JP2008034230A - Ion implantation apparatus and its adjustment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion implantation apparatus capable of improving uniformity of a beam current density distribution in the Y-direction of an ion beam in a ribbon shape at an injection position. <P>SOLUTION: The ion implantation apparatus is provided with a plurality of gas introducing parts 38 introducing raw material gas 34 into an ion source 2 generating a ribbon-shape ion beam 4 and arranged in the Y-direction, and a plurality of flow regulators 36 controlling the flow of the introducing raw material gas 34. Furthermore, it is provided with a beam measuring instrument 46 measuring a beam current density distribution in the Y-direction of the ion beam 4, and a control device 50 controlling each flow regulator 36 based on the measured information and uniformalizing the beam current density distribution in the Y-direction of the ion beam 4 at an injection position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ion implantation apparatus configured to perform ion implantation by causing a ribbon-shaped ion beam to enter a target and an adjustment method thereof.

  When the source gas is ionized to generate plasma and the two directions substantially perpendicular to each other are the X direction and the Y direction, the dimension in the Y direction is larger than the dimension in the X direction and larger than the dimension in the Y direction of the target. An ion source that generates an ion beam having a large ribbon shape (sometimes referred to as a sheet shape or a band shape), and an implantation position at which the ion beam is incident on the target. An example of an ion implantation apparatus including a target driving device that moves in a crossing direction is described in Patent Document 1.

  In such an ion implantation apparatus, in order to improve the uniformity of ion implantation with respect to the target, the uniformity of the beam current density distribution in the Y direction (that is, the longitudinal direction) of the ion beam at the implantation position where the ion beam is incident on the target. It is important to increase

  As a technique for improving the uniformity of the ion beam, in Patent Document 1, (a) the ion source has a plurality of filaments arranged in the Y direction, and the filament current flowing through each filament is controlled, A technique for controlling the plasma density distribution in the ion source, and (b) a technique in which an electric field lens or a magnetic lens is provided in the ion beam transport path and the ion beam is locally bent in the Y direction by this lens are described. Has been.

Japanese Patent Laying-Open No. 2005-327713 (paragraphs 0019, 0021, 0023, FIGS. 1-4, 7 and 11)

  The technique for controlling the filament current flowing through the plurality of filaments shown in (a) above cannot be applied to an ion source that does not have a plurality of filaments.

  In the technique using the electric field lens or magnetic field lens shown in (b) above, the configuration of the lens and the power supply therefor is complicated.

  Therefore, the present invention provides an ion implantation apparatus capable of improving the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position, regardless of whether or not the ion source has a plurality of filaments. One purpose is to provide a method for the adjustment.

  Also provided are an ion implantation apparatus and an adjustment method thereof that can improve the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position with a simpler configuration than when using an electric field lens or a magnetic field lens. For other purposes

  One of the ion implantation apparatuses according to the present invention is to ionize a source gas to generate plasma, and when two directions substantially orthogonal to each other are defined as an X direction and a Y direction, the dimension in the Y direction is An ion source that generates a ribbon-like ion beam that is larger than the dimension and larger than the dimension in the Y direction of the target, and a direction in which the target intersects the main surface of the ion beam at an implantation position where the ion beam is incident on the target In the ion implantation apparatus including the target driving device to be moved to the plurality of gas introduction portions, each of the source gases is introduced into the ion source and arranged in the Y direction, and the gas introduction portions are introduced from the gas introduction portions. It is characterized by comprising a plurality of flow rate regulators for regulating the flow rate of the source gas.

  In general, the beam current density of an ion beam extracted from the ion source is proportional to the plasma density in the ion source. Therefore, the beam current density at each position in the Y direction of the ribbon-like ion beam is proportional to the plasma density at the position corresponding to that position. The plasma density is proportional to the density of the source gas in the ion source. In this ion implantation apparatus, the density of the source gas in the Y direction in the ion source can be controlled by adjusting the source gas flow rate by each flow rate regulator, so that the plasma density distribution in the Y direction and thus in the Y direction can be controlled. The beam current density distribution can be controlled. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be improved regardless of whether or not the ion source has a plurality of filaments.

  One of the adjustment methods of the ion implantation apparatus according to the present invention is to measure the beam current density distribution in the Y direction by receiving the ion beam in the vicinity of the upstream side or the downstream side of the implantation position in the ion implantation apparatus. The flow rate of the raw material gas introduced from the gas introduction unit corresponding to the region where the beam current density is relatively large by adjusting the flow rate controller based on the measurement information obtained by the beam measurement device. And at least one of increasing the flow rate of the source gas introduced from the gas introduction portion corresponding to the region where the beam current density is relatively small, and performing the ion beam in the Y direction at the implantation position. The beam current density distribution is made uniform.

