JP2010262797A - Ion beam irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion beam irradiation device, capable of widely supplying low-energy electrons to ion beams having large dimensions in the Y direction than the dimensions in the X direction, thereby uniformly controlling charges of a substrate. <P>SOLUTION: The ion beam irradiation device has an electrode 20a installed at a position opposed to the side on X direction side of the ion beams 2. An annular permanent magnet 24 large in Y direction and a permanent magnet 26 which is arranged inside that and has an opposite polarity to the permanent magnet 24 and is large in Y direction are installed in the electrode 20a. The device has, further, an electron source 30a which supplies electrons 50 to a region of a tunnel-shape magnetic field formed between both permanent magnets 24, 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ion beam irradiation apparatus that irradiates a substrate with an ion beam and performs processing such as ion implantation and alignment processing on the substrate, and more specifically, charging of the substrate (charge-up) associated with ion beam irradiation. ) With good uniformity.

  In the vicinity of the upstream side of the substrate, low energy (for example, about 20 eV or less) electrons generated from an electron source are supplied to the ion beam, and the electrons reach the substrate together with the ion beam. An ion beam irradiation apparatus that suppresses charging has been conventionally proposed (see, for example, Patent Document 1). The reason why low-energy electrons are supplied is to suppress the negative charging voltage of the substrate to be small when the electrons are excessively supplied to the substrate. In the apparatus described in Patent Document 1, electrons are generated from a plasma source, but this can also be said to be an electron source in a broad sense.

  The ion beam irradiation apparatus described in Patent Document 1 supplies low energy electrons relatively concentrated from one place to the ion beam.

However, in the ion beam irradiation apparatus, referring to FIG. 1, if two directions substantially orthogonal to each other in a plane substantially orthogonal to the traveling direction Z of the ion beam 2 are defined as an X direction and a Y direction, X There is an apparatus for irradiating a substrate with an ion beam 2 having a dimension W _{Y in the} Y direction larger than a dimension W _{X in the} direction. Such an ion beam 2 is sometimes called a ribbon-shaped (or sheet-shaped) ion beam. When such an ion beam 2 is used, the dimension of the substrate in the Y direction is usually large according to the dimension W _Y of the ion beam 2 in the Y direction. For example, the dimension in the Y direction of the substrate is made slightly smaller than the dimension W _{Y in} the Y direction of the ion beam 2.

  Even if low-energy electrons are supplied from one place to the ion beam 2 as described above, for example, on the side surface (main surface) 3 thereof according to the technique described in Patent Document 1, the ion beam 2 is long in the Y direction. Therefore, it is difficult to supply the electrons without bias. As a result, the uneven distribution of electrons affects the suppression of charging of the substrate, so that it is difficult to suppress charging of the substrate with good uniformity.

  This is because, in the region where electrons are supplied to the ion beam, there is often a leakage magnetic field from other equipment (for example, an analysis electromagnet) constituting the ion beam irradiation apparatus, and in addition there is geomagnetism. This is because the low-energy electrons supplied from the electron source are restrained by these magnetic fields, causing the uneven distribution of electrons, thereby making the substrate charge-suppressing effect non-uniform.

Incidentally, as can be seen from the following equation, the lower the energy of the electrons, the smaller the Larmor radius R in the magnetic field, and the more easily the electrons are unevenly distributed. Here, B is a magnetic flux density, m is an electron mass, V is an electron extraction voltage (corresponding to energy), and e is an electric charge. For example, when the magnetic flux density B is 3 × 10 ⁻⁴ T, the Larmor radius R of electrons having an energy of 20 eV is only about 5 cm.

[Equation 1]
R = (1 / B) √ (2 mV / e)

  Therefore, the present invention can supply a wide range of low-energy electrons to an ion beam having a dimension in the Y direction larger than that in the X direction as described above, thereby suppressing the charging of the substrate with good uniformity. An object of the present invention is to provide an ion beam irradiation apparatus capable of performing the above.

  One of the ion beam irradiation apparatuses according to the present invention is such that, when two directions substantially orthogonal to each other in a plane substantially orthogonal to the traveling direction of the ion beam are defined as an X direction and a Y direction, the dimension of the ion beam irradiation apparatus In an ion beam irradiation apparatus that irradiates a substrate held by a holder with an ion beam having a large dimension in the Y direction, the ion beam irradiation apparatus is provided at a position upstream of the holder and facing a side surface on the X direction side of the ion beam. A plate-like first electrode made of a non-magnetic material, a first polarity magnetic pole on the ion beam side, provided in the plane of the first electrode, and the Y An annular first permanent magnet extending in a direction, and a space between the first permanent magnet and in the plane of the first electrode and inside the annular first permanent magnet And the above-mentioned ion A second permanent magnet having a magnetic pole of a second polarity opposite to the first polarity on the beam side and extending along the Y direction; and the first and second permanent magnets And a first electron source for supplying electrons to a region of a magnetic field formed therebetween.

  In this ion beam irradiation apparatus, electrons (primary electrons) supplied from the electron source to the magnetic field region are trapped by the magnetic field and spirally wound around the magnetic field lines of the magnetic field, thereby causing a gradient. Due to the B drift and the E × B drift, an annular drift motion is performed along the annular space between the first and second permanent magnets. While the primary electrons are in the spiral motion and drift motion, the primary electrons collide with residual gas molecules, and thus electrons having lower energy than the primary electrons are generated. The generation of the low energy electrons is performed in a wide region extending along the Y direction since the primary electrons drift in a ring shape.

