Ion beam neutralization method, ion beam neutralization device and ion implantation equipment

Abstract

The invention discloses an ion beam neutralization method, an ion beam neutralization device and ion implantation equipment, and the ion neutralization method comprises the steps: providing an ion beam, and before the ion beam bombards a target workpiece, arranging an electron absorption layer on at least the periphery of a neutralization region surrounding an ion beam transmission path, the electron absorption layer is used for absorbing free electrons which do not participate in the ion beam neutralization. Neutralizing electrons are injected into the ion beam, and the amount of current in the electron absorption layer is measured to obtain the amount of remaining free electrons except for the neutralizing ion beam. The total amount of neutralizing electrons generated is measured. An actual amount of electrons in the neutralized ion beam is calculated based on the total amount of neutralized electrons and the amount of free electrons. And adjusting the total generation amount of neutralizing electrons according to the actual electron amount of the neutralizing ion beam. Furthermore, the electronic quantity of the actual neutralization ion beam can be monitored, the total electron generation quantity is adjusted based on the electronic quantity of the actual neutralization ion beam, excessive free electrons are prevented from being generated, and the energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and in particular to an ion beam neutralization method, an ion beam neutralization device and ion implantation equipment. Background Art

[0002] The principle of ion implantation is that charged positive ions are accelerated in a magnetic field and then injected into the wafer. During the ion implantation process, if a large number of positive ions are injected into the wafer, positive charges will accumulate on the wafer, causing the devices on the wafer to break down. Therefore, the ion beam injected into the wafer needs to remain electrically neutral to ensure that it does not affect the devices on the wafer. In the prior art, generally before the ion beam is implanted, the ion beam needs to pass through a plasma flood gun, which can generate a large number of electrons to neutralize the positive ions in the ion beam, so that the ions injected into the wafer are electrically neutral.

[0003] However, current detection methods can only detect the size of electrons generated by the plasma gun, but cannot detect the size of electrons used to neutralize positive ions in the ion beam. Since it cannot be measured, it can only provide a large number of electrons in an oversaturated manner. The oversaturated electrons floating in space will affect the normal operation of the machine or the measurement of the ion beam, thereby affecting the ion implantation yield. In addition, if the plasma gun fails, resulting in insufficient electron supply, it will not be able to effectively neutralize the positive ions in the ion beam, resulting in the accumulation of positive charge on the wafer, affecting the circuit devices, and even causing the wafer to be scrapped. Summary of the invention

[0004] In view of the above shortcomings of the prior art, an object of the present invention is to provide an ion beam neutralization method, an ion beam neutralization device and an ion implantation device, so as to monitor the amount of electrons in the neutralized ion beam and prevent oversaturation of electrons.

[0005] In order to achieve the above object and other related objects, the present invention provides an ion beam neutralization method, comprising:

[0006] providing an ion beam, the ion beam being used to bombard a target workpiece to implant ions into the target workpiece;

[0007] Before the ion beam bombards the target workpiece, an electron absorption layer is arranged at least at the periphery of a neutralization region surrounding the ion beam transmission path, the electron absorption layer is used to absorb free electrons that are not involved in the neutralization of the ion beam, and the two ends of the neutralization region are respectively an ion beam entrance end and an ion beam exit end;

[0008] Injecting neutralizing electrons into the ion beam in a neutralization region surrounding the ion beam transmission path in a direction perpendicular to the ion beam transmission path;

[0009] Measuring the amount of current in the electron absorption layer to obtain the amount of remaining free electrons other than the neutralized ion beam;

[0010] Measuring the total production of neutralizing electrons;

[0011] Based on the total amount of neutralized electrons produced and the amount of freed electrons, the amount of electrons actually neutralizing the ion beam is calculated;

[0012] The total amount of neutralizing electrons generated is adjusted according to the amount of electrons that actually neutralize the ion beam.