  The control of the raw material gas flow rate using the flow rate controller may be performed by a control device.

  In another ion implantation apparatus according to the present invention, when the source gas is ionized to generate plasma, and the two directions substantially perpendicular to each other are the X direction and the Y direction, the dimension in the Y direction is the X direction. And an ion source that generates a ribbon-like ion beam that is larger than the dimension in the Y direction of the target, and an implantation position at which the ion beam is incident on the target, and the target intersects the main surface of the ion beam. In an ion implantation apparatus including a target driving device that moves in a direction, an inert gas is respectively introduced into a transport path of the ion beam between the ion source and the implantation position, and arranged in the Y direction. A plurality of gas introduction units, and a plurality of flow rate regulators for adjusting the flow rates of the inert gas introduced from the gas introduction units. It is characterized in that.

  Although the ion beam diverges by its own space charge and the transport efficiency decreases, when an inert gas is introduced into the transport path of the ion beam, the ion beam collides with the inert gas and a beam plasma is generated. Since the space charge of the ion beam is neutralized by electrons and negative ions in the beam plasma, the transport efficiency of the ion beam is improved. In the region where the density of the inert gas is increased, the density of the beam plasma is increased, the space charge neutralization rate is increased, and the transport efficiency of the ion beam is increased. The reverse is true for the reversed area.

  In this ion implantation apparatus, the density of the inert gas in the Y direction of the transport path of the ion beam can be controlled by adjusting the flow rate of the inert gas by each flow rate regulator. By controlling the density distribution, the amount of ion beam reaching the implantation position can be controlled at a plurality of positions in the Y direction. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be improved with a simpler configuration than when an electric field lens or a magnetic field lens is used.

  Another aspect of the ion implantation apparatus adjustment method according to the present invention is that in the ion implantation apparatus, the ion beam is received near the upstream side or the downstream side of the implantation position and the beam current density distribution in the Y direction is measured. And an inert gas introduced from the gas inlet corresponding to the region where the beam current density is relatively large by adjusting the flow rate controller based on the measurement information obtained by the beam meter. At least one of decreasing the flow rate of the gas and increasing the flow rate of the inert gas introduced from the gas introduction unit corresponding to the region where the beam current density is relatively small. The beam current density distribution in the Y direction is made uniform.

  The control of the inert gas flow rate using the flow rate controller may be performed by a control device.

  According to the first aspect of the present invention, a plurality of gas introduction portions and a plurality of flow rate regulators as described above are provided, and the density of the source gas in the Y direction in the ion source is determined by the source gas by each flow rate regulator. Since it can be controlled by adjusting the flow rate, it is possible to control the plasma density distribution in the Y direction and thus the beam current density distribution in the Y direction. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be improved regardless of whether or not the ion source has a plurality of filaments.

  According to invention of Claim 2, there exists the following further effect. That is, since the beam measuring device and the control device as described above are further provided, adjustment for improving the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be performed with reduced labor.

  According to the third aspect of the present invention, the flow rate adjuster is adjusted based on the measurement information from the beam measuring device to adjust the flow rate of the raw material gas introduced from the gas introduction unit into the ion source. The beam current density distribution in the Y direction of the ion beam can be uniformized more easily and reliably.

  According to the fourth aspect of the present invention, the density of the inert gas in the Y direction of the ion beam transport path can be controlled by adjusting the flow rate of the inert gas by each flow rate regulator. The amount of ion beam reaching the implantation position can be controlled at a plurality of positions in the Y direction by controlling the beam plasma density distribution in the direction. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be improved with a simpler configuration than when an electric field lens or a magnetic field lens is used.

  According to invention of Claim 5, there exists the following further effect. That is, since the beam measuring device and the control device as described above are further provided, adjustment for improving the uniformity of the beam current density distribution in the Y direction of the ion beam at the implantation position can be performed with reduced labor.

  According to the sixth aspect of the present invention, the flow rate adjuster is adjusted based on the measurement information from the beam measuring device to adjust the flow rate of the inert gas introduced from the gas introduction unit into the ion beam path. The beam current density distribution in the Y direction of the ion beam can be made uniform more easily and reliably.