  The low-energy electrons generated as described above diffuse into the region where the magnetic field is weak, that is, away from the surface of the first electrode, and are attracted by the positive beam potential of the ion beam and are drawn into the ion beam. And reaches the substrate together with the ion beam.

  With the above-described action, low-energy electrons can be supplied over a wide range to an ion beam having a dimension in the Y direction larger than the dimension in the X direction, thereby suppressing the charging of the substrate with good uniformity. it can.

  A second electrode provided to face the first electrode in the X direction with an ion beam interposed therebetween, and third and fourth permanent magnets provided in the plane of the second electrode; You may have.

  A bias power source that applies a DC bias voltage to the first electrode or between the first and second electrodes may be further provided.

  In another ion beam irradiation apparatus according to the present invention, when two directions substantially orthogonal to each other in a plane substantially orthogonal to the traveling direction of the ion beam are defined as an X direction and a Y direction, In the ion beam irradiation apparatus for irradiating a substrate held by a holder with an ion beam having a large dimension in the Y direction, a tube made of a non-magnetic material surrounds the periphery of the ion beam on the upstream side of the holder. A ring-shaped electrode, an annular first permanent magnet provided in a plane of the electrode so as to surround the periphery of the ion beam, and having a magnetic pole having a first polarity on the ion beam side; In the plane of the electrode, downstream of the first permanent magnet and spaced from the first permanent magnet so as to surround the periphery of the ion beam. And an annular second permanent magnet having a magnetic pole having a second polarity opposite to the first polarity on the ion beam side, and the second permanent magnet in the plane of the electrode. The ion beam is provided on the downstream side of the second permanent magnet so as to surround the periphery of the ion beam and has the first polarity magnetic pole on the ion beam side. An annular third permanent magnet, and one or more electrons for supplying electrons to regions of the magnetic field formed between the first and second permanent magnets and between the second and third permanent magnets, respectively. It is characterized by having a source.

  According to the first aspect of the present invention, the electrons (primary electrons) supplied from the electron source spirally move in the magnetic field between the first and second permanent magnets, and the first and second permanent magnets. Since a circular drift motion is generated between the magnets, low-energy electrons can be generated in a wide region extending along the Y direction using the spiral motion and the drift motion. As a result, low-energy electrons can be supplied over a wide range with respect to an ion beam having a dimension in the Y direction larger than that in the X direction, thereby suppressing the charging of the substrate with good uniformity.

  According to invention of Claim 2, there exists the following further effect. That is, by controlling the electric field in the vicinity of the surface of the first electrode by the bias voltage applied to the first electrode from the bias power source, the electron drift speed due to the E × B drift can be controlled, Thereby, the generation state of low energy electrons can be controlled. As a result, it becomes possible to more effectively suppress the charging of the substrate.

  According to invention of Claim 3, there exists the following further effect. (A) an annular magnetic field formed between the third and fourth permanent magnets, (b) a magnetic field formed between the first and third permanent magnets facing each other across the ion beam, and (C) Among the relatively high energy electrons supplied from the electron source by the magnetic field formed between the second and fourth permanent magnets facing each other across the ion beam, the first and second Electrons that escape the magnetic field between the permanent magnets can be captured. It can also be expected that the electrons collide with the second electrode and disappear. Therefore, it is possible to more reliably suppress the relatively high energy electrons from reaching the substrate together with the ion beam.

  According to invention of Claim 4, there exists the following further effect. That is, since the low energy electrons can be supplied to the ion beam from the second electrode side by the same configuration and operation as the first electrode side, a large amount of low energy electrons can be supplied to the ion beam in a wider range. Can be supplied from. Therefore, it becomes possible to suppress the charging of the substrate with higher uniformity, and it becomes easy to cope with the case where the beam current of the ion beam is large.

  According to invention of Claim 5, there exists the following further effect. That is, the electric field between the two electrodes is controlled by the bias voltage applied between the first and second electrodes from the bias power source, and the electron drift speed due to the E × B drift near the surface of both electrodes is controlled. Can thereby control the production of low energy electrons. As a result, it becomes possible to more effectively suppress the charging of the substrate.

  According to the sixth aspect of the present invention, electrons (primary electrons) supplied from the electron source are between the permanent magnets between the first and second permanent magnets and between the second and third permanent magnets. While the spiral motion is performed in a magnetic field, the annular drift motion surrounds the ion beam. Therefore, low energy electrons can be generated in a wide region surrounding the ion beam using the spiral motion and the drift motion. it can. As a result, low-energy electrons can be supplied over a wide range with respect to an ion beam having a dimension in the Y direction larger than that in the X direction, thereby suppressing the charging of the substrate with good uniformity.

  According to the seventh aspect of the present invention, the following further effect is obtained. That is, the electric field in the vicinity of the surface of the electrode can be controlled by the bias voltage applied to the electrode from the bias power source, and the electron drift speed due to E × B drift can be controlled, thereby generating low energy electrons. You can control the situation. As a result, it becomes possible to more effectively suppress the charging of the substrate.

