JP2011018578A - Ion implantation device equipped with two or more uniformizing lenses, and selecting method of two or more uniformizing lenses - Google Patents

Abstract

PROBLEM TO BE SOLVED: To irradiate an ion beam having sufficiently uniform current density distribution against a semiconductor substrate even when energy reduction of the ion beam is advanced.SOLUTION: This ion injection device includes: an accelerating and decelerating device to accelerate or decelerate a ribbon-shaped ion beam in order to irradiate the ribbon-shaped ion beam having a desired energy onto the semiconductor substrate; a first uniformizing lens and a second uniformizing lens in order to uniformly control the electric current density distribution in the longitudinal direction of the ribbon-shaped ion beam; a treatment room in which the semiconductor substrate is arranged; and a beam current meter which is arranged in the treatment room and carries out measurement of the current density distribution in the longitudinal side direction of the ribbon-shaped ion beam. Then, when a route of the ribbon-shaped ion beam is seen from a treatment room side, the second uniformizing lens, the accelerating and decelerating device, and the first uniformizing lens are arranged in this order along the route of the ion beam.

Description

  The present invention relates to, for example, an ion implantation apparatus having a plurality of uniformizing lenses for controlling the current density distribution of the ion beam in the long side direction of the ribbon-like ion beam to be uniform. Further, the present invention relates to a method for properly using a plurality of uniformizing lenses.

  Conventionally, ion implantation apparatuses have been provided with an accelerator / decelerator having a function of accelerating or decelerating an ion beam in order to irradiate a semiconductor substrate such as silicon with an ion beam having a desired energy. Further, when manufacturing a device, it is desired to manufacture a device having uniform characteristics over the entire surface of the semiconductor substrate. Therefore, the ion implantation apparatus is provided with a uniformizing lens for uniformly controlling the current density distribution of the ion beam irradiated to the semiconductor substrate.

  In general, the ion beam diverges under the influence of the space charge effect. The degree of divergence of the ion beam becomes more remarkable as the flight distance of the ion beam becomes longer and the energy of the ion beam becomes lower. If the ion beam diverges sufficiently, the beam diameter of the ion beam applied to the wafer increases, reducing the efficiency of beam irradiation at the target location, and the angle of the traveling direction of each ion particle within the beam diameter. And the angle of incidence on the substrate during irradiation also increases. Therefore, the incident angle deteriorates with a certain angle width from the set angle. In other words, the uniformity of the current density distribution deteriorates. In order to improve this, in an ion implantation apparatus that handles a low-energy ion beam, an accelerator / decelerator is installed as close as possible to the processing chamber in which the semiconductor substrate is placed, and the semiconductor substrate is irradiated with the ion beam. Immediately before, the energy of the ion beam was lowered.

  In addition, the energy range of the ion beam handled by the ion implantation apparatus is wide. For example, in a current ion implantation apparatus, the energy range of an ion beam to be handled ranges from several keV to several hundred keV. Note that the energy here refers to the energy of an ion beam applied to the semiconductor substrate. When deflecting an ion beam having high energy, a strong electric field or a strong magnetic field is required. On the other hand, in the case of an ion beam having low energy, a weak electric field or a weak magnetic field is sufficient. As a lens driving source for generating an electric field or a magnetic field, a DC power source is usually used, and an AC power source is used in some cases. When the energy of the ion beam handled by the homogenizing lens covers a wide range, it is necessary to use a power source voltage that can be set within a wide range.

  On the other hand, since a power supply capable of setting a voltage over a wide range is expensive, there is a demand for not using it. Therefore, in the conventional ion implantation apparatus, in the path through which the ion beam passes, a uniformizing lens is arranged on the upstream side of the accelerator / decelerator, and the ion beam before the ion beam energy conversion is performed by the accelerator / decelerator. Uniformity control was performed for (ion beams whose energy range is not wide).