  FIG. 1 is a schematic side view showing an embodiment of an ion implantation apparatus according to the present invention. In the following drawings, the traveling direction of the ion beam 4 is always the Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are an X direction and a Y direction. For example, the X direction and the Z direction are horizontal directions, and the Y direction is a vertical direction. Further, in this specification, the case where ions constituting the ion beam 4 are positive ions is described as an example.

  This ion implantation apparatus is an apparatus that performs ion implantation by causing a ribbon-like ion beam 4 to enter a target 40, ionizes the introduced source gas 34 to generate plasma 10, and generates a ribbon-like ion beam 4. The target 40 held by the holder 42 intersects the main surface 5 of the ion beam 4 (see also FIG. 2) at the ion source 2 to be generated and the implantation position where the ion beam 4 is incident on the target 40 to perform ion implantation. And a target driving device 44 that reciprocates linearly in the direction (see, for example, arrow C), that is, mechanically scans. In some cases, the incident angle of the ion beam 4 with respect to the target 40 (that is, the incident angle of the ion beam 4 with respect to a perpendicular line standing on the target surface) has a predetermined angle other than 0 degrees.

  Between the ion source 2 and the target driving device 44, an analysis electromagnet and an analysis slit for performing momentum analysis (for example, mass analysis, the same applies hereinafter) of the ion beam 4 and acceleration or deceleration of the ion beam 4 are performed as necessary. An accelerator / decelerator is provided. The transport path of the ion beam 4 from the ion source 2 to the target 40 is in a vacuum container (see, for example, the vacuum container 48 in FIG. 4) and maintained in a vacuum atmosphere.

For example, as shown in FIG. 2, the ion beam 4 generated from the ion source 2 and transported to the target 40 has a ribbon shape in which the dimension W _{Y in the} Y direction is larger than the dimension W _X in the X direction. Even if the ion beam 4 has a ribbon shape, it does not mean that the dimension W _{X in the} X direction is as thin as paper or cloth. For example, the dimension W _{X in} the X direction of the ion beam 4 is about 30 mm to 80 mm, and the dimension W _{Y in the} Y direction is about 300 mm to 500 mm, although it depends on the dimension of the target 40. The larger surface of the ion beam 4, that is, the surface along the YZ plane is the main surface 5.

The ion source 2 generates a ribbon-like ion beam 4 in which the dimension W _{Y in} the Y direction is larger than the dimension T _{Y in} the Y direction of the target 40. For example, if the dimension T _Y is 300 mm to 400 mm, the dimension W _Y is about 400 mm to 500 mm. The ion beam 4 is transported to the target 40 while maintaining a relationship in which the dimension W _{Y in} the Y direction is larger than the dimension T _{Y in} the Y direction of the target 40. By this and by reciprocating the target 40 as described above, the ion beam 4 can be incident on the entire surface of the target 40 to perform ion implantation.

  The target 40 is, for example, a semiconductor substrate, a glass substrate, or another substrate. The planar shape may be a circle or a rectangle.

  The ion source 2 also serves as an anode and is a container for generating plasma 10 therein, and includes a plasma generation container 6 having an ion extraction port 8 extending in the Y direction. The ion extraction port 8 is, for example, an ion extraction slit. The plasma generation container 6 has, for example, a rectangular parallelepiped box shape. Into this plasma generation vessel 6, a source gas (including vapor) 34 for generating plasma 10 is introduced from each gas introduction section 38 described later.

  A magnet 14 for generating a magnetic field 16 along the Y direction is provided inside the plasma generation container 6 outside the plasma generation container 6. For example, the magnet 14 is an electromagnet having magnetic poles on both sides of the plasma generation container 6 in the Y direction, but may be a permanent magnet. The direction of the magnetic field 16 may be opposite to that shown in the figure.

  The magnetic field 16 thereby functions to confine electrons in the plasma generation container 6 and prevent the electrons from colliding with the wall surface of the plasma generation container 6, thereby increasing the ionization efficiency of the source gas 34 and increasing the plasma density. . Instead of the magnet 14 as described above, a magnet for generating a cusp magnetic field along the Y direction may be provided in the plasma generation container 6.

  An indirectly heated cathode 20 that emits thermoelectrons into the plasma generation container 6 is disposed on both sides in the Y direction of the plasma generation container 6. That is, two indirectly heated cathodes 20 are provided in this embodiment.