It is a perspective view which shows an example of a ribbon-shaped ion beam. 1 is a schematic plan view showing an embodiment of an ion beam irradiation apparatus according to the present invention. FIG. 3 is a perspective view illustrating an example of a first electrode and an electron source area illustrated in FIG. 2. FIG. 3 is an enlarged longitudinal sectional view taken along line AA in FIG. 2. FIG. 5 is a front view showing the first electrode and the like shown in FIG. It is a figure which shows the direction of the gradient B drift in the area | region C in FIG. It is a figure which shows the direction of the E * B drift in the area | region C in FIG. It is a longitudinal section showing other examples around an electrode and an electron source. It is a perspective view which shows the example of the surroundings of the electrode and electron source which comprise other embodiment of the ion beam irradiation apparatus which concerns on this invention. FIG. 10 is a longitudinal sectional view taken along line HH in FIG. 9.

  FIG. 2 is a schematic plan view showing an embodiment of an ion beam irradiation apparatus according to the present invention. This ion beam irradiation apparatus is configured to introduce the ion beam 2 extracted from the ion source 4 into the processing chamber 10 after performing momentum analysis (for example, mass separation) by the analysis electromagnet 6. The path of the ion beam 2 from the ion source 4 to the processing chamber 10 is maintained in a vacuum atmosphere by the vacuum vessel 8 or the like.

When the traveling direction of the ion beam 2 is a Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are an X direction (for example, a horizontal direction) and a Y direction (for example, a vertical direction), In this embodiment, referring to FIG. 3 as well, the ion beam 2 having a shape in which the dimension W _{Y in the} Y direction is larger than the dimension W _{X in the} X direction (also referred to as a ribbon shape as described above). And the ion beam 2 having the above-described shape is introduced into the processing chamber 10 without being scanned by the ion beam 2.

The dimension W _{X in} the X direction of the ion beam 2 is, for example, about 5 cm to 30 cm, and the dimension W _{Y in the} Y direction is, for example, about 80 cm to 200 cm, but is not limited thereto.

  Instead of providing the analysis electromagnet 6, the ion beam 2 extracted from the ion source 4 may be introduced into the processing chamber 10 without performing mass separation.

  Further, after extracting an ion beam having a size smaller than that at the time of introduction into the processing chamber 10 from the ion source 4 and scanning the ion beam in the Y direction by a scanner provided in the middle, the ribbon-shaped ion beam 2 is obtained. Alternatively, it may be configured to be introduced into the processing chamber 10.

  In the processing chamber 10, a holder 12 that holds the substrate 14 is provided. The substrate 14 held by the holder 12 is irradiated with the ion beam 2, and the substrate 14 is subjected to, for example, ion implantation and alignment processing. It is configured to perform processing.

  In this embodiment, the holder 12 and the substrate 14 are reciprocally driven in a direction intersecting the side surface (main surface) 3 of the ion beam 2 as shown by an arrow G in FIG. As a result, the entire surface of the substrate 14 can be irradiated with the ion beam 2.

  The substrate 14 is, for example, a semiconductor substrate, a glass substrate, a substrate with an alignment film, or the like, but is not limited thereto.

  The first electrode 20 a is provided near the upstream side of the holder 12, more specifically, in the vacuum vessel 8 near the inlet of the processing chamber 10 in this embodiment.

  3 to 5, the electrode 20 a is a flat electrode made of a non-magnetic material, and is spaced from one side surface (that is, the main surface) 3 on the X direction side of the ribbon-like ion beam 2. Are provided at opposite positions. In this embodiment, the electrode 20a has a rectangular shape with the long side in the Y direction.

The electrode 20a may be at ground potential, or a DC bias voltage V _B may be applied from a bias power source 56 described later.

  An annular first permanent magnet 24 extending along the Y direction is provided in the main surface of the electrode 20a. More specifically, in this embodiment, the permanent magnet 24 has a rectangular frame shape with long sides in the Y direction, but is not limited thereto. For example, the shape may be an ellipse having a major axis in the Y direction, a racetrack shape, or the like. The permanent magnet 24 has a magnetic pole having a first polarity (N pole in this embodiment) on the ion beam 2 side.

  The permanent magnet 24 has a magnetic pole on the inner surface of the electrode 20a (the ion beam 2 side is referred to as the inner side and the opposite side is referred to as the outer side, as in the examples shown in FIGS. 3 to 5). As in the example shown in FIG. 10, the permanent magnet 24 is embedded from the outside of the electrode 20a to the vicinity of the surface thereof, and the magnetic pole of the permanent magnet 24 is placed inside the electrode 20a. You may make it not expose on the surface. The same applies to permanent magnets 26, 64, and 66 described later.

  A second permanent magnet 26 is provided in the main surface of the electrode 20 a and inside the annular first permanent magnet 24 with a space between the permanent magnet 24. The permanent magnet 26 extends in the Y direction and has a magnetic pole having a second polarity (S pole in this embodiment) opposite to the permanent magnet 24.

  In this embodiment, the permanent magnet 26 is divided into two linear permanent magnets 26 because an opening 22 described later is located in the middle of the permanent magnet 26. However, the present invention is not limited to this. For example, the permanent magnet 26 may be an annular shape surrounding the opening 22 and having a shape similar to the permanent magnet 24, or the opening 22 may be shifted to the side to form a single linear shape. The same applies to the permanent magnet 66 described later.

  The polarities of the magnetic poles inside the permanent magnets 24 and 26 may be opposite to those in the above example. In that case, the polarity of the magnetic poles inside the permanent magnets 64 and 66 shown in FIG. Similarly, the polarity of the magnetic poles inside the permanent magnets 84, 86, 88 shown in FIG. 10 may be opposite to that of the illustrated example. In either case, since the direction of the magnetic field B is opposite to that in the illustrated example, the direction of gradient B drift and E × B drift of the electron 50 described later is opposite to that in the illustrated example, and the electron 50 is in the direction opposite to that in the illustrated example. It will only go around.

