JP2008135207A - Ion implantation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion implantation device that suppresses the occurrence of energy contamination while enhancing ion-beam transport efficiency by compensating divergence in the Y-direction of an ion beam due to space-charge effects or the like. <P>SOLUTION: The ion implantation device is provided with first/second magnets 50, 52 that are arranged so as to face each other in the Y-direction across a ribbon-like path of an ion beam 4 while intersecting with an advancing direction of the ion beam 4. Each magnet has a length covering a dimension in the X-direction of the ion beam 4. Both magnets 50, 52 respectively have a pair of magnetic poles each on the entrance side and the exit side of the ion beam 4 while each magnetic pole of the magnet 50 has a polarity reverse to that of each magnetic pole of the magnet 52. Both magnets generate a magnetic field in the direction causing an inward Lorentz force to act on between both magnets 50, 52 with respect to the ion beam 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a ribbon-like shape having a dimension in the X direction larger than the dimension in the Y direction substantially perpendicular to the X direction without being scanned in the X direction or without being scanned in the X direction. The present invention relates to an ion implantation apparatus configured to perform ion implantation by irradiating a target with an ion beam having a shape of a band (also referred to as a band shape), and more specifically to improvement of means for narrowing the ion beam in the Y direction.

  FIG. 16 shows a conventional example of this type of ion implantation apparatus. A similar ion implantation apparatus is described in Patent Document 1, for example. In this specification and the drawings, the ion constituting the ion beam 4 is described as an example of positive ions.

  This ion implantation apparatus mass-separates an ion beam 4 having a small cross-sectional shape (for example, a round or square spot shape) generated from an ion source 2 and serving as a source of a ribbon-like ion beam through a mass separator 6. After acceleration or deceleration through the accelerator / decelerator 8, energy separation through the energy separator 10, scanning in the X direction (for example, horizontal direction) through the scanner 12, and parallel beam through the beam collimator 14, the holder 26 The target (for example, a semiconductor substrate) 24 held on the substrate 24 is irradiated and ion implantation is performed on the target 24. The path of the ion beam 4 from the ion source 2 to the target 24 is kept in a vacuum atmosphere.

  The target 24 is mechanically scanned (reciprocated) in the direction along the Y direction (for example, the vertical direction) by the target driving device 28 within the irradiation region of the ion beam 4 from the beam collimator 14 together with the holder 26. The

  In this specification and the drawings, the traveling direction of the ion beam is the Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are the X direction and the Y direction.

  The beam collimator 14 cooperates with the scanner 12 that scans the ion beam 4 by a magnetic field or an electric field (in this example, a magnetic field), and converts the ion beam 4 scanned in the X direction into a magnetic field or an electric field (in this example). The ion beam 4 is bent back so as to be substantially parallel to the reference axis 16 by a magnetic field to form a parallel beam, and has a ribbon shape in which the dimension in the X direction is larger than the dimension in the Y direction (see FIG. 17). The ribbon shape does not mean that the dimension in the Y direction is as thin as paper or cloth. For example, the dimension of the ion beam 4 in the X direction is about 35 cm to 50 cm, and the dimension in the Y direction is about 5 cm to 10 cm. The beam collimator 14 is called a beam collimating magnet when a magnetic field is used as in this example.

  The ion implantation apparatus is an example in which the target 24 is irradiated with the ion beam 4 having a ribbon shape through scanning in the X direction, and the ribbon ion beam 4 is generated from the ion source 2. In some cases, the target 24 may be irradiated with the ion beam 4 having a ribbon shape without undergoing scanning in the X direction.

  Although the transport path of the ion beam 4 is in a vacuum container (not shown) and is maintained in a vacuum atmosphere, there is always a small amount of gas such as residual gas or outgas. When the ion beam 4 collides with the gas molecules and neutral particles are generated and enter the target 24, adverse effects such as deterioration of the uniformity of the injection amount distribution and an injection amount error occur. .

  In order to prevent this, the ion beam deflector in which the ion beam 4 in the energy state irradiated in the target 24 (in other words, the final energy state after passing through the accelerometer 8) is provided near the target 24 is provided. The deflected ion beam 4 is deflected by the action of a magnetic field or an electric field to separate the deflected ion beam 4 from the neutral particles 18 that travel straight without deflection, thereby preventing the neutral particles 18 from entering the target 24. Preferably, the beam collimator 14 also serves as the ion beam deflector.

  By the way, the ion beam 4 diverges due to the space charge effect during the transportation thereof. From the standpoint of increasing the throughput of the apparatus and decreasing the ion implantation depth for miniaturization of the semiconductor device formed on the target 24, the ion beam 4 irradiated to the target 24 should have a low energy and a large current. As desired, the divergence of the ion beam 4 due to the space charge effect increases as the ion beam 4 has lower energy and higher current.

  Although the divergence of the ion beam 4 occurs in both the X and Y directions, the size in the X direction of the ion beam 4 is originally considerably larger than that in the Y direction as described above, so that the adverse effect due to the divergence in the Y direction is greater. . In the following, attention is paid to the divergence in the Y direction.

