JP2008305666A - Ion implanting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion implantation device in which a uniformity of a beam current density distribution in a Y direction of the ion beam can be improved even if a plasma density distribution is not uniform in a plasma generator of an ion source. <P>SOLUTION: The ion implantation device is composed of an extraction electrode of an iron source 2 which is divided in a plurality of extraction electrode pieces in a Y direction. Furthermore, the device includes an extraction power source 42 which can control independently a potential difference V<SB>d</SB>between a plasma electrode 12 and each of the extraction electrode pieces, a beam monitor 56 for measuring a beam current density distribution in a Y direction of an ion beam 8, a controlling unit 60 which controls the extraction power source 42 based on a measured date by the beam monitor 56 and controls each of the potential differences Vd and controls so that the beam current density distribution measured by the beam monitor 56 may become uniform. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a so-called ribbon-like shape (which may also be referred to as a sheet-like shape or a belt-like shape) may be referred to as a sheet-like shape or a belt-like shape. The present invention relates to an ion implantation apparatus configured to extract an ion beam and irradiate a target with the ion beam.

  An ion implantation apparatus configured to extract a so-called ribbon-shaped ion beam having a dimension in the Y direction substantially perpendicular to the X direction from the ion source and irradiate the target with the ion beam. Various proposals have been made in the past. For example, see Patent Document 1.

  The ion source includes a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma in the plasma generation unit by the action of an electric field. The extraction electrode system usually has a plurality of electrodes.

JP 2007-115511 A (paragraphs 0029-0039, FIG. 1 and FIG. 2)

  In the conventional ion implantation apparatus, each electrode constituting the extraction electrode system of the ion source is a single electrode that is long in the Y direction, and the dimension in the Y direction is determined using the extraction electrode system having such a configuration. Pulls out a large ribbon-like ion beam.

  Here, focusing on the Y direction, the distribution in the Y direction of the plasma density generated in the plasma generation unit of the ion source is not necessarily uniform. Therefore, when a ribbon-like ion beam having a large dimension in the Y direction is extracted from an ion source having the extraction electrode system configured as described above, the ion beam is affected by the nonuniformity of the plasma density distribution in the plasma generation unit. There is a problem that the uniformity of the beam current density distribution in the Y direction is not good. This causes deterioration of the injection uniformity in the Y direction with respect to the target.

  SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide an ion implantation apparatus that can improve the uniformity of the beam current density distribution in the Y direction of the ion beam even when the plasma density distribution in the plasma generation section of the ion source is not uniform. It is said.

  The ion implantation apparatus according to the present invention generates plasma when the traveling direction of an ion beam is a Z direction and two directions substantially perpendicular to each other in a plane substantially perpendicular to the Z direction are an X direction and a Y direction. A plasma generating unit that extracts the ion beam from the plasma, and the ion electrode is extracted from the plasma by a potential difference between the plasma electrode disposed on the most plasma side and the plasma electrode disposed on the downstream side. In the ion implantation apparatus configured to extract an ion beam having a dimension in the Y direction larger than the dimension in the X direction from an ion source including an extraction electrode system having an extraction electrode to be extracted, and irradiate the target with the ion beam. The electrode is divided into a plurality of extraction electrode pieces in the Y direction, and the plastic An extraction power source capable of independently controlling the potential difference between the main electrode and each extraction electrode piece, and the beam current density distribution in the Y direction of the ion beam received by the ion beam And a beam to be measured by the beam monitor by controlling the extraction power source based on measurement data from the beam monitor and controlling a potential difference between the plasma electrode and each extraction electrode piece. And a control device having a function of performing a control to make the current density distribution uniformly approach.

  The beam current density of the ion beam extracted from the ion source largely depends on the potential difference between the plasma electrode and the extraction electrode. Therefore, as in the present invention, the extraction electrode of the ion source is divided into a plurality of extraction electrode pieces in the Y direction, and the control device based on the measurement data from the beam monitor causes the plasma electrode and each extraction electrode piece to be separated. The beam current density in the Y direction of the ion beam is controlled even when the plasma density distribution in the plasma generation unit of the ion source is not uniform by controlling the potential difference between them and making the beam current density distribution measured by the beam monitor uniform. The uniformity of distribution can be improved.