  Since the permanent magnets 24 and 26 are configured as described above, an annular magnetic field similar to the planar shape of the permanent magnet 24 is formed between the permanent magnets 24 and 26 as a whole. Is done. In other words, a closed tunnel-like magnetic field which is annular and has no end is formed. This tunnel-like magnetic field is represented by several magnetic field lines 28 as representatives.

  The ion beam irradiation apparatus further includes a first electron source 30 a that supplies electrons 50 to the tunnel-like magnetic field region formed between the permanent magnets 24 and 26.

  More specifically, as shown in FIGS. 2 and 4, the electron source 30 a is provided outside the vacuum vessel 8, provided through the electron transport tube 52 penetrating the vacuum vessel 8 and on the electrode 20 a. Through the formed opening 22, electrons 50 are supplied from the outside (back side) of the electrode 20a to the region of the tunnel-like magnetic field.

  Referring to FIG. 4, the electron source 30 a introduces a gas such as Xe and Ar into the plasma generation container 32 and causes arc discharge between the filament 34 and the plasma generation container 32 in this embodiment. The gas is ionized to generate a plasma 36, and electrons 50 are extracted from the plasma 36 through a plasma electrode 38 and a ground electrode 40. 41 is an insulator.

Filament 34 is heated by a filament power supply 42. A DC arc power supply 44 is connected between one end of the filament 34 and the plasma generation vessel 32 with the latter as the positive electrode side. A DC extraction voltage V _E is applied between the plasma generation container 32 and the plasma electrode 38 having the same potential as that of the plasma generation container 32 and the ground electrode 40 from the extraction power supply 46 with the latter as the positive electrode side. The energy of the electrons 50 extracted from the electron source 30a is determined by the extraction voltage V _E. For example, the extraction voltage V _E is about 80V to 100V, and therefore the energy of the electrons 50 drawn from the electron source 30a is about 80eV to 100eV.

  If the energy of the electrons 50 drawn out from the electron source 30a is relatively large as described above, even if there is a leakage magnetic field from another device as described above, the electron source 30a is transferred to the tunnel-like magnetic field. Supply of the electrons 50 is facilitated. That is, the supply of the electrons 50 can be performed more efficiently.

  The electron source 30a may be another type, for example, a type that generates the plasma 36 by high-frequency discharge (for example, microwave discharge). The same applies to the second electron source 30b described later.

  The electrode 20a is provided with the opening 22 for introducing the electrons 50 as described above. It is preferable to provide the opening 22 in the middle of the permanent magnet 26 divided into two parts as in this embodiment because the symmetry of the vertical and horizontal directions of electron introduction is good. good. For example, as described above, one permanent magnet 26 may be provided, and the opening 22 may be provided between the permanent magnet 26 and the permanent magnet 24.

  The electron transport tube 52 may be made of a ferromagnetic material (for example, SUS430; SUS is an abbreviation for stainless steel; the same applies hereinafter) in order to shield an external magnetic field. By doing so, the trajectory of the electrons 50 can be prevented from being disturbed by an external magnetic field, and the transport efficiency of the electrons 50 in the electron transport tube 52 can be increased.

  In this ion beam irradiation apparatus, the electrons (primary electrons) 50 supplied from the electron source 30a to the region of the tunnel-like magnetic field have a partial example as shown in FIGS. While being trapped by the tunnel-like magnetic field and spiraling so as to wrap around the magnetic field lines 28, the gradient B drift and the E × B drift cause an annular drift motion along the annular space between the permanent magnets 24 and 26. To do. That is, the electron 50 drifts on the circular orbit continuous track 51 shown in FIG.

  The gradient B drift and the E × B drift will be described by taking the region C in FIG. 5 as an example. Regarding the electron gradient B drift and E × B drift in the vicinity of the surface of the permanent magnet, for example, Japanese Unexamined Patent Application Publication No. 2007-80691 (see, for example, FIGS. 3 and 7 and their descriptions) and Japanese Unexamined Patent Application Publication No. 2000-260596 It is also described in publications (see, for example, FIGS. 5 and 10 and their descriptions).

  If the magnetic field formed between the permanent magnets 24 and 26 is B, the magnetic field B is generated in the + Z direction in the region C as shown in FIG. Further, the magnetic field B formed between the permanent magnets 24 and 26 becomes weaker as the distance from the surfaces of the permanent magnets 24 and 26 increases in the + X direction, so that a magnetic field gradient gradB is generated in the −X direction. Accordingly, the electron 50 drifts in the direction of the outer product gradB × B of both gradB and B (both are vectors) (the −Y direction in the illustrated example). This is the gradient B drift.

The ion beam 2 has a positive beam potential V _P. The magnitude of the beam potential V _P is, for example, about several tens of volts to several hundreds of volts, although it depends on the beam current of the ion beam 2 and the like. Therefore, even if the bias voltage V _B is not applied to the electrode 20a from a bias power source 56, which will be described later, that is, even if the electrode 20a is at the ground potential, the ion beam 2 and the electrode 20a are not shown in FIGS. As shown, the electric field E is generated in the −X direction. Therefore, the electron 50 drifts in the direction of the outer product E × B of the electric field E (which is also a vector) and the magnetic field B (−Y direction in the illustrated example). This is E × B drift. This E × B drift is also in the same direction as the gradient B drift.

