JP2008010282A - Ion beam generating device, ion doping device, ion beam generating method, and mass separation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mass separation device for separating one or a plurality of ion species contained in an introduced ion beam by curving an orbit of an ion beam by magnetic field action depending on ion mass, capable of improving mass separation performance without decreasing an ion beam current amount. <P>SOLUTION: The mass separation device 130 for separating the one or the plurality of ion species contained in the ion beam by curving the orbit of the ion beam by the magnetic field action depending on the ion mass improves mass separation performance without greatly reducing an ion beam current by entering the ion beam by inclining from a vertical direction with respect to an ion beam incident surface 130a of the mass separation device 130, and thus the ion beam separated by mass with high precision can be generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ion beam generator capable of outputting an ion beam composed of a specific ion species, an ion doping device capable of implanting specific ions into a substrate using the ion beam generator, and the ion beam generator. The present invention relates to a method for generating an ion beam using sapphire and a mass separation method used therefor.

  Conventionally, in the manufacturing process of a semiconductor device such as an IC (semiconductor integrated circuit) or a TFT liquid crystal device, an ion implantation (ion doping) process is performed on a semiconductor in order to form a semiconductor having a predetermined conductivity type in a predetermined region. It has been subjected.

  In addition to the conventional requirement for ion implantation of specific ion species to semiconductors with respect to this ion implantation (ion doping) treatment process, in recent years, a larger area ion implantation treatment has been required. Has been. That is, an ion beam generator capable of outputting a large area ion beam bundle made of specific ion species is desired.

  As a conventional ion beam generator capable of meeting this requirement, for example, Patent Document 1 discloses an ion implantation apparatus capable of outputting a vertically long ion beam bundle made of a specific ion species.

  FIG. 7 is a longitudinal sectional view schematically showing a basic configuration example of a conventional ion beam generator described in Patent Document 1.

  In FIG. 7, a conventional ion beam generating apparatus 200 makes an ion source 210 that generates a first ion beam bundle Ia and a first ion beam bundle Ia from the ion source 210 incident on the way, depending on the ion species. A mass separator 220 that emits the second ion beam bundle Ib separated by bending and the third ion beam bundle Ic of a predetermined ion species is taken out from the second ion beam bundle Ib curved according to the ion species. And a slit plate 230.

  The ion source 210 outputs a first ion beam bundle Ia composed of a plurality of types of ions. The first ion beam bundle Ia is a beam bundle having a rectangular cross section (vertically long) having a predetermined width in the direction perpendicular to the paper surface (hereinafter referred to as the y direction) and the x direction in FIG. A beam bundle that is vertically long in the direction. The y direction is a direction of a magnetic field By described later, and the x direction is a direction perpendicular to the y direction (direction of the magnetic field By) in the cross section of the ion beam bundle.

  In the mass separator 220, the orbits of the plurality of types of ions included in the first ion beam bundle Ia output from the ion source 210 are each curved with a radius corresponding to the mass of the ion type by the magnetic field action. The two-ion beam bundle Ib is output from the output unit 220a to the outside.

  In the slit plate 230, only ions of a specific mass that can pass through the slit-like long hole 231 pass out of the ions of the second ion beam bundle Ib that are output with the trajectory curved by the mass separator 220. And output as a third ion beam bundle Ic of a specific ion species.

  The third ion beam bundle Ic outputted from the slit plate 230 is irradiated onto a semiconductor substrate 240 as an object to be ion-implanted, and selectively formed by using a resist mask formed in a predetermined pattern. An ion implantation process is performed on a predetermined region.

  Here, the mass separator 220 will be described in more detail with reference to FIG.

  FIG. 8 is a cross-sectional view of the main part when the yoke is viewed from the downstream side in the z direction toward the upstream side in the mass separator 220 of FIG.

  As shown in FIG. 8, the mass separator 220 mainly includes a rectangular annular yoke 221 having an inner yoke 221a and an outer yoke 221b, and an inner side in which a conductor (eg, copper wire) is wound around the inner yoke 221a. A coil 222, an outer coil 223 in which a conductor (eg, copper wire) is wound around the outer yoke 221b, and a vacuum case 224 provided in a space portion (opening 221c) in the rectangular annular yoke 221 I have.