  When the ion beam 4 diverges in the Y direction, a part of the ion beam 4 in the Y direction is cut by a vacuum vessel surrounding the path of the ion beam 4, a mask for shaping the ion beam 4, and the like. The transport efficiency to 24 is reduced.

For example, between the beam collimator 14 and the target 24, as shown in FIGS. 16 and 17 and as described in, for example, Japanese Patent No. 356749, an opening 22 through which the ion beam 4 passes is provided. In many cases, a mask 20 for shaping the ion beam 4 is provided. This is because the mask 20 can cut an unnecessary skirt portion in the Y direction of the ion beam 4 to reduce the distance L ₂ for escaping the target 24 from the ion beam 4.

  When the ion beam 4 diverges in the Y direction due to the space charge effect, for example, the ratio of being cut by the mask 20 is increased, so that the amount of the ion beam 4 that can pass through the mask 20 is reduced and the transport efficiency of the ion beam 4 is reduced. Decreases.

  The above problem also exists when a ribbon-shaped ion beam 4 is generated from the ion source 2 and the target 24 is irradiated with the ribbon-shaped ion beam 4 without scanning in the X direction. To do.

  As a means for compensating for the divergence in the Y direction due to the space charge effect of the ion beam 4, it is described in the path of the ion beam 4, for example, in the vicinity of the downstream side or the upstream side of the beam collimator 14, for example. It is conceivable to provide an electric field lens (which is also called an electrostatic lens).

An example of the electric field lens is shown in FIG. The electric field lens 30 includes an entrance electrode 32, an intermediate electrode 34, and an exit electrode 36 that are arranged at intervals in the traveling direction Z of the ion beam 4. The inlet electrode 32 and the outlet electrode 36 are kept at the same potential (ground potential in the illustrated example). A positive (in the illustrated example) or negative DC voltage V ₁ is applied to the intermediate electrode 34 from the DC power supply 38, and the intermediate electrode 34 is kept at a different potential from the entrance electrode 32 and the exit electrode 36. Each of the electrodes 32, 34, and 36 has a shape corresponding to the shape of the ion beam 4, and may be, for example, a cylindrical electrode or a parallel plate electrode.

The electric field lens 30 functions as an Einzel lens (which is also referred to as a unipotential lens), and changes the energy of the ion beam 4 even when a positive or negative DC voltage V ₁ is applied to the intermediate electrode 34. The ion beam 4 is narrowed in the Y direction. In FIG. 18, the ion beam 4 is not focused for simplification of illustration, but is actually narrowed.

JP-A-8-115701 (paragraph 0003, FIG. 1) Writer Toshiyoshi Takagi, University of Electrical Engineers, “Electron / Ion Beam Engineering”, First Edition, The Institute of Electrical Engineers of Japan, March 1, 1995, pages 105-108

  In the technique of focusing the ion beam 4 using the electric field lens 30 as described above, although the divergence in the Y direction due to the space charge effect of the ion beam 4 can be compensated and the transport efficiency of the ion beam 4 can be increased, the energy contamination is increased. There is a problem of occurrence of nation (that is, mixing of undesired energy particles).

That is, when a negative DC voltage V ₁ is applied to the intermediate electrode 34 of the electric field lens 30, the ion beam 4 is once accelerated in a region between the entrance electrode 32 and the intermediate electrode 34, and then the intermediate electrode 34 and the exit electrode 36. It is decelerated in the area between and becomes the original energy. In this acceleration region, when the ion beam 4 collides with the residual gas and neutral particles are generated by charge conversion, neutral particles having energy higher than the energy of the incident ion beam 4 are generated and travel downstream. As a result, it causes energy contamination of high energy components.

When a positive DC voltage V ₁ is applied to the intermediate electrode 34 as shown in FIG. 18, the ion beam 4 is once decelerated in the region between the entrance electrode 32 and the intermediate electrode 34, and then the intermediate electrode 34 and the exit electrode 36. It is accelerated in the area between and becomes the original energy. In this deceleration region, when the ion beam 4 collides with the residual gas and neutral particles are generated by charge conversion, neutral particles having energy lower than the energy of the incident ion beam 4 are generated and travel downstream. In other words, it causes energy contamination of low energy components.

As described above, energy contamination occurs even when a positive or negative DC voltage V ₁ is applied to the intermediate electrode 34.

Further, when a positive DC voltage V ₁ is applied to the intermediate electrode 34, as shown in FIG. 18, electrons in a drift space without an electric field (that is, a space without an electric field upstream and downstream from the vicinity of the intermediate electrode 34). Since 39 is drawn into the intermediate electrode 34 and disappears, the amount of electrons in the drift space decreases, the divergence due to the space charge effect of the ion beam 4 increases, and the transport efficiency of the ion beam 4 decreases greatly.

  Therefore, the present invention provides an ion implantation apparatus that can compensate for the divergence in the Y direction due to the space charge effect of the ion beam, increase the ion beam transport efficiency, and suppress the occurrence of energy contamination. The main purpose is to do.