  The control device, based on the measurement data from the beam monitor, calculates an average current density for each measurement region of a plurality of measurement regions in the Y direction corresponding to each extraction electrode piece and a predetermined set current density. A current density difference is obtained, and the extraction power source is controlled between the plasma electrode and each extraction electrode piece so that all the current density differences fall within a predetermined allowable range according to the current density difference. It may have a function of controlling each potential difference.

  The control device obtains a current density difference between an average current density of all measured current densities and a predetermined set current density based on measurement data from the beam monitor, and according to the current density difference, A coarse adjustment function for performing rough adjustment to control the potential difference between the plasma electrode and each extraction electrode piece uniformly by controlling the extraction power supply so that the current density difference falls within a predetermined allowable range; b) After the coarse adjustment, based on the measurement data from the beam monitor, the average current density for each measurement region and the set current density of the plurality of measurement regions in the Y direction corresponding to the extraction electrode pieces Current density difference between the plasma electrode and each extraction electrode piece by controlling the extraction power source so that the current density difference is all within the allowable range according to the current density difference. The potential difference of It may have and this adjustment function to respective control.

  (A) Based on the measurement data from the beam monitor, the control device determines an average current density of one measurement region among a plurality of measurement regions in the Y direction corresponding to each extraction electrode piece and a predetermined value. A current density difference from the set current density is obtained, and the plasma power source and each extraction electrode piece are controlled by controlling the extraction power source so that the current density difference falls within a predetermined allowable range according to the current density difference. A coarse adjustment function for performing rough adjustment to uniformly control the potential difference between the first and second potentials, and (b) after the coarse adjustment, based on measurement data from the beam monitor, each remaining measurement in the plurality of measurement regions Obtain the current density difference between the average current density for each region and the set current density, and control the extraction power source according to the current density difference so that all the current density differences are within the allowable range. Each remaining measurement The corresponding frequency may have a present adjustment function of controlling the respective potential difference between the extraction electrode piece and the plasma electrode.

  According to the first aspect of the present invention, the extraction electrode of the ion source is divided into a plurality of extraction electrode pieces as described above, and includes the beam monitor and control device as described above. Even when the plasma density distribution in the plasma generation section of the ion source is not uniform, the uniformity of the beam current density distribution in the Y direction of the ion beam can be improved.

  According to invention of Claim 2, there exists the following further effect. That is, since the control device has the control function as described above, the beam current density distribution in the Y direction of the ion beam can be brought close to the set current density and within an allowable range.

  According to invention of Claim 3, there exists the following further effect. That is, the control device has the coarse adjustment function as described above in addition to the main adjustment function as described above, so that the entire beam current density distribution can be quickly brought close to the set current density on average by the coarse adjustment. As a result, the control by this adjustment becomes easy, and as a result, the beam current density distribution in the Y direction of the ion beam can be brought closer to the set current density more quickly and within the allowable range.

  According to invention of Claim 4, there exists the following further effect. That is, the control device has the coarse adjustment function as described above in addition to the main adjustment function as described above, and the entire beam current density distribution can be quickly brought close to the set current density using the representative value by the coarse adjustment. Therefore, the control in this adjustment is facilitated, and as a result, the beam current density distribution in the Y direction of the ion beam can be brought closer to the set current density more quickly and within the allowable range. In addition, at the time of this adjustment, it is only necessary to control the measurement region other than the measurement region used at the time of the coarse adjustment, so that the control content is simplified and the time required for the control can be shortened.

  According to invention of Claim 5, there exists the following further effect. That is, since each divided portion of the extraction electrode is arranged obliquely with respect to the X direction, even if the beam current density is disturbed downstream of the divided portion due to the influence of the divided portion, the pattern of the disturbance is It is averaged over the target by mechanical scanning of the target. In other words, it is relaxed or diluted. Therefore, the influence of the disturbance can be suppressed on the target.

  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 8 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. For example, the X direction and the Z direction are horizontal directions, and the Y direction is a vertical direction. Further, the case where the ions constituting the ion beam 8 are positive ions is described as an example.

As shown in FIG. 2, this ion implantation apparatus extracts a ribbon-like ion beam 8 having a dimension W _{Y in the} Y direction larger than the dimension W _X in the X direction, as shown in FIG. The target 50 is irradiated. The transport path of the ion beam 8 from the ion source 2 to the target 50 and the beam monitor 56 is in a vacuum vessel (not shown) and kept in a vacuum atmosphere.