  The side surface of the yoke 221 viewed from the direction perpendicular to the paper surface (y direction) in FIG. 7 has a fan shape. Hereinafter, the radial direction of the sector is defined as the r direction. Further, the cross-sectional configuration shown in FIG. 8 in which the yoke 221 is viewed from the downstream side in the z direction (direction orthogonal to the ry plane) along the fan-shaped curve is a square shape having an opening 221c in the center portion. It is ring-shaped and has a square shape.

  An inner coil 222 and an outer coil 223 are wound around the inner yoke portion 221a and the outer yoke portion 221b of the square-shaped yoke 221, respectively. The ion beam passes through the internal space 224a of the vacuum case 224 provided in the opening 221c.

  A current flows through the inner coil 222 and the outer coil 223 so as to generate a magnetic field in the directions of arrows vi and vo in FIG. 8, and the repulsive action of the magnetic field generated by both the coils 222 and 223. Thus, a magnetic field By in the y direction is formed in the opening 221c (internal space 224a of the vacuum case 224). Due to the action of the magnetic field By, the trajectory of ions traveling through the opening 221c (the internal space 224a of the vacuum case 224) is curved substantially along the z direction.

  With the above configuration, since the square-shaped, round-shaped yoke 221 is used and the repulsive action of the magnetic field by both the coils 222 and 223 is used, the width of the opening 221c in the y direction, that is, between the magnetic poles Even if the gap is wide, a uniform magnetic field (∂By / ∂y≈0) can be efficiently formed in the y direction. As a result, even an ion beam bundle that is vertically long in the y direction can be uniformly bent. Therefore, a highly accurate mass of a specific ion species is also obtained for the first ion beam bundle Ia that is vertically long in the y direction. Separation can be performed. As a result, it is possible to output a vertically long ion beam bundle (third ion beam bundle Ic) made of a specific ion species as an ion beam for ion implantation. Note that Patent Document 1 describes a configuration in which each of the inner coil 222 and the outer coil 223 is further divided into a plurality of coils so that the above action becomes more prominent.

  On the other hand, Patent Document 2 discloses a technique for reducing the weight of a mass separator by forming a magnet of the mass separator using an air-core coil.

   Patent Document 3 discloses a technique for performing ion mass separation of a large-diameter ion beam by using an air-core excitation current path.

Furthermore, Patent Literature 4 discloses a technique for adjusting mass separation performance by adjusting the slit opening size at the outlet of the mass separation device in the conventional ion mass separation method described in Patent Literature 3. Yes.
Japanese Patent No. 3449198 JP 2004-152557 A Japanese Patent Laid-Open No. 2002-203805 JP 2005-71737 A

  Thus, in the ion doping apparatus using the conventional mass separation apparatus disclosed in Patent Documents 1 to 4, ion mass separation is performed from an ion beam composed of a plurality of ion species, and an ion beam composed only of a specific ion species is obtained. It can be taken out and a specific ion species can be ion-implanted onto the target semiconductor substrate.

  Also, when used for applications that require more accurate mass separation performance of specific ion species, that is, when it is necessary to take out an ion beam from which specific ion species have been mass separated with higher accuracy. Can be dealt with by narrowing the specific mass range of ion species that can be passed by narrowing the slit opening size at the outlet of the mass separation device to improve the mass separation performance.

  However, in the ion doping apparatus using the conventional mass separation apparatus disclosed in Patent Documents 1 to 4, when the slit opening size is narrowed in order to improve the mass separation performance, the ion beam current obtained therewith is reduced. There is a risk that the amount will decrease and the time required for the actual ion doping process will also increase greatly.

  The present invention solves the above-described problems, and can improve the mass separation performance without reducing the ion beam current without reducing the slit opening size for improving the mass separation performance. It is an object of the present invention to provide an ion beam generator, an ion doping apparatus using the ion beam generator, an ion beam generation method using the ion beam generator, and a mass separation method used therefor.

  An ion beam generator of the present invention includes an ion source that outputs an ion beam composed of a plurality of ion species, and a specific trajectory included in the ion beam by curving the orbit of the ion beam according to an ion mass by a magnetic field action. A mass separation device that separates one or a plurality of ion species and outputs an ion beam of the specific ion species, and is provided between the ion source and the mass separation device, and the ion beam from the ion source is separated into the mass Beam tilting means for tilting and entering the apparatus by a predetermined tilt angle, thereby achieving the above object.