  The ion implantation apparatus according to the present invention is upstream of the target, is opposed to each other in the Y direction across the ribbon-shaped ion beam path, and is in the traveling direction of the ribbon-shaped ion beam. A first magnet and a second magnet arranged so as to intersect with each other, and the first magnet and the second magnet are respectively paired on an entrance side and an exit side of the ion beam. A magnetic field having a magnetic pole and having opposite polarities between the first magnet and the second magnet and generating a magnetic field in a direction in which an inward Lorentz force is applied between the magnets with respect to the ion beam It is characterized by that.

  According to this ion implantation apparatus, the first and second magnets can generate a magnetic field having a component orthogonal to the traveling direction of the ion beam over the entire region in the X direction of the ribbon-shaped ion beam. (However, the magnetic fields generated by the two magnets are in opposite directions), and the ion beam receives an inward Lorentz force in the Y direction. Thereby, the ion beam can be narrowed in the Y direction.

  The first magnet and the second magnet are symmetrical with each other passing through the center in the Y direction of the path of the ion beam and substantially orthogonal to the X direction and the Y direction, except that the polarities are opposite to each other. It is preferable to arrange it substantially plane-symmetric with respect to the plane.

  The first magnet and the second magnet may be arranged so as to obliquely intersect the traveling direction of the ion beam.

  The first magnet and the second magnet may be permanent magnets or electromagnets.

  According to the present invention, since the ion beam can be narrowed in the Y direction by the magnetic field generated by the first and second magnets, the divergence in the Y direction due to the space charge effect of the ion beam is compensated, and the ion beam The transportation efficiency can be increased.

  In addition, unlike the case where an electric field lens is used, the ion beam can be narrowed without acceleration / deceleration, so that the occurrence of energy contamination can be suppressed.

  And the said effect can be show | played by the simple structure of the 1st and 2nd magnet.

  According to the second aspect of the present invention, since the magnetic field having good symmetry with respect to the symmetry plane can be generated by the first and second magnets, the ion beam can be narrowed with good symmetry. There is an effect.

  According to the third aspect of the present invention, the magnetic field component orthogonal to the traveling direction of the ion beam can be further increased, and the ion beam can be more strongly focused in the Y direction.

  According to the fourth aspect of the present invention, there is a further effect that the ion beam can be uniformly narrowed in the Y direction over the entire region in the X direction of the ion beam substantially parallel scanned in the X direction. .

  According to the fifth aspect of the present invention, there is a further effect that the ion beam can be uniformly narrowed in the Y direction over the entire region in the X direction of the ion beam scanned in a fan shape in the X direction.

  According to the sixth aspect of the present invention, the ion beam can be uniformly narrowed in the Y direction over the entire area in the X direction of the ribbon-shaped ion beam without passing through the scanning in the X direction. The effect which becomes.

  According to invention of Claim 7, since the 1st and 2nd magnet is a permanent magnet, there exists the further effect that a structure can be simplified more.

  The invention according to claim 8 has the following further effect. That is, since the first and second magnets are electromagnets, it is easy to adjust the strength of the magnetic field generated by them, and therefore, the degree of narrowing the ion beam in the Y direction can be easily controlled. . In addition, it is possible to generate a stronger magnetic field than the permanent magnet, and to focus the ion beam more strongly.

  FIG. 1 is a plan view partially showing one embodiment of an ion implantation apparatus according to the present invention. Portions that are the same as or correspond to those in the conventional example shown in FIG. 16 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

  The ion implantation apparatus is provided on the upstream side of the target 24, and more specifically, the beam also serves as an ion beam deflector that separates the ion beam 4 and the neutral particles 18 (see FIG. 16). A first magnet 50 and a second magnet 52 are provided near the downstream side of the collimator 14 and arranged to face each other in the Y direction across the path of the ribbon-like ion beam 4. ing. In FIG. 1, since the second magnet 52 (see FIG. 3) is hidden under the first magnet 50 and does not appear, the reference numeral 52 is described in parentheses.

  On the downstream side of the beam collimator 14, the ion beam 4 is scanned substantially in parallel in the X direction by the cooperation of the scanner 12 and the beam collimator 14 to form a ribbon shape. ing.

  In the present embodiment, the first and second magnets 50 and 52 are permanent magnets having a substantially straight shape.

  Both magnets 50 and 52 are arranged so as to intersect with the traveling direction Z of the ribbon-like ion beam 4, more specifically in this embodiment, so as to intersect obliquely. In addition, in this embodiment, both the magnets 50 and 52 have a length that covers the dimension in the X direction of the ribbon-like ion beam 4. That is, both the magnets 50 and 52 have an elongated bar-like or plate-like shape in which the dimension in the X direction is larger than the dimension in the X direction of the ribbon-like ion beam 4.

  The above “oblique crossing” means that the angle β formed by the vertical line 60 standing on the long side 50a of the magnet 50 and the traveling direction of the ion beam 4 is other than 0 degrees as in the example shown in FIG. is there. In other words, the perpendicular 60 is a line parallel to the short axis of the magnet 50 (which is also the magnetic axis in this example). When the angle β is 0 degree, the magnet 50 intersects substantially perpendicular to the traveling direction of the ion beam 4 as in the example shown in FIG. The same applies to the second magnet 52.