  Each indirectly heated cathode 20 includes a cathode member 22 that emits thermoelectrons when heated, and a filament 24 that heats the cathode member 22. It is easy to increase the thickness of the cathode member 22. A more specific structure in which the cathode member 22 and the filament 24 are arranged with respect to the plasma generation vessel 6 is shown in a simplified manner in FIG. 1 (and FIGS. 3 and 4 described later), for example, Japanese Patent No. 3758667. What is necessary is just to employ | adopt a well-known structure as described in gazette etc.

  As shown in FIG. 3, each filament 24 is connected to a filament power source 26 for heating it. Each filament power supply 26 may be a DC power supply as shown in the figure, or an AC power supply.

  Between each filament 24 and the cathode member 22, the direct current bombardment which accelerates the thermoelectrons emitted from the filament 24 toward the cathode member 22 and heats the cathode member 22 using the impact of the thermoelectrons. The power supplies 28 are respectively connected with the cathode member 22 as the positive electrode side.

  Between each cathode member 22 and the plasma generation container 6, the thermoelectrons emitted from the cathode member 22 are accelerated to ionize the source gas 34 introduced into the plasma generation container 6 and to the inside of the plasma generation container 6. Are connected to each other with the cathode member 22 as the negative electrode side.

  The density of the entire plasma 10 can be increased or decreased by increasing or decreasing one or more of the outputs of each power supply 26, 28, 30.

  Referring again to FIG. 1, an extraction electrode system 12 for extracting the ion beam 4 from the plasma 10 in the plasma generation vessel 6 is provided near the outlet of the ion extraction port 8. The extraction electrode system 12 is not limited to one electrode as in the illustrated example.

  A plurality of gas introduction portions 38 for introducing the source gas 34 into the ion source 2 (more specifically, in the plasma generation vessel 6, the same applies hereinafter) are arranged in the Y direction on the wall surface of the plasma generation vessel 6. Has been. In this embodiment, the gas introduction portion 38 is provided on the wall surface facing the ion extraction port 8, but is not limited thereto, and is provided on a wall surface that is substantially orthogonal to the wall surface (that is, a wall surface along the YZ plane). It may be provided.

  The number of gas introducing portions 38 is not limited to five as shown in FIG. The same applies to a gas inlet 58 described later.

  The structure of each gas introduction part 38 is a pipe (that is, a gas introduction pipe) in the example shown in FIG. 1, but other structures may be used. For example, a nozzle shape, a porous shower head shape, or a structure in which a baffle plate is provided at a gas discharge port may be used. The same applies to each gas inlet 58 described later.

The number, arrangement interval, structure, and the like of the gas introduction portions 38 are the dimension W _{Y in} the Y direction of the ion beam 4, the accuracy of the beam current density distribution uniformization control, and the characteristics that the ion source 2 originally has (particularly the plasma density). It may be determined according to the distribution characteristics). The same applies to a gas inlet 58 described later.

  Between the gas source 32 for supplying the source gas 34 and each gas introduction part 38, a flow rate regulator 36 for adjusting the flow rate of the source gas 34 introduced from each gas introduction part 38 into the ion source 2 is provided. It has been.

  In general, the beam current density of an ion beam extracted from an ion source is proportional to the plasma density in the ion source. Therefore, also in the ion source 2, the beam current density at each position in the Y direction of the ribbon-like ion beam 4 is proportional to the density of the plasma 10 at the position corresponding to the position. The density of the plasma 10 is proportional to the density of the source gas 34 in the ion source 2. In this ion implantation apparatus, since the density of the source gas 34 in the Y direction in the ion source 2 can be controlled by adjusting the flow rate of the source gas 34 by each flow rate controller 36, the plasma density in the Y direction is thereby controlled. The distribution and thus the beam current density distribution in the Y direction can be controlled. In that case, the thermoelectrons emitted from the cathode member 22 of each indirectly heated cathode 20 reciprocate in the Y direction along the magnetic field 16 to ionize the source gas 34 introduced from each gas introduction part 38. It functions to generate plasma 10.

  For example, if the amount of the source gas 34 introduced into the ion source 2 from the gas introduction part 38 connected thereto through a certain flow controller 36 is increased, the source gas 34 is diffused in the ion source 2 even if the source gas 34 is diffused. In the vicinity of the gas introduction part 38, the density of the source gas 34 is increased, the density of the plasma 10 is also increased, and the beam current density of the ion beam 4 at the position corresponding to the gas introduction part 38 is also increased. On the other hand, when the amount of the raw material gas 34 to be introduced is reduced (including the case where it is set to 0), the density of the raw material gas 34 is lowered in the vicinity of the gas introducing portion 38, and the density of the plasma 10 is also lowered. The beam current density of the ion beam 4 at the position corresponding to the introduction part 38 is also lowered.