Even if the ion beam 8 is ribbon-shaped, 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 8 is about 30 mm to 80 mm, and the dimension W _{Y in the} Y direction is about 300 mm to 500 mm, depending on the dimension of the target 50. The larger surface of the ion beam 8, that is, the surface along the YZ plane is the main surface 8a.

  The target 50 is, for example, a semiconductor substrate, a glass substrate, or another substrate. The planar shape may be a circle or a square.

In this embodiment, the target 50 is held by the holding unit 52 of the target driving device 54 and, for example, X in the direction intersecting the main surface 8a of the ion beam 8 as shown by the arrow C by the target driving device 54. It is mechanically scanned (reciprocated) in a direction along the direction. The dimension W _{Y in} the Y direction of the ion beam 8 drawn out from the ion source 2 is larger than the dimension in the Y direction of the target 50, and this and the above scanning of the target 50 cause the ion beam 8 to be incident on the entire surface of the target 50. An injection can be performed.

  The ion source 2 includes, for example, a plasma generator 4 that generates plasma 6 by ionizing a gas (including vapor) by arc discharge, high-frequency discharge, and the like, and the action of an electric field from the plasma 6 in the plasma generator 4. An extraction electrode system 10 for extracting the ion beam 8 is provided.

  The extraction electrode system 10 has at least a plasma electrode 12 and an extraction electrode 13. More specifically, in this embodiment, referring also to FIG. 3, the plasma electrode 12, the extraction electrode 13, the suppression electrode 14, and the ground electrode 15 are arranged from the most plasma side to the downstream side. In this embodiment, the plasma electrode 12 is set to the same potential as the plasma generator 4 (more specifically, the container constituting it) 4. The extraction electrode system 10 shown in FIG. 1 corresponds to the AA view of FIG.

  As shown in FIG. 3, each of the electrodes 12 to 15 has ion extraction holes 16 to 19 for extracting the ion beam 8 at corresponding positions. Although each ion extraction hole 16-19 is a slit-shaped thing in the example shown in FIG. 3, it is not restricted to it. For example, like the ion extraction hole 17 shown in FIG. 14, FIG. 15, many holes (for example, circular holes) arrange | positioned at 1 row or multiple rows may be sufficient.

  When each of the ion extraction holes 16 to 19 is formed in a slit shape, they may be provided from the upper end to the lower end in the Y direction of each electrode 12 to 15 as in the example shown in FIG. And it may not be provided near the lower end. In the case of the example shown in FIG. 3, the left and right electrode pieces in the X direction of the respective electrodes 12 to 15 are electrically connected by the conductors 21 to 24 (see FIG. 4 for the conductor 22).

The plasma electrode 12 is an electrode for determining the energy of the ion beam 8 which elicit a positive acceleration voltage V _a is applied with respect to the ground potential from the DC acceleration power supply 40. Extraction electrode 13 is an electrode withdrawing the ion beam 8 from the plasma 6 by the potential difference V _d between the plasma electrode 12 are located immediately downstream of the plasma electrode 12, a plasma electrode from a DC extraction power source 42 in this example A negative extraction voltage V _e is applied with reference to the potential of 12. That is, an extraction power source 42 is connected between the plasma electrode 12 and the extraction electrode 13 with the extraction electrode 13 on the negative electrode side. The suppression electrode 14 is an electrode that suppresses backflow electrons from the downstream side, and a negative suppression voltage V _s is applied from the DC suppression power supply 44 with reference to the ground potential. The ground electrode 15 is an electrode that determines the position of the ground potential, and is electrically grounded.

  The ion implantation apparatus is configured by dividing the extraction electrode 13 into a plurality of n extraction electrode pieces 30 in the Y direction with reference to FIG. In the illustrated example, n = 7 since it is divided into seven, but this is not restrictive. There are divided portions 32 between two extraction electrode pieces 30 adjacent in the Y direction, and are electrically separated here. As described above, the two extraction electrode pieces 30 arranged in the X direction with the ion extraction hole 17 interposed therebetween are electrically connected by the conductor 22 as described above. It is a piece. This is clearer with reference to the example of FIG.

In this embodiment, there are a plurality of extraction power sources 42 (the same number as the extraction electrode pieces 30), and the extraction power supply 42 is connected to each extraction electrode piece 30 and independently applies an extraction voltage V _e applied to each extraction electrode piece 30. Can be controlled. Thereby, the potential difference V _d between the plasma electrode 12 and each extraction electrode piece 30 can be controlled independently for each extraction electrode piece 30. However, one more extraction power source 42 is not necessarily required to be separately disposed, that can them together into one, independently control the extraction voltage V _e applied to each lead electrode pieces 30 It is good also as one drawer power supply.

