JP2005085538A - Mass separation device and mass separating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the mass separation of a sheet-like ion beam by a light and small device. <P>SOLUTION: This mass separation device 12 has electrodes 14 disposed face to face with the passage of a sheet-like ion beam 8 accelerated to prescribed energy between to make pairs, and each electrode 14 extends along the width direction of the ion beam 8. The device is equipped with a plurality of the pairs of the electrodes 14 formed by a plurality of the electrodes 14 making such pairs which are arranged in the advancing direction Z of the ion beam 8, and an oscillating power supply 16 to apply an oscillating voltage V<SB>B</SB>with a fixed cycle between each pair of the electrodes 14 so as to apply an oscillating electric field with a fixed cycle which has a directional component perpendicular to the advancing direction Z of the ion beam 8 by using each pair of the electrodes 14, and the device is structured so that ions 8d with desired masses in the ion beam 8 are selectively derived while oscillating them by synchronizing them with the oscillating electric field. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mass separation apparatus and a mass separation method for selectively deriving (ie, mass-separating) ions having a desired mass from a sheet-like ion beam accelerated to a predetermined energy.

  In the case of performing ion implantation, ion doping, or the like by irradiating an irradiation object with a large area with an ion beam, a sheet-like ion beam may be used in order to improve processing efficiency.

  A sheet-like ion beam refers to an ion beam having a shape whose thickness is sufficiently smaller than the width. It may be called a thin plate shape, a ribbon shape, or the like. The cross section cut at right angles to the ion beam traveling direction has an elongated rectangular shape.

  In general, the irradiated object is irradiated with an ion beam subjected to mass separation in order to avoid an excessive increase in temperature or contamination with impurities.

  As a mass separation apparatus, for example, as described in Patent Document 1, a mass separation electromagnet that performs mass separation by bending an ion beam with Lorentz force using a static magnetic field has been generally used.

  Moreover, as a mass separation apparatus using an alternating voltage, for example, as described in Patent Document 2, a quadrupole mass that performs mass separation by applying a direct voltage and an alternating voltage to a quadrupole structure electrode. Separation devices have been proposed.

Japanese Utility Model Publication No. 64-7753 (Fig. 1) JP 7-24080 A (paragraph 0008, FIG. 1)

  Although the above-mentioned mass separation electromagnet is effective for mass separation of a thin ion beam, there are some problems with a sheet-like ion beam having a long cross section in the direction of a magnetic field applied for mass separation. is there. That is, in order to perform mass separation with high accuracy, it is necessary to generate a uniform magnetic field in a long region in the width direction of the sheet-like ion beam. For this purpose, a large iron core is required. Increases in size and weight.

  On the other hand, in the above-described quadrupole mass separation apparatus, effective mass separation is performed only when the ion beam passes near the center axis of the quadrupole electrode, so the ion beam needs to be a pencil-like thin beam. It is unsuitable for mass separation of sheet-like ion beams.

  Therefore, the main object of the present invention is to realize mass separation of a sheet-like ion beam with a light and small apparatus.

  The mass separator according to the present invention is a pair of electrodes arranged so as to face each other across a path of a sheet-like ion beam accelerated to a predetermined energy, and each electrode is a member of the ion beam. A plurality of pairs of electrodes that are arranged in the traveling direction of the ion beam, and each pair of electrodes is used to form the ion beam. An oscillating power source for applying an oscillating voltage having a constant period between the pair of electrodes so as to apply an oscillating electric field having a constant period having a direction component perpendicular to the traveling direction, and a desired power source in the ion beam It is characterized in that it is configured to selectively derive (pass through) ions having a mass of (5) in synchronization with the oscillating electric field (corresponding to claim 1).

  The method of facing the electrodes forming a pair is basically facing the front (facing), but may be facing diagonally.

  According to this mass separator, an ion beam having a predetermined energy travels while being bent by the oscillating electric field having a direction component perpendicular to the traveling direction thereof. In that case, only ions of a mass having a certain relationship with the energy of the ion beam, the frequency of the oscillating electric field and the distance between adjacent electrodes are derived from the apparatus after continuing the periodic motion synchronized with the oscillating electric field. Ions having a mass different from the above cannot continue the periodic motion synchronized with the oscillating electric field, and disappear in the middle or are emitted from the apparatus at an angle different from that of the ions. By such an action, ions having a desired mass in the ion beam can be selectively (ie, selectively) derived, that is, mass-separated.

  Moreover, in this mass separation apparatus, each electrode extends along the width direction of the sheet-like ion beam, so that the mass separation of the sheet-like ion beam can be performed.