  That is, by adjusting the flow rate of the source gas 34 introduced from each gas introduction part 38 into the ion source 2 by each flow rate controller 36, the beam current density of the ion beam 4 at the position corresponding to each gas introduction part 38 is set. By controlling (increasing / decreasing), the beam current density distribution in the Y direction of the ion beam 4 can be controlled. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be improved regardless of whether the ion source 2 has a plurality of filaments.

  However, this does not exclude the case where the ion source 2 has a plurality of filaments. That is, the ion source 2 may have one or a plurality of filaments together with or in place of the indirectly heated cathode 20. The same applies to the embodiment shown in FIG.

  Further, instead of disposing the indirectly heated cathode 20 on both sides in the Y direction of the plasma generation vessel 6 as in the ion source 2, the indirectly heated cathode 20 is disposed on one side in the Y direction, and on the opposite side, In other words, on the other side in the Y direction, a reflective electrode that functions to reflect (repel) electrons in the plasma generation container 6 (mainly thermionic electrons from the indirectly heated cathode 20) is disposed opposite to the indirectly heated cathode 20. May be. When such a reflective electrode is provided, electrons reciprocate between the indirectly heated cathode 20 (more specifically, the cathode member 22) and the reflective electrode while turning in the magnetic field 16 about the direction of the magnetic field 16. As a result, the collision probability between the electrons and the source gas molecules is increased, and the ionization efficiency of the source gas is increased, so that the generation efficiency of the plasma 10 is increased. Therefore, even if the indirectly heated cathode 20 is provided on one side, an effect close to that provided on both sides can be achieved. The same applies to the embodiment shown in FIG.

  A beam current density in the Y direction by receiving the ion beam 4 in the vicinity of the downstream side of the implantation position where the ion beam 4 is incident on the target 40 (in the case of the example of FIGS. 1 and 4) or the upstream side. A beam measuring device 46 for measuring the distribution may be provided and used to adjust each flow controller 36 (or a flow controller 56 described later).

  When the beam measuring device 46 is provided on the downstream side of the implantation position, the target 40 and the holder 42 may be moved to a position that does not interfere with the measurement at the time of measurement. When the beam measuring device 46 is provided on the upstream side of the implantation position, the beam measuring device 46 may be moved to a position that does not interfere with the implantation when ions are implanted into the target 40.

In this example, the beam measuring device 46 is a multi-point beam measuring device in which a large number of measuring devices (for example, Faraday cups) for measuring the beam current of the ion beam 4 are arranged in parallel in the Y direction. It is also possible to use a structure that moves the lens in the Y direction by a moving mechanism. With respect to the X direction, each measuring device is preferably of a size that can cover the dimension W _X in the X direction of the ion beam 4 at the measurement position. This is because the target 40 is scanned along the X direction as described above, and the integrated value of the ion beam 4 in the X direction affects the ion implantation amount. From this beam measuring device 46 is measured information D _P representative of the beam current density distribution is output. The measurement information D _P includes a plurality of n ₃ pieces of measurement information (n ₃ is the same as the number of Faraday cups).

Then, based on the measurement information D _P by the beam measuring device 46, for example, the worker adjusts each flow rate adjuster 36, and the raw material introduced from the gas introducing portion 38 corresponding to the region where the beam current density is relatively large. At least one of decreasing the flow rate of the gas 34 (including the case where the gas current density is set to 0) and increasing the flow rate of the source gas 34 introduced from the gas introduction unit 38 corresponding to the region where the beam current density is relatively small. The beam current density distribution in the Y direction of the ion beam 4 at the implantation position is made uniform.

According to this adjustment method, the flow rate adjuster 36 is adjusted based on the measurement information D _P by the beam measuring device 46 to adjust the flow rate of the source gas 34 introduced from the gas introduction unit 38 into the ion source 2. The beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be made uniform more easily and reliably.

As in the embodiment shown in FIG. 1, each flow rate adjuster 36 is controlled based on the measurement information D _P from the beam measuring device 46, and the ion beam at the implantation position is controlled according to the same control content as the adjustment method described above. 4 may be provided with a control device 50 that performs control to equalize the beam current density distribution in the Y direction. As a result, the adjustment for improving the uniformity of the beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be performed while saving labor. In this example, the controller 50 outputs a plurality of n ₁ control signals S ₁ (n ₁ is the same as the number of the flow regulators 36) and supplies the control signals S ₁ to the respective flow regulators 36. 36 are controlled.