In this ion implantation apparatus, the extraction electrode 13 is divided into a plurality of extraction electrode pieces 30 as described above, and the potential difference V _d between each extraction electrode piece 30 and the plasma electrode 12 is determined for each extraction electrode piece 30. Since the potential can be controlled independently, the potential difference V _d and the extraction voltage V _e may differ for each extraction electrode piece 30. Therefore, if it is necessary to distinguish the potential difference V _d and the extraction voltage V _e for each extraction electrode piece 30, the subscript i is added to the potential difference V _di and the extraction voltage V _ei. If there is no need to explain separately, the suffix i is not added. i is a natural number from 1 to n. n is the number of divisions of the extraction electrode 13 described above.

An example of the potential of the extraction electrode system 10 of this embodiment is shown in FIG. In this embodiment, the potential difference V _d is determined as it is based on the extraction voltage V _e output from each extraction power source 42. That is, V _d = V _e . The potential setting range P _s of the extraction electrode 13 is between the potential of the plasma electrode 12 and the potential of the suppression electrode 14. That is, since the potential of the extraction electrode 13 can be set higher or lower than the ground potential, the potential setting range P _s is wide.

  It is not preferable to connect the extraction power source 42 between the extraction electrode 13 and the ground potential portion so that the extraction electrode 13 has a positive potential. By doing so, if ions hit the extraction electrode 13 when the ion beam 8 is extracted, a reverse current flows through the extraction power source 42.

Since the energy of the ion beam 8 extracted from the extraction electrode system 10 is determined by the acceleration voltage V _a that is the potential difference between the plasma electrode 12 and the ground electrode 15, the potential difference V _d between each extraction electrode piece 30 and the plasma electrode 12. However, the energy of the extracted ion beam 8 is the same (ie, uniform) everywhere.

  Referring again to FIG. 1, the ion implantation apparatus further includes a beam monitor 56 that receives the ion beam 8 and measures a beam current density distribution in the Y direction of the ion beam 8. In this embodiment, the beam monitor 56 is provided in the vicinity of an implantation position where the ion beam 8 is incident on the target 50 to perform ion implantation, and the beam in the Y direction of the ion beam 8 at a position corresponding to the implantation position. The current density distribution is measured.

  When the beam monitor 56 is provided on the downstream side of the injection position as in the illustrated example, the target 50 and the holding unit 52 may be moved to a position that does not interfere with the measurement during measurement. When the beam monitor 56 is provided on the upstream side of the implantation position, the beam monitor 56 may be moved to a position that does not interfere with the implantation when ions are implanted into the target 50.

  In this example, the beam monitor 56 is a multi-point beam monitor in which a large number of measuring devices (for example, Faraday cups) for measuring the beam current density of the ion beam 8 are arranged in parallel in the Y direction. A structure in which the measuring device is moved in the Y direction by a moving mechanism may be used.

The ion implantation apparatus further controls each extraction power source 42 based on the measurement data DA from the beam monitor 56 and controls each extraction voltage V _e extracted from each extraction power source 42, that is, the plasma electrode 12. And a control device 60 having a function of controlling the beam current density distribution in the Y direction measured by the beam monitor 56 uniformly by controlling the potential difference V _d between each of the lead electrode pieces 30 and each extraction electrode piece 30. I have. There are n control signal lines from the control device 60, and a control signal from the control device 60 is applied to each of the drawer power sources 42 (see FIG. 4).

The beam current density of the ion beam 8 extracted from the ion source 2 greatly depends on the potential difference V _d between the plasma electrode 12 and the extraction electrode 13. More specifically, the beam current density is proportional to the 3/2 power of the potential difference V _{d according to} the known Child Langmuir equation (this is also called the 3/2 power law).

Therefore, as in this ion implantation apparatus, the extraction electrode 13 of the ion source 2 is divided into a plurality of extraction electrode pieces 30 in the Y direction, and the control apparatus 60 performs plasma based on the measurement data DA from the beam monitor 56. By controlling the potential difference V _d between the electrode 12 and each extraction electrode piece 30 so as to make the beam current density distribution measured by the beam monitor 56 uniform, the plasma density in the plasma generator 4 of the ion source 2 is increased. Even when the distribution is not uniform, the uniformity of the beam current density distribution in the Y direction of the ion beam 8 can be improved. More specifically, the uniformity of the beam current density distribution in the Y direction of the ion beam 8 near the implantation position with respect to the target 50 can be improved.

