JP2008112673A - Ion implanting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the uniformity of an longitudinal direction (Y direction) ion beam current density distribution at an implantation position to a substrate. <P>SOLUTION: This ion implanting device includes an ion source 100 for generating an ion beam 50, an electron beam source Gn for emitting an electron beam 138 scanned in the Y direction to generate plasma 12, a power source 114 for the electron beam source, an ion beam monitor 80 for measuring the Y direction beam current density distribution of the ion beam 50 in the vicinity of the implanting position, and a control device 90. The control device 90 controls the power source 114 based on the measured data from the monitor 80, thereby increasing the scanning speed of the electron beam 138 at a position corresponding to the monitor point at which the beam current density measured by the monitor 80 is large, but decreasing the scanning speed of the electron beam 138 at a position corresponding to the monitor point at which the beam current density measured by the monitor 80 is small, which provides the uniformity of the Y direction beam current density measured by the monitor 80. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ion implantation apparatus that implants ions into a substrate by using a ribbon-like ion beam incident on the substrate and moving the substrate in a direction intersecting the main surface of the ion beam.

  In this type of ion implantation apparatus, in order to improve the uniformity of ion implantation with respect to the substrate, the longitudinal direction (in this specification) of the ion beam in the form of a ribbon (which may be referred to as a sheet shape or a band shape). It is important that the uniformity of the ion beam current density distribution in the Y direction is good.

  As a technique for improving the uniformity of the ion beam current density distribution in the longitudinal direction of a ribbon-like ion beam, for example, in Patent Document 1, an electron beam scanned in one dimension is incident on a plasma generation container of an ion source. A technique for improving the beam current density distribution of an ion beam extracted from an ion source by ionizing a gas with this electron beam to generate plasma is described.

Japanese Patent Laying-Open No. 2005-38689 (paragraphs 0006-0008, FIG. 1)

  In the technique described in Patent Document 1, even if the uniformity of the ion beam extracted from the ion source can be improved, the uniformity may deteriorate during the transport of the ion beam. There is no guarantee that the uniformity of the current density distribution is good.

  Accordingly, the main object of the present invention is to provide an ion implantation apparatus capable of improving the uniformity of the ion beam current density distribution in the longitudinal direction (Y direction) at the implantation position with respect to the substrate.

In the first ion implantation apparatus according to the present invention, the traveling direction of the ion beam is the Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are the X direction and the Y direction. An ion implantation apparatus that transports a ribbon-like ion beam having a dimension in the Y direction larger than a dimension in the X direction and irradiates the ribbon-like ion beam to perform ion implantation,
(A) a plasma generation container into which a gas is introduced, and an electron beam generated and emitted into the plasma generation container to ionize the gas by the electron beam to generate plasma, One or more electron beam sources that scan the electron beam in the Y direction in the plasma generation container, and an extraction electrode system that extracts the ion beam from the plasma generated in the plasma generation container, An ion source for generating the ribbon-like ion beam having a dimension larger than a dimension in the Y direction of the substrate;
(B) a substrate driving device that moves the substrate in a direction intersecting a main surface of the ion beam at an implantation position where the ion beam is incident on the substrate;
(C) one or more electron beam power supplies for supplying each electron beam source with an extraction voltage for controlling the generation amount of the electron beam and a scanning voltage for scanning,
(D) an ion beam monitor that measures an ion beam current density distribution in the Y direction of the ion beam at a plurality of monitor points in the Y direction at or near the implantation position;
(E) By controlling the electron beam power source based on the measurement data from the ion beam monitor, the amount of the electron beam generated from each electron beam source is kept substantially constant while the ion beam monitor is kept constant. A relatively high scanning speed of the electron beam at a position in the ion source corresponding to a monitor point having a relatively large ion beam current density measured in step 1, and a monitor point having a relatively small ion beam current density measured A function of equalizing the ion beam current density distribution in the Y direction measured by the ion beam monitor by performing at least one of relatively reducing the scanning speed of the electron beam at the position in the ion source corresponding to And a control device.

  In the first ion implantation apparatus, the ion beam current density distribution in the Y direction at or near the implantation position is measured by an ion beam monitor. The control device controls the electron beam power source based on the measurement data from the ion beam monitor, controls the scanning speed of the electron beam in the plasma generation container of the ion source, and generates plasma generated by the electron beam. To control the density. Specifically, the amount of the electron beam generated from each electron beam source is kept substantially constant, while the ion beam current density measured by the ion beam monitor is at a position in the ion source corresponding to the monitor point having a relatively large ion beam current density. At least one of relatively increasing the scanning speed of the electron beam and relatively decreasing the scanning speed of the electron beam at the position in the ion source corresponding to the monitor point where the measured ion beam current density is relatively small. To control the ion beam current density distribution in the Y direction measured by the ion beam monitor to be uniform. Thereby, the uniformity of the ion beam current density distribution in the Y direction at the implantation position can be improved.

  (A) a function of supplying the scanning device to each electron beam power source with a scanning signal that is a source of the scanning voltage supplied from the electron beam power source to each electron beam source; A function for calculating an error in the Y direction distribution, which is a difference between the measured ion beam current density in the Y direction distribution and a predetermined set ion beam current density, a monitor point where the calculated error is greater than a predetermined allowable error, and a monitor thereof A function for determining the sign of error at a point, a function for determining the electron beam source corresponding to the determined monitor point and its scanning voltage, and the measured ion beam current based on the sign of the determined error The scanning speed of the electron beam at a scanning voltage corresponding to a monitor point having a higher density is increased in proportion to the magnitude of the error, and the measured ions The scanning speed of the electron beam at a scanning voltage corresponding to a monitoring point having a smaller beam current density is decreased in proportion to the magnitude of the error so that substantially all the monitoring points where the ion beam is incident are used. It has a function of shaping the waveform of the scanning signal so that the error is equal to or less than the allowable error, and a function of saving data of the shaped scanning signal. The beam power supply may include an amplifier that amplifies a scanning signal supplied from the control device to generate the scanning voltage.