  As an example of a more specific configuration, a configuration may be adopted in which an oscillating voltage having the same phase is applied from the oscillating power source to adjacent electrodes of the plurality of pairs of electrodes (corresponding to claim 2). In this case, for example, when the energy of the ion beam is K, the mass of the desired ion is m, the frequency of the oscillation voltage is f, and the distance between the centers of the adjacent electrodes is L, By configuring to satisfy the relationship or a mathematically equivalent relationship, only ions of the desired mass m are selectively derived after continuing the periodic motion synchronized to the oscillating electric field.

[Equation 1]
f = (1 / 2L) √ (2K / m)

  An oscillating voltage having an opposite phase may be applied from the oscillating power source to the adjacent electrodes of the plurality of pairs of electrodes (corresponding to claim 3). In that case, for example, by configuring so as to satisfy the relationship of the following formula 2 or a mathematically equivalent relationship thereof, only ions of a desired mass m are selectively selected after continuing the periodic motion synchronized with the oscillating electric field. To be derived.

[Equation 2]
f = (1 / L) √ (2K / m)

  The plurality of pairs of electrodes may be arranged to form an arc, and an oscillating voltage having an opposite phase may be applied from the oscillating power source to adjacent electrodes of the plurality of pairs of electrodes (corresponding to claim 4). In that case, for example, by configuring so as to satisfy the relationship of Equation 1 or a mathematically equivalent relationship thereof, only an ion having a desired mass m can be viewed as a whole while continuing a periodic motion synchronized with the oscillating electric field. It is selectively derived through a circular motion. Moreover, by arranging a plurality of pairs of electrodes so as to form an arc as described above, the entire apparatus can be further reduced in size.

  The vibration power source may be a sine wave AC power source (corresponding to claim 5), a square wave AC power source (corresponding to claim 6), or a square wave power source that outputs a unipolar square wave voltage ( Equivalent to claim 7).

  The square wave AC voltage or the square wave voltage has a longer time of constant amplitude than the sine wave AC voltage, and the voltage can be used more efficiently for electrostatic deflection of ions of a desired mass. Ion transmission is improved.

  The pairs of electrodes may be rod-shaped electrodes parallel to each other (corresponding to claim 8) or plate-shaped electrodes parallel to each other (corresponding to claim 9).

  By using plate-like electrodes parallel to each other, it is possible to use the ion beam focusing action during electrostatic deflection, so that ions of a desired mass are transported while repeating focusing, and the loss is reduced. Ion transmission is improved.

  As a combination of the electrode shape and the type of vibration power source, it is preferable to use a sine wave AC power source in the case of a rod-shaped electrode, and to use a square wave AC power source or a square wave power source in the case of a plate electrode. This is because the way of changing the oscillating electric field between the electrode pair and the shape of the electrode are better in doing so.

  The vibration power supply may be a power supply in which the frequency f of the vibration voltage output therefrom is variable (corresponding to claim 10).

  In this way, as can be seen from the equation (1) or (2), the mass of ions to be selectively derived can be adjusted by adjusting the frequency f of the oscillating voltage.

  You may provide the electrode space | interval adjustment mechanism which adjusts the distance L between the centers of the adjacent electrodes of the said several pairs of electrodes (equivalent to Claim 11).

  In this way, as can be seen from the equation (1) or (2), the mass of ions to be selectively derived can be adjusted by adjusting the distance L.

  In each of the mass separators as described above, by adjusting at least one of the frequency f of the oscillating voltage, the energy K of the ion beam, and the distance L between the electrodes, it is selective as can be seen from the equation 1 or 2. It is possible to adjust the mass of ions to be led out. The mass separation method according to the present invention performs this (corresponding to claims 12 to 14).

  As described above, according to the first to fourth aspects of the present invention, mass separation of a sheet-like ion beam can be performed by an oscillating electric field without using a magnetic field. Since an electrode for forming an oscillating electric field can be lighter and smaller than a conventional electromagnet, sheet-shaped ion beam mass separation can be realized with a lighter and smaller apparatus.

  According to the fifth aspect of the present invention, since the vibration power source is a sine wave AC power source, there is an additional effect that it is easy to obtain the power source.

  According to the invention described in claim 6 or 7, the square wave AC voltage or the square wave voltage has a longer time of constant amplitude than the sine wave AC voltage, and a voltage is applied to electrostatic deflection of ions of a desired mass. Since it can utilize more efficiently, there exists the further effect that the transmittance | permeability of the ion of desired mass improves.