  Preferably, the ion beam generator of the present invention further includes an ion beam extraction electrode for extracting an ion beam from the ion source, and the ion beam extraction electrode surface of the ion beam extraction electrode is The ion beam is installed in parallel to a surface inclined by a predetermined inclination angle in the ion beam bending direction in the mass separator with respect to the ion beam incident surface.

  Further preferably, as a beam tilting means in the ion beam generator of the present invention, an ion beam extraction electrode surface of an ion beam extraction electrode for extracting an ion beam from the ion source, and an ion beam incident surface of the mass separation device A spacer member is provided between the ion beam extraction electrode surface and the ion beam incident surface of the mass separation device.

  Further preferably, in the ion beam generator of the present invention, an ion beam incident surface of the mass separator is installed in a direction perpendicular to a horizontal direction, and the ion beam incident surface of the mass separator is The beam extraction electrode surface is inclined.

  Further preferably, in the ion beam generator of the present invention, the ion beam extraction electrode surface is installed in a direction orthogonal to a horizontal direction, and the ion beam incidence of the mass separation device is incident on the ion beam extraction electrode surface. The surface is installed with an inclination.

  Further preferably, in the ion beam generator of the present invention, when the ion beam is obliquely incident into the mass separation device through the ion beam incident surface, the ion beam is directed in a direction perpendicular to the ion beam incident surface. On the other hand, the incident light is inclined upward.

  Further preferably, in the ion beam generator of the present invention, when the ion beam is obliquely incident into the mass separation device through the ion beam incident surface, the ion beam is directed in a direction perpendicular to the ion beam incident surface. On the other hand, the incident light is inclined downward.

  Further preferably, in the ion beam generator of the present invention, a shielding member having a slit opening portion having a predetermined slit width is provided on the outlet side of the mass separation device.

  Further preferably, in the ion beam generator of the present invention, the ion beam incident surface side of the beam tilting means and the ion beam incident surface side of the mass separator are electrically connected so as to have the same potential. In the beam tilting means, there is no electric field.

  The ion doping apparatus of the present invention is a substrate mounting on which the ion beam generating apparatus of the present invention and a substrate on which ion implantation is performed by irradiating the ion beam from the ion beam generating apparatus can be mounted and fixed. And the above object is achieved.

  According to the mass separation method of the present invention, an ion beam composed of a plurality of ion species is introduced into a mass separation device, and the trajectory of the ion beam is curved according to the ion mass by a magnetic field action, and a specific one included in the ion beam is obtained. Alternatively, in the mass separation method for separating a plurality of ion species, the ion beam is made to enter the mass separation device at a predetermined inclination angle through the ion beam incident surface, thereby achieving the above object. Is done.

  Preferably, the ion beam in the mass separation method of the present invention is incident with being inclined upward with respect to a direction perpendicular to the ion beam incident surface of the mass separator.

  Further, preferably, the ion beam in the mass separation method of the present invention is incident with being inclined downward with respect to a direction perpendicular to the ion beam incident surface of the mass separation device.

  The ion beam generation method of the present invention separates and outputs an ion beam composed of the specific ion species using the ion beam generation apparatus of the present invention, thereby achieving the above object.

  The operation of the present invention will be described below with the above configuration.

  In the present invention, the ion beam trajectory is curved with a radius corresponding to the ion mass by the magnetic field action, and the ion beam is separated from the mass separation device that separates one or more specific ion species contained in the ion beam. By making the beam incident on the ion beam incident surface of the mass separator while being tilted by a predetermined angle, the ion beam can be bent more in the mass separator, so that the mass can be improved to improve the mass separation performance as in the past. Since there is no need to narrow the slit opening size of the output part of the separation device, it becomes possible to perform mass separation with higher accuracy without greatly reducing the obtained ion beam current.