In the second ion implantation apparatus according to the present invention, if the traveling direction of the ion beam is the Z direction, and the two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are the X direction and the Y direction, An ion implantation apparatus that transports a ribbon-like ion beam having a dimension in the Y direction larger than a dimension in the X direction and irradiates the ribbon-like ion beam to perform ion implantation,
(A) a plasma generation container into which a gas is introduced, and an electron beam generated and emitted into the plasma generation container to ionize the gas by the electron beam to generate plasma, One or more electron beam sources that scan the electron beam in the Y direction in the plasma generation container, and an extraction electrode system that extracts the ion beam from the plasma generated in the plasma generation container, An ion source for generating the ribbon-like ion beam having a dimension larger than a dimension in the Y direction of the substrate;
(B) a substrate driving device that moves the substrate in a direction intersecting a main surface of the ion beam at an implantation position where the ion beam is incident on the substrate;
(C) one or more electron beam power supplies for supplying each electron beam source with an extraction voltage for controlling the generation amount of the electron beam and a scanning voltage for scanning,
(D) an ion beam monitor that measures an ion beam current density distribution in the Y direction of the ion beam at a plurality of monitor points in the Y direction at or near the implantation position;
(E) controlling the electron beam power source based on measurement data from the ion beam monitor, thereby maintaining the scanning speed of the electron beam generated from each electron beam source substantially constant, A relatively small amount of the electron beam generated at a position in the ion source corresponding to a monitor point having a relatively large ion beam current density measured by the monitor, and a monitor having a relatively small ion beam current density measured. A function of making the ion beam current density distribution in the Y direction measured by the ion beam monitor uniform by performing at least one of relatively increasing the generation amount of the electron beam at the position in the ion source corresponding to the point. And a control device having

  In the second ion implantation apparatus, the ion beam current density distribution in the Y direction at or near the implantation position is measured by an ion beam monitor. The control device controls the electron beam power source based on the measurement data from the ion beam monitor, controls the generation amount of the electron beam from the electron beam source, and generates the electron beam in the plasma generation container. Control the density of plasma. Specifically, ions corresponding to monitor points having a relatively large ion beam current density measured by an ion beam monitor while keeping the scanning speed of the electron beam generated from each electron beam source in the Y direction substantially constant. Reducing the generation amount of the electron beam at the source position relatively, and increasing the generation amount of the electron beam at the ion source position corresponding to the monitor point where the measured ion beam current density is relatively small. By performing at least one of the above, control is performed to make the ion beam current density distribution in the Y direction measured by the ion beam monitor uniform. Thereby, the uniformity of the ion beam current density distribution in the Y direction at the implantation position can be improved.

  (A) a function of supplying the control device with an extraction signal that is a source of the extraction voltage supplied from the electron beam power source to the electron beam source to the electron beam power source; A function for calculating an error in the Y direction distribution, which is a difference between the measured ion beam current density in the Y direction distribution and a predetermined set ion beam current density, a monitor point where the calculated error is greater than a predetermined allowable error, and a monitor thereof A function for determining the sign of error at a point, a function for determining the electron beam source corresponding to the determined monitor point and its scanning voltage, and the measured ion beam current based on the sign of the determined error The extraction voltage at the time of the scanning voltage corresponding to a monitor point having a higher density is reduced in proportion to the magnitude of the error, and the measured ion beam The extraction voltage at the scanning voltage corresponding to a monitor point having a smaller flow density is increased in proportion to the magnitude of the error, and the error is allowed at substantially all the monitor points where the ion beam is incident. It has a function of shaping the waveform of the extraction signal so as to be equal to or less than an error, and a function of storing data of the extraction signal after the shaping, and (b) the power source for each electron beam, An amplifier for amplifying an extraction signal supplied from the control device to generate the extraction voltage may be provided.

  According to the first to sixth aspects of the present invention, since the configuration is as described above, it is possible to improve the uniformity of the ion beam current density distribution in the Y direction at the implantation position with respect to the substrate. As a result, the uniformity of ion implantation for the substrate can be improved.

  FIG. 1 is a schematic side view showing an embodiment of an ion implantation apparatus according to the present invention. In this specification and the drawings, the traveling direction of the ion beam 50 is always the Z direction, and the two directions substantially orthogonal to each other in the plane substantially orthogonal to the Z direction are the X direction and the Y direction. For example, the X direction and the Z direction are horizontal directions, and the Y direction is a vertical direction. The Y direction is a constant direction, but the X direction is not an absolute direction. The ion beam transport system 170 may be bent in the XZ plane, and the X direction in that case varies depending on the position of the ion beam 50 on the path. Further, in this specification, the case where ions constituting the ion beam 50 are positive ions is described as an example.

  This ion implantation apparatus is configured to generate a ribbon-like ion beam 50 from the ion source 100, transport it to the substrate 60, irradiate the substrate 60, and perform ion implantation on the substrate 60. The path of the ion beam 50 from the ion source 100 to the substrate 60 is in a vacuum container (not shown) and is maintained in a vacuum atmosphere.

The ion beam 50 generated from the ion source 100 and transported to the substrate 60 has, for example, a ribbon shape in which the dimension W _{Y in the} Y direction is larger than the dimension W _X in the X direction, as shown in FIG. That is, W _Y > W _X. Even if the ion beam 50 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 50 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 substrate 60. The larger surface of the ion beam 50, that is, the surface along the YZ plane is the main surface 52.

  The ion beam transport system 170 from the ion source 100 to the substrate 60 may be linear or bent. The ion beam transport system 170 may include, for example, an analysis electromagnet that performs momentum analysis (for example, mass analysis) of the ion beam 50. In this case, the ion beam transport system 170 is bent in the XZ plane. The ion beam transport system 170 may include elements other than the analysis electromagnet, such as an analysis slit, an accelerator / decelerator for the ion beam 50, and the like.