  According to the eighth aspect of the present invention, since it is easy to pass the refrigerant through the electrode, there is a further effect that the cooling of the electrode is facilitated.

  According to the ninth aspect of the invention, since the ion beam focusing action during electrostatic deflection can be used by using plate-like electrodes parallel to each other, ions of a desired mass are repeatedly focused. It has the further effect that the loss is reduced by being transported and the transmittance of ions having a desired mass is improved.

  According to the tenth aspect of the invention, there is an additional effect that the mass of ions to be selectively derived can be adjusted by adjusting the frequency of the oscillating voltage.

  According to the eleventh aspect of the present invention, there is an additional effect that the mass of ions selectively derived can be adjusted by adjusting the distance between adjacent electrodes.

  According to the twelfth aspect of the present invention, the mass of ions to be selectively derived can be adjusted without changing the energy of the ion beam or the distance between adjacent electrodes. Since the frequency adjustment of the oscillating voltage is easy, and the distance between the electrodes does not need to be changed, the mass adjustment of the selected ions is easy. In addition, it is not necessary to change the energy of the ion beam, which is advantageous in using an ion beam having a desired energy.

  According to the thirteenth aspect of the invention, the mass of ions to be selectively derived can be adjusted without changing the frequency of the oscillating voltage or the distance between adjacent electrodes. Since it is not necessary to change the distance between electrodes, adjustment is easy. Moreover, since the frequency of the oscillating voltage can be made constant, a resonant circuit including an electrode pair can be configured, thereby improving power efficiency.

  According to the fourteenth aspect of the present invention, the mass of ions to be selectively derived can be adjusted without changing the frequency of the oscillating voltage or the energy of the ion beam. Since the frequency of the oscillating voltage can be made constant, a resonant circuit including an electrode pair can be configured, thereby improving power efficiency. In addition, it is not necessary to change the energy of the ion beam, which is advantageous in using an ion beam having a desired energy.

  FIG. 1 is a cross-sectional view showing an example of an ion beam irradiation apparatus including a mass separation apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view showing one of the ion beam and electrode pair in FIG.

  The ion beam irradiation apparatus 2 is attached to one end of a vacuum vessel 4 via an insulator 10 and emits a sheet-like ion beam 8 accelerated to a certain energy toward the inside of the vacuum vessel 4. An ion source 6 is provided. The emission direction (traveling direction) of the ion beam 8 is taken as the Z direction.

  With reference to FIG. 2 as well, the sheet-like ion beam 8 has a sufficiently small thickness T in the Y direction perpendicular to both the X and Z directions compared to the width W in the X direction perpendicular to the traveling direction Z. A cross section S perpendicular to the traveling direction Z of the ion beam 8 has an elongated rectangular shape. The upper and lower surfaces 8s of the ion beam 8 may be referred to as a sheet surface.

A DC acceleration power source 18 for accelerating the ion beam 8 to a constant energy is connected between the ion source 6 and the grounded vacuum vessel 4 with the former as the positive electrode side. The output voltage is the acceleration voltage V _A. If the charge of ions constituting the ion beam 8 is q, the energy K of the ion beam 8 is expressed by the following equation.

[Equation 3]
K = q · V _A

  In the vacuum vessel 4, a plurality of pairs (8 pairs in the illustrated example but not limited thereto) of electrodes 14 are arranged in series along the traveling direction Z of the ion beam 8 as constituting the mass separator 12. ing. The distances between the centers of the electrodes 14 are adjacent to each other (adjacent in the beam traveling direction Z. The same applies to other cases).

  The electrode 14 is configured such that two electrodes 14 (more specifically, the upper electrode 14a and the lower electrode 14b in the figure) arranged to face each other across the path of the ion beam 8 form a pair. ing. In the embodiment of FIG. 1, each pair of electrodes 14 faces the front (facing).

  Each electrode 14 also extends along the width W direction of the ion beam 8 (for example, in parallel) with reference to FIG. That is, it extends in the X direction.

  The length G of each electrode 14 in the X direction is preferably larger than the width W of the ion beam, and more preferably sufficiently larger than the width W. This is because the influence of the disturbance of the electric field at the end of each electrode 14 on the ion beam 8 can be further reduced.

  In this embodiment, each pair of electrodes 14 is a rod-like electrode parallel to each other. More specifically, each pair of electrodes 14 has a solid or hollow round bar shape, a columnar shape, or a cylindrical shape. This is because the electric field distribution can be made smoother. In addition, the rod-shaped electrode has an advantage that it is easy to cool by flowing a refrigerant therein.