JP 2008-97975 A (paragraph 0275-0276, paragraph 0228-0229, FIG. 1)

  The circuit pattern formed on the semiconductor substrate is increasingly miniaturized year by year. Accordingly, it is important to implant ions at a shallow position from the surface of the semiconductor substrate. The position where ions are implanted from the surface of the semiconductor substrate depends on the energy of the ion beam. Ions are implanted at a shallower position from the surface of the semiconductor substrate as the energy of the ion beam applied to the semiconductor substrate is lower.

  In the future, when further miniaturization is required and further reduction in energy of the ion beam is required, it becomes difficult to manufacture a device having uniform characteristics over the entire surface of the semiconductor substrate with the conventional ion implantation apparatus. The reason is that in the conventional ion implantation apparatus, there is no homogenization lens for performing the ion beam homogenization control between the accelerator / decelerator and the semiconductor substrate. Until now, even if there was some divergence of the ion beam depending on the physical distance between the accelerometer and the semiconductor substrate, the uniformity of the ion beam current density distribution is acceptable in device fabrication. It was within the range. However, if the ion beam is converted to a lower energy than before by the accelerator / decelerator, the ion beam will further diverge and eventually exceed the allowable range.

  For this reason, the conventional ion implantation apparatus has a problem that when the energy of the ion beam is reduced, the semiconductor substrate cannot be irradiated with an ion beam having a sufficiently uniform current density distribution.

  Accordingly, the main object of the present invention is to irradiate a semiconductor substrate with an ion beam having a sufficiently uniform current density distribution even when the energy of the ion beam is reduced.

  The ion implantation apparatus according to the present invention includes an acceleration / decelerator for accelerating or decelerating the ribbon-like ion beam to irradiate a semiconductor substrate with a ribbon-like ion beam having a desired energy, and the ribbon-like ion beam. A first uniformizing lens and a second uniformizing lens for uniformly controlling the current density distribution in the long side direction, a processing chamber in which the semiconductor substrate is disposed, and a ribbon shape disposed in the processing chamber. An ion implantation apparatus comprising a beam current measuring device for measuring a current density distribution in the long side direction of the ion beam when the path of the ribbon-like ion beam is viewed from the processing chamber side. The uniformizing lens, the accelerator / decelerator, and the first uniforming lens are arranged in this order along the path of the ion beam.

  According to one aspect of the present invention, an ion beam having a sufficiently uniform current density distribution can be irradiated onto a semiconductor substrate even when the energy of the ion beam is reduced.

It is a top view which shows one Embodiment of the ion implantation apparatus which concerns on this invention. It is a perspective view of an ion beam. It is a top view of a beam current measuring device. It is a perspective view of a uniform lens. It is the current density distribution along the Y-axis direction measured by the beam current measuring instrument. FIG. 5 is a diagram in which an average value of a whole beam current density and a predetermined range are added to FIG. It is the figure which added the average value of the beam current density in a predetermined range and each group to FIG. It is a flowchart which shows the control by a uniformization lens. It is a flowchart which shows the proper use method of the uniformization lens by the energy of an ion beam. It is a flowchart which shows the proper use method of the uniformization lens by the electric current amount of an ion beam. It is a perspective view of the homogenization lens in another mode.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an ion implantation apparatus according to the present invention. In FIG. 1, the Z-axis direction refers to the traveling direction of the ion beam 2.

  In this ion implantation apparatus, the ion beam 2 emitted from the ion source 1 has a length in the X-axis direction and the Y-axis direction orthogonal to the Z-axis direction, and when comparing the lengths, The ion beam has a shape that is longer in the Y-axis direction than in the X-axis direction. Such a beam is also called a ribbon beam, a sheet beam, or a long beam. In FIG. 1, only the center trajectory is shown as the trajectory of the ion beam 2 for convenience.

  More specifically, as shown in FIG. 2, such an ion beam has a length BH (specifically, about 300 to 500 mm) along the Y-axis direction, and an X-axis orthogonal to the Y-axis. The direction has a length BW (specifically, about 80 to 100 mm).

  After the ion beam 2 is emitted from the ion source 1, it passes through the mass analysis magnet 3 and the analysis slit 4. Thereby, selection of ion species to be implanted into the semiconductor substrate 8 is performed. Specifically, the semiconductor substrate 8 is a glass substrate on which a silicon wafer or a semiconductor element is formed.