  In the region in which the direction of the magnetic field B is opposite to that of the region C, for example, in the region D in FIG. 5, gradient B drift and E × B drift occur in the direction opposite to that in FIGS.

  Accordingly, the electrons 50 supplied to the tunnel magnetic field region drift in a ring shape along the continuous trajectory 51 while spirally moving.

  While the electrons 50 are spirally wound around the magnetic force lines 28 and the drift motion, the electrons 50 collide with residual gas molecules, and thus electrons with lower energy than the electrons 50 are generated. That is, even in the vacuum vessel 8, there is always a residual gas in the vicinity of the path of the ion beam 2. Therefore, the electrons 50 collide with the residual gas molecules, and (a) the residual gas molecules are ionized to reduce the residual gas molecules. While energy secondary electrons are generated, (b) the electrons 50 lose energy and become low energy electrons. (C) As described above, a part of the moving electron 50 collides with the surface of the electrode 20a and the like, and low energy secondary electrons are emitted therefrom. In this way, low energy electrons are generated. For example, when the electrons 50 have the above energy, the energy of the low energy electrons is usually about 20 eV or less, more specifically about 10 eV or less.

Moreover, the generation of the low energy electrons is performed in a wide region extending along the Y direction because the electrons 50 drift in a ring shape. In this way, the low energy electrons generated in a wide region, the region having a weak magnetic field, i.e. with diffuse away from the surface of the electrode 20a, is attracted by the positive beam potential V _P of the ion beam 2, ions The laser beam is drawn into the beam 2 and reaches the substrate 14 (see FIG. 2) together with the ion beam 2 and has an effect of suppressing charging of the substrate 14 due to the ion beam irradiation.

  As described above, in this ion beam irradiation apparatus, the electrons 50 supplied from the electron source 30a drift in an annular shape while spirally moving in the magnetic field between the permanent magnets 24 and 26. Using the motion, low energy electrons can be generated in a wide region extending along the Y direction. As a result, low-energy electrons can be supplied over a wide range to the ion beam 2 having a dimension in the Y direction larger than the dimension in the X direction, thereby suppressing the charging of the substrate 14 with good uniformity.

  Further, since the electrons 50 supplied from the electron source 30a to the region of the tunnel-like magnetic field are wrapped around the magnetic field lines 28 and trapped as described above, the relatively high energy electrons 50 reach the substrate 14. Can be suppressed. If electrons are excessively supplied to the substrate 14, the substrate 14 may be negatively charged to a voltage corresponding to the energy of the electrons, but relatively high energy electrons reach the substrate 14 due to the above action. Therefore, the negative charging voltage of the substrate can be reduced.

  In FIG. 5, for the sake of simplification, the magnetic lines of force 28 are not shown in front of the opening 22, but the magnetic lines of force 28 spread, so that the magnetic lines of force 28 actually exist in front of the opening 22. Accordingly, the electrons 50 emitted from the opening 22 are captured by the magnetic field lines 28 and perform the above-described spiral motion and drift motion. One or more of the following means may be employed in order to more reliably capture the electrons 50 by the magnetic field lines 28. The same applies to other embodiments described later.

  (A) The electron transport tube 52 and the electron source 30a are not substantially perpendicular to the electrode 20a, but may be disposed obliquely with respect to the electrode 20a, for example, as shown by the line 18 in FIG. By doing so, since the electrons 50 can be emitted from the opening 22 toward a region where the magnetic field is stronger, the electrons 50 can be more reliably captured by the magnetic lines of force 28.

  (B) A part of the opening 22 may be provided with a thin lid that is long in the Y direction, for example. By doing so, the electrons 50 emitted from the opening 22 are emitted from both the left and right sides of the lid, whereby the electrons 50 can be emitted toward a region where the magnetic field is stronger. Can be captured more reliably.

  (C) The opening 22 may be provided between the permanent magnets 24 and 26. By doing so, the magnetic field between the permanent magnets 24 and 26 is strong, and the electrons 50 can be emitted from the openings 22, so that the electrons 50 can be more reliably captured by the magnetic field lines 28. In this case, as described above, the permanent magnet 26 may be a single magnet.

  The electrode 20 a having the permanent magnets 24 and 26 is preferably provided near the substrate 14. In this way, low energy electrons can be generated near the substrate 14 and supplied to the ion beam 2, so that the travel distance of the low energy electrons can be shortened, so that the low energy electrons are more efficient by the substrate 14. Supplying well can suppress the charging of the substrate 14 more efficiently. The same applies to other embodiments described later.

A bias power source 56 that applies a DC bias voltage V _B to the electrode 20a may be provided. The polarity of the bias voltage V _B applied to the electrode 20a may be negative or positive with respect to the ground potential. 3 and 4 show examples in the negative case. The absolute value of the bias voltage V _B is, for example, about 0 V to 100 V, but is not limited thereto.

By controlling the electric field in the vicinity of the surface of the electrode 20a by the bias voltage V _B , the drift velocity of the electrons 50 due to the E × B drift can be controlled, thereby controlling the generation state of low energy electrons. it can. As a result, it becomes possible to more effectively suppress the charging of the substrate 14.