  This ion implantation apparatus has a holder 502 for holding the substrate 60, and intersects the main surface 52 (see FIG. 2) of the ion beam 50 at an implantation position where the ion beam 50 is incident on the substrate 60. A substrate driving device 500 that moves in the direction is provided. This movement is, for example, a reciprocating linear movement. An example of the moving direction is indicated by an arrow C in FIG. This moving direction is not limited to the direction parallel to the X direction, and may have a predetermined angle (an angle corresponding to the injection angle) from the X direction.

The ion source 100 generates a ribbon-like ion beam 50 in which the dimension W _{Y in} the Y direction is larger than the dimension T _{Y in} the Y direction of the substrate 60. For example, if the dimension T _Y is 300 mm to 400 mm, the dimension W _Y is about 400 mm to 500 mm. By such a dimensional relationship and the movement of the substrate 60 as described above, ion implantation can be performed by irradiating the entire surface of the substrate 60 with the ion beam 50.

  The substrate 60 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 100 includes a plasma generation container 118 for generating a plasma 124 and one or more (three in this embodiment) electron beam sources that emit an electron beam 138 scanned in the Y direction into the plasma generation container 118. Gn and an extraction electrode system 126 for extracting the ion beam 50 from the plasma 124 generated in the plasma generation container 118 are provided.

The plasma generation container 118 is a container for generating a plasma 124 by introducing a desired gas (including the case of vapor) 120 from a gas introduction port 119 and ionizing it by impact with an electron beam 138. The gas 120 is a gas containing a desired element (for example, a dopant such as B, P, or As). More specific examples include gases containing source gases such as BF ₃ , PH ₃ , AsH ₃ , and B ₂ H ₆ .

  A plurality of gas inlets 119 may be provided in the Y direction as necessary. By doing so, it becomes easy to make the plasma density distribution uniform by making the gas concentration distribution in the plasma generation vessel 118 uniform.

  As shown in FIG. 3, the plasma generation container 118 has slit-like ion extraction holes 122 extending in the Y direction on the front surface thereof. However, the ion extraction holes 122 may be small holes, and a plurality (many) of them may be arranged in the Y direction. The shape, arrangement, and the like of the ion extraction holes 122 may be set in accordance with the cross-sectional shape of the ion beam 50 to be extracted. The same applies to ion extraction holes 128 of an extraction electrode system 126 described later.

  The extraction electrode system 126 is provided in the vicinity of the downstream side of the ion extraction hole 122 and has one or more (two in the illustrated example) electrodes. Each electrode has an ion extraction hole 128 having a shape and arrangement corresponding to the ion extraction hole 122. The number of electrodes constituting the extraction electrode system 126 is not limited to the example shown in the drawing, and may be one or more.

  In this example, the plasma generation container 118 has an electron beam incident port 121 through which the electron beam 138 emitted from each electron beam source Gn enters the plasma generation container 118 on the surface opposite to the ion extraction hole 122. is doing. The number of electron beam entrances 121 may be the same as the number of electron beam sources Gn.

  Each electron beam source Gn generates an electron beam 138, emits it into the plasma generation container 118, ionizes the gas 120 by impact by the electron beam 138, and generates a plasma 124. The electron beam 138 is scanned one-dimensionally in the Y direction in the plasma generation container 118.

  Each electron beam source Gn may be partly or wholly located in the plasma generation container 118. However, as in this embodiment, each electron beam source Gn should be arranged near the outside of the plasma generation container 118. This is preferable from the viewpoint of avoiding mutual interference between the electron beam source Gn and the plasma 124. Further, as in this embodiment, each electron beam source Gn is preferably disposed in a differential evacuation chamber 130 that is evacuated separately from the plasma generation vessel 118 as indicated by an arrow Q. By doing so, the degree of vacuum in each electron beam source Gn can be improved, so that the function of each electron beam source Gn is prevented from being deteriorated by the gas 120 introduced into the plasma generation container 118. Can do.

Each electron beam source Gn is supplied with an extraction voltage for controlling the generation amount of the electron beam 138 and a scanning voltage for Y-direction scanning from the corresponding electron beam power supply 114. The number of the electron beam source Gn and the number of electron beam power sources 114 for the electron beam source Gn is three in this embodiment. However, the number of electron beam sources Gn is not limited to three. That is, the number of both is arbitrary with 1 or more, and may be appropriately selected according to the required dimension W _{Y of} the ion beam 50 in the Y direction.

  A magnet for forming a multipolar magnetic field (multicusp magnetic field) for generating and maintaining the plasma 124 may be disposed around the plasma generation container 118. The ion source having such a structure is also called a bucket type ion source (or a multipole magnetic field type ion source).

  An example of the configuration of each electron beam source Gn and each electron beam power supply 114 is shown in FIG.

  In this embodiment, each electron beam source Gn is disposed between a filament 140 that emits electrons (thermoelectrons), an anode 144 that extracts the electrons as an electron beam 138, and both 140 and 144. It has an extraction electrode 142 that controls the amount of electron beam generation without changing energy, and a pair of scanning electrodes 146 that scan an electron beam 138 taken out in the Y direction. These are housed in a cylindrical case 148 made of metal. In this embodiment, the case 148 and the anode 144 are electrically connected to the plasma generation vessel 118 via a terminal 168 in order to fix their potentials.

  With such a configuration, each electron beam source Gn generates an electron beam 138 and emits it into the plasma generation container 118 of the ion source 100, and the electron beam 138 ionizes the gas 120 to generate the plasma 124. Can be generated. In addition, the electron beam 138 can be scanned one-dimensionally in the Y direction in the plasma generation container 118.

  Further, if the components (filament 140, extraction electrode 142, anode 144, scanning electrode 146) of the electron beam source Gn are housed and integrated in the case 148 as in this example, the number of electron beam sources Gn is reduced. Increase / decrease, exchange of the electron beam source Gn, etc. are facilitated.