  The ion beam 2 subjected to mass analysis passes through the first homogenizing lens 5, the accelerator / decelerator 6, and the second homogenizing lens 7, and then is irradiated onto the semiconductor substrate 8 disposed in the processing chamber 9.

  In order to irradiate the entire surface of the semiconductor substrate 8 with the ion beam 2 while the ion beam 2 is irradiated onto the semiconductor substrate 8 disposed in the processing chamber 9, the semiconductor substrate 8 is placed on the X axis by a drive mechanism (not shown). Reciprocating scanning is performed in the parallel W direction. During this reciprocating scanning, the semiconductor substrate 8 is completely moved to a region where the ion beam 2 is not irradiated onto the semiconductor substrate 8. Even when the ion implantation process is not performed on the semiconductor substrate 8 at the time of setting up the ion implantation apparatus or the like, the semiconductor substrate 8 passes through the path through which the ion beam passes by a driving mechanism (not shown) at a position where the ion beam 2 is not irradiated. The substrate 8 is retracted.

  In the processing chamber 9, a beam current measuring instrument 10 is disposed on the downstream side of the semiconductor substrate 8 at a position where the central trajectory of the ion beam 2 passes. The beam current measuring instrument 10 is composed of a plurality of Faraday cups.

  An example of the beam current measuring instrument 10 is shown in FIG. Here, the beam current measuring instrument 10 is composed of 16 Faraday cups 12, and each Faraday cup 12 is arranged along the Y axis. Thus, the ion beam 2 is irradiated to the beam current measuring instrument 10 while the semiconductor substrate 8 is not irradiated with the ion beam 2, that is, during the ion implantation process or when the ion implantation process is not performed due to the setup of the apparatus. The beam current density distribution measurement in the long side direction of the ion beam 2 becomes possible. The dimension of the beam current measuring instrument 10 in the Y-axis direction is set so as to sufficiently cover the dimension of the designed ion beam 2 in the Y-axis direction assumed in the processing chamber.

  The data of the beam current density distribution measured by the beam current measuring instrument 10 is transmitted to the control device 11 of FIG. 1, and the control device 11 uses the first uniformizing lens 5 or the second uniformization based on the transmitted data. The control lens 6 is controlled, and uniform control of the ion beam 2 is performed.

  Here, a method of uniformization control by the control device 11 will be described.

  FIG. 4 shows an example of the first homogenizing lens 5 and the second homogenizing lens 6. Here, an electric field lens is used as the homogenizing lens. In this electric field lens, nine electrode pairs 15 including electrodes A13 and B14 provided so as to sandwich the ion beam 2 from the X-axis direction are arranged along the long side direction of the ion beam.

  In this example, nine electrode pairs 15 are sandwiched from the traveling direction (Z direction) of the ion beam, and the shielding plate 16 is disposed at a position that does not interfere with the ion beam 2 in the X-axis direction. The shielding plate 16 is electrically grounded, and is provided to prevent the electric field from the adjacent accelerometer 6 from leaking to the homogenizing lens side. It should be noted that the shielding plate 16 of the homogenizing lens on the side not adjacent to the accelerator / decelerator 6 prevents the ion beam 2 from colliding with the electrode pair 15 constituting the homogenizing lens and changing the potential of the electrode pair. It is provided to prevent this. The shielding plate of the homogenizing electrode located on the processing chamber side plays a role of preventing contaminants from the homogenizing electrode from flowing out to the processing chamber side.

  Electrode A13 and electrode B14 are electrically connected by a conductor (not shown). Each of the nine electrode pairs is connected to an individual DC power source. An electric field can be generated between the electrode pairs by changing the value of the voltage applied to each electrode pair 15. By this electric field, the ion beam can be deflected in some direction from the Z-axis direction, which is the traveling direction, to the Y-axis direction.