For example, as shown in FIGS. 3 and 4, when a negative bias voltage V _B is applied to the electrode 20a, the bias voltage V _B is added to the beam potential V _P and the electric field E is increased. By increasing the drift speed of the electrons 50 due to the E × B drift, the electrons 50 can be circulated (drifted) quickly. Thereby, the generation of low energy electrons can be made more uniform on the continuous orbit 51. This is effective, for example, when the residual gas pressure is high and the electrons 50 tend to disappear.

On the other hand, when a positive bias voltage V _B is applied to the electrode 20a, the bias voltage V _B is subtracted from the beam potential V _P and the electric field E is reduced. Therefore, the drift velocity of the electrons 50 due to the E × B drift is increased. The electron 50 can be made to circulate slowly by making it small. In this case, if the absolute value of the bias voltage V _B is made larger than the absolute value of the beam potential V _P , the electric field E is reversed from the example shown in FIGS. 3 and 7, and the direction of the E × B drift is also reversed. Therefore, the gradient B drift can also be suppressed. This is effective, for example, when a large number of electrons 50 are present near the opening 22 and many low-energy electrons are desired to be generated there.

  A plate-like magnetic body 58 that covers the back surfaces of the permanent magnets 24 and 26 may be provided as in the example indicated by the two-dot chain line in FIG. This magnetic body 58 is like the magnetic body 94 shown in FIG. The magnetic body 58 is made of, for example, SUS430. When such a magnetic body 58 is provided, the tunnel-like magnetic field can be strengthened and the leakage magnetic field to the outside can be reduced. The same applies to the permanent magnets 64 and 66 shown in FIG.

  Next, another embodiment will be described. In the following, the same or corresponding parts as those of the above-described embodiment are denoted by the same reference numerals, and differences from the embodiment described above will be mainly described.

  In the embodiment shown in FIG. 8, the second electrode 20b is arranged so as to face the first electrode 20a in the X direction with the ion beam 2 interposed therebetween. The electrode 20b is also a flat electrode made of a nonmagnetic material and has substantially the same shape as the electrode 20a. That is, the second electrode 20b is arranged almost symmetrically with the first electrode 20a with the ion beam 2 as the center.

The electrode 20b may be at ground potential, or a bias voltage V _B may be applied from the bias power source 56 between the electrode 20b. This will be described later.

  A third permanent magnet 64 having substantially the same shape as the first permanent magnet 24 is provided in the main surface of the electrode 20b so as to face the permanent magnet 24 in the opposite polarity. That is, in this embodiment, the permanent magnet 64 has an S-pole magnetic pole on the ion beam 2 side.

  Further, a fourth permanent magnet 66 having substantially the same shape as the second permanent magnet 26 is provided in the main surface of the electrode 20b so as to face the permanent magnet 26 with the opposite polarity. That is, in this embodiment, the permanent magnet 66 has an N-pole magnetic pole on the ion beam 2 side.

  Therefore, a tunnel-like magnetic field similar to that on the electrode 20a side is formed near the inner surface of the electrode 20b. The tunnel-like magnetic field is represented by several magnetic field lines 68 as a representative.

  Further, magnetic fields are also formed between the permanent magnets 24 and 64 and the permanent magnets 26 and 66 facing each other with the ion beam 2 interposed therebetween. These magnetic fields are represented by several magnetic field lines 70 and 72 as representatives. These magnetic fields have a curtain shape.

  If the electrode 20b having the permanent magnets 64 and 66 as described above is further provided, (a) an annular magnetic field (tunnel-shaped magnetic field) formed between the third and fourth permanent magnets 64 and 66, (b ) A magnetic field formed between the first and third permanent magnets 24 and 64 facing each other across the ion beam 2, and (c) a second and fourth permanent magnet facing each other across the ion beam 2 The tunnel-like magnetic field between the first and second permanent magnets 24 and 26 among the relatively high energy electrons (primary electrons) 50 supplied from the electron source 30a by the magnetic field formed between the first and second permanent magnets 26 and 66. It is possible to trap (trap) the electrons that have escaped from. The action of trapping electrons 50 in the tunnel-like magnetic field (a) is the same as that described with reference to FIGS. 3 to 7 on the electrode 20a side. The reason why the electrons 50 are trapped in the magnetic fields (b) and (c) is that the electrons 50 are wound around the magnetic field and the magnetic field functions like a cage.

  It can also be expected that the electrons 50 that have escaped the tunnel-like magnetic field between the permanent magnets 24 and 26 collide with the second electrode 20b and disappear. Accordingly, it is possible to more reliably suppress the relatively high energy primary electrons 50 from reaching the substrate 14 together with the ion beam 2. Thereby, an increase in the negative charging voltage of the substrate 14 can be more reliably suppressed.

  A second electron source 30b that supplies electrons 50 to a region of a tunnel-like magnetic field formed between the permanent magnets 64 and 66 may be further provided.

  The electron source 30b, the electron transport tube 52 that transports the electrons 50, the insulator 54, and the opening 22 provided in the electrode 20b are, for example, the electron source 30a and the electron transport tube 52 described with reference to FIGS. Since it is the same as the insulator 54 and the opening 22, the description thereof is referred to, and the duplicate description is omitted here.

  If the electron source 30b is provided, low-energy electrons can be supplied to the ion beam 2 from the second electrode 20b side by the same configuration and action as the first electrode 20a side. The beam 2 can supply a large amount of low-energy electrons from a wider range. Therefore, charging of the substrate 14 can be suppressed with higher uniformity, and it is easy to cope with a case where the beam current of the ion beam 2 is large.