  Each electron beam power source 114 includes a filament power source 150 for heating the filament 140, an extraction power source 152 for applying a DC extraction voltage Ve for controlling the generation amount of the electron beam 138 between the filament 140 and the extraction electrode 142, and An energy control power source 154 that applies a DC anode voltage Va between the filament 140 and the anode 144 and an amplifier 156 that applies a scanning voltage Vy for Y-direction scanning between the pair of scanning electrodes 146 are provided. The filament power supply 150 is a DC power supply in this embodiment, but may be an AC power supply.

  The amplifier 156 amplifies (voltage amplifies) a scanning signal Sy supplied from the control device 90 described later to generate (output) the scanning voltage Vy. In this example, the scanning voltage Vy is swung in the ± direction with reference to the potential of the anode 144. With such a configuration, each electron beam power supply 114 supplies, to each electron beam source Gn corresponding thereto, an extraction voltage Ve for controlling the generation amount of the electron beam 138, a scanning voltage Vy for Y-direction scanning, and the like. be able to.

  Simply speaking, the energy of the electron beam 138 taken out from the electron beam source Gn is determined by the magnitude of the anode voltage Va, and the energy is Va [eV]. The energy of the electron beam 138 is set such that the gas 120 can be ionized by electron impact in the plasma generation container 118. For example, when the gas 120 is the kind of gas as described above, it may be set to about 500 eV to 3 keV, more specifically about 1 keV.

Referring to FIG. 1 again, this ion implantation apparatus has a beam current density in the Y direction of the ion beam 50 at or near the implantation position where the ion beam 50 is incident on the substrate 60 and at a plurality of monitoring points in the Y direction. An ion beam monitor 80 that measures the distribution and outputs measurement data D ₁ representing the beam current density distribution, and a control that controls each electron beam power supply 114 based on the measurement data D ₁ provided from the ion beam monitor 80. Device 90. In this example, the control device 90 has a function of supplying the scanning signal Sy that is the source of the scanning voltage Vy.

  The ion beam monitor 80 may be provided near the rear of the implantation position (in other words, downstream) as in the example shown in FIG. 1, for example, or near the front of the implantation position (in other words, upstream). Alternatively, it may be moved to the injection position. The ion beam monitor 80, the substrate 60, and the holder 502 may be configured not to interfere with each other. For example, when the ion beam monitor 80 is provided near the rear of the implantation position, the substrate 60 and the holder 502 may be moved to a position that does not interfere with the measurement during measurement. When the ion beam monitor 80 is provided near the front of the implantation position, the ion beam monitor 80 may be moved to a position that does not interfere with the implantation at the time of implantation.

The ion beam monitor 80 measures the ion beam current density distribution in the Y direction of the ion beam 50 at a plurality of monitor points in the Y direction. The ion beam monitor 80 has a plurality (a large number) of beam current measuring devices (for example, Faraday cups) 82 arranged in the Y direction, for example, as in the example shown in FIG. The plurality of beam current measuring devices 82 may be arranged in the Y direction somewhat longer than the dimension W _Y in the Y direction of the ion beam 50 as in this example. By doing so, the entire Y direction of the ion beam 50 can be measured. Each beam current measuring device 82 corresponds to each monitor point.

Each beam current measuring device 82 has a strip shape extending in the X direction in this example. In this case, each beam current measuring device 82 is set such that the dimension in the X direction is larger than the dimension W _{X in} the X direction of the ion beam 50 incident thereon, as in this example. It may be possible to receive the entire beam 50. By doing so, the influence of the ion beam current density distribution in the X direction of the ion beam 50 can be eliminated. In other words, the average ion beam current density can be measured in the X direction. As described above, the substrate 60 is moved along the X direction (not necessarily parallel to the X direction). Therefore, if each beam current measuring device 82 is set as described above, actual ion implantation into the substrate 60 is performed. In a close state, the ion beam current density distribution of the ion beam 50 can be measured.

  However, the number, shape, arrangement, etc. of the beam current measuring devices 82 are not limited to those shown in FIG. For example, a plurality of circular beam current measuring devices 82 may be arranged in the Y direction.

  The ion beam monitor 80 may have a structure in which one beam current measuring device 82 is moved in the Y direction by a moving mechanism.

In this specification, the monitor point is not a point having no mathematical area, but a predetermined area whose dimension in the Y direction is sufficiently smaller than the dimension W _Y in the Y direction of the ion beam 50. It is a small measurement point having

  Since the area of each monitoring point is known in advance, measuring the beam current of the ion beam 50 at each monitoring point is substantially the same as measuring the beam current density at each monitoring point. This is because the beam current density at each monitor point can be obtained by dividing the beam current measured at each monitor point by the area.

  In this embodiment, the control device 90 includes a computer having a CPU, a storage device, an input AD converter, an output DA converter, and the like. The control device 90 has a function of performing the following control (A) or (B). The controls (A) and (B) are not performed simultaneously.

(A) Scanning speed control of electron beam In this case, the control device 90 generates each electron beam source Gn by controlling each electron beam power source 114 based on the measurement data D ₁ from the ion beam monitor 80. While maintaining the amount of the electron beam 138 substantially constant, (a) in the ion source corresponding to a monitor point having a relatively large ion beam current density measured by the ion beam monitor 80 (more specifically, the plasma generation container). 118. Similarly, the scanning speed of the electron beam 138 at the position is relatively increased, and (b) the electron beam at the position in the ion source corresponding to the monitor point where the measured ion beam current density is relatively small. The ion beam current density in the Y direction measured by the ion beam monitor 80 is obtained by both reducing the scanning speed of 138 relatively. It has the function to homogenize the distribution.