  FIG. 4 is a schematic side view showing another embodiment of the ion implantation apparatus according to the present invention. Parts that are the same as or correspond to those in the embodiment of FIG. 1 are denoted by the same reference numerals, and in the following, differences from the embodiment of FIG. 1 will be mainly described.

  The transport path of the ion beam 4 from the ion source 2 to the target 40 and further to the beam measuring device 46 is in a vacuum vessel 48 and kept in a vacuum atmosphere. That is, the inside of the vacuum vessel 48 is evacuated by an evacuation device (not shown). The vacuum vessel 48 may be divided into a plurality of vacuum vessels. A part of the target driving device 44 may be provided outside the vacuum vessel 48, for example.

  In the case of this embodiment, the ion source 2 may be provided with at least one gas introduction part 38 for introducing the source gas 34, but it is preferable to provide a plurality of gas introduction parts 38.

  A plurality of gas introducing portions 58 for introducing the inert gas 54 into the transport path of the ion beam 4 between the ion source 2 and the implantation position with respect to the target 40 are provided on the wall surface of the vacuum vessel 48 (the wall surface along the YZ plane). They are arranged side by side. In this embodiment, each gas introducing portion 58 is provided on the wall surface on one side of the vacuum vessel 48, which is usually sufficient, but may be provided on the wall surfaces on both sides as necessary.

The structure of each gas inlet 58 is the same as that described above for the gas inlet 38, for example. The number, arrangement interval, structure, and the like of the gas introduction portions 58 are also the characteristics of the ion source 2 that the ion source 2 originally has, that is, the dimension W _{Y of} the ion beam 4 in the Y direction, the accuracy of the beam current density distribution uniformization control, and the like. It may be determined according to the density distribution characteristics).

  Between the gas source 52 that supplies the inert gas 54 and each flow rate regulator 56, a flow rate regulator that regulates the flow rate of the inert gas 54 that is introduced into the transport path of the ion beam 4 from each gas introduction unit 58. 56 are provided.

The inert gas 54 is an inert gas in a broad sense in this specification, and is a noble gas (He, Ne, Ar, Kr, Xe, Rn) or nitrogen (N ₂ ) gas. A mixed gas of these plural kinds of gases may be used.

Among these, it is preferable to use a gas having a large ionization cross section such as N ₂ , Ar, and Xe, so that the beam plasma can be generated more efficiently.

  The ion beam 4 diverges due to its own space charge, and the transport efficiency decreases. More specifically, divergence due to space charge of the ion beam 4 occurs in both the X and Y directions. Here, attention is paid to the divergence in the X direction. When the ion beam 4 diverges in the X direction, the ion beam 4 is a structure existing in the transport path, for example, an analysis electromagnet that performs momentum analysis of the ion beam 4, an analysis slit, a mask that shapes the ion beam 4, and a vacuum container. It becomes easy to collide with the wall surface etc. of this, and the transport efficiency to the target 40 of the ion beam 4 falls.

  When the inert gas 54 is introduced into the transport path of the ion beam 4, the ion beam 4 collides with the inert gas 54, and the inert gas 54 is ionized to generate beam plasma. Since the space charge of the ion beam 4 is neutralized by electrons and negative ions in the beam plasma, divergence of the ion beam 4 in the X direction is suppressed, and the transport efficiency of the ion beam 4 is improved. In that case, in the region where the density of the inert gas 54 is increased, the collision probability of the ion beam 4 against the inert gas 54 is increased, the density of the beam plasma is increased, the space charge neutralization rate is increased, and the ion beam 4 is increased. The transportation efficiency of is high. The reverse is true for the reversed area.

  In this ion implantation apparatus, the density of the inert gas 54 in the Y direction of the transport path of the ion beam 4 can be controlled by adjusting the flow rate of the inert gas 54 by each flow rate regulator 56, thereby By controlling the beam plasma density distribution in the Y direction, the amount of ion beam that reaches the implantation position can be controlled at a plurality of positions in the Y direction.