  A more specific example of the control function of the control device 60 will be described below.

First, an example of the beam current density distribution in the Y direction of the ion beam 8 measured by the beam monitor 56 is shown in FIG. In the following, considered separately the measurement region by the beam monitor 56, the plurality of measurement regions M _i in the Y direction that support each lead electrode strips 30. i = 1 to n (the same applies hereinafter). n is the number of divisions of the extraction electrode 13 as described above. For example, as in the example shown in FIGS. 1 and 6, the measurement areas M _{1 to} M ₇ are divided.

Controller 60, with reference to FIG. 6, on the basis of the measured data DA from the beam monitor 56, the current density difference between the average current density J _i and a predetermined set current density J _{The set} for each measurement region M _i .DELTA.J seeking _i, respectively, in accordance with the current density difference .DELTA.J _i, the current density difference .DELTA.J _i are all to fall within a predetermined tolerance epsilon, each extraction electrode piece and the plasma electrode 12 controls the extraction power source 42 30 has a function of controlling the potential difference V _di between 30 and 30 respectively. The set current density J _set and the allowable range ε are set in the control device 60. The allowable range ε is, for example, a range of ± what% with respect to the set current density J _set .

The control content in the control device 60 is shown in a flowchart in FIG. Assuming that measurement / control is started from the _first measurement region M1, i = 1 is set (step 100).

Next, a current density difference ΔJ _i in the i-th measurement region M _i is obtained according to the following equation (step 101). J _i is an average beam current density (average current density) in the i-th measurement region M _i . Measurement area M instead of the beam current density of a point in _i, use the average of the beam current density at a plurality of points in the measurement region M _i, the person is, correspondence easy to take the respective extraction electrode pieces 30 Because.

[Equation 1]
ΔJ _i = J _i −J _set

Next, it is determined whether or not the current density difference ΔJ _i is within the allowable range ε (step 102). If it is within the allowable range ε, the process proceeds to step 104, and if it is not within the allowable range ε, the process proceeds to step 103.

In step 103, the potential difference V _di is controlled by controlling the extraction voltage V _ei applied to the extraction electrode piece 30 corresponding to the measurement region M _i in the direction in which the current density difference ΔJ _i falls within the allowable range ε. To do. That is, when the average current density J _i is larger than the set current density J _{set, the} potential difference V _di is decreased, and when the average current density J _i is smaller than the set current density J _{set, the} potential difference V _di is increased. . More specifically, if the potential difference before the control is V _di and the new potential difference after the control is V _di ′, the new potential difference V _di ′ is obtained from the following equation and controlled to be the same. The following formula is an application of the above-mentioned Child Langmuir formula. The same applies to Equation 4 described later.

[Equation 2]
V _di '= αV _di (J _set / J _i ) ^2/3 + β

  α is a correction coefficient depending on the ion abundance ratio in the ion beam 8. β is a correction coefficient depending on the structure of the beam line, such as the distance from the ion source 2 to the beam monitor 56 and the presence or absence of a lens. When measurement is performed in the immediate vicinity of the ion source 2, α = 1 and β = 0 are usually obtained. The same applies to Equation 4 described later.

After step 103, the process returns to step 101, and the control of steps 101 to 103 is repeated until the current density difference ΔJ _i falls within the allowable range ε.

  In step 104, it is determined whether or not i is n (that is, the final number). If it is not n, the process proceeds to step 105, i is increased by 1, and then the process returns to step 101 and the above control is repeated until i becomes n. .

Through the control as described above, the current density difference ΔJ _i of all the measurement regions M _i can be within the allowable range ε. That is, the average current density J _i of all the measurement areas M _i can be within the allowable range ε with respect to the set current density J _set . In this way, the beam current density distribution in the Y direction of the ion beam 8 can be brought close to the set current density J _set and within the allowable range ε.