Furthermore, as a component of the mass separator 12, each pair of electrodes 14 is used to form an ion beam 8, more specifically, a sheet surface 8 s of a certain period having a direction component perpendicular to the beam traveling direction Z. A vibration power source 16 for applying a vibration voltage V _B having a constant period is provided between each pair of electrodes 14 so as to apply a vibration electric field E _B (see FIG. 2). More precisely, an oscillating electric field E _B having a direction component perpendicular to the beam traveling direction Z is applied to the center of the cross section S of the ion beam 8. In this embodiment, the electrode 14 forming each pair as because you face, almost all of the components of the oscillating electric field E _B are perpendicular to the ion beam traveling direction Z.

The vibration power source 16 is normally disposed outside the vacuum container 4. Then, the frequency of the oscillating voltage V _B to be output is defined as f.

In this embodiment, all of the electrodes 14 on one side (electrode 14a side) forming each pair are connected to one output terminal a of the vibration power source 16, and all the electrodes 14 on the other side (electrode 14b side) are connected. The other output terminal b of the vibration power supply 16 is connected. Therefore, the vibration voltage V _B having the same phase is applied from the vibration power source 16 to the adjacent electrodes 14 of the plurality of pairs of electrodes 14.

In this embodiment, the oscillating voltage V _B is a sine wave AC voltage, the oscillating power source 16 is a sine wave AC power source that outputs the sine wave AC voltage, and the oscillating electric field E _B is a sine wave AC electric field. is there.

According to this mass separator 12, the ion beam 8 having a predetermined energy K vibrates (meanders) in the Y direction as shown by the oscillating electric field E _B having a direction component perpendicular to the traveling direction Z. As a whole, it proceeds in the Z direction while being bent (substantially goes straight).

In that case, the energy K of the ion beam, only ions 8d of mass m with a distance L between the fixed relationship between the frequencies f and the adjacent electrodes of the oscillating electric field E _B has continued periodic motion synchronized with the oscillating electric field E _B Later derived from the device. To briefly explain this, for the ion 8d having a desired mass, for example, at the moment of passing between the first-stage electrode pair, the polarity of the upper electrode 14a becomes positive, so the ion 8d is pushed back, At the moment of passing between the second-stage electrodes, the phase of the oscillating voltage V _B is reversed 180 degrees during that time, and the polarity of the lower electrode 14b becomes positive, so that the ions 8d are pushed back, The action is repeated, and the ions 8d are led out while traveling in the Z direction as a whole while vibrating up and down. Ion 8e having different mass than the above, different from the oscillating electric field E can not be followed by a synchronous periodic motion to _B, or disappear like collides with the electrode 14 on the way, the ion 8d from the device angle To be released.

  By the operation as described above, ions 8d having a desired mass m in the ion beam 8 can be selectively (ie, selectively) derived, that is, mass-separated. The conditions for this mass separation will be described later.

  In addition, in the mass separation device 12, each electrode 14 extends along the width direction of the sheet-like ion beam 8, so that the mass separation of the sheet-like ion beam 8 can be performed. The ion beam comprising the mass-separated ions 8d having a desired mass m is also in the form of a sheet (the same applies to other embodiments).

  In this embodiment, the ion (ion beam) 8d having a desired mass m which has been mass-separated is irradiated to the irradiation object 20 disposed in the vacuum vessel 4. Thereby, the irradiation object 20 can be subjected to processes such as ion implantation and ion doping. In this case, by driving (scanning) the irradiation object 20 in the Y direction, the entire surface of the irradiation object 20 having a large area can be irradiated with the ions 8d.

The conditions for mass separation in the mass separator 12 will be described in detail. The rate of ion 8d of desired mass m and v, it When t the time through the distance L between the electrodes, is the ion 8d when the number of the next 4 is satisfied synchronized to the oscillating electric field E _B As a whole, it proceeds in the beam traveling direction Z while vibrating.

[Equation 4]
t = L / v = 1 / 2f

  On the other hand, the energy K of the ions 8d is expressed by the following formula 5.

[Equation 5]
K = mv ^2/2

  From the equations 4 and 5, the equation 1 is obtained. The number 1 is a condition for selectively deriving ions 8d having mass m, and in this embodiment, the condition is satisfied.

  The equation (1) can be rewritten into the following equation (6) by substituting the equation (3).