  For example, if the amount of the inert gas 54 introduced into the transport path of the ion beam 4 from the gas introduction part 58 connected thereto through a certain flow controller 56 is increased, the inert gas 54 is diffused in the transport path of the ion beam 4. Even in consideration, the density of the inert gas 54 is increased in the vicinity of the gas introduction part 58, the density of the generated beam plasma is also increased, and as a result, the X direction of the ion beam 4 at the position corresponding to the gas introduction part 58 is increased. The ion beam 4 transport efficiency is increased, and the amount of the ion beam 4 that reaches the implantation position is increased at the Y-direction position corresponding to the gas introduction part 58. On the contrary, if the amount of the inert gas 54 to be introduced is reduced (including the case where it is set to 0), the density of the inert gas 54 is reduced in the vicinity of the gas introducing portion 58, and the density of the generated beam plasma is also reduced. As a result, the suppression of the divergence of the ion beam 4 at the position corresponding to the gas introduction part 58 is reduced, and the improvement of the transport efficiency of the ion beam 4 is reduced, and the injection position is reached at the Y direction position corresponding to the gas introduction part 58. The amount of ion beam 4 to be reduced is reduced.

  That is, the beam plasma density at the position corresponding to each gas introduction unit 58 is controlled by adjusting the flow rate of the inert gas 54 introduced from each gas introduction unit 58 into the transport path of the ion beam 4 by each flow rate regulator 56. The amount of the ion beam 4 reaching the implantation position can be controlled at a plurality of positions in the Y direction. Therefore, the uniformity of the beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be improved with a simpler configuration than when an electric field lens or a magnetic lens is used.

  The gas introduction part 58 is preferably provided in a place having a relatively high degree of vacuum in the transport path of the ion beam 4 from the ion source 2 to the target 40. This is because the difference between the case where a large amount of inert gas 54 is introduced to generate a thick beam plasma and the case where a small amount of inert gas 54 is introduced to thin the beam plasma becomes clearer.

  For example, as described in Patent Document 1, an analysis electromagnet that performs momentum analysis of the ion beam 4 may be provided in the transport path of the ion beam 4. When such an analysis electromagnet 62 is shown in a simplified manner by a two-dot chain line in FIG. 4, the degree of vacuum is relatively high in the vicinity of the downstream side of the analysis electromagnet 62. It may be provided.

  If it is difficult to generate a beam plasma simply by introducing the inert gas 54 from the gas introduction part 58 into the transport path of the ion beam 4 in relation to the energy of the ion beam 4, an electron source 66 is provided and then generated. It is also possible to cause the electron beam 68 to travel in the Y direction so as to pass in the vicinity of the front of each gas introducing portion 58 arranged in the Y direction. That is, the generation of beam plasma may be assisted by the electron beam 68. By doing so, since the electron beam 68 has a higher ionization capability than ions, it becomes easier to generate plasma by ionizing the inert gas 54 introduced from each gas introduction part 58. The energy of the electron beam 68 may be about 300 eV to 500 eV, for example.

Also in this embodiment, as in the previous embodiment, based on the measurement information D _P by the beam measuring device 46, for example, an operator adjusts each flow rate adjuster 56 so that the beam current density becomes relative. Reducing the flow rate of the inert gas 54 introduced from the gas introduction unit 58 corresponding to a large region (including the case where the inert gas 54 is set to 0) and the gas introduction unit 58 corresponding to a region where the beam current density is relatively small. An adjustment method may be adopted in which at least one of increasing the flow rate of the inert gas 54 introduced from is performed to uniformize the beam current density distribution in the Y direction of the ion beam 4 at the implantation position.

According to this adjustment method, the flow rate adjuster 56 is adjusted based on the measurement information D _P by the beam measuring device 46 to adjust the flow rate of the inert gas 54 introduced from the gas introduction unit 58 into the ion beam path. The beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be made uniform more easily and reliably.

Further, as in the embodiment shown in FIG. 4, each flow rate adjuster 56 is controlled based on the measurement information D _P from the beam measuring device 46, and the control content similar to the adjustment method described above is used at the injection position. You may provide the control apparatus 60 which performs control which makes the beam current density distribution in the Y direction of the ion beam 4 uniform. As a result, the adjustment for improving the uniformity of the beam current density distribution in the Y direction of the ion beam 4 at the implantation position can be performed while saving labor. In this example, the control device 60 outputs a plurality of n ₂ (n ₂ is the same as the number of the flow regulators 56) control signals S ₂ and gives them to the respective flow regulators 56. 56 are controlled.