  In this example, the ion beam is assumed to have a positive charge. At this time, a negative voltage is applied to the first electrode pair from the top in the Y-axis direction of the electrode pair 15 of the uniformizing lens, and the other electrode pairs are grounded. Then, a part of the ion beam passing between the first and second electrode pairs from the top is deflected somewhat from the Z direction toward the first electrode pair side by the electric field generated between the electrode pairs. That is, a part of the ion beam passing between the first and second electrode pairs has an angle with respect to the Z direction by this deflection. Since no electric field is generated in the other electrode pairs, the deflection of the ion beam passing between the other electrode pairs does not occur. In this way, the uniformizing lens can achieve deflection of a local ion beam (a portion of the entire ion beam that passes through a portion where an electric field is generated).

  What voltage is applied to the electrode pair is changed according to the measurement result of the current density distribution. In the example of FIG. 4, since there are nine electrode pairs 15 constituting the homogenizing lens, there are eight spaces between the electrode pairs in the Y-axis direction. On the other hand, the 16 Faraday cups constituting the beam measuring device of FIG. 3 are divided into 8 groups A to H, with adjacent Faraday cups as a group, and formed between the electrode pairs described above. Each of the eight spaces is made to correspond.

  5 to 7 are beam current density distributions measured by the beam current measuring instrument 10. In the figure, the horizontal axis shows regions corresponding to the groups A to H grouped by the beam current measuring instrument 10, and the vertical axis shows the ion beam current density.

  This will be described together with the flowcharts of the equalization control shown in FIGS.

  In the uniformity control flowchart of FIG. 8, first, the average value (AVE A to H) of the beam current density measured in each group from A to H and the total beam current density (measured in all groups from A to H). The average value (AVE TOTAL) of the sum of the current densities is obtained.

  Next, in the flow of FIG. 8, it is determined whether or not the average value in each group is within a predetermined range. If it is within the predetermined range, the flow ends, assuming that the uniformity satisfies a desired condition. The term “within the predetermined range” as used herein refers to a value set in advance by the operator of the ion implantation apparatus, and is determined according to the degree of uniformity of the desired current density distribution of the ion beam. Specifically, the predetermined range is set based on the average value of the entire beam current density.

  In order to explain the processing of this part in more detail, FIG. 6 and FIG. 7 are referred to. In FIG. 6, the average value (AVE TOTAL) of the entire beam current density is indicated by a two-dot chain line, and the predetermined range with respect to the average value of the entire beam current density is indicated by a solid line. In FIG. 7, the average value (AVE A to H) of the beam current density measured in each group from A to H is indicated by a one-dot chain line. In FIG. 7, it can be seen that the average value of the beam current densities in the groups E and F is out of the predetermined range.

  Next, in the flow of FIG. 8, an operation of extracting an average value of current densities of groups that do not satisfy the predetermined range is performed. Hereinafter, in order to make the description easier to understand, a specific number will be used as an example. The average value of the current density of the entire ion beam is 200, the predetermined range is a range (190 to 210) of 5% from the average value of the whole, and the average values in groups D to G are 195, 215, 225, and 200, respectively. . The unit is omitted.

  According to the measurement result of FIG. 7, since it is outside the predetermined range, the average value data of groups E and F is extracted. Next, it is determined whether or not the average value of the extracted group exceeds the upper limit of the predetermined range. In this case, the upper limit is exceeded in any group.

  Next, the average value of the target group (in this case, the average value of group E and group F) is compared with the average value of the adjacent groups. First, when looking at group E, the groups adjacent to group E are groups D and F. The average values of group E are 215 for group E, 195 for group D, and 225 for group F, respectively. Next, each difference is calculated and compared. The difference between group E and group D (215-195) is 20, and the difference between group E and group F (215-225) is -10. On the other hand, when looking at the group F, the groups adjacent to the group F are the groups E and G, the difference between the group F and the group E (225-215) is 10, and the difference between the group F and the group G (225-200). ) Is 25.