  As described above, according to the present invention, since the ion beam is incident on the ion beam incident surface of the mass separator in a state inclined by a predetermined angle, the ion beam can be further curved in the mass separator, In order to improve the mass separation performance as before, without increasing the slit opening size of the output part of the mass separation device, the mass separation performance is improved without greatly reducing the ion beam current, and the mass is more accurately measured. A separated ion beam can be generated. Accordingly, by using the ion doping apparatus of the present invention, a low carrier density conductive layer of an LDD structure transistor that requires an ion doping process for a semiconductor, particularly a highly accurate ion doping process, or a low dose ion for adjusting a threshold voltage. Can be formed at high speed with high accuracy.

  Embodiments of an ion doping apparatus provided with an ion beam generator of the present invention will be described below with reference to the drawings.

  In the present embodiment, the ion beam extraction electrode surface of the ion beam extraction electrode for extracting the ion beam from the ion source is inclined by a predetermined angle in the ion beam bending direction with respect to the ion beam incident surface of the mass separator. By placing the ion beam in parallel in a tilted state, the ion beam can be bent more, and the ion beam current can be more curved without greatly reducing the resulting ion beam current. An example of an ion doping apparatus that enables accurate mass separation will be described.

  FIG. 1 is a cross-sectional view schematically showing a configuration example of a main part of an ion doping apparatus using an ion beam generator according to an embodiment of the present invention.

  In FIG. 1, an ion doping apparatus 10 of this embodiment includes an ion beam generation apparatus 100 that outputs an ion beam consisting of only a specific type of ion species to the outside, and ions of a specific ion type from the ion beam generation apparatus 100. A semiconductor substrate 11 that is a target irradiated with an ion beam for implantation is mounted and fixed, and the semiconductor substrate 11 is movable. A specific ion species can be ion-implanted into a predetermined region of the semiconductor substrate 11 so as to be movable.

  The ion beam generator 100 mainly includes an ion source 110 that outputs an ion beam composed of a plurality of ion species, an ion beam extraction electrode 120 for extracting the ion beam Iin from the ion source 110, and the ion beam extraction electrode 120. Is included in the ion beam Ib (for example, separated as Ib1 and Ib2) which is curved according to the ion mass, and the trajectory of the ion beam Ib is curved with a radius according to the ion mass. Mass separation device 130 for separating one or more specific ion species (for example, Ib1), and an ion beam extraction electrode 120 and mass separation device 130, and mass separation of the ion beam from ion source 110 A beam tilting hand that enters the apparatus 130 with a predetermined tilt angle α. Spacer member 140 (hereinafter referred to as spacer 140), a shielding member 150 provided with a slit opening 151 having a predetermined slit width on the ion beam output side (exit portion 130b side) of the mass separator 130, and the shielding member 150 And an internal acceleration electrode 160 provided on the ion beam downstream side of the member 150.

  The ion source 110 is disposed so that the ion beam extraction surface 110a, which is the exit portion thereof, is parallel to the ion beam extraction electrode surface of the ion beam extraction electrode 120, and face each other. The ion beam Iin consisting of a plurality of ion species is extracted and emitted from the ion source 110 by an electric field due to a potential difference between the ion beam extraction electrode 120 and the ion beam emission surface 110a of the ion source 110.

  The ion beam extraction electrode 120 is arranged in the ion beam bending direction with respect to the ion beam incident surface 130a of the mass separator 130 so that the angle formed with the ion beam incident surface 130a of the mass separator 130 is a predetermined inclination angle α. It is installed in parallel with a plane inclined by a predetermined angle α.

The ion beam Iin extracted from the ion beam extraction electrode 120 proceeds perpendicularly to an equipotential surface formed by an electric field between the ion beam extraction electrode 120 and the ion beam emission surface 110a at the exit of the ion source 110, The light is incident on an ion beam incident surface 140 a of a spacer 140 having a predetermined inclination angle α installed at a connection portion between the ion source 110 and the ion beam extraction electrode 120 and the mass separation device 130. When the spacer 140 is installed, the ion beam incident surface 130a of the mass separator 130 and the ion beam incident surface 140a of the spacer 140 are electrically connected so as to have the same potential. Then, no electric field is generated.
The mass separator 130 mainly includes a rectangular annular yoke 221 having an inner yoke 221a and an outer yoke 221b, an inner coil 222 having a conductor (for example, copper wire) wound around the inner yoke 221a, and the outer yoke 221b. An outer coil 223 around which a conductor (for example, copper wire) is wound, and a vacuum case 224 provided in a space portion in the rectangular annular yoke 221. A magnetic field Hy uniform in the y direction is formed in the internal space of the vacuum case 224 by the repulsive action of the magnetic field generated by the current flowing through the inner coil 222 and the outer coil 223. However, since the spacer 140 is not included in the mass separator 130, no magnetic field is formed inside the spacer 140.