[Equation 6]
f = (1 / 2L) √ (2q · V _A / m)

In the mass separator 12, in order to further increase the effect of mass separation, (a) the intensity of the oscillating electric field E _B is increased, (b) the trajectory of the ions 8e to be removed is calculated in advance, For example, (c) increasing the distance L _W from the outlet of the mass separator 12 to the irradiated object 20 may be employed to optimize the number of stages and the structure of the electrode pair. The same applies to other embodiments described later.

  FIG. 3 shows an example of the results of an experiment conducted using a mass separator based on the same principle as the mass separator 12 of FIG.

In this experiment, a gas mixture of helium and nitrogen was introduced into the ion source 6 and the ion beam 8 containing helium ions was accelerated by the acceleration voltage V _A and extracted. However, this experiment is close to the principle experiment, and the ion beam 8 is not a sheet but a thin pencil beam. The number of pairs of electrodes 14 was 4 (4 steps), and the distance L between the electrodes was 4 mm. The vibration power source 16 was a sine wave AC power source, and the frequency f was constant at 13.56 MHz. An inductance is connected between both ends of the vibration power source 16 (for example, between the output terminals a and b), and a parallel resonance circuit is configured by the inductance and the capacitance between the electrode pairs, and between the electrodes 14 forming a pair. A constant amplitude AC voltage was applied efficiently.

Further, a Faraday cup is installed at a position corresponding to the irradiated object 20, and the ion beam current is measured with the Faraday cup. The time integral value of the current is used as the beam intensity, and the relative value is represented on the vertical axis in FIG. . Then, the energy K of the ion beam 8 was adjusted by adjusting the acceleration voltage V _A (see Equation 3), and an experiment was conducted to determine whether or not desired helium ions were separated by mass separation.

As a result, as shown in FIG. 3, a sharp peak of the ion beam current is seen in the vicinity of V _A = 0.5 kV, and it can be seen that a good mass separation action is obtained. That is, it can be seen that the effect of synchronization between the beam speed and the AC electric field, which is the basic principle of mass separation according to the present invention, appears. The asynchronous beam forms a background beam around the peak value, and in this experiment, the component ratio of the synchronous beam and the asynchronous beam can be 10: 1 or more even if estimated to be small.

In order to synchronize the ion beam velocity and the AC electric field, the equation 1 or 6 can be understood instead of adjusting the acceleration voltage V _{A and} the energy K of the ion beam 8 as in the above experimental example. In addition, the distance L between the electrodes may be adjusted, or the frequency f of the vibration power supply 16 may be adjusted. In order to adjust the interelectrode distance L, an electrode interval adjusting mechanism may be provided. In order to adjust the frequency f of the vibration power source 16, the vibration power source 16 may be a variable frequency power source. In order to adjust the energy K of the ion beam 8, for example, the acceleration voltage V _A output from the acceleration power source 18 may be made variable. The same applies to other embodiments described later.

As a modification of the mass separator 12 shown in FIG. 1, as in the embodiment shown in FIG. 4, an oscillating voltage V _B having an opposite phase is applied from the oscillating power supply 16 to the plural pairs of adjacent electrodes 14. It may be configured. Arrows a and b attached to the electrodes 14 in FIG. 4 indicate that they are electrically connected to the output terminals a and b of the vibration power source 16 (the same applies to the other drawings).

  In the case of this embodiment, the following equation 7 becomes the synchronization condition instead of the equation 4.

[Equation 7]
t = L / v = 1 / f

  From Equation 7 and Equation 5, Equation 2 is obtained. The number 2 is a condition for selectively deriving the mass 8 ions 8d, and this embodiment is configured to satisfy this condition.

  Further, the equation (2) can be rewritten into the following equation (8) by substituting the equation (3).

[Equation 8]
f = (1 / L) √ (2q · V _A / m)

  Further, as a modification of the mass separator 12 shown in FIG. 1, as in the embodiment shown in FIG. 5, a pair of electrodes 14 (more specifically, an upper electrode 14a and a lower electrode 14b in the figure). May be arranged so as to face each other diagonally across the path of the ion beam 8. In short, this embodiment is like omitting every other electrode 14 of FIG.

In this embodiment, the oscillating electric field E _B is formed obliquely with respect to the traveling direction Z of the ion beam 8, but the oscillating electric field E _B has a direction component perpendicular to the traveling direction Z of the ion beam 8. Therefore, this component is applied to the ion beam 8, whereby the mass separation action as described above can be achieved.

  The conditional expression in the case of this embodiment is the above expression 1 or 6, if the distance between adjacent electrodes 14 is 2L, and is the same expression as in FIG.