Based on the measurement data DA from the beam monitor 56, the control device 60 determines the average current density J _{ave of} the total measurement current density (that is, the current density of all measurement points measured by the beam monitor 56) and the set current. seeking current density difference .DELTA.J _ave between the density J _{the set,} the current density difference in accordance with .DELTA.J _ave, as the current density difference .DELTA.J _ave falls within the allowable range epsilon, the plasma electrode 12 controls the extraction power source 42 and a coarse adjustment function for coarse adjustment to control uniformly the potential difference V _d between the extraction electrode strips 30, after (b) the rough adjustment, based on the measurement data DA from the beam monitor 56, the measurement region seeking the average current density J _i for each M _i set current density J _{the set} and the current density difference .DELTA.J _i, respectively, in accordance with the current density difference .DELTA.J _i, the current density difference .DELTA.J _i all within the allowable range ε Drawer power supply 4 to enter 2 may be used to control the potential difference V _di between the plasma electrode 12 and each extraction electrode piece 30.

  The control contents in the control device 60 in this case are shown in a flowchart in FIG. Steps 110 to 112 are rough adjustments, and steps 113 to 118 are main adjustments.

In the coarse adjustment, first, based on the measurement data DA from the beam monitor 56, a current density difference ΔJ _ave between the average current density J _ave of all the measured current densities and the set current density J _set is obtained according to the following equation (step 110). .

[Equation 3]
ΔJ _ave = J _ave −J _set

Next, it is determined whether or not the current density difference ΔJ _ave is within the allowable range ε (step 111). If it is within the allowable range ε, the process proceeds to step 113 of this adjustment, and if it is not within the allowable range ε, the process proceeds to step 112.

In step 112, the extraction voltage V _e applied to all the extraction electrode pieces 30 is uniformly controlled so that the current density difference ΔJ _ave falls within the allowable range ε, and the potential difference V _d is uniformly controlled. That is, when the average current density J _ave is larger than the set current density J _{set, the} potential difference V _d is uniformly reduced. When the average current density J _ave is smaller than the set current density J _{set, the} potential difference V _d is uniformly increased. Control. More specifically, assuming that the potential difference before the uniform control is V _d and the new potential difference after the uniform control is V _d ′, the new potential difference V _d ′ is obtained from the following equation and controlled to become it.

[Equation 4]
_{V d '= αV d (J} set / J ave) 2/3 + β

After step 112, the process returns to step 110, and the control of steps 110 to 112 is repeated until the current density difference ΔJ _ave falls within the allowable range ε.

  Since the control contents of steps 113 to 118 of this adjustment are the same as the control contents of steps 100 to 105 shown in FIG.

If the control function in the control device 60 is divided into the rough adjustment and the main adjustment as described above, the entire beam current density distribution can be quickly brought close to the _set current density J _set by the rough adjustment. As a result, the beam current density distribution in the Y direction of the ion beam 8 can be brought closer to the set current density J _set more quickly and within the allowable range ε.

Based on the measurement data DA from (a) the beam monitor 56, the control device 60 determines _whether the average current density J _r and the set current density J _set in any one of the plurality of measurement areas M _r are _set . seeking current density difference .DELTA.J _r, in accordance with the current density difference .DELTA.J _r, such that the current density difference .DELTA.J _r falls within the allowable range epsilon, each extraction electrode piece and the plasma electrode 12 controls the extraction power source 42 And (b) a rough adjustment function for uniformly adjusting the potential difference V _d between the first and second potential differences between the first and second potential differences Vd, and after the rough adjustment, based on the measurement data DA from the beam monitor 56, seeking remaining current density difference .DELTA.J _i between the average current density J _i and setting the current density J _{the set} for each measurement region M _i, respectively, in accordance with the current density difference .DELTA.J _i, the current density difference .DELTA.J _i all The drawer power supply 42 is controlled so as to be within the allowable range ε. It may be those having a present adjustment function of controlling each of the potential difference V _di between each extraction electrode pieces 30 and the plasma electrode 12 corresponding to the remainder of each measurement region M _i Te.

  The control contents in the control device 60 in this case are shown in a flowchart in FIG. Steps 120 to 122 are rough adjustments, and steps 123 to 128 are main adjustments.

The coarse adjustment, first, on the basis of the measured data DA from the beam monitor 56, the current density difference between the average current density J _r of any one measurement region M _r of the plurality of measurement regions and setting the current density J _{The set} the .DELTA.J _r determined according to the following equation (step 120). In FIG. 9, as an example, the above any one of the measurement area M _r, when the measurement area M ₁ endmost, that is, when the r = 1.