  Based on this result, local deflection of the ion beam is performed. Specifically, the local deflection of the ion beam from the space formed between the electrode pairs of the homogenizing lens corresponding to group E to the space formed between the electrode pairs of the homogenizing lens corresponding to group D Appropriate voltages are applied to each electrode pair so that is achieved. At the same time, local deflection of the ion beam is performed from the space formed between the electrode pairs of the homogenizing lens corresponding to the group F to the space formed between the electrode pairs of the homogenizing lens corresponding to the group G. Appropriate voltages are applied to each electrode pair as achieved. By this equalization control, the current density is averaged over the whole. An appropriate voltage is applied between the other electrode pairs so that the potential difference between the electrode pairs becomes zero so as not to cause local deflection of the ion beam.

  As a result of the uniform control, it is confirmed again whether the average value of each group is within a predetermined range. At this time, if it is outside the predetermined range, the above-described equalization control is performed again.

  An appropriate voltage is applied to each electrode pair in the uniformization control. This will be described in detail.

  Even if an electric field having the same strength is generated between the electrode pairs of the homogenizing lens, the amount of deflection of the ion beam differs depending on the energy of the ion beam to be handled. For this reason, the relationship between the ion beam energy, the potential difference (electric field strength) generated between the electrode pairs, and the local deflection amount of the ion beam is preliminarily determined by conducting an experiment before actual uniformization control. The result of the examination is stored, and the result of the examination is stored in the control device 11 in the form of a data table.

  Further, even if the value of the potential difference that generates the electric field is known, the voltage value specifically applied to the electrode pair can be selected innumerably. Therefore, the electrode pair provided in the portion where the ion beam does not need to be deflected is always grounded (0 V), and this value is used as a reference value when a voltage corresponding to the potential difference is applied. When the reference value is set in this manner, an appropriate voltage can be applied to each electrode pair according to the value of the potential difference based on the reference value. However, although the numerical value of 0V is selected here for convenience, other values may be used.

  On the other hand, before the ion implantation process is performed, the ion beam energy value set by the operator of the ion implantation apparatus is transmitted to the control device via an interface or the like when the operator sets the value. Keep it. Further, it may be input directly to the control device.

  Further, the beam current density data (data described in FIGS. 5 to 7) measured by the beam current measuring device is also appropriately transmitted to the control device before or during the ion implantation process. .

  Further, when performing the homogenization control, in order to make the entire current density flat, it is conceivable that the deflection amount of the ion beam is gradually decreased as the homogenization control is repeated. In this way, the ion beam transition is always performed with a large deflection amount every time the control is performed, so that the control does not converge, and the ion beam transition is always performed with a small deflection amount, so that the control takes time. Can be solved.

  More specifically, for example, the second deflection amount is set to be the first deflection amount so that the ion beam deflection amount is gradually reduced at each number of equalization control, such as the first time, the second time, the third time, and so on. It is set in the control device using a predetermined rule such as a few percent smaller than the deflection amount. The number of times of equalization control mentioned here is counted as a series of flows from the determination of whether the average value of each group is within a predetermined range until the same determination is made again. is doing. The number of times of equalization control is determined by how many times counting has been performed from the start of the uniformity control.

  In this way, during the actual homogenization control, the controller is appropriately preliminarily preliminarily determined based on the result of measurement by the beam current measuring instrument and the ion beam energy value set by the operator of the ion implantation apparatus. The control device reads an appropriate value from the data table including the stored energy, deflection amount, and voltage value, and based on this value, the homogenization control by the homogenization lens can be automated.

  Note that the homogenization control may be performed manually. In this case, the measurement result obtained by the beam current measuring instrument 10 is monitored by the operator of the ion implantation apparatus while adjusting the set value of the voltage applied to each electrode pair of the homogenizing lens.

  Next, the proper use of the first uniformizing lens 5 and the second uniformizing lens 7 will be described. These homogenizing lenses are selectively used depending on the energy of the ion beam 2 applied to the semiconductor substrate 8 and the amount of beam current measured by the beam current measuring device 10.

  First, how to use the ion beam 2 according to energy will be described.

  When the energy of the ion beam 2 irradiated to the semiconductor substrate 8 is high, the ion beam is accelerated by the accelerator / decelerator 6. For this reason, the energy of the ion beam passing through the second homogenizing lens 7 becomes high. When the homogenization control is performed using the second homogenization lens 7, a power source corresponding to a high voltage for generating a strong electric field is required.