  Both magnets 50 and 52 have a pair of magnetic poles (N pole and S pole) on the entrance side and the exit side of the ion beam 4, respectively. That is, the two long sides 50a, 52a of the elongated magnets 50, 52 (that is, the entrance side and the exit side of the ion beam 4) are magnetic poles over substantially their entire length. That is, both ends in the short direction of the magnets 50 and 52 are magnetic poles. This point is greatly different from the reference example in which the short sides 80b and 82b are magnetic poles as shown in FIGS. Moreover, the polarities of the magnetic poles are reversed between the first magnet 50 and the second magnet 52, as shown in FIG.

  Further, in this embodiment, the first magnet 50 and the second magnet 52 pass through the center in the Y direction of the path of the ion beam 4 and in the X direction and the Y direction, except that the polarities are opposite to each other. They are arranged in substantially plane symmetry with respect to a substantially orthogonal plane of symmetry 58 (see FIG. 3). More specifically, the magnet 50 and the magnet 52 have substantially the same shape and dimensions, and the magnets 50 and 52 are substantially opposed in the Y direction (in other words, overlap each other in the Y direction). And the distances from the symmetry plane 58 to the two magnets 50 and 52 are substantially equal to each other. Accordingly, in the vicinity of the symmetry plane 58, the upper and lower magnetic fields cancel each other and the magnetic field strength becomes substantially zero, and the magnetic field strength increases as the distance from the symmetry plane 58 increases in the Y direction.

  Table 1 summarizes the relationship between the installation locations of both magnets 50 and 52 and the polarity of the magnetic poles. The embodiment shown in FIG. 1 corresponds to Example 1 in Table 1. Example 2 will be described later.

Table 1 above is for the case where the angle β is positive (but smaller than 90 degrees) when the angle β is taken counterclockwise with respect to the incident ion beam 4 as shown in FIG. Further, when the angle γ shown in FIG. 6 is taken clockwise with respect to the incident ion beam 4, the angle γ is positive (however, smaller than 90 degrees). Similarly, when the angle φ shown in FIG. 8 is clockwise with respect to the incident ion beam, the angle φ is positive (but smaller than 90 degrees). The angle beta, gamma, if φ is negative, the direction of orthogonal component B _R to be described later is reversed, the polarity of the magnets 50 and 52 it is sufficient to reverse to those shown in Table 1. That is, in any case, the polarities of the magnetic poles of the two magnets 50 and 52 generate a magnetic field in a direction in which a Lorentz force is applied inwardly between the two magnets 50 and 52 with respect to the ion beam 4.

  This will be described first with reference to FIGS. The first magnet 50 generates a magnetic field B in a direction intersecting the ion beam 4 at an angle β on the path side of the ion beam 4. The magnetic field B generated by the magnet 50 is schematically shown by magnetic lines 54 in FIG. Unlike the reference examples shown in FIGS. 14 and 15, the magnetic poles of the magnet 50 are in the short direction, so that the magnetic field B as described above can be generated.

The magnetic field B is, for the angle β is present, and a component (orthogonal component) B _R orthogonal to the traveling direction Z of the ion beam 4. Such orthogonal component B _R is generated over the entire region in the X direction of the ion beam 4. Due to this orthogonal component _BR , the ion beam 4 receives an inward (downward in FIG. 3) Lorentz force F in the Y direction.

  The second magnet 52 also generates a magnetic field similar to the magnetic field B generated by the first magnet 50 except that the direction is opposite. A magnetic field generated by the magnet 52 is schematically shown by magnetic lines 56 in FIG. Due to the orthogonal component of this magnetic field, the ion beam 4 receives an inward (upward in FIG. 3) Lorentz force F in the Y direction.

  The ion beam 4 can be narrowed in the Y direction by the Lorentz force F. The degree to which the ion beam 4 is narrowed is proportional to the magnetic flux density of the magnetic field B and inversely proportional to the energy of the ion beam 4. Therefore, if the magnetic flux density is kept constant, the ion beam 4 with lower energy can be focused more strongly.

  An example of the state in which the ion beam 4 is focused is shown in FIG. This is an example in which the incident ion beam 4 diverging in the Y direction is focused so as to be focused. However, the state of the illustrated ion beam 4 is merely an example (the same applies to FIGS. 4, 9, 11, and 13). By adjusting the degree to which the ion beam 4 is narrowed, other narrowing methods are possible. For example, it is possible to derive a parallel ion beam whose divergence is substantially zero in the Y direction. The same applies to other embodiments described later.

  As described above, according to this ion implantation apparatus, the ion beam 4 can be narrowed in the Y direction by the magnetic field generated by the first and second magnets 50 and 52, so that the Y caused by the space charge effect of the ion beam 4 and the like. Compensating for the divergence in the direction, the transport efficiency of the ion beam 4 to the target 24 can be increased.

  Since the ion beam 4 can be narrowed in the Y direction, divergence in the Y direction due to other than the space charge effect of the ion beam 4 can also be suppressed. Further, as described above, by adjusting the degree of narrowing the ion beam 4 in the Y direction, it becomes possible to derive the parallel ion beam 4 whose divergence is substantially zero in the Y direction.