  Therefore, neither an electric field nor a magnetic field is present inside the spacer 140, and the ion beam Iin incident perpendicularly to the ion beam incident surface 140a of the spacer 140 advances straight inside the spacer 140 without being bent, and has a mass. The light beam is incident on the ion beam incident surface 130a of the separation device 130 while being inclined by a predetermined angle α upward from the vertical direction (x-axis positive (+) direction) into the mass separation device 130.

  FIG. 2 is a cross-sectional view schematically showing another configuration example of the main part of the ion doping apparatus 10 including the ion beam generating apparatus 100 according to the embodiment of the present invention.

  In FIG. 1, the mass separation device 130 is installed such that its ion beam incident surface is orthogonal to the horizontal direction, and the ion source 110 and the ion beam extraction electrode 120 are set at a predetermined angle α with respect to the ion beam incident surface. Although the configuration in which the ion beam is incident on the ion beam incident surface of the mass separator 130 by being inclined by a predetermined angle α by tilting is shown, the present invention is not limited to this, and as shown in FIG. The ion beam extraction electrode surface 120a is installed in a direction orthogonal to the horizontal direction, and the ion beam incident surface side of the mass separator 130 is inclined by a predetermined angle α with respect to the ion source 110 and the ion beam extraction electrode 120. It is also possible to do. In this case, the mass separation device 130 is installed so that the angle formed by the ion beam extraction electrode surface 120a of the ion beam extraction electrode 120 and the ion beam incidence surface 130a of the mass separation device 130 is a predetermined inclination angle α. Further, by setting the relative inclination angle α of the ion source 110 and the ion beam extraction electrode 120 and the mass separator 130 to a negative value, the ion beam Iin is made to the ion beam incident surface 130 a of the mass separator 130. It is also possible to incline downward from the vertical direction.

  The ion beam Iin incident on the mass separator 130 is separated by a magnetic field effect such that the trajectories of a plurality of ion species are curved like the ion beams Ib1 and Ib2 with a radius corresponding to the mass of each ion species. The ion beam Ib1 is output as the ion beam Iout. Of the ion species whose trajectory is curved by the mass separator 130, only ion species having a specific mass that can pass through the slit opening 151 of the shielding member 150 are extracted and accelerated by the acceleration electrode 160 on the semiconductor substrate 11. Is irradiated.

  Next, a conventional ion beam generator that does not tilt the ion source and ion beam extraction electrode with respect to the mass separation device, and the ion source 110 and ion beam extraction electrode 120 with respect to the mass separation device 130 by a predetermined inclination angle α. FIG. 3A and FIG. 4B show changes in the flying trajectory when two types of ions having a mass ratio of 1: 2 are generated using the tilted ion beam generator 100 of the present embodiment. An example will be described.

  FIG. 3 is a diagram schematically showing changes in the flying trajectories of two types of ion species having different masses in the mass separator. FIG. 3A shows an ion beam perpendicularly incident on the mass separator. FIG. 5B is a diagram showing a case where a conventional ion beam generator is used, and FIG. 5B is a diagram showing a case where the ion beam generator of FIG.

  When the mixed ion beam Iin ′ having two types of ion masses of mass ratio 1: 2 extracted from the ion source is vertically incident on the ion beam incident surface of the mass separator as in the prior art, FIG. As shown in (a), individual ion species included in the ion beam Iin ′ are curved in accordance with each ion mass by the magnetic field Hy in the ion deflection casing, respectively, and are changed into the ion beam Ib1 ′ and the ion beam Ib2 ′. To be separated. At this time, the interval between the ion beams Iout ′ at the exit of the mass separator is A ′.