(B) Control of Electron Beam Amount In this case, the controller 90 controls the electron beam power source 114 based on the measurement data D ₁ from the ion beam monitor 80, thereby generating electrons generated from each electron beam source Gn. While keeping the scanning speed of the beam 138 in the Y direction substantially constant, (a) the position of the electron beam 138 at the position in the ion source corresponding to the monitor point where the ion beam current density measured by the ion beam monitor 80 is relatively large. Both the generation amount is relatively reduced, and (b) the generation amount of the electron beam 138 is relatively increased at the position in the ion source corresponding to the monitor point where the measured ion beam current density is relatively small. And the ion beam current density distribution in the Y direction measured by the ion beam monitor 80 is made uniform.

  In both cases (A) and (B), the control device 90 may perform at least one of the controls (a) and (b). However, the ion beam current density is better when both are performed. Since the control to make the distribution uniform is faster, it is preferable. The “function” can be rephrased as “means”. The same applies to other functions to be described later.

  A more specific example of the controls (A) and (B) will be described below.

(A) Electron Beam Scanning Speed Control In this case, the electron beam power supply 114 shown in FIG. 5 is used. In this example, the extraction voltage Ve output from the extraction power supply 152 is kept constant, and the amount of electron beam generated from the electron beam source Gn is kept constant. Since it is preferable that the anode voltage Va output from the energy control power supply 154 is also constant and the energy of the electron beam 138 is also constant, in this embodiment, they are constant. In this case, flowcharts of control performed using the control device 90 are shown in FIGS.

  Prior to control, the correspondence between the monitor point Py on the ion beam monitor 80, the electron beam source Gn sharing the increase / decrease of the ion beam current density at the monitor point Py, and the scanning voltage Vy supplied to the electron beam source Gn. The relationship is examined in advance and stored in the control device 90. However, when there is one electron beam source Gn, since the electron beam source Gn is uniquely determined, it is not necessary to investigate and store the electron beam source Gn to be shared. It is not necessary to include the electron beam source Gn in the following correspondence relationship.

  In terms of this correspondence, if attention is paid to an arbitrary monitoring point Py on the ion beam monitor 80, which electron beam source Gn increases or decreases the ion beam current density at the monitoring point Py, and supplies the electron beam source Gn to the electron beam source Gn. The relationship is what value the scanning voltage Vy is, and can be expressed by the following equation (1). The subscripts i, j, and k represent more specific positions and are integers. This correspondence can be determined, for example, by examining at which scanning voltage Vy of which electron beam source Gn the ion beam current density at which monitor point Py increases or decreases. Since this correspondence is uniquely determined by the device configuration, it may be determined once unless the device configuration is changed. Data corresponding to this correspondence relationship may be stored in the control device 90 (more specifically, the storage device).

[Equation 1]
Py _i ← → (Gn _j , Vy _k )

  The subsequent steps will be described with reference to FIG. A desired ion beam current density Iset of the ion beam 50 irradiated to the substrate 60 and its allowable error ε are set in the control device 90 (step 600). This set ion beam current density Iset is called a set ion beam current density. The allowable error ε is the degree to which the actual ion beam current density, specifically, the ion beam current density Imon measured by the ion beam monitor 80 is allowed to deviate from the set ion beam current density Iset. It is.

  Next, a scanning signal Sy having an initial waveform is supplied from the control device 90 to each electron beam power supply 114 (more specifically, the amplifier 156), and a scanning voltage Vy having the same waveform is output (step 601). This initial waveform is, for example, a triangular wave. The frequency is, for example, 10 kHz, but is not limited to this.

Each electron beam source Gn generates an electron beam 138 scanned in the Y direction with the initial waveform. The gas 120 is ionized by the electron beam 138, the plasma 124 is generated in the ion source 100, and the ion beam 50 is extracted (step 602). The ion beam 50 is received by the ion beam monitor 80, and the ion beam current density Imon is measured (step 603). A schematic example of the measurement result is shown in FIG. 8A. Broadly speaking, AG ₁ ~AG ₃ are respectively the first to third contribution region of the electron beam source Gn ₁ ~Gn ₃ of. However, this figure is only a schematic diagram.

  Next, an error Ierr in the Y direction distribution, which is the difference between the measured ion beam current density Imon in the Y direction distribution and the set ion beam current density Iset, is calculated according to the following equation, for example (step 604).

[Equation 2]
Ierr = Imon-Iset

  Next, it is determined whether or not the error magnitude (absolute value) | Ierr | is equal to or smaller than the allowable error ε at all monitor points Py on which the ion beam 50 is incident (step 605). If there is at least one, go to Step 606, otherwise go to Step 607.

  However, although it is preferable to determine all the monitor points Py on which the ion beam 50 is incident as in this embodiment, the determination on some unimportant monitor points Py may be excluded. Further, it is not necessary to determine the monitoring point Py where the ion beam 50 is not incident. That is, it may be determined for substantially all monitor points on which the ion beam 50 is incident.

  Step 606 is an electron beam scanning speed control subroutine, the contents of which are shown in FIG. Here, first, determination of the monitor point Py having the above error magnitude | Ierr | larger than the allowable error ε (in other words, specific, the same applies hereinafter) and the sign of the error Ierr at the large monitor point Py are determined. (Step 620). As can be seen from the above formula 2, in this example, the measured ion beam current density Imon is positive when it is larger than the set ion beam current density Iset, and negative when it is small. See also FIG. 8A. The number of monitoring points Py determined as described above is usually large at the beginning of the control, and decreases as the control proceeds.

  Next, the electron beam source Gn corresponding to each of the determined monitor points Py and its scanning voltage Vy are determined (step 621). This can be done using the correspondence relationship described above (see Equation 1 and its description). However, when the number of electron beam sources Gn is one, the electron beam source Gn is uniquely determined, and therefore it is not necessary to determine the electron beam source Gn.