  More specifically, when the above-described mask 20 is provided on the downstream side of the two magnets 50 and 52 as in the example shown in FIG. 1, ions are interposed between the beam collimator 14 and the mask 20. By compensating for the divergence in the Y direction due to the space charge effect of the beam 4, the amount of the ion beam 4 passing through the opening 22 of the mask 20 can be increased, and the transport efficiency of the ion beam 4 to the target 24 can be increased.

  In addition, unlike the case of using an electric field lens, the ion beam 4 can be narrowed without acceleration / deceleration, so that the occurrence of energy contamination can be suppressed.

  In addition, the above-described effect can be achieved with a simple configuration of the first and second magnets 50 and 52.

  Furthermore, this embodiment has the following advantages.

  That is, since both the magnets 50 and 52 are permanent magnets, the configuration can be further simplified.

Since both the magnets 50 and 52 are disposed so as to obliquely intersect the traveling direction Z of the ion beam 4, the orthogonal component _BR is increased to further narrow the ion beam in the Y direction. Can do.

  Since both magnets 50 and 52 are provided in the path of the ion beam 4 scanned substantially in parallel in the X direction, the ion beam is uniformly distributed over the entire region of the ion beam 4 scanned substantially in parallel in the X direction. 4 can be narrowed down in the Y direction.

  The first magnet 50 and the second magnet 52 are disposed substantially in plane symmetry with respect to the symmetry plane 58, and a magnetic field having good symmetry with respect to the symmetry plane 58 is provided by the first and second magnets 50 and 52. Since it can be generated, the ion beam 4 can be narrowed with good symmetry.

By the way, strictly speaking, magnetic fields B ₁ and B ₂ in the Y direction are generated between the magnetic poles of the first magnet 50 and the magnetic pole of the second magnet 52 as in the example shown in FIG. . Both magnetic fields B ₁ and B ₂ are opposite to each other, and become stronger as the distance between the magnets 50 and 52 in the Y direction becomes smaller. Due to the magnetic fields B ₁ and B ₂ , the ion beam 4 receives Lorentz forces F ₁ and F ₂ opposite to each other in the X direction and passes between the magnets 50 and 52 as shown in FIG. Bent in the X direction, a difference (orbit difference) ΔX occurs in the trajectory in the X direction between the entrance and exit of the magnets 50 and 52. If the strengths of both magnetic fields B ₁ and B ₂ are made substantially equal to each other, the incident ion beam 4 and the irradiated ion beam 4 become substantially parallel to each other. Even if the trajectory difference ΔX as described above occurs, the purpose of narrowing the ion beam 4 in the Y direction can be achieved. In addition, the trajectory difference ΔX as described above is usually small, so there is no particular inconvenience if it occurs, but if it is inconvenient, it can be dealt with by other means.

  In FIG. 5, the ion beam 4 is representatively shown as a single line, but the ion beam 4 at other locations is the same as shown in the figure (this is the same for FIGS. 6 and 12). ).

Further, focusing on the fact that the ion beam 4 is bent in the X direction while passing between the two magnets 50 and 52 as described above, the magnets 50 and 52 are caused to travel by the ion beam 4 as in the example shown in FIG. You may arrange | position so that it may cross | intersect at right angles with respect to the direction Z (in other words, the angle (beta) shown in FIG. 2 may be substantially 0 degree | times). Also in this case, the angle γ formed by the ion beam 4 passing between the magnets 50 and 52 and the magnetic field B is greater than 0 degree, and a component (orthogonal component) B orthogonal to the traveling direction of the ion beam 4 is obtained. _{Since R} occurs, the ion beam 4 receives an inward Lorentz force F in the Y direction by this orthogonal component B _R as in the examples of FIGS. 2 and 3 (however, the magnitude is As a result, the ion beam 4 can be narrowed in the Y direction.

  As can be seen with reference to FIG. 5, the same phenomenon occurs in the examples of FIGS. 2 and 3 when viewed strictly. Accordingly, if attention is also paid to the angle γ, the angle formed by the traveling direction of the ion beam 4 passing between the magnets 50 and 52 and the magnetic field B is β + γ.

  The magnet 50 may be constituted by a single permanent magnet, or may be constituted by arranging a plurality of permanent magnets 68 having the same polarity in parallel as in the example shown in FIG. The same applies to the magnet 52. The same applies to the arc-shaped magnets 50 and 52 described later (see FIGS. 8 and 9).

14 and 15, it is not preferable to provide magnetic poles at both ends in the longitudinal direction of the first magnet 80 and the second magnet 82, that is, on the two short sides 80b and 82b side. . When such a magnetic pole is provided, magnetic field lines 84 and 86 along the Y direction are generated between the magnets 80 and 82 only in the vicinity of the magnetic poles at both ends in the X direction, as shown in FIG. This is because the Lorentz forces F ₃ and F ₄ that cause the ion beam 4 to diverge outwardly act in the vicinity of both ends of the beam 4 in the X direction, and the ion beam 4 cannot be narrowed in the Y direction.