  By using such a power supply capable of applying a high voltage, the ion beam can be locally deflected to control the uniformity of the ion beam, but it is still difficult to deflect the high energy ion beam. Therefore, the control becomes difficult as compared with the control for the low energy ion beam, and the efficiency at the time of performing the uniform control is lowered.

  In order to achieve the same amount of ion beam deflection, a high energy ion beam requires a wider range of voltage values than a low energy ion beam. Depending on the energy size, for example, when a low-energy ion beam is deflected 0 to 10 degrees in the Y-axis direction with respect to the Z-axis direction, the potential difference applied to the electrode pair of the uniformizing lens is 0 to several V is enough. On the other hand, in the case of a high energy ion beam, a wide range of 0 to several thousand volts is required.

  On the other hand, it is easy to perform the homogenization control on the ion beam 2 before passing through the accelerator / decelerator 6 as is conventionally done. This is because the energy of the ion beam 2 to be handled is relatively low. Therefore, when irradiating the semiconductor substrate 8 with the high energy ion beam 2, the uniformization control is performed on the ion beam 2 before being converted into the high energy from the viewpoint of the efficiency of the uniformization control. desirable. Therefore, when irradiating the semiconductor substrate 8 with a high energy ion beam, the homogenization control is performed using the first homogenization lens 5 on the upstream side of the accelerator / decelerator 6.

  On the other hand, when irradiating the semiconductor substrate 8 with the low-energy ion beam 2, it is difficult to perform the homogenization control using the first homogenization lens 5. This is because the low-energy ion beam 2 is easily affected by the space charge effect, and when it reaches the semiconductor substrate 8, it is no longer emitted as the ion beam 2 and uniform control becomes difficult.

  If this is explained in full detail, the external shape of the whole ion beam 2 will spread by the space charge effect. On the other hand, when viewed from a macro viewpoint, that is, when attention is paid to individual portions of the ion beam 2, the ion beam 2 travels in all directions under the influence of the space charge effect. The direction in which the ion beam 2 travels depends on the state of charge of the ion beam 2 in the focused area, the concentration of the residual gas present in the ion beam path, the amount of electrons ionized from the residual gas, etc. Depends on the situation. These situations change over time. Therefore, it is very difficult to predict in which direction a part of the ion beam travels due to the space charge effect.

  Consider a case where uniformization control is performed using the first homogenization lens 5 when the energy of the ion beam 2 irradiated to the semiconductor substrate 8 is low. Since an accelerator / decelerator exists between the first homogenizing lens 5 and the semiconductor substrate 8, the physical distance from the first homogenizing lens 5 to the semiconductor substrate 8 is long. Therefore, the ion beam 2 controlled by the first homogenizing lens 5 is strongly affected by the space charge effect before reaching the semiconductor substrate 8.

  When individual portions of the ion beam 2 are viewed, the ion beam 2 that reaches the semiconductor substrate 8 travels in a direction different from the traveling direction controlled by the first uniformizing lens 5, so that it is uniform. The semiconductor substrate 8 cannot be irradiated with the ion beam 2 having a sufficiently uniform current density distribution due to the control.

  Therefore, in the present invention, when the ion beam 2 irradiated to the semiconductor substrate 8 has low energy, the homogenization control is performed using the second homogenization lens 7. By using them in this way, an expensive power supply that can set a voltage over a wide range is not necessary. Furthermore, the distance between the second uniformizing lens 7 and the semiconductor substrate 8 is short. Therefore, since the influence by the space charge effect does not occur so much, it is advantageous compared with the prior art in that the semiconductor substrate 8 can be irradiated with the ion beam 2 having a sufficiently uniform current density distribution.

Note that the uniformity of the current density distribution in the X-axis direction is not a problem in this embodiment. In this embodiment, since the semiconductor substrate is scanned across the ion beam in the direction of W parallel to the X axis, the beam current in the Y axis direction can be obtained even if the current density distribution in the X axis direction is not uniform. If the uniformity of the density distribution is maintained, uniform ion implantation can be performed on the entire surface of the semiconductor substrate.