[0013] Optionally, the step of providing an electron absorption layer around a neutralization region surrounding the ion beam transmission path includes:

[0014] A first electron absorption layer is arranged at the ion beam inlet end of the neutralization region, and an ion beam inlet is arranged on the first electron absorption layer;

[0015] A second electron absorption layer is arranged at the ion beam outlet end of the neutralization region, an ion beam outlet is arranged on the second electron absorption layer, and the ion beam inlet and the ion beam outlet are arranged coaxially;

[0016] A third electron absorption layer is arranged around the neutralization region.

[0017] Optionally, after the step of providing an electron absorption layer at least at the periphery of a neutralization region surrounding the ion beam transmission path, and before the step of injecting neutralizing electrons into the ion beam in the neutralization region surrounding the ion beam transmission path along a direction perpendicular to the ion beam transmission path, the method further comprises:

[0018] A first electric field is formed at the ion beam entrance end of the neutralization region, and a second electric field is formed at the ion beam exit end of the neutralization region. The first electric field points from a low potential to a high potential along the direction from the ion beam entrance end to the ion beam exit end, and the second electric field points from a high potential to a low potential along the direction from the ion beam entrance end to the ion beam exit end.

[0019] Optionally, the potential difference in the first electric field is equal to the potential difference in the second electric field.

[0020] Optionally, before the step of injecting neutralizing electrons into the ion beam in a neutralization region surrounding the ion beam transmission path in a direction perpendicular to the ion beam transmission path, the method further comprises:

[0021] forming a first magnetic field in a region near an ion beam entrance end in the neutralization region;

[0022] A second magnetic field is formed in the neutralization region near the ion beam outlet end. The first magnetic field and the second magnetic field form a magnetic field that intersects the ion beam transmission path. The first magnetic field and the second magnetic field are arranged in parallel and in opposite directions.

[0023] Optionally, the first magnetic field generating end of the first magnetic field or the second magnetic field is arranged on one side of the ion beam and on the same side as the entrance of the neutralized electrons, and the second magnetic field generating end is arranged on the other side of the ion beam opposite to the first magnetic field generating end.

[0024] According to one aspect of the present invention, an ion beam neutralization device is also provided. The ion beam neutralization device is arranged before the ion beam bombards the target workpiece and is used to inject neutralizing electrons into the ion beam. The ion beam neutralization device comprises:

[0025] The neutralization chamber comprises an intermediate wall body which is annularly closed around the neutralization region of the ion beam transmission path, and a neutralization electron inlet is arranged on the intermediate wall body; an ion beam inlet is arranged at one end of the intermediate wall body, and an ion beam outlet is arranged at the other end of the intermediate wall body, and the ion beam inlet and the ion beam outlet are arranged coaxially;

[0026] The electron absorption layer is arranged in the neutralization cavity and at least arranged on the middle wall in the neutralization cavity and is in contact with the inner surface of the middle wall;

[0027] The first current monitoring device is connected to the electron absorption layer to monitor the current in the electron absorption layer.

[0028] Optionally, the neutralization chamber further comprises:

[0029] A first end wall is arranged at one end of the middle wall body, and an ion beam inlet is arranged on the first end wall;

[0030] A second end wall is arranged at the other end of the middle wall body, and the ion beam outlet is arranged on the second end wall;

[0031] The electron absorbing layer includes:

[0032] A first electron absorption layer is in contact with the inner surface of the first end wall of the neutralization cavity;

[0033] A second electron absorption layer is in contact with the inner surface of the second end wall of the neutralization cavity;

[0034] The third electron absorption layer is in contact with the inner surface of the middle wall.

[0035] Optionally, the first electron absorption layer, the second electron absorption layer and the third electron absorption layer are all graphite layers.

[0036] Optionally, the ion neutralization device further comprises:

[0037] A first constant voltage source is electrically connected to the first electron absorption layer and the second electron absorption layer respectively;

[0038] The second constant voltage source is electrically connected to the third electron absorption layer. The input voltage of the first constant voltage source is lower than the input voltage of the second constant voltage source, and the third electron absorption layer is isolated from the first electron absorption layer and the second electron absorption layer respectively.