A bias power source 56 that applies a DC bias voltage V _B may be provided between the first and second electrodes 20a and 20b. The polarity of the bias voltage V _B may be positive on the electrode 20b side as in the example shown in FIG. 8, or may be negative on the contrary.

The electric field E between the electrodes 20a and 20b can be controlled by the bias voltage V _B to control the drift velocity of the electrons 50 due to the E × B drift in the vicinity of the surfaces of the electrodes 20a and 20b. The generation state of energetic electrons can be controlled. The details are the same as described for the examples shown in FIGS. As a result, it becomes possible to more effectively suppress the charging of the substrate 14.

  The ion beam irradiation apparatus of the embodiment shown in FIGS. 9 and 10 surrounds the periphery of the ion beam 2 in the vicinity of the upstream side of the holder 12 (see FIG. 2), and is a cylindrical electrode made of a nonmagnetic material. 80. A more specific example of the place where the electrode 80 is provided is the same place as the electrode 20a (and 20b) shown in FIG.

The electrode 80 may be at ground potential, or a DC bias voltage V _B may be applied from the bias power source 56.

  In this embodiment, the electrode 80 has a rectangular cylindrical shape with a cross section along the XY plane having a long side in the Y direction, but is not limited thereto. For example, the cross section may have an elliptical shape, a racetrack shape, or the like whose major axis is the Y direction.

  In the side surface (main surface) of the electrode 80, annular first to third permanent magnets 84, 86, 88 are provided so as to surround the periphery of the ion beam 2. The permanent magnet 86 is provided on the downstream side of the permanent magnet 84 with a gap from the permanent magnet 84, and the permanent magnet 88 is provided on the downstream side of the permanent magnet 86 with a gap between the permanent magnet 86. It has been. In this example, the permanent magnet 86 is partially cut off at the position of the opening 22, but such a magnet is also called an annular shape in this specification.

  The permanent magnet 84 has a magnetic pole having a first polarity (N pole in this embodiment) on the ion beam 2 side, and the permanent magnet 86 is a second opposite to the first polarity on the ion beam 2 side. The permanent magnet 88 has a magnetic pole of the first polarity (N pole) on the ion beam 2 side. As described above, the polarities of the magnetic poles inside these permanent magnets 84, 86, and 88 may all be reversed from the illustrated example.

  Since the permanent magnets 84, 86, 88 are configured as described above, a first annular magnetic field surrounding the ion beam 2 is formed between the permanent magnets 84, 86. In other words, a first tunnel-like magnetic field surrounding the ion beam 2 is formed. Similarly, a second annular magnetic field surrounding the ion beam 2 is formed between the permanent magnets 86 and 88. In other words, a second tunnel-like magnetic field surrounding the ion beam 2 is formed. These tunnel-like magnetic fields are represented by several magnetic field lines 90 and 92 as representatives.

  In this embodiment, an electron source 30a that supplies electrons 50 to the first and second tunnel-like magnetic field regions formed between the permanent magnets 84 and 86 and between the permanent magnets 86 and 88 is further provided.

  The electron source 30a, the electron transport tube 52 for transporting the electrons 50, an insulator between the electrode 80 and the electrode 80 (not shown; equivalent to the insulator 54 shown in FIG. 4), and the opening 22 provided in the electrode 80 are, for example, 2 to 5 are the same as those of the electron source 30a, the electron transport tube 52, the insulator 54, and the opening 22 described above with reference to FIGS.

  In the case of this embodiment, the electrons (primary electrons) 50 supplied from the electron source 30a to the region of the tunnel-like magnetic field between the permanent magnets 84 and 86 are captured by the tunnel-like magnetic field and wound around the magnetic field lines 90. In this way, the drifting motion is performed in an annular manner so as to surround the ion beam 2 along the annular space between the permanent magnets 84 and 86 by the gradient B drift and the E × B drift. Similarly, the electrons (primary electrons) 50 supplied from the electron source 30a to the region of the tunnel-like magnetic field between the permanent magnets 86 and 88 are trapped by the tunnel-like magnetic field and spirally wound around the magnetic field lines 92. However, the gradient B drift and the E × B drift cause an annular drift motion so as to surround the ion beam 2 along the annular space between the permanent magnets 86 and 88. The details of both drift motions are as described above.

  The mechanism by which the primary electrons 50 supplied from the electron source 30a are captured by the tunnel-like magnetic field and the mechanism by which low-energy electrons are generated by the drift motion of the electrons 50 are the same as in the above-described embodiment. Since it is almost the same, redundant description is omitted here.

  As described above, in the ion beam irradiation apparatus of this embodiment, the electrons 50 supplied from the electron source 30a spiral between the permanent magnets 84 and 86 and between the permanent magnets 86 and 88 in a magnetic field between these permanent magnets. Since the ring-shaped drift motion surrounds the ion beam 2 while moving, low-energy electrons can be generated in a wide region surrounding the ion beam 2 by using the spiral motion and the drift motion. As a result, low-energy electrons can be supplied over a wide range to the ion beam 2 having a dimension in the Y direction larger than the dimension in the X direction, thereby suppressing the charging of the substrate 14 with good uniformity. In addition, in the case of this embodiment, compared to the embodiments shown in FIGS. 3 and 8, low-energy electrons can be supplied to the ion beam 2 in a wider range, thereby charging the substrate 14. Can be suppressed with higher uniformity.