  On the other hand, as in this embodiment, a mixed ion beam having two types of ion masses with a mass ratio of 1: 2 extracted from the ion source 110 is applied to the ion beam incident surface 130a of the mass separator 130. When the light beam is incident from the vertical direction upward (x-axis positive (+) direction) by a predetermined inclination angle α, the ion beam is irradiated in the same manner as in FIG. 3A in which the mixed ion beam Iin ′ is vertically incident. Iin is separated into the ion beam Ib1 and the ion beam Ib2, and the interval A between the ion beams Iout at the outlet 130b of the mass separator 130 is the same as that of the conventional ion beam generator as shown in FIG. Compared with the interval A ′ when used, it is greatly expanded. This is because the ion beam is incident on the ion beam incident surface 130a of the mass separator 130 by being inclined at a predetermined inclination angle α upward from the vertical direction, thereby substantially passing through the mass separator 130. Since the angle is increased by the tilt incident angle α, and the trajectory is further bent due to the influence of the magnetic field Hy (to bend more), the difference in curvature due to the ion mass is expanded (difference in the bending radius is increased). (Enlarge).

  Next, the change in the MSI (mass separation current) dependence of Iout was simulated by actually changing the incident angle, and the effect of improving the mass separation performance by the oblique incidence in the mass separation method according to the present embodiment was verified. For comparison, the MSI (mass separation current) dependence change of Iout when changing the outlet opening size of the outlet of the mass separator disclosed in Patent Document 1 was also simulated.

In this simulation, hydrogen diluted diborane (B ₂ H ₆ ) is used as the source gas of the ion source, and calculation is performed on the assumption that mixed ion beams of various ion species of Hx, BHx, and B ₂ Hx are introduced into the mass separator. went. As the evaluation parameters, the tilt incident angle α = 0 [deg] (normal incidence), 10 [deg] and 15 [deg], the mass separator outlet portion opening dimension L = 150 (standard conditions) [mm], 80 [mm] ] And 50 [mm], and all other parameters were set to constant conditions. In addition, in order to verify the case of oblique incidence downward, a simulation was also performed for the case of the oblique incidence angle α = −15 [deg].

  First, the MSI (mass separation current) dependence change of the ion beam Iout when the exit opening size of the mass separation apparatus is changed using the method disclosed in Patent Document 1 will be described with reference to FIGS. This will be described with reference to FIG.

  4 (a) to 4 (c) show the dependence of the output ion beam current intensity on the mass separation current when the aperture size of the mass separation device is changed in the conventional mass separation device disclosed in Patent Document 1. FIG. It is a graph which shows the result of having performed simulation about.

As shown in FIGS. 4A to 4C, the BHx ion beam [normal incidence is increased as the exit opening size L (for example, the slit width of the slit opening 151 of the shielding member 150) becomes narrower. At this time, the overlapping ratio of MSI: 90 [A]] and the B ₂ Hx ion beam (at the time of vertical incidence, MSI: 120 [A]) is greatly reduced. This shows that the mass separation performance of the BHx ion beam and the B ₂ Hx ion beam is greatly improved.

  However, as the mass separation performance is improved, the ion beam current intensity is decreasing. For example, in the BHx system, the ion beam current intensity is greatly reduced to 60% when the aperture size is halved and to 40% when the aperture size is 1/3.

  On the other hand, the ion beam in the case where the degree of the oblique incidence of the ion beam to the ion beam incident surface 130a of the mass separator 130 is changed from the vertical direction to the upper side by using the mass separation method according to the present embodiment. Changes in Iout depending on MSI (mass separation current) will be described with reference to FIGS.

  5 (a) to 5 (c) show the dependence of the output ion beam current intensity on the mass separation current when the incident angle of the ion beam to the mass separation device is changed in the ion beam generator 100 of FIG. It is a graph which shows the result of having performed simulation about.

As shown in FIGS. 5A to 5C, as the inclination angle α of the ion beam with respect to the ion beam incident surface 130a of the mass separator 130 is increased, the BHx ion beam and the B ₂ Hx ion are used. The beam superposition ratio is reduced, and the mass separation performance of the ion beam is improved. Although the improvement in mass separation performance (decrease in the degree of ion beam superimposition) is smaller than that in the case of narrowing the aperture size, the decrease in ion beam current accompanying the improvement in mass separation performance is slight. It can be seen that the ion beam is separated without greatly reducing the current intensity.

  Next, the MSI (mass separation current) -dependent change of the ion beam Iout when the ion beam is inclined upward and downward from the vertical direction with respect to the ion beam incident surface 130a of the mass separator 130 will be described with reference to FIG. It demonstrates using a)-FIG.6 (c).