1 is a schematic side view showing an embodiment of an ion implantation apparatus according to the present invention. It is a schematic perspective view which shows an example of a ribbon-shaped ion beam partially. It is a figure which shows an indirectly heated cathode with a power supply. It is a schematic side view which shows other embodiment of the ion implantation apparatus which concerns on this invention.

Explanation of symbols

2 ion source 4 ion beam 10 plasma 32 gas source 34 source gas 36 flow rate regulator 38 gas introduction unit 40 target 44 target drive unit 46 beam measuring instrument 50 control unit 52 gas source 54 inert gas 56 flow rate regulator 58 gas introduction unit 60 Control device

Claims (6)

When the source gas is ionized to generate plasma and the two directions substantially perpendicular to each other are the X direction and the Y direction, the dimension in the Y direction is larger than the dimension in the X direction and larger than the dimension in the Y direction of the target. An ion source that generates a large ribbon-shaped ion beam,
In an ion implantation apparatus comprising: a target driving device that moves the target in a direction intersecting with the main surface of the ion beam at an implantation position where the ion beam is incident on the target;
A plurality of gas introduction portions that introduce the source gas into the ion source and are arranged in the Y direction;
An ion implantation apparatus comprising: a plurality of flow rate regulators that respectively regulate the flow rates of the source gases introduced from the gas introduction units. A beam measuring device that receives the ion beam and measures a beam current density distribution in the Y direction in the vicinity of the upstream side or the downstream side of the implantation position;
Based on the measurement information by the beam measuring device, the flow rate controller is controlled to reduce the flow rate of the source gas introduced from the gas introducing unit corresponding to the region where the beam current density is relatively large; At least one of increasing the flow rate of the source gas introduced from the gas introduction portion corresponding to the region where the current density is relatively small is performed, and the beam current density distribution in the Y direction of the ion beam at the implantation position is made uniform. The ion implantation apparatus according to claim 1, further comprising: a control device that performs control to convert to an ion.   2. The ion measuring apparatus according to claim 1, wherein a beam measuring device that receives the ion beam in the vicinity of the upstream side or the downstream side of the implantation position and measures the beam current density distribution in the Y direction is used. And adjusting the flow rate controller to reduce the flow rate of the source gas introduced from the gas inlet corresponding to the region where the beam current density is relatively large, and the beam current density is relatively And at least one of increasing the flow rate of the source gas introduced from the gas introduction portion corresponding to a small area to uniformize the beam current density distribution in the Y direction of the ion beam at the implantation position. A method for adjusting an ion implantation apparatus, which is characterized. When the source gas is ionized to generate plasma and the two directions substantially perpendicular to each other are the X direction and the Y direction, the dimension in the Y direction is larger than the dimension in the X direction and larger than the dimension in the Y direction of the target. An ion source that generates a large ribbon-shaped ion beam,
In an ion implantation apparatus comprising: a target driving device that moves the target in a direction intersecting with the main surface of the ion beam at an implantation position where the ion beam is incident on the target;
A plurality of gas introduction portions arranged in the Y direction, each for introducing an inert gas into a transport path of the ion beam between the ion source and the implantation position;
An ion implantation apparatus comprising: a plurality of flow rate adjusters that respectively adjust flow rates of the inert gases introduced from the gas introduction units. A beam measuring device that receives the ion beam and measures a beam current density distribution in the Y direction in the vicinity of the upstream side or the downstream side of the implantation position;
Based on the measurement information by the beam measuring device, the flow rate controller is controlled to reduce the flow rate of the inert gas introduced from the gas introducing unit corresponding to the region where the beam current density is relatively large; The beam current density distribution in the Y direction of the ion beam at the implantation position by performing at least one of increasing the flow rate of the inert gas introduced from the gas introduction portion corresponding to the region where the beam current density is relatively small. The ion implantation apparatus according to claim 4, further comprising a control device that performs control for equalizing the pressure.   5. The ion measuring apparatus according to claim 4, wherein a beam measuring device that receives the ion beam in the vicinity of the upstream side or the downstream side of the implantation position and measures the beam current density distribution in the Y direction is used. And adjusting the flow rate controller to reduce the flow rate of the inert gas introduced from the gas inlet corresponding to the region where the beam current density is relatively large, and the beam current density is At least one of increasing the flow rate of the inert gas introduced from the gas introduction portion corresponding to a relatively small region is performed to uniformize the beam current density distribution in the Y direction of the ion beam at the implantation position. A method for adjusting an ion implantation apparatus.

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