[Equation 5]
ΔJ _r = J _r −J _set

Next, it is determined whether or not the current density difference ΔJ _r is within the allowable range ε (step 121). If it is within the allowable range ε, the process proceeds to step 123 of the main adjustment, and if not within the allowable range ε, the process proceeds to step 122.

In step 122, the extraction voltage V _e applied to all the extraction electrode pieces 30 is uniformly controlled so that the current density difference ΔJ _r falls within the allowable range ε, and the potential difference V _d is uniformly controlled. That is, when the average current density J _r is greater than the set current density J _{The set} will reduce the potential difference V _d uniformly, increases uniformly the potential difference V _d is smaller than the average current density J _r is set current density J _{The set} Control. More specifically, assuming that the potential difference before the uniform control is V _d and the new potential difference after the uniform control is V _d ′, the new potential difference V _d ′ is obtained from the following equation and controlled to become it.

[Equation 6]
_{V d '= αV d (J} set / J r) 2/3 + β

After step 122 returns to step 110 until the current density difference .DELTA.J _r falls within the allowable range epsilon, repeated control step 120 - 122.

  The control contents of steps 123 to 128 of this adjustment are substantially the same as the control contents of steps 100 to 105 shown in FIG. To explain the difference, here, the range that i can take is all of the remaining 1 to n other than r as a representative. For example, when r = 1, i is 2 to n.

When the control function in the control device 60 is divided into the rough adjustment and the main adjustment as described above, the entire beam current density distribution is quickly set by using the representative value (that is, the average current density J _r of the measurement region M _i ). Since the current density J _set can be approximated, the control by this adjustment becomes easy. As a result, the beam current density distribution in the Y direction of the ion beam 8 can be brought closer to the set current density J _set more quickly and allowed. It can be within the range ε. In addition, at the time of this adjustment, it is only necessary to control the measurement area other than the measurement area _Mr used at the time of the coarse adjustment, so that the control content is simplified and the time required for the control can be shortened.

  The extraction electrode system 10 does not have the suppression electrode 14, and the extraction electrode 13 also serves as a suppression electrode, that is, the extraction electrode 13 also functions to suppress backflow electrons from the downstream side. Examples are shown in FIGS. In this way, the number of electrodes constituting the extraction electrode system 10 can be reduced by one. 10 and 12, only one drawing power source 42 is shown, but the actual state is as described above with reference to FIG.

  FIG. 10 shows an example in which a drawer power source 42 is connected in the same manner as in the case shown in FIGS.

An example of the potential of the extraction electrode system 10 in this case is shown in FIG. The potential difference V _d is also V _d = V _e in this example. However, the potential setting range P _s of the extraction electrode 13 needs to be a negative potential in order to suppress the backflow electrons from the downstream side, and thus is narrower than in the case of FIGS.

  FIG. 12 shows an example in which an extraction power source 42 is connected between the ground potential portion and the extraction electrode 13 (more specifically, each extraction electrode piece 30) with the extraction electrode 13 on the negative electrode side.

An example of the potential of the extraction electrode system 10 in this case is shown in FIG. In this example, the potential difference V _d is V _d = V _a + V _e . The potential setting range P _s of the extraction electrode 13 is the same as in the case of FIGS.

  By the way, in this embodiment, the target 50 is mechanically scanned in the direction intersecting with the main surface 8a of the ion beam 8 as described above. When this is viewed in a plane in the traveling direction Z of the ion beam 8, the target 50 is scanned along the X direction as shown in FIG. 15, for example (see arrow C). Each extraction electrode piece 30 of the extraction electrode 13 may be arranged along the X direction as in the examples shown in FIGS. 4 and 14, but as in the example shown in FIG. May be arranged diagonally.

  If it is arranged obliquely, even if the beam current density is disturbed downstream of the dividing portion 32 due to the influence of the dividing portion 32, the disturbance pattern is not directly transferred onto the target 50, It is averaged on the target 50 by mechanical scanning of the target 50. In other words, it is relaxed or diluted. Accordingly, the influence of the disturbance can be suppressed on the target 50. As a result, the disturbance of the uniformity of implantation with respect to the target 50 can be suppressed small. The same applies to the case where the ion extraction hole 17 has the slit shape described above.