  The first and second magnets 50 and 52 may be provided near the upstream side of the beam collimator 14 instead of being provided near the downstream side of the beam collimator 14 as in the above embodiment. By doing so, it is possible to increase the amount of the ion beam 4 incident on the beam collimator 14 and passing therethrough, so that it becomes easy to increase the transport efficiency of the ion beam 4.

  The first and second magnets 50 and 52 may be provided in at least one of the vicinity of the downstream side and the upstream side of the beam collimator 14, or may be provided in both. If both are provided, the amount of the ion beam 4 passing through the beam collimator 14 can be increased, and the divergence in the Y direction of the ion beam that has passed through the beam collimator 14 can be suppressed. The transport efficiency to the target 24 can be further increased.

  When the first and second magnets 50 and 52 are provided in the path of the ion beam 4 scanned in a fan shape in the X direction by the scanner 12 (see FIG. 16) as in the vicinity of the upstream side of the beam collimator 14. The magnets 50 and 52 are preferably formed by bending the magnets 50 and 52 shown in FIGS. 1 and 2 into an arc shape, that is, the following arc shape.

  That is, both the magnets 50 and 52 are in an arc shape protruding in the traveling direction of the ion beam 4 as in the embodiment shown in FIGS. 8 and 9, and the traveling direction of the ion beam 4 at each scanning position in the X direction. It is preferable that the angle φ formed by the straight line 62 connecting the pair of magnetic poles (N pole and S pole) of the magnets 50 and 52 with the shortest distance is an arc that is always substantially constant.

More specifically, assuming that the center point of the scanning of the ion beam 4 by the scanner 12 is a and that a point separated from the center point a by the distance L _{6 in the} X direction is b, two arc-shaped magnets 50 and 52 are provided. The two arc sides 50c and 52c (that is, the entrance side and the exit side of the ion beam 4) are each part of a circle centered on the point b. Each of the arcuate sides 50c and 52c is a magnetic pole over substantially the entire length thereof.

When the magnets 50 and 52 are formed in an arc as described above, the angle φ is substantially constant regardless of the scanning position of the ion beam 4. The magnetic field B generated by the two magnets 50 and 52 by this angle φ (plus the angle γ described with reference to FIG. 6 when strictly speaking) is a component (orthogonal) orthogonal to the traveling direction of the ion beam 4. It will have a component) B _R. Due to this orthogonal component _BR , the ion beam 4 receives an inward Lorentz force F in the Y direction, whereby the ion beam 4 can be narrowed in the Y direction. The angle φ increases as the distance L ₆ increases.

  In addition, since the angle φ is substantially constant regardless of the scanning position of the ion beam 4, the ion beam 4 is uniformly narrowed in the Y direction over the entire area of the ion beam 4 scanned in a fan shape in the X direction. be able to.

  Example 2 in Table 1 corresponds to the embodiment shown in FIGS.

  When a ribbon-like ion beam is generated from the ion source 2 (see FIG. 16) and the ribbon-like ion beam 4 is incident on the target 24 without performing scanning in the X direction, the ion beam 4 The first and second magnets 50 and 52 having a substantially straight shape described with reference to FIGS. 1 to 7 may be provided in this path. By doing so, the ion beam 4 can be uniformly narrowed in the Y direction over the entire region of the ion beam 4 in the X direction.

  The straight and arc-shaped first and second magnets 50 and 52 as described above may be constituted by electromagnets instead of permanent magnets as in the above embodiment. In the following, an embodiment in which an electromagnet is configured will be described mainly with respect to differences from the embodiment configured with the permanent magnet.

  An embodiment in which the straight first and second magnets 50 and 52 are constituted by electromagnets is shown in FIGS. This corresponds to the embodiment shown in FIGS.

  Each of the magnets 50 and 52 has an iron core 70 having a shape and arrangement corresponding to the magnets 50 and 52 shown in FIGS. 1 to 6 and a coil 72 wound in the longitudinal direction of the iron core. ing. The two long side 70a sides (that is, the entrance side and the exit side of the ion beam 4) of the iron core 70 are magnetic poles over substantially the entire length thereof.

Both magnets 50 and 52 are supplied with excitation currents I ₁ and I ₂ from DC power supplies 74 and 76, respectively, and generate a magnetic field having the same polarity as that of the embodiment shown in FIGS. Therefore, the ion beam can be narrowed in the Y direction by the same operation as the embodiment shown in FIGS.

In addition, since the first and second magnets 50 and 52 are electromagnets, it is easy to adjust the strength of the magnetic field generated by them, and thus the degree to which the ion beam 4 is narrowed in the Y direction is easily controlled. can do. For example, by changing the strength of the magnetic field to be generated in accordance with the energy of the ion beam 4, the ion beam 4 can be similarly focused at any energy. Further, by changing the strength of the magnetic field to be generated, the focusing state (for example, focal length) of the ion beam 4 in the Y direction can be changed. It is also possible to control the beam dimension d _t , the divergence angle α, and the deviation angle θ described later. In addition, it is possible to generate a stronger magnetic field than the permanent magnet, and to focus the ion beam 4 more strongly. The same applies to the embodiment shown in FIG.