  Next, the scanning speed of the electron beam 138 when the error Ierr is the scanning voltage Vy corresponding to each positive monitoring point Py is increased in proportion to the error magnitude | Ierr |, and the error Ierr is negative. The waveform of the scanning signal Sy is shaped so that the scanning speed of the electron beam 138 at the scanning voltage Vy corresponding to the monitor point Py is decreased in proportion to the error magnitude | Ierr | (step 622). As a result, the waveform of the scanning signal Sy is somewhat modified from the initial triangular wave. Simply put, the slope at the position where the scanning speed is increased or decreased is a waveform that is increased or decreased from the initial triangular wave.

  In order to perform more precise control, the scanning speed between two points having different scanning speeds is preferably set to a scanning speed obtained by interpolating the scanning speeds of both points.

  When the scanning speed of the electron beam 138 is increased, the generation of the plasma 124 by the electron beam 138 at the increased position is reduced (thin), and the beam current density of the ion beam 50 drawn therefrom is reduced. When the scanning speed of the electron beam 138 is reduced, the generation of the plasma 124 by the electron beam 138 at the reduced position is increased (intensified), and the beam current density of the ion beam 50 extracted therefrom is increased.

  Increasing the scanning speed of the electron beam 138 means increasing the time change rate dSy / dt of the scanning signal Sy, and thus increasing the time change rate dVy / dt of the scanning voltage Vy, and decreasing the scanning speed. This means that the rate of time change dSy / dt and hence dVy / dt is decreased.

  A proportional constant for increasing or decreasing the scanning speed of the electron beam 138 in proportion to the magnitude of error | Ierr | may be determined as appropriate. Increasing this proportionality constant increases the speed of control, but there is a high risk of not converging. Conversely, if it is decreased, the control will be slowed but the above-mentioned fear disappears.

  Then, the electron beam 138 generated from each electron beam source Gn is scanned using the scanning signal Sy after waveform shaping as described above (step 623). That is, the electron beam 138 is scanned using the scanning signal Vy obtained by amplifying the waveform-shaped scanning signal Sy by the amplifier 156. As a result, the error Ierr is reduced, and the number of monitor points Py that are larger than the allowable error ε is also reduced.

  After the electron beam scanning speed control subroutine in step 606, the process may return to step 605. However, if the fact that the error Ierr in the Y-direction distribution may change due to the influence of the waveform shaping described above is more accurate. In order to ensure proper control, it is preferable to return to step 604 as in this example. The above control is repeated until YES is determined in step 605. As a result, the error magnitude | Ierr | becomes equal to or smaller than the allowable error ε at all (or substantially all) monitor points Py on which the ion beam 50 is incident. A schematic example of this state is shown in FIG. 8B.

  If “YES” is determined in step 605, the data of the scanning signal Sy after the waveform shaping, and other data as necessary are stored in the control device 90 (more specifically, the storage device) ( Step 607). Thus, the control for uniformizing the ion beam current density distribution in the Y direction using the control device 90 is completed.

  After completion of the homogenization control, the ion beam 50 may be extracted from the ion source 100 using the stored data as necessary, and ion implantation into the substrate 60 may be performed.

  As described above, according to this ion implantation apparatus, the uniformity of the ion beam current density distribution in the Y direction at the implantation position with respect to the substrate 60 can be improved. As a result, the uniformity of ion implantation for the substrate 60 can be improved.

(B) Control of electron beam amount An example of this case will be described mainly with reference to FIGS. In these drawings, the same or corresponding parts as those in the control (A) are denoted by the same reference numerals, and the difference from the control (A) will be mainly described below.

  In this case, the electron beam power supply 114 shown in FIG. 9 is used. The electron beam power supply 114 has an amplifier 162 for applying an extraction voltage Ve for controlling the generation amount of the electron beam 138 between the filament 140 and the extraction electrode 142 instead of the DC extraction power supply 152. . In this example, the control device 90 has a function of supplying an extraction signal Se that is a source of the extraction voltage Ve, and the amplifier 162 amplifies the extraction signal Se supplied from the control device 90 (voltage amplification). ) To produce (output) the extraction voltage Ve. Further, instead of the amplifier 156, a scanning power source 166 that simply outputs a triangular scanning voltage Vy is provided.

  That is, in this example, the scanning voltage Vy has a constant waveform and magnitude, and the scanning speed of the electron beam 138 generated from the electron beam source Gn is constant. Since it is preferable that the anode voltage Va output from the energy control power supply 154 is also constant and the energy of the electron beam 138 is also constant, in this embodiment, they are constant. The frequency of the scanning voltage Vy is, for example, 10 kHz, but is not limited to this.

  Flow charts of control performed using the control device 90 in this case are shown in FIGS. In FIG. 10, step 601 shown in FIG. 6 is replaced with step 608, and step 606 is replaced with step 609.

  In step 608, the extraction signal Se having an initial waveform is supplied from the control device 90 to each electron beam power source 114 (more specifically, the amplifier 162), and an extraction voltage Ve having the same waveform is output. This initial waveform is a DC voltage having a constant voltage value, for example.

  Step 609 is an electron beam amount control subroutine, the contents of which are shown in FIG. Steps 620 and 621 are the same as those in FIG.

  In step 624 following step 621, the extraction voltage Ve when the error Ierr is the scanning voltage Vy corresponding to each positive monitoring point Py is decreased in proportion to the magnitude of the error | Ierr | The waveform of the extraction signal Se is shaped so that the extraction voltage Ve when the scanning voltage Vy corresponding to each monitor point Py having a negative Ierr is increased in proportion to the magnitude of the error | Ierr |. As a result, the waveform of the extraction signal Se is somewhat modified from the initial constant value. In short, the voltage value at the position where the amount of electron beam is increased or decreased becomes a waveform that increases or decreases from a constant value of the initial waveform.

  When the extraction signal Se and hence the extraction voltage Ve are increased, the amount of the electron beam at the increased position increases, and the generation of the plasma 124 by the electron beam 138 at that position increases (intensifies), and the ion beam extracted therefrom The beam current density of 50 increases. When the extraction signal Se and hence the extraction voltage Ve are decreased, the amount of the electron beam at the decreased position is reduced, and the generation of the plasma 124 by the electron beam 138 at that position is reduced (thinned), and the ion beam extracted therefrom. The beam current density of 50 is reduced.