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 expands and shows partially the ion beam shown in FIG. It is a schematic perspective view which expands and shows the extraction electrode system shown in FIG. 1, and the plate | board thickness of each electrode is abbreviate | omitted. It is a figure which shows in more detail the extraction electrode, extraction power supply, and control apparatus which are shown in FIG. It is a figure which shows an example of the electric potential of the extraction electrode system shown in FIG. It is a figure which shows an example of the beam current density distribution measured with a beam monitor. It is a flowchart which shows an example of the control content in the control apparatus shown in FIG. It is a flowchart which shows the other example of the control content in the control apparatus shown in FIG. 6 is a flowchart showing still another example of control contents in the control device shown in FIG. 1. It is a figure which shows the other example of an extraction electrode system periphery. It is a figure which shows an example of the electric potential of the extraction electrode system shown in FIG. It is a figure which shows the further another example around an extraction electrode system. It is a figure which shows an example of the electric potential of the extraction electrode system shown in FIG. It is a front view which shows the other example of an extraction electrode. It is a front view which shows the further another example of an extraction electrode with a target.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Ion source 4 Plasma generation part 6 Plasma 8 Ion beam 10 Extraction electrode system 12 Plasma electrode 13 Extraction electrode 30 Extraction electrode piece 32 Dividing part 42 Extraction power supply 50 Target 54 Target drive device 56 Beam monitor 60 Control apparatus

Claims (5)

When 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, a plasma generating unit that generates plasma, An extraction electrode system for extracting an ion beam, the plasma electrode disposed on the most plasma side and the extraction electrode system disposed on the downstream side thereof and having an extraction electrode for extracting the ion beam from the plasma by a potential difference with the plasma electrode; In an ion implantation apparatus configured to extract an ion beam having a dimension in the Y direction larger than the dimension in the X direction from the ion source including:
The extraction electrode is divided into a plurality of extraction electrode pieces in the Y direction,
And an extraction power source capable of independently controlling the potential difference between the plasma electrode and each extraction electrode piece for each extraction electrode piece,
A beam monitor that receives the ion beam and measures a beam current density distribution in the Y direction of the ion beam;
By controlling the extraction power source based on the measurement data from the beam monitor and controlling the potential difference between the plasma electrode and each extraction electrode piece, the beam current density distribution measured by the beam monitor is made uniform. And an ion implantation apparatus characterized by comprising a control device having a function of performing a control approaching to.   The control device, based on the measurement data from the beam monitor, calculates an average current density for each measurement region of a plurality of measurement regions in the Y direction corresponding to each extraction electrode piece and a predetermined set current density. Each of the current density differences is obtained, and according to the current density difference, the extraction power source is controlled so that all the current density differences fall within a predetermined allowable range. The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus has a function of controlling each of the potential differences. The controller is
(A) Based on the measurement data from the beam monitor, a current density difference between an average current density of all measured current densities and a predetermined set current density is obtained, and the current density difference is determined according to the current density difference. A coarse adjustment function for performing coarse adjustment to control the extraction power source so as to fall within a predetermined allowable range and uniformly control the potential difference between the plasma electrode and each extraction electrode piece;
(B) After the coarse adjustment, based on the measurement data from the beam monitor, the average current density and the set current density for each measurement region of the plurality of measurement regions in the Y direction corresponding to the extraction electrode pieces Current density difference between the plasma electrode and each of the extraction electrode pieces by controlling the extraction power source so that the current density difference is all within the allowable range according to the current density difference. The ion implantation apparatus according to claim 1, further comprising a main adjustment function for controlling a potential difference therebetween. The controller is
(A) Based on the measurement data from the beam monitor, an average current density of one measurement region among a plurality of measurement regions in the Y direction corresponding to each extraction electrode piece and a predetermined set current density A current density difference is obtained, and a potential difference between the plasma electrode and each extraction electrode piece is controlled by controlling the extraction power source so that the current density difference falls within a predetermined allowable range according to the current density difference. A coarse adjustment function that performs coarse adjustment to uniformly control
(B) After the rough adjustment, based on the measurement data from the beam monitor, a current density difference between the average current density and the set current density for each of the remaining measurement areas of the plurality of measurement areas is obtained. Then, according to the current density difference, the extraction power source is controlled so that all the current density differences fall within the allowable range, and the extraction electrode pieces and the plasma electrodes corresponding to the remaining measurement areas are controlled. The ion implantation apparatus according to claim 1, further comprising a main adjustment function for controlling a potential difference between the two. The target is mechanically scanned in a direction intersecting the main surface of the ion beam,
The ion implantation apparatus according to claim 1, wherein each divided portion of the extraction electrode is disposed obliquely with respect to the X direction.

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