[0039] Optionally, the first current monitoring device is a source meter, and the second constant voltage source providing device and the first current detection device are the same source meter.

[0040] Optionally, the ion beam neutralization device further comprises:

[0041] The electron generating device is located at the neutralizing electron inlet, and the electron emitting end of the electron generating device corresponds to the neutralizing electron inlet.

[0042] Optionally, the electron generating device comprises:

[0043] The plasma gun includes an arc power supply, and the change of the current of the arc power supply is used to control the amount of neutralizing electrons generated by the plasma gun;

[0044] The second current monitoring device is electrically connected to the arc power supply to monitor the current of the plasma gun.

[0045] Optionally, the voltage difference between the second constant voltage source and the first constant voltage source is greater than the voltage of the arc power source.

[0046] Optionally, the ion beam neutralization device further comprises:

[0047] A first pair of magnets is disposed on the outer wall of the middle wall and is disposed near the ion beam entrance. The first pair of magnets includes a first magnet and a second magnet. The first magnet and the second magnet are separately disposed on opposite sides of the ion beam transmission path. The first magnet and the second magnet have opposite polarities at relative positions.

[0048] The second pair of magnets is arranged on the outer wall of the middle wall body and is arranged near the exit of the ion beam. The second pair of magnets includes a third magnet and a fourth magnet. The third magnet and the fourth magnet are separately arranged on two opposite sides of the ion beam transmission path. The polarities of the relative positions of the third magnet and the fourth magnet are opposite. The direction of the magnetic field formed by the first pair of magnets is opposite to the direction of the magnetic field formed by the second pair of magnets.

[0049] According to one aspect of the present invention, there is also provided an ion implantation device, comprising:

[0050] An ion beam providing device, used for providing an ion beam;

[0051] An ion beam neutralization device receives the ion beam emitted by the ion beam providing device and neutralizes the received ion beam, and the ion beam neutralization device is the above-mentioned ion beam neutralization device;

[0052] The target workpiece is bombarded by the ion beam neutralized by the ion beam neutralization device to perform ion implantation.

[0053] Compared with the prior art, the ion beam neutralization method, ion beam neutralization device and ion implantation equipment of the present invention have at least the following beneficial effects:

[0054] The ion beam neutralization method of the present invention includes, before the ion beam bombards the target workpiece, setting an electron absorption layer at least at the periphery of a neutralization area surrounding the ion beam transmission path, the electron absorption layer is used to absorb free electrons that do not participate in the neutralization of the ion beam, after the neutralization electrons are injected into the ion beam, measuring the current of the electron absorption layer to obtain the free electron amount, and calculating the actual amount of electrons in the neutralized ion beam based on the measured total amount of neutralized electrons and the amount of free electrons. Furthermore, the present invention can measure and monitor the actual amount of electrons in the neutralized ion beam, and control the total amount of electrons generated in real time based on the actual amount of electrons in the neutralized ion beam, thereby realizing closed-loop control of electrons, avoiding the generation of excessive free electrons, and reducing energy consumption.

[0055] Furthermore, the ion beam neutralization method of the present invention also includes forming a first electric field at the ion beam entrance end of the neutralization region, and forming a second electric field at the ion beam exit end of the neutralization region, the first electric field points from a low potential to a high potential along the direction from the ion beam entrance end to the ion beam exit end, and the second electric field points from a high potential to a low potential along the direction from the ion beam entrance end to the ion beam exit end. Thus, due to the setting of the electric field at the ion beam entrance and the ion beam exit, the electrons are subjected to a force opposite to the direction of the electric field and cannot escape from the neutralization region, and are then used to neutralize the ion beam or are absorbed by the electron absorption layer, thereby improving the measurement accuracy of free electrons. At the same time, the design of the electric field solves the problem of electron ionization and eliminates the influence of free electrons on the Faraday cup measurement. Moreover, since the potential difference between the first electric field and the electric field is the same, the two electric fields have no effect on the energy and path of the ion beam.