  In each of the embodiments described above, the number of pairs (stages) of the plurality of pairs of electrodes 14 increases the mass resolution. However, if the number of pairs is too large, the amount of ions 8d having a desired mass to be extracted (that is, the amount of beam current) decreases. You just have to decide on a balance. For example, 4 stages or more and 10 stages or less are realistic.

In each of the above embodiments, the oscillating voltage V _B may be a square wave AC voltage, the oscillating power supply 16 may be a square wave AC power source that outputs the square wave AC voltage, and the oscillating electric field E _B may be a square wave AC electric field. . Alternatively, the oscillating voltage V _B may be a unipolar square wave voltage, the oscillating power source 16 may be a square wave power source that outputs the square wave voltage, and the oscillating electric field E _B may be a square wave electric field. In each of the above embodiments, each pair of electrodes 14 may be a plate-like electrode parallel to each other. A typical example of this is a parallel plate electrode. In any case, the mass separation can be performed by applying the oscillating electric field E _B satisfying the condition of Equation 1 or Equation 6 to the ion beam 8.

  As a combination of the shape of the electrode 14 and the type of the vibration power source 16, in the case of the rod-shaped electrode 14, it is preferable to use a sine wave AC power source as in the above embodiment. In the case of a plate-like electrode, it is preferable to use a square wave AC power source or a square wave power source as in the embodiments described later. This is because the way of changing the oscillating electric field between the electrode pair and the shape of the electrode are better in doing so. That is, a power source that applies a sinusoidal AC voltage with a smooth amplitude change is preferable for an electrode having a gradual change in electric field between adjacent electrodes, such as a rod-like electrode 14, such as a plate-like electrode. In addition, a power source that outputs a square wave AC voltage or a square wave voltage with a sharp amplitude transition is preferable for an electrode having a shape in which an electric field changes rapidly between adjacent electrodes.

  FIG. 6 shows an embodiment of the mass separator 12 using parallel plate electrodes 14 as electrode pairs. In the following, differences from the embodiment shown in FIG. 1 will be mainly described.

  Two electrodes 14 (more specifically, 14a and 14b) facing each other across the path of the ion beams 8, 8a and 8b form a pair. Each electrode 14 extends along the direction of the width W (see FIG. 2) of the ion beams 8, 8a, 8b, similarly to the electrode 14 shown in FIG. That is, it is long in the X direction.

In this embodiment, the oscillating voltage V _B is a square wave AC voltage, the oscillating power source 16 is a square wave AC power source that outputs the square wave AC voltage, and the oscillating electric field E _B is a square wave AC electric field. .

  Therefore, the sheet-like ion beam 8 drawn out from the ion source 6 is distributed to the two paths in the Y direction by the first-stage electrode pair 14 every half cycle of the square wave AC voltage. One of them is an ion beam 8a, and the other is an ion beam 8b.

  In this embodiment, two pairs of even-numbered electrode pairs are provided in parallel with each other at a predetermined distance in the Y direction so that the ion beams 8a and 8b distributed in two paths are electrostatically deflected, respectively. The odd-numbered electrode pairs are provided where the ion beams 8a and 8b are gathered, and are common to both ion beams 8a and 8b.

  Looking at the ion beam 8a or 8b on one path, a plurality of pairs of electrodes 14 are arranged in series in the traveling direction Z of the ion beam 8a or 8b. Then, a square wave AC voltage having an opposite phase is applied to the electrodes 14 adjacent in the beam traveling direction Z.

  Accordingly, when the distance between the centers of the adjacent electrodes 14 is L, as in the case of the embodiment shown in FIG. In this embodiment, this condition is satisfied.

  Therefore, also in the mass separator 12 of this embodiment, the sheet-like ion beams 8, 8a, 8b are subjected to mass separation by the same operation as in the above-described embodiment, and ions 8d having a desired mass are selectively derived. can do.

  In addition, by using the parallel plate electrode 14, the ion beam focusing action during electrostatic deflection can be used, so that ions of a desired mass are transported while repeating focusing, and the loss is reduced, so that ions of the desired mass are reduced. The transmittance of 8d is improved.

  In addition, the square wave AC voltage has a longer time of constant amplitude than the sine wave AC voltage, and the voltage can be used more efficiently for electrostatic deflection of ions of a desired mass. The transmittance of mass ions 8d is improved.

  Further, in this embodiment, since the ion beams 8a and 8b of two paths can be finally collected and derived in one path by the electrode configuration as described above, a desired mass can be obtained in both positive and negative phases of the square wave AC voltage. Ions 8d can be derived. Therefore, the transmittance of the ion beam is large.