The exciting currents I ₁ and I ₂ may be the same or different. In the case of the same size, one DC power source may be used for both magnets 50 and 52. Further, one or both of the DC power supplies 74 and 76 may be bipolar power supplies so that the directions of the excitation currents I ₁ and I ₂ can be reversed. The same applies to the embodiment shown in FIG.

  An embodiment in which the arc-shaped magnets 50 and 52 are constituted by electromagnets is shown as a representative example of the first magnet 50 in FIG. Since the cross section is the same as that of FIG. 11, reference is made thereto. This corresponds to the embodiment shown in FIGS.

  Each of the magnets 50 and 52 has an iron core 70 having a shape and arrangement corresponding to the magnets 50 and 52 shown in FIGS. 8 and 9, and a coil 72 wound in the longitudinal direction of the iron core. ing. The two arcuate sides 70c of the iron core 70 (that is, the entrance side and the exit side of the ion beam 4) are magnetic poles over substantially the entire length thereof. Although the coil 72 may be wound straight in the longitudinal direction of the iron core 70, it is preferable that the coil 72 is wound in an arc along the arc-shaped side 70c as in the illustrated example. By doing so, it is possible to generate a uniform magnetic field over both arcuate sides 70c, that is, over substantially the entire length of both magnetic poles.

Both magnets 50 and 52 are supplied with excitation currents I ₁ and I ₂ from DC power supplies 74 and 76, respectively, and generate magnetic fields having the same polarities as those in the embodiment shown in FIGS. Therefore, the ion beam can be narrowed in the Y direction by the same operation as the embodiment shown in FIGS.

An example of controlling the beam size d _t , the divergence angle α, and the deviation angle θ of the ion beam 4 in the Y direction when the first and second magnets 50 and 52 are electromagnets will be described below.

Referring to FIG. 1, a front multi-point Faraday 42 and a rear multi-point Faraday in which a plurality of detectors for measuring the beam current of the ion beam 4 are arranged in parallel in the X direction on the upstream side and the downstream side of the target 24, respectively. For example, as in the technique described in Japanese Patent Application Laid-Open No. 2005-195417, both multipoint Faraday 42 and 44 and a shutter driven in the Y direction in front of the multipoint Faraday 42 are used. , beam size d _f in the Y direction of the ion beam 4 in two places in the traveling direction Z of the ion beam 4, and d _b, a distance L _4, L ₅ between the distance L ₃ and both locations and the target 24 between the two portions Based on the above, the beam dimension d _{t in} the Y direction of the ion beam 4 at the position of the target 24 and the divergence angle α in the Y direction of the ion beam 4 may be measured according to the following equation. Instead of providing a shutter in front of the front multipoint Faraday 42, the front multipoint Faraday 42 may be driven in the Y direction by providing the front multipoint Faraday 42 in the vicinity of the downstream side of the mask 20, for example.

[Equation 1]
d _t = (L ₅ / L ₃ ) d _f + (L ₄ / L ₃ ) d _b (where L ₃ = L ₄ + L ₅ )

[Equation 2]
α = tan ⁻¹ {(d _b −d _f ) / 2L ₃ }

Based on the measurement data of the beam dimension d _t and the divergence angle α, the DC power sources 74 and 76 and the excitation currents I ₁ and I ₂ may be feedback-controlled by a control device (not shown). For example, when the beam dimension _{dt in} the Y direction of the ion beam 4 and the divergence angle α are large, the absolute values (magnitudes) of the excitation currents I ₁ and I ₂ may be controlled to increase accordingly. . As a result, the ion beam 4 is more strongly focused in the Y direction by the two magnets 50 and 52, so that the beam dimension _dt and the divergence angle α can be reduced. It is also possible to perform ion implantation by setting the divergence angle α at the position of the target 24 to be substantially 0 degree and causing the ion beam 4 having high parallelism in the Y direction to enter the target 24.

When both magnets 50 and 52 are supplied with exciting currents I ₁ and I ₂ having the same magnitude, and both magnets 50 and 52 generate magnetic fields having the same strength as each other, for example, as shown in FIG. If the incident ion beam 4 is inclined in the Y direction for some reason, the outgoing ion beam 4 also has a deviation angle θ in the Y direction. The deviation angle θ is an angle formed by the central trajectory of the ion beam 4 and the symmetry plane 58 in the YZ plane.

This can be corrected by supplying exciting currents I ₁ and I ₂ having different magnitudes to the two magnets 50 and 52 and generating magnetic fields having different strengths by the two magnets 50 and 52. For example, when the incident ion beam 4 is tilted upward in the Y direction as in the example shown in FIG. 13, the excitation current I ₁ supplied to the tilted magnet 50 is increased and the opposite side. it may be performed at least one of reducing the exciting current I ₂ supplied to the magnet 52 of the. Thereby, the magnetic field generated by the inclined magnet 50 becomes stronger, the downward Lorentz force F becomes larger, and the deviation angle θ can be reduced. It can be substantially 0 degree. When the deviation angle θ is opposite to the above, it may be reversed.