  FIG. 9 shows a specific example of how to use the uniformizing lens described so far.

  It has been stated that the influence of the space charge effect depends on the distance and energy of the ion beam path. Here, paying attention to this point, the uniformizing lens is selectively used.

In the flowchart shown in FIG. 9, first, the energy of the ion beam 2 irradiated to the semiconductor substrate 8 is set. This is appropriately performed by the operator of the ion implantation apparatus. Next, a comparison is made between the set energy (referred to as final energy for convenience) and predetermined energy (referred to as reference energy for convenience) provided in advance.

  The reference energy is set depending on the configuration of each ion implantation apparatus. The reason for this setting is that the distance between the acceleration / decelerator and the semiconductor substrate in each ion implantation apparatus is not constant, and the influence of the space charge effect differs even when handling ion beams with the same energy. is there. This reference energy means the energy at the boundary between high energy and low energy, and is a value determined from experiments using an ion implantation apparatus and empirical rules of designers.

  As a result of comparison, if the final energy is smaller than the reference energy, the final energy is low, so that the homogenization control is performed using the second homogenization lens 7 provided on the downstream side of the accelerator / decelerator 6. The On the other hand, if the final energy is larger than the reference energy, the final energy is high, so that the homogenization control is performed using the first homogenization lens 5 provided on the downstream side of the accelerator / decelerator 6. .

  The determination function shown in the flowchart shown in FIG. 9 may be provided in the control device 11. In that case, a reference energy value is stored in the control device 11 in advance. Thereafter, when the operator of the ion implantation apparatus sets the final energy, the information is appropriately input to the control apparatus 11 via the user interface. Then, it is possible to automatically perform all the selection determination of the uniformizing lens to be used and the uniformization control using the selected uniformizing lens.

  On the other hand, it can also be performed manually by an operator of the ion implantation apparatus. A reference energy value is obtained in advance, and when setting the final energy, the operator may appropriately select a uniformizing lens to be used for comparison.

  Although the method of selectively using the uniformizing lens based on the energy value has been described, the uniformizing lens may be selectively used based on the beam current value (beam current amount) by the beam current measuring device.

  Since the low energy ion beam is strongly affected by the space charge effect, the outer shape of the ion beam is greatly expanded compared to the high energy ion beam. Therefore, when attention is paid to the beam current amount measured by the beam current measuring device 10 including a plurality of Faraday cups, the current amount of the low energy ion beam is smaller than the current amount of the high energy ion beam. In other words, the outer shape of a low-energy ion beam spreads out, so that it protrudes from the beam current measuring instrument. For this reason, since measurement cannot be performed for all ion beams, the amount of beam current decreases.

  A specific method in this case is performed according to FIG. In the case of the beam current amount, as in the case of energy, an experiment is performed in advance to determine a predetermined beam current amount serving as a reference. Then, the beam current amount actually measured by the beam current measuring device is compared with a predetermined beam current amount, and a uniformizing lens to be used is appropriately selected.

  In the case of the selection method using the beam current amount, as in the case of the selection method using energy, the selection may be performed by the control device or may be left to the operator's judgment.

  In addition, until now, the method of properly using the uniformizing lens based on the ion beam energy and the amount of ion beam current has been described. For example, the uniformizing lens should be used in the same way even if the spread angle of the entire ion beam is used. I can do it. This is because these parameters indicate how much the effect of the space charge effect appears on the ion beam irradiated to the semiconductor substrate. Therefore, the parameters to be noted in the present invention are not limited to the energy and current amount of the ion beam. Other parameters indicating the influence of the space charge effect on the ion beam irradiated on the semiconductor substrate due to the difference in the energy of the ion beam. The parameters may be

<Other embodiments>
The present invention is not limited to the above-described embodiment, and the following form may be adopted.

  The first homogenizing lens 5 and the second homogenizing lens 7 may be different members, but it is desirable to use the same member from the viewpoint of controllability. Further, as an example, the one using the electric field lens composed of the electrostatic lens array shown in FIG. 4 has been described. However, the present invention is not limited to this, and a magnetic lens conventionally used for uniformizing the beam current density may be used. I do not care.