  That is, the ion beams 8a and 8b of the two paths may be separated from each other by different paths, and ions 8d having a desired mass may be derived from the two paths. Since the ion beam is allowed to pass only during one phase of the voltage (ie, positive or negative), the ion beam transmittance is halved compared to this embodiment. Even in that case, if the ion beams 8a and 8b of two paths are finally collected in one path, the transmittance of the ion beam becomes the same as that of this embodiment. Since the electrode 14 is shared for the two-path ion beams 8a and 8b, there is still an advantage that the number of electrodes can be reduced.

  In the embodiment shown in FIG. 6 as well, the concept of the number of pairs (stages) of a plurality of pairs of electrodes 14 is the same as described above. However, since odd stages are used, for example, there are 5 or more stages and 11 or less odd stages. Realistic.

  In FIG. 7, a plurality of pairs of electrodes 14 are arranged in series so as to form an arc, and are configured to form a part of a cylindrical shape as a whole (this is because the central angle α is smaller than 360 degrees). An embodiment is shown. In simple terms, this is like bending one beam line of the mass separator 12 of FIG. 6 into an arc. In the following, differences from the embodiment shown in FIG. 1 will be mainly described.

  Two electrodes 14 (more specifically, the outer electrode 14a and the inner electrode 14b) facing each other across the path of the ion beam 8 form a pair. Each pair of electrodes 14 is a plate-like electrode parallel to each other, but each electrode 14 is bent so as to form an arc. Each electrode 14 extends along the direction of the width W (see FIG. 2) of the ion beam, like the electrode 14 shown in FIG. That is, it is long in the X direction (the front and back direction of the paper).

In this embodiment, the oscillating voltage V _B is, for example, a square wave AC voltage. In this case, the oscillating power source 16 is a square wave AC power source that outputs the square wave AC voltage, and the oscillating electric field E _B is A square wave AC electric field.

A square wave AC voltage V _B having an opposite phase is applied from the square wave AC power supply 16 to the electrodes 14 adjacent in the traveling direction of the ion beam 8.

  In the case of this embodiment, when the distance between the centers of the adjacent electrodes 14 (more precisely, the distance on the arc) is L, the equation 1 or the equation 6 is the same as the embodiment shown in FIG. In this embodiment, the ion 8d having the mass m is selectively derived. In this embodiment, the condition is satisfied.

In FIG. 7, the ion beam 8 is shown as a simple arc having a radius R for the sake of simplicity of illustration, but in reality, the ion beam 8 is caused by an oscillating electric field (AC electric field) E _B between the pair of electrodes 14. 8 advances in a circular arc shape as a whole while being bent inward and outward. At this time, the outer electrode 14 always appears to have the same polarity (more specifically, positive polarity) for the ion 8d having a mass m satisfying the condition of Equation 1 or Equation 6. That is, ion 8d desired mass m while being periodically vibrated in and out direction in synchronism with the oscillating electric field E _B, is bent in an arc shape having a radius R as a whole, it is derived from the electrode pair in the final stage. Since other ions cannot be synchronized, they collide with either the inner or outer electrode 14 and disappear. In this way, also in the mass separation device 12, it is possible to selectively derive ions 8d having a desired mass by performing mass separation of the sheet-like ion beam 8.

  In the case of this embodiment as well, as in the case of using parallel plate electrode arrays as shown in FIG. 6, the ion beam focusing action during electrostatic deflection can be used. More specifically, by setting the center angle α of the electrode array to about 127 degrees, the ion beam 8 focused between the first electrode pairs is refocused between the last electrode pairs. As a result, the focused position of the ion beam becomes clear, so that the ion beam can be easily used.

In this embodiment, during the half cycle of the square wave AC voltage V _B, since the ion beam 8 can not pass through the electrode array takes a different track from the track shown in Figure 7, the square-wave AC voltage V _B If the duty ratio is 50%, the ion beam transmittance is 50% or less.

In order to solve this problem, for example, another electrode array is provided outside the electrode array shown in FIG. 7, that is, the electrode arrays are provided in an inner and outer double, and ions are generated during a half cycle of the square wave AC voltage V _B. The beam 8 may be mass-separated through one (for example, the inner) electrode row, and may be mass-separated through the other (for example, the outer) electrode row during the remaining half period. By doing so, mass separation of the ion beam 8 is possible in almost all periods of one cycle of the square wave AC voltage V _B , and thus the transmittance of the ion beam is twice that of the example of FIG.

In the case of an arc-shaped electrode array as shown in FIG. 7, a square wave power source that outputs a unipolar square wave voltage can be used as the vibration power source 16 instead of the square wave AC power source. This is also because mass separation can be performed by applying the oscillating electric field E _B satisfying the condition of Equation 1 or Equation 6 to the ion beam 8.