[0056] Furthermore, the ion beam neutralization method of the present invention also includes forming a first magnetic field in a region near the entrance end of the ion beam in the neutralization region, and forming a second magnetic field in a region near the exit end of the ion beam in the neutralization region, wherein the first magnetic field and the second magnetic field form a magnetic field that intersects the ion beam transmission path, and the first magnetic field and the second magnetic field are arranged in parallel, and the magnetic field directions are opposite. Under the influence of the two magnetic fields, the electrons increase the movement path and trajectory, greatly improving the probability of being carried away by the ion beam and the utilization rate of the electrons. At the same time, the magnetic flux of the two electric fields is the same, and the electric fields are opposite in direction. The deflection directions of the ion beam under the action of the two electric fields are opposite, and the deflection amounts are the same, so that the two deflections of the ion beam can be corrected back to the initial path and angle, and thus have no effect on the original path of the ion beam.

[0057] The ion neutralization device and ion implantation equipment in the present invention are applied to the above-mentioned ion neutralization method and also have the above-mentioned technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A schematic diagram of the structure of an existing plasma gun (PFG) for neutralizing an ion beam;

[0059] Figure 2 is a method flow chart of an ion beam neutralization method according to an embodiment of the present invention;

[0060] Figure 3 A schematic diagram of the three-dimensional structure of the neutralization chamber of the ion beam neutralization device in an embodiment of the present invention;

[0061] Figure 4 For along Figure 3 A schematic diagram of the cross-sectional structure along the A-A' direction;

[0062] Figure 5 For along Figure 3 Schematic diagram of the cross-sectional structure along the B-B' direction;

[0063] Figure 6 is a schematic structural diagram of an electron generating device in an embodiment of the present invention;

[0064] Figure 7 The edge of the ion beam neutralization device in the embodiment of the present invention is Figure 3 A cross-sectional view taken along the line AA' (the electron generating device in the figure is only for illustration and is not cut);

[0065] Figure 8 The edge of the ion beam neutralization device in the embodiment of the present invention is Figure 3 A cross-sectional view taken along the BB' direction (the electron generating device in the figure is only for illustration and is not cut; the wall of the neutralization chamber is not shown in the figure);

[0066] Fig. 9 For Figure 8 Based on the above, the schematic diagram of the movement path of electron and ion beams;

[0067] Fig.10 is an equivalent circuit diagram of an ion beam neutralization device in an embodiment of the present invention;

[0068] Fig.11 It is a schematic diagram of the principle of the influence of the electric field in the ion beam neutralization device on the ion beam or the motion path in an embodiment of the present invention.

[0069] Fig.12 It is a schematic diagram of the principle of the influence of the magnetic field in the ion beam neutralization device on the movement path of the ion beam or electrons in an embodiment of the present invention.

[0070] List of reference numerals:

[0071] 1 Plasma Gun

[0072] 2 Electronics

[0073] 3 Ion beam

[0074] 4 Wafer

[0075] 100 Neutralization chamber

[0076] 101 Intermediate wall

[0077] 1011 Zhonghe Electronic Entrance

[0078] 102 first end wall

[0079] 1021 Ion beam entrance

[0080] 103 Second end wall

[0081] 1022 Ion beam exit

[0082] 201 First electron absorption layer

[0083] 202 Second electron absorption layer

[0084] 203 The third electron absorption layer

[0085] 210 Insulation isolation layer

[0086] 220 Insulation Mounting Block

[0087] 301 First current monitoring device / second constant voltage source

[0088] 302 First constant pressure source

[0089] 401 First pair of magnets

[0090] 402 Second pair of magnets

[0091] 410 First Magnet

[0092] 420 Second Magnet

[0093] 430 Third Magnet

[0094] 440 Fourth Magnet

[0095] 500 Electron Generator

[0096] 5011 Arc Power Supply

[0097] 5012 Filament Power Supply

[0098] 502 Second current monitoring device DETAILED DESCRIPTION

[0099] The following specific embodiments illustrate the embodiments of the present invention, and those familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0100] It should be noted that the diagrams provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Although the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of each component can be changed at will during actual implementation, and the layout of the components may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that can be implemented in this application, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by the present invention.