  A proportional constant for increasing or decreasing the extraction voltage Ve in proportion to the magnitude of the error | Ierr | may be determined as appropriate. Increasing this proportionality constant increases the speed of control, but there is a high risk of not converging. Conversely, if it is decreased, the control will be slowed but the above-mentioned fear disappears.

  Then, the electron beam 138 is generated from each electron beam source Gn using the extraction signal Se after waveform shaping as described above (step 625). As a result, the error Ierr is reduced, and the number of monitor points Py that are larger than the allowable error ε is also reduced.

  After the electron beam amount control subroutine in step 609, the process may return to step 605. However, if the fact that the error Ierr of the Y-direction distribution may change due to the influence of the waveform shaping described above can be more accurate. For control purposes, it is preferable to return to step 604 as in this example. The above control is repeated until YES is determined in step 605. As a result, the error magnitude | Ierr | becomes equal to or smaller than the allowable error ε at all (or substantially all) monitor points Py on which the ion beam 50 is incident. A schematic example of this state is the same as that shown in FIG. 8B.

  If YES is determined in step 605, the data of the extracted signal Se after waveform shaping and, if necessary, other data are stored in the control device 90 (more specifically, the storage device) ( Step 607). Thus, the control for uniformizing the ion beam current density distribution in the Y direction using the control device 90 is completed.

  Also according to this embodiment, the uniformity of the ion beam current density distribution in the Y direction at the implantation position with respect to the substrate 60 can be improved. As a result, the uniformity of ion implantation for the substrate 60 can be improved.

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 front view which shows an example of the ion extraction hole of a plasma production container seeing in an ion beam extraction direction. It is a schematic front view which shows an example of a structure of the ion beam monitor shown in FIG. It is a figure which shows an example of a structure of the electron beam source shown in FIG. 1, and the power supply for electron beams. 3 is a flowchart showing a more specific example of control contents for making the ion beam current density distribution in the Y direction uniform using the control device shown in FIG. 1. It is a flowchart which shows an example of the electron beam scanning speed control subroutine shown in FIG. FIG. 7 is a schematic diagram showing a process in which the ion beam current density distribution in the Y direction is made uniform by performing the electron beam scanning speed control shown in FIG. 6. It is a figure which shows the other example of a structure of the electron beam source shown in FIG. 1, and the power supply for electron beams. FIG. 6 is a flowchart showing another specific example of the control content for making the ion beam current density distribution in the Y direction uniform using the control device shown in FIG. 1. It is a flowchart which shows an example of the electron beam amount control subroutine shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 50 Ion beam 60 Substrate 80 Ion beam monitor 90 Control device 100 Ion source 114 Electron beam power supply 118 Plasma generation container 120 Gas 124 Plasma 126 Extraction electrode system Gn Electron beam source 138 Electron beam 156, 162 Amplifier 500 Substrate driving device

Claims (6)