In addition, although the beam transmittance is reduced, in the above-described FIGS. 6 and 7 and the modified embodiments thereof, instead of the plate-like electrode 14, a rod-like electrode (for example, a round bar-like shape, a cylindrical shape, a cylindrical shape, etc.) Pairs can also be used. A sinusoidal AC power supply can also be used as the vibration power supply 16. In any case, the mass separation can be performed by applying the oscillating electric field E _B satisfying the condition of the formula 1 or the formula 2 to the ion beam 8. A preferable combination of the shape of the electrode and the type of the vibration power source is as described above.

  The present invention can be used, for example, in a technical field in which an object is irradiated with an ion beam to perform ion implantation, ion doping, surface modification, new material creation, semiconductor device formation, and the like.

It is sectional drawing which shows the example of an ion beam irradiation apparatus provided with the mass separator which concerns on one Embodiment of this invention. It is a perspective view which expands and shows one of the ion beam and electrode pair in FIG. It is a figure which shows an example of the experimental result performed using the mass separator based on the same principle as the mass separator of FIG. It is a figure which shows the modification of the mass separator of FIG. It is a figure which shows the further another modification of the mass separator of FIG. It is sectional drawing which shows the example of an ion beam irradiation apparatus provided with the mass separator which concerns on other embodiment of this invention. It is the schematic which shows the mass separator which concerns on other embodiment of this invention.

Explanation of symbols

6 Ion source 8, 8a, 8b Ion beam 8d Ion of desired mass 12 Mass separation device 14, 14a, 14b Electrode 16 Vibration power source

Claims (14)

A mass separation device for mass-separating a sheet-like ion beam accelerated to a predetermined energy,
The electrodes are arranged so as to be opposed to each other across the path of the ion beam, each electrode extends along the width direction of the ion beam, and the electrode forming the pair is the ion beam A plurality of pairs of electrodes arranged in the beam traveling direction; and
Vibration that applies a oscillating voltage of a fixed period between the electrodes of each pair so that a oscillating electric field of a fixed period having a direction component perpendicular to the traveling direction is applied to the ion beam using each pair of electrodes. With a power supply,
A mass separation apparatus configured to selectively derive ions having a desired mass in the ion beam while vibrating in synchronization with the oscillating electric field.   The mass separator according to claim 1, wherein an oscillating voltage having the same phase is applied from the oscillating power source to adjacent electrodes of the plurality of pairs of electrodes.   The mass separator according to claim 1, wherein an oscillating voltage having an opposite phase is applied from the oscillating power source to electrodes adjacent to the plurality of pairs of electrodes.   The plurality of pairs of electrodes are arranged so as to form an arc, and are configured to apply an oscillating voltage having an opposite phase from the oscillating power source to adjacent electrodes of the plurality of pairs of electrodes. Mass separator.   5. The oscillating voltage is a sine wave AC voltage, the oscillating power source is a sine wave AC power source that outputs the sine wave AC voltage, and the oscillating electric field is a sine wave AC electric field. Mass separator.   5. The oscillating voltage is a square wave AC voltage, the oscillating power source is a square wave AC power source that outputs the square wave AC voltage, and the oscillating electric field is a square wave AC electric field. Mass separator.   The oscillating voltage is a unipolar square wave voltage, the oscillating power source is a square wave power source that outputs the square wave voltage, and the oscillating electric field is a square wave electric field. Mass separator.   The mass separator according to any one of claims 1 to 7, wherein each pair of electrodes is a bar-shaped electrode parallel to each other.   The mass separator according to any one of claims 1 to 7, wherein each pair of electrodes is a plate-like electrode parallel to each other.   The mass separator according to claim 1, wherein the vibration power source is a power source having a variable frequency of the vibration voltage output therefrom.   The mass separator according to claim 1, further comprising an electrode interval adjustment mechanism that adjusts a distance between centers of adjacent electrodes of the plurality of pairs of electrodes.   12. The mass separation apparatus according to claim 1, wherein the mass of ions to be selectively derived is adjusted by adjusting a frequency of the oscillating voltage.   12. The mass separation apparatus according to claim 1, wherein the mass of ions to be selectively derived is adjusted by adjusting energy of the ion beam.   12. The mass separator according to claim 1, wherein the mass of ions to be selectively derived is adjusted by adjusting a distance between centers of adjacent electrodes of the plurality of pairs of electrodes. Mass separation method.

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