[0101] like Figure 1 As shown, the plasma gun 1 is arranged on the transmission path of the ion beam 3, and the plasma gun 1 generates electrons 2, which perform plasma bathing on the positively charged ions in the ion beam 3, and the electrons 2 are neutralized with the positively charged ions in the ion beam 3. Since the ion beam 3 is positively charged, it attracts the electrons 2, and the ion beam 3 takes away the electrons 2, so that the ions injected into the wafer 4 become electrically neutral.

[0102] However, currently only the amount of electrons generated by the plasma gun can be monitored, but the amount of electrons used to neutralize the ion beam cannot be monitored. In order to avoid the accumulation of positive charges in the wafer, the plasma gun can only provide electrons at an oversaturated level, which will cause the oversaturated electrons that do not participate in the neutralization of the ion beam to be free in the space of the ion implantation machine. Generally, a Faraday cup for measuring the ion beam dose is set up in the ion implantation machine, and the ion implantation amount is subsequently obtained through the measured ion beam dose. When the oversaturated electrons are freed to the Faraday cup, it will cause the Faraday cup to deviate from the measurement of the ion beam, affecting the test results and further affecting the subsequent ion implantation yield.

[0103] In order to solve the background technology and the above-mentioned technical problems, this embodiment provides an ion beam neutralization method, an ion beam neutralization device and an ion implantation device to accurately measure the amount of electrons in the neutralized ion beam to prevent the electrons from escaping to other areas of the machine and affecting the ion implantation.

[0104] The present embodiment is described in detail below with reference to specific examples.

[0105] Example 1

[0106] This embodiment provides an ion beam neutralization method, referring to Figure 2 , the ion beam neutralization method comprises:

[0107] S1: providing an ion beam, wherein the ion beam is used to bombard a target workpiece to implant ions into the target workpiece;

[0108] Specifically, an ion beam is provided, wherein the ions in the ion beam can be generated by an ion source generating device, and an ion beam generated by the ions generated by the ion source generating device is generated by a beam transmission device for implantation into a wafer. The ion source generating device and the beam transmission device are conventional components in the prior art and will not be described in detail herein.

[0109] S2: before the ion beam bombards the target workpiece, an electron absorption layer is arranged on the periphery of a neutralization region surrounding the ion beam transmission path, the electron absorption layer is used to absorb free electrons that are not involved in the neutralization of the ion beam, and the two ends of the neutralization region are respectively an ion beam entrance end and an ion beam exit end;

[0110] In order to prevent the electrons that are not involved in the neutralization of the ion beam from being ionized to other positions of the machine and affecting the ion implantation, this embodiment provides a neutralization area for neutralizing the ion beam and the electrons before the ion beam bombards the target workpiece. One end of the neutralization area is the ion beam entrance end, and the other end is the ion beam exit end. The ion beam enters from the ion beam entrance end and is ejected from the ion beam exit end. An ion beam transmission path is formed in the direction from the ion beam entrance end to the ion beam exit end. An electron absorption layer is arranged on the periphery of the neutralization area surrounding the ion beam transmission path. The electron absorption layer can absorb the ion beam that is not involved in the neutralization of the ion beam, thereby preventing it from being ionized to other positions of the machine.

[0111] In one example, the step of setting an electron absorption layer at least on the periphery of the neutralization region surrounding the ion beam transmission path includes: setting a first electron absorption layer at the ion beam inlet end of the neutralization region, and setting an ion beam inlet on the first electron absorption layer. Setting a second electron absorption layer at the ion beam outlet end of the neutralization region, and setting an ion beam outlet on the second electron absorption layer, and the ion beam inlet and the ion beam outlet are coaxially arranged. Setting a third electron absorption layer on the periphery surrounding the neutralization region. Optionally, the materials of the first electron absorption layer, the second electron absorption layer, and the third electron absorption layer are materials that can absorb electrons, such as graphite.

