beam to a substrate, At the tip of the magnetic pole of the deflection magnet, a non-magnetic plate is covered with a detachable shield plate covering the surface of the non-magnetic plate with a coating film made of an element constituting the substrate, and the shield plate attaches the tip of the magnetic pole. An ion irradiation device characterized by covering the surface.