The ion beam 4 at two locations in the traveling direction of the ion beam 4 is used, for example, in the same manner as the technique described in Japanese Patent Application Laid-Open No. 2005-195417 using the preceding multipoint Faraday 42 and the subsequent multipoint Faraday 44. The deviation angle θ may be measured according to the following equation based on the center positions y _f and y _{b in} the Y direction and the distance L ₃ between the two locations.

[Equation 3]
θ = tan ⁻¹ {(y _b −y _f ) / L ₃ }

Then, based on the measurement data of the deviation angle θ, the DC power sources 74 and 76 and the excitation currents I ₁ and I are controlled by a control device (not shown) so that the deviation angle becomes small (for example, substantially 0 degree). ₂ may be feedback controlled as described above.

It is a top view which shows partially one Embodiment of the ion implantation apparatus which concerns on this invention. It is a top view which expands and shows the 1st magnet and ion beam which are shown in FIG. FIG. 4 is a cross-sectional view showing a first magnet, a second magnet, and an ion beam generally along line CC in FIG. 3. It is the figure which added the magnetic field of the Y direction to FIG. It is a top view which expands and shows the shift | offset | difference of the track | orbit in the X direction of an ion beam, and the ion beam has shown and represented only one line. It is a top view which shows embodiment which has arrange | positioned the 1st magnet substantially at right angle with respect to the ion beam, and the ion beam has shown and represented only one line. It is a top view which shows the example which comprised the 1st magnet by arranging several permanent magnets in parallel. It is a top view which shows embodiment which provided the 1st and 2nd magnet in the upstream vicinity of the beam collimator shown in FIG. FIG. 9 is a cross-sectional view showing the first magnet, the second magnet, and the ion beam substantially along line DD in FIG. 8. It is a top view which shows the example of the 1st magnet comprised with the electromagnet, the power supply for it, and an ion beam, and respond | corresponds to FIG. FIG. 11 is a cross-sectional view showing a first magnet, a second magnet, a power source therefor, and an ion beam, generally along line EE of FIG. 10. It is a figure which shows the example which comprised the 1st magnet shown in FIG. 8 with the electromagnet instead of the permanent magnet with a power supply. It is a figure for demonstrating the example which controls the deviation angle of an ion beam using the 1st and 2nd magnet comprised with the electromagnet. It is a top view which shows the example of the 1st magnet and ion beam which have a magnetic pole in the both ends of a longitudinal direction as a reference example. FIG. 15 is a front view showing the first magnet, the ion beam, and the second magnet shown in FIG. 14 when viewed in the direction of arrow P in FIG. 4. It is a top view which shows an example of the conventional ion implantation apparatus. It is a front view which expands and shows the mask and target in FIG. 16 seeing in the advancing direction of an ion beam. It is a side view which shows an example of an electric field lens with a power supply.

Explanation of symbols

4 Ion beam 14 Beam collimator (ion beam deflector)
24 target 50 first magnet 52 second magnet

Claims (8)

An ion beam having a ribbon-like shape whose X-direction dimension is larger than the Y-direction dimension substantially orthogonal to the X-direction is passed through the X-direction scan or without the X-direction scan. In an ion implantation apparatus configured to irradiate
Located upstream of the target, arranged to face each other in the Y direction across the ribbon-shaped ion beam path, and to cross the traveling direction of the ribbon-shaped ion beam. A first magnet and a second magnet,
Each of the first magnet and the second magnet has a pair of magnetic poles on the entrance side and the exit side of the ion beam, and the polarities of the first magnet and the second magnet are opposite to each other. An ion implantation apparatus characterized by generating a magnetic field in a direction in which an inward Lorentz force is exerted between both magnets with respect to the ion beam.   The first magnet and the second magnet are symmetrical with each other passing through the center in the Y direction of the path of the ion beam and substantially orthogonal to the X direction and the Y direction, except that the polarities are opposite to each other. The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus is disposed substantially symmetrically with respect to a plane.   3. The ion implantation apparatus according to claim 1, wherein the first magnet and the second magnet are disposed so as to obliquely intersect the traveling direction of the ion beam.   The first magnet and the second magnet are provided in a path of an ion beam scanned substantially in parallel in the X direction, and the first magnet and the second magnet are substantially straight. The ion implantation apparatus according to claim 1, 2 or 3, wherein the ion implantation apparatus has a simple shape.   The first magnet and the second magnet are provided in a path of an ion beam scanned in a fan shape in the X direction, and the first magnet and the second magnet are in a traveling direction of the ion beam. An overhanging arc shape in which the angle between the traveling direction of the ion beam at each scanning position in the X direction and the straight line connecting the pair of magnetic poles of each magnet at the shortest distance is always substantially constant. The ion implantation apparatus according to claim 1, 2 or 3.   The first magnet and the second magnet are provided in a path of an ion beam having a ribbon shape without being scanned in the X direction, and the first magnet and the second magnet are substantially 4. The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus has a straight shape.   The ion implantation apparatus according to claim 1, wherein the first magnet and the second magnet are permanent magnets.   The ion implantation apparatus according to claim 1, wherein the first magnet and the second magnet are electromagnets.

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