  FIGS. 6A to 6C show mass separation currents of the output ion beam current intensity when the incident angle of the ion beam to the mass separation device of the ion beam generator of the present invention is changed upward and downward. It is a graph which shows the result of having performed simulation about dependence.

As shown in FIGS. 6A to 6C, when the ion beam is incident on the ion beam incident surface 130a of the mass separation device 130 with an inclination downward from the vertical direction, the ion beam is mass separated. Contrary to the case where the ion beam incidence surface 130a of the apparatus 130 is obliquely incident upward from the vertical direction, the overlapping ratio of the BHx ion beam and the B ₂ Hx ion beam is increased. Therefore, although the ion beam mass separation performance is lowered, the ion beam current intensity can be increased. Furthermore, since the rate of change of the ion beam current with respect to the change in MSI (mass separation current) (degree of inclination of the curve in FIG. 6) becomes gentle, the effect of widening the margin for the change in MSI (mass separation current) can be obtained. .

  As described above, according to the present embodiment, the ion beam trajectory is curved according to the ion mass by the magnetic field action, and in the mass separation device 130 that separates one or more types of ion species included in the ion beam, By causing the beam to be incident obliquely upward from the vertical direction with respect to the ion beam incident surface 130a of the mass separation device 130, mass separation performance is improved without greatly reducing the ion beam current, and mass separation is performed with higher accuracy. Ion beam can be generated. On the contrary, when the ion beam is tilted downward from the vertical direction with respect to the ion beam incident surface 130a of the mass separator 130, the ion beam current intensity is increased, although the mass separation performance is reduced, and the ion beam is increased. It becomes possible to widen the margin for the MSI (mass separation current) change of the beam current intensity.

  Therefore, by using the ion doping apparatus 10 that performs mass separation using the mass separation method of the present embodiment, low carrier density conduction in an LDD structure transistor that requires ion doping processing on a semiconductor, particularly high-precision ion doping processing. Layers and channel portions doped with low dose ions for threshold voltage adjustment can be formed with high accuracy and high speed.

  As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to an ion beam generator capable of outputting an ion beam composed of a specific ion species, an ion doping device capable of implanting specific ions into a substrate using the ion beam generator, and the ion beam generator. In the field of an ion beam generation method using the ion beam and a mass separation method used therefor, the ion beam trajectory is curved with a radius corresponding to the ion mass by the action of a magnetic field, and one or more types of ions included in the ion beam Since the ion beam is incident on the ion beam incident surface of the mass separation device that separates the ion beam at a predetermined angle, the ion beam can be curved more strongly in the mass separation device. In order to improve the mass separation performance, the slit opening size of the output part of the mass separator is not narrowed. Nbimu current greatly improved mass separation performance without reducing, it is possible to generate a mass separated ion beam more accurately. Accordingly, by using the ion doping apparatus of the present invention, a low carrier density conductive layer of an LDD structure transistor that requires an ion doping process for a semiconductor, particularly a highly accurate ion doping process, or a low dose ion for adjusting a threshold voltage. Can be formed at high speed with high accuracy.

It is sectional drawing which shows typically the example of a principal part structure of the ion doping apparatus using the ion beam generator which concerns on embodiment of this invention. It is sectional drawing which shows typically the example of another principal part structure of the ion doping apparatus provided with the ion beam generator which concerns on embodiment of this invention. FIG. 6 is a diagram schematically showing changes in the flying trajectories of two types of ion species having different masses in the mass separator, and (a) shows a conventional ion beam in which an ion beam is vertically incident on the mass separator. FIG. 5B is a diagram showing a case where the generator is used, and FIG. 5B is a diagram showing a case where the ion beam generator of FIG. (A)-(c) performs the simulation about the mass separation current dependence of the output ion beam current intensity at the time of changing the opening size of the mass separation apparatus in the conventional mass separation apparatus disclosed in Patent Document 1. It is a graph which shows the result. (A)-(c) is a graph which shows the result of having performed the simulation about the mass-separation current dependence of the output ion beam current intensity at the time of changing an incident angle in the ion beam generator which concerns on embodiment of this invention. It is. (A) to (c) are simulations of the dependence of the output ion beam current intensity on the mass separation current when the incident angle of the ion beam to the mass separator of the ion beam generator of the present invention is changed upward and downward. It is a graph which shows the result of having performed. It is a longitudinal cross-sectional view which shows typically the example of a basic composition of the conventional ion beam generator. FIG. 8 is a cross-sectional view of a main part when the yoke is viewed from the downstream side in the z direction toward the upstream side in the mass separator of FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ion doping apparatus 11 Semiconductor substrate 100 Ion beam generator 110 Ion source 110a Ion source ion beam exit surface 120 Ion beam extraction electrode 130 Mass separator 130a Mass separator apparatus ion beam entrance surface 130b Ion beam exit surface of mass separator 140 Spacer 140a Ion beam incident surface of spacer 150 Shield member 160 Accelerating electrode