If the traveling direction of the ion beam is the Z direction, and two directions substantially orthogonal to each other in the plane substantially orthogonal to the Z direction are the X direction and the Y direction, the dimension in the Y direction is larger than the dimension in the X direction. An ion implantation apparatus that transports a ribbon-like ion beam and irradiates it with a substrate to perform ion implantation,
(A) a plasma generation container into which a gas is introduced, and an electron beam generated and emitted into the plasma generation container to ionize the gas by the electron beam to generate plasma, One or more electron beam sources that scan the electron beam in the Y direction in the plasma generation container, and an extraction electrode system that extracts the ion beam from the plasma generated in the plasma generation container, An ion source for generating the ribbon-like ion beam having a dimension larger than a dimension in the Y direction of the substrate;
(B) a substrate driving device that moves the substrate in a direction intersecting a main surface of the ion beam at an implantation position where the ion beam is incident on the substrate;
(C) one or more electron beam power supplies for supplying each electron beam source with an extraction voltage for controlling the generation amount of the electron beam and a scanning voltage for scanning,
(D) an ion beam monitor that measures an ion beam current density distribution in the Y direction of the ion beam at a plurality of monitor points in the Y direction at or near the implantation position;
(E) By controlling the electron beam power source based on the measurement data from the ion beam monitor, the amount of the electron beam generated from each electron beam source is kept substantially constant while the ion beam monitor is kept constant. A relatively high scanning speed of the electron beam at a position in the ion source corresponding to a monitor point having a relatively large ion beam current density measured in step 1, and a monitor point having a relatively small ion beam current density measured A function of equalizing the ion beam current density distribution in the Y direction measured by the ion beam monitor by performing at least one of relatively reducing the scanning speed of the electron beam at the position in the ion source corresponding to And an ion implantation apparatus including the control device. (A) The number of the electron beam source and the power source for the electron beam is one,
(B) The control device includes:
A function of supplying, to the electron beam power source, a scanning signal that is a source of the scanning voltage supplied from the electron beam power source to the electron beam source;
A function of calculating an error in the Y direction distribution, which is a difference between the ion beam current density in the Y direction distribution measured by the ion beam monitor and a predetermined set ion beam current density;
A function for determining the monitoring point where the calculated error is greater than a predetermined allowable error and the sign of the error at the monitoring point;
A function of determining a scanning voltage corresponding to the determined monitor point;
Based on the sign of the determined error, increase the scanning speed of the electron beam at the scanning voltage corresponding to the monitor point where the measured ion beam current density is larger, in proportion to the magnitude of the error, and The scanning speed of the electron beam at the scanning voltage corresponding to the monitor point where the measured ion beam current density is smaller is decreased in proportion to the magnitude of the error so that substantially all of the ion beam is incident. A function of shaping the waveform of the scanning signal so that the error is less than or equal to the allowable error at the monitor point;
Having the function of storing the data of the scanned signal after the shaping,
(C) The ion implantation apparatus according to claim 1, wherein the electron beam power supply includes an amplifier for amplifying a scanning signal supplied from the control device to generate the scanning voltage. (A) The number of the electron beam source and the electron beam power source is both plural.
(B) The control device includes:
A function of supplying a scanning signal, which is a source of the scanning voltage supplied from each electron beam power source to each electron beam source, to each electron beam power source;
A function of calculating an error in the Y direction distribution, which is a difference between the ion beam current density in the Y direction distribution measured by the ion beam monitor and a predetermined set ion beam current density;
A function for determining the monitoring point where the calculated error is greater than a predetermined allowable error and the sign of the error at the monitoring point;
A function of determining the electron beam source corresponding to the determined monitor point and its scanning voltage;
Based on the sign of the determined error, increase the scanning speed of the electron beam at the scanning voltage corresponding to the monitor point where the measured ion beam current density is larger, in proportion to the magnitude of the error, and The scanning speed of the electron beam at the scanning voltage corresponding to the monitor point where the measured ion beam current density is smaller is decreased in proportion to the magnitude of the error so that substantially all of the ion beam is incident. A function of shaping the waveform of the scanning signal so that the error is less than or equal to the allowable error at the monitor point;
Having the function of storing the data of the scanned signal after the shaping,
(C) The ion implantation apparatus according to claim 1, wherein each of the electron beam power supplies includes an amplifier that amplifies a scanning signal supplied from the control device to generate the scanning voltage. If the traveling direction of the ion beam is the Z direction, and two directions substantially orthogonal to each other in the plane substantially orthogonal to the Z direction are the X direction and the Y direction, the dimension in the Y direction is larger than the dimension in the X direction. An ion implantation apparatus that transports a ribbon-like ion beam and irradiates it with a substrate to perform ion implantation,
(A) a plasma generation container into which a gas is introduced, and an electron beam generated and emitted into the plasma generation container to ionize the gas by the electron beam to generate plasma, One or more electron beam sources that scan the electron beam in the Y direction in the plasma generation container, and an extraction electrode system that extracts the ion beam from the plasma generated in the plasma generation container, An ion source for generating the ribbon-like ion beam having a dimension larger than a dimension in the Y direction of the substrate;
(B) a substrate driving device that moves the substrate in a direction intersecting a main surface of the ion beam at an implantation position where the ion beam is incident on the substrate;
(C) one or more electron beam power supplies for supplying each electron beam source with an extraction voltage for controlling the generation amount of the electron beam and a scanning voltage for scanning,
(D) an ion beam monitor that measures an ion beam current density distribution in the Y direction of the ion beam at a plurality of monitor points in the Y direction at or near the implantation position;
(E) controlling the electron beam power source based on measurement data from the ion beam monitor, thereby maintaining the scanning speed of the electron beam generated from each electron beam source substantially constant, A relatively small amount of the electron beam generated at a position in the ion source corresponding to a monitor point having a relatively large ion beam current density measured by the monitor, and a monitor having a relatively small ion beam current density measured. A function of making the ion beam current density distribution in the Y direction measured by the ion beam monitor uniform by performing at least one of relatively increasing the generation amount of the electron beam at the position in the ion source corresponding to the point. An ion implantation apparatus comprising: a control device having: (A) The number of the electron beam source and the power source for the electron beam is one,
(B) The control device includes:
A function of supplying, to the electron beam power source, an extraction signal that is a source of the extraction voltage supplied from the electron beam power source to the electron beam source;
A function of calculating an error in the Y direction distribution, which is a difference between the ion beam current density in the Y direction distribution measured by the ion beam monitor and a predetermined set ion beam current density;
A function for determining the monitoring point where the calculated error is greater than a predetermined allowable error and the sign of the error at the monitoring point;
A function of determining a scanning voltage corresponding to the determined monitor point;
Based on the sign of the determined error, the extraction voltage at the scanning voltage corresponding to a monitor point having a larger measured ion beam current density is decreased in proportion to the magnitude of the error, and the measurement is performed. The extraction voltage at the scanning voltage corresponding to a monitor point having a smaller ion beam current density is increased in proportion to the magnitude of the error, and the error is detected at substantially all monitor points where the ion beam is incident. A function of shaping the waveform of the extraction signal so that is equal to or less than the tolerance,
And having a function of storing the data of the extraction signal after the shaping,
(C) The ion implantation apparatus according to claim 4, wherein the electron beam power supply includes an amplifier for amplifying an extraction signal supplied from the control device to generate the extraction voltage. (A) The number of the electron beam source and the electron beam power source is both plural.
(B) The control device includes:
A function of supplying an extraction signal, which is a source of the extraction voltage supplied from the power source for each electron beam to the electron beam source, to the power source for each electron beam;
A function of calculating an error in the Y direction distribution, which is a difference between the ion beam current density in the Y direction distribution measured by the ion beam monitor and a predetermined set ion beam current density;
A function for determining the monitoring point where the calculated error is greater than a predetermined allowable error and the sign of the error at the monitoring point;
A function of determining the electron beam source corresponding to the determined monitor point and its scanning voltage;
Based on the sign of the determined error, the extraction voltage at the scanning voltage corresponding to a monitor point having a larger measured ion beam current density is decreased in proportion to the magnitude of the error, and the measurement is performed. The extraction voltage at the scanning voltage corresponding to a monitor point having a smaller ion beam current density is increased in proportion to the magnitude of the error, and the error is detected at substantially all monitor points where the ion beam is incident. A function of shaping the waveform of the extraction signal so that is equal to or less than the tolerance,
And having a function of storing the data of the extraction signal after the shaping,
(C) The ion implantation apparatus according to claim 4, wherein each of the electron beam power supplies includes an amplifier that amplifies an extraction signal supplied from the control device to generate the extraction voltage.

Images