Further, as the uniformizing lens, a lens as shown in FIG. 11 may be used for finer control. The lens of FIG. 11 has the two uniformizing lenses shown in FIG. 2 arranged in the Z direction, and the electrode pair of the other lens is arranged in the Y axis direction between the electrode pair of one lens. This is a uniform lens arranged in a shifted manner. With such a uniform lens,
The accuracy of the homogenization control can be improved.

  Furthermore, the beam current measuring instrument 10 is arranged in the processing chamber and has a plurality of Faraday cups arranged in the Y-axis direction as an example, but is not limited thereto. For example, the beam current measuring device is constituted by one Faraday cup. In combination with this, by providing a drive mechanism capable of moving the beam current measuring instrument along the Y-axis direction, a beam current measuring instrument having an equivalent function can be realized.

  In addition, when a low energy ion beam is handled, the outer shape of the ion beam is expanded. As a result, the ion beam may collide with a member or the like constituting the ion implantation apparatus before reaching the semiconductor substrate and disappear. Therefore, for the ion beam having a low energy, the first homogenization lens 5 temporarily narrows the outer shape of the ion beam before the homogenization control is performed by the second homogenization lens. You may be allowed to do.

DESCRIPTION OF SYMBOLS 1 Ion source 2 Ion beam 3 Mass analysis magnet 4 Analysis slit 5 1st homogenization lens 6 Accelerator / decelerator 7 2nd homogenization lens 8 Substrate 9 Processing chamber 10 Beam current measuring device 11 Controller

Claims (5)

An acceleration / decelerator for accelerating or decelerating the ribbon ion beam to irradiate the semiconductor substrate with a ribbon ion beam having a desired energy, and a uniform current density distribution in the long side direction of the ribbon ion beam A first homogenizing lens and a second homogenizing lens for controlling the semiconductor substrate, a processing chamber in which the semiconductor substrate is disposed, a current density in a long side direction of the ribbon-shaped ion beam disposed in the processing chamber In an ion implantation apparatus comprising a beam current measuring device that measures distribution, when the path of the ribbon-shaped ion beam is viewed from the processing chamber side, the second uniformizing lens, the accelerometer, An ion implantation apparatus characterized by being arranged along a path of an ion beam in the order of the first uniformizing lens. 2. The ion implantation apparatus according to claim 1, wherein the first homogenizing lens and the second homogenizing lens are homogenizing lenses having the same configuration. By comparing the energy value of the ribbon-shaped ion beam irradiated on the semiconductor substrate with the energy value serving as a reference, either the first homogenizing lens or the second homogenizing lens is used. The ion implantation apparatus according to claim 1, further comprising a control device having a function of determining whether to perform uniform control of current density distribution in a long side direction of the ribbon-shaped ion beam. By comparing the beam current amount measured by the beam current measuring device with the value of the reference beam current amount, it is possible to use either the first uniformizing lens or the second uniformizing lens to form the ribbon shape. The ion implantation apparatus according to claim 1, further comprising a control device having a function of determining whether to perform uniform control of current density distribution in the long side direction of the ion beam. An acceleration / decelerator for accelerating or decelerating the ribbon ion beam to irradiate the semiconductor substrate with a ribbon ion beam having a desired energy, and a uniform current density distribution in the long side direction of the ribbon ion beam A first homogenizing lens and a second homogenizing lens for controlling the semiconductor substrate, a processing chamber in which the semiconductor substrate is disposed, and a current density in a long side direction of the ribbon-shaped ion beam disposed in the processing chamber A beam current measuring device for measuring distribution, and when the ion beam path is viewed from the processing chamber side, the second homogenizing lens, the accelerometer, and the first homogenizing lens are arranged in this order. In the ion implantation apparatus, the semiconductor substrate is irradiated to uniformly control the current density distribution in the long side direction of the ribbon-like ion beam. According to the current amount of energy or ion beam of the ion beam, a method of selecting the first uniform lens with uniform lens characterized by selectively using said second homogenization lens.