Claims (14)

An ion source that outputs an ion beam comprising a plurality of ion species;
A mass separation device for bending a trajectory of the ion beam according to an ion mass by a magnetic field action to separate one or more specific ion species included in the ion beam and outputting an ion beam of the specific ion species When,
An ion beam generator comprising: a beam tilting unit provided between the ion source and the mass separation device and configured to incline an ion beam from the ion source into the mass separation device with a predetermined tilt angle.   An ion beam extraction electrode for extracting an ion beam from the ion source, and an ion beam extraction electrode surface of the ion beam extraction electrode is an ion in the mass separation device with respect to an ion beam incident surface of the mass separation device; The ion beam generating apparatus according to claim 1, wherein the ion beam generating apparatus is installed in parallel with a surface inclined by a predetermined inclination angle in the beam bending direction.   As the beam tilting means, an angle formed by an ion beam extracting electrode surface of an ion beam extracting electrode for extracting an ion beam from the ion source and an ion beam incident surface of the mass separation device is a predetermined tilt angle. The ion beam generator according to claim 1, wherein a spacer member is provided between the ion beam extraction electrode surface and the ion beam incident surface of the mass separation device.   The ion beam incident surface of the mass separator is installed in a direction orthogonal to the horizontal direction, and the ion beam extraction electrode surface is installed inclined with respect to the ion beam incident surface of the mass separator. 4. The ion beam generator according to 3.   The ion beam extraction electrode surface is installed in a direction orthogonal to a horizontal direction, and the ion beam incident surface of the mass separation device is installed inclined with respect to the ion beam extraction electrode surface. Ion beam generator.   5. The ion beam is incident obliquely upward in a direction perpendicular to the ion beam incident surface when the ion beam is incident on the mass separator through the ion beam incident surface. Ion beam generator.   6. The ion beam according to claim 3 or 5, wherein the ion beam is obliquely incident downward with respect to a direction perpendicular to the ion beam incident surface when the ion beam is incident on the mass separator through the ion beam incident surface. Ion beam generator.   The ion beam generator according to any one of claims 1 to 3, wherein a shielding member having a slit opening with a predetermined slit width is provided on the outlet side of the mass separator.   The ion beam incident surface side of the beam tilting means and the ion beam incident surface side of the mass separator are electrically connected so as to have the same potential, so that the inside of the beam tilting means is in an electric field-free state. The ion beam generator according to claim 1 or 3.   A substrate mounting that enables fixing by mounting the ion beam generator according to any one of claims 1 to 9 and a substrate on which an ion beam is irradiated from the ion beam generator to perform an ion implantation process. An ion doping apparatus comprising a table. An ion beam composed of a plurality of ion species is introduced into the mass separation apparatus, and the trajectory of the ion beam is bent according to the ion mass by the magnetic field action, thereby separating one or more specific ion species included in the ion beam. In the mass separation method,
A mass separation method in which the ion beam is incident on the mass separator through a predetermined inclination angle through the ion beam incident surface.   The mass separation method according to claim 11, wherein the ion beam is incident while being inclined upward with respect to a direction perpendicular to an ion beam incident surface of the mass separation device.   The mass separation method according to claim 11, wherein the ion beam is incident while being inclined downward with respect to a direction perpendicular to an ion beam incident surface of the mass separation device.   An ion beam generating method for separating and outputting an ion beam composed of the specific ion species using the ion beam generator according to claim 1.

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