  Further, in this embodiment, as can be seen from FIG. 10, the magnetic field between the permanent magnets 84 and 86 and the magnetic field between the permanent magnets 86 and 88 are opposite to each other. Since the drift between 84 and 86 and the drift between the permanent magnets 86 and 88 are opposite to each other, the electrons 50 revolve in opposite directions (in the embodiment shown in FIG. 5, the electrons 50 circulate in one direction). Therefore, it becomes easy to cancel the density of the electrons 50 and thus the density of the low-energy electrons generated. Therefore, low-energy electrons can be supplied to the ion beam 2 with higher uniformity, thereby suppressing charging of the substrate 14 with higher uniformity.

  A cylindrical magnetic body 94 may be provided on the back surface of the permanent magnets 84, 86, 88. Examples of the materials, effects, and the like are the same as in the case of the magnetic body 58.

  A second electron source may be provided to supply the electrons 50 to the tunnel-like magnetic field from the opposite side of the electron source 30a. The example of the concrete structure, the effect, etc. are the same as that of the electron source 30b shown in FIG.

A bias power source 56 that applies a DC bias voltage V _B to the electrode 80 may be provided. Examples of the polarity, operational effects, and the like are the same as those of the bias power source 56 shown in FIGS. That is, the electric field in the vicinity of the surface of the electrode 80 can be controlled by the bias voltage V _B to control the drift velocity of the electrons 50 due to the E × B drift, thereby controlling the generation state of low energy electrons. Can do. As a result, it becomes possible to more effectively suppress the charging of the substrate 14.

  Note that the number of the first electron sources 30a and the second electron sources 30b is not limited to one shown in each of the above embodiments, and may be plural if necessary. In that case, the electron transport tube 52, the opening 22 and the like may be provided according to the number of the electron sources 30a and 30b.

2 Ion beam 12 Holder 14 Substrate 20a, 20b Electrode 24, 26 Permanent magnet 30a, 30b Electron source 50 Electron (primary electron)
56 Bias power supply 64, 66 Permanent magnet 80 Electrode 84, 86, 88 Permanent magnet

JP-A-6-203785

Claims (7)

When two directions substantially perpendicular to each other in a plane substantially perpendicular to the traveling direction of the ion beam are defined as an X direction and a Y direction, an ion beam having a dimension in the Y direction larger than the dimension in the X direction is held in the holder. In an ion beam irradiation apparatus for irradiating a formed substrate,
A plate-like first electrode made of a non-magnetic material, provided upstream of the holder and at a position facing the side surface on the X direction side of the ion beam;
An annular first permanent magnet that is provided in the plane of the first electrode, has a magnetic pole of a first polarity on the ion beam side, and extends along the Y direction;
The first permanent magnet is provided in the plane of the first electrode and inside the annular first permanent magnet with a space between the first permanent magnet and the first beam on the ion beam side. A second permanent magnet having a magnetic pole having a second polarity opposite to the polarity of the second permanent magnet and extending along the Y direction;
An ion beam irradiation apparatus comprising: a first electron source that supplies electrons to a region of a magnetic field formed between the first and second permanent magnets.   The ion beam irradiation apparatus according to claim 1, further comprising a bias power source that applies a DC bias voltage to the first electrode. A plate-like second electrode made of a non-magnetic material, disposed so as to face the first electrode across the ion beam in the X direction;
A third permanent magnet having substantially the same shape as the first permanent magnet and provided in the plane of the second electrode so as to oppose the first permanent magnet with a polarity opposite to that of the first permanent magnet; ,
A fourth permanent magnet having substantially the same shape as the second permanent magnet and provided in the plane of the second electrode so as to oppose the second permanent magnet with a polarity opposite to that of the second permanent magnet; An ion beam irradiation apparatus according to claim 1.   The ion beam irradiation apparatus according to claim 3, further comprising a second electron source that supplies electrons to a region of a magnetic field formed between the third and fourth permanent magnets.   The ion beam irradiation apparatus according to claim 3, further comprising a bias power source that applies a DC bias voltage between the first and second electrodes. When two directions substantially perpendicular to each other in a plane substantially perpendicular to the traveling direction of the ion beam are defined as an X direction and a Y direction, an ion beam having a dimension in the Y direction larger than the dimension in the X direction is held in the holder. In an ion beam irradiation apparatus for irradiating a formed substrate,
A cylindrical electrode surrounding the periphery of the ion beam on the upstream side of the holder, and made of a non-magnetic material;
An annular first permanent magnet which is provided in the surface of the electrode so as to surround the periphery of the ion beam and has a magnetic pole of a first polarity on the ion beam side;
In the plane of the electrode, provided downstream of the first permanent magnet and with a space between the first permanent magnet and surrounding the periphery of the ion beam, An annular second permanent magnet having a magnetic pole of a second polarity opposite to the first polarity on the ion beam side;
In the plane of the electrode, provided downstream of the second permanent magnet and spaced from the second permanent magnet so as to surround the periphery of the ion beam, An annular third permanent magnet having the first polarity magnetic pole on the ion beam side;
One or more electron sources for supplying electrons to regions of a magnetic field formed between the first and second permanent magnets and between the second and third permanent magnets, respectively, Beam irradiation device.   The ion beam irradiation apparatus according to claim 6, further comprising a bias power source that applies a DC bias voltage to the electrode.

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