[0112] In one example, in order to prevent free electrons that do not participate in the neutralization of the ion beam from escaping from the neutralization region, after the step of setting an electron absorption layer at least on the periphery of the neutralization region, it also includes: forming a first electric field at the ion beam inlet end of the neutralization region, and forming a second electric field at the ion beam outlet end of the neutralization region, the first electric field points from a low potential to a high potential along the direction from the ion beam inlet end to the ion beam outlet end, and the second electric field points from a high potential to a low potential along the direction from the ion beam inlet end to the ion beam outlet end. It can be seen from the movement characteristics of electrons in the electric field that the force exerted on the electrons in the electric field is opposite to the direction of the electric field, so they will move from a low potential to a high potential. Since the inlet and outlet ends of the ion beam are both at low potential, the electrons will not move toward the inlet and outlet ends of the ion beam, thereby preventing the escape of electrons.

[0113] Since the energy of the ion beam is in the kilovolt level, and the voltage source forming the first electric field and the second electric field is in the volt level, there is a difference of more than a thousand times in magnitude between the two sides. The influence of the electric field on the ion beam can be said to be negligible, and this subtle influence is also considered and solved in the present invention. In order to avoid the influence of the first electric field and the second electric field on the ion beam, the present invention sets the potential difference of the first electric field and the potential difference of the second electric field to be the same in one example. When the ion beam reaches the first electric field at the entrance of the ion beam, the energy is reduced due to the reverse voltage. Later, when it reaches the second electric field at the exit of the ion beam, it becomes a forward voltage, the energy increases, and the two voltage potentials are the same, so the setting of the two electric fields has no effect on the energy of the ion beam.

[0114] In order to increase the efficiency of combining neutralizing electrons with ion beams and improve the utilization rate of neutralizing electrons, in one example, before the step of injecting neutralizing electrons into the ion beam in a direction perpendicular to the ion beam transmission path in the neutralizing region surrounding the ion beam transmission path, it also includes: forming a first magnetic field in the neutralizing region near the ion beam entrance end. Forming a second magnetic field in the neutralizing region near the ion beam exit end, the first magnetic field and the second magnetic field form a magnetic field that intercepts the ion beam, the first magnetic field and the second magnetic field are arranged in parallel, and the magnetic field directions are opposite. For the ion beam passing through the magnetic field, after the ion beam passes through the first magnetic field, the ion beam will be slightly deflected to one side, and after passing through the second magnetic field, due to the change in the direction of the magnetic field, the ion beam will be deflected in the opposite direction to the first deflection, that is, the magnetic fields in two opposite directions correct the deflection of the ion beam and correct it back to the initial path and angle. The two magnetic fields are formed by two sets of magnets of the same length, so that the magnetic flux is the same and the deflection amount of the ion beam is equal twice. For electrons in the magnetic field, since the mass of the electrons is very small, they will rotate continuously under the action of the magnetic field, which greatly increases the trajectory and path of the electrons, that is, increases the path of the electrons hitting the electron absorption layer, thereby greatly increasing the probability of being taken away by the ion beam, improving the utilization rate of the neutralized electrons, and reducing the probability of the electrons escaping from the outlet. Since the neutralization area is provided with an ion beam inlet and an ion beam outlet, it is not completely sealed. Although the magnetic field design in this example increases the electron path and utilization rate, a small amount of electrons will still escape from both ends, resulting in inaccurate current measurement in the electron absorption layer in the subsequent steps. Therefore, the magnetic field can be combined with the electric field in the above example to prevent the escape of free electrons and improve the accuracy of the measurement.

[0115] Optionally, the first magnetic field generating end of the first magnetic field or the second magnetic field is arranged on one side of the ion beam and is arranged on the same side as the entrance of the neutralizing electrons, and the second magnetic field generating end is arranged on the other side of the ion beam opposite to the first magnetic field generating end. Arranging one generating end of the magnetic field on the same side as the entrance of the neutralizing electrons can have an effect on most of the directly incident neutralizing electrons, increase the movement trajectory and path of the directly incident neutralizing electrons, help increase the probability of more neutralizing electrons being taken away by the ion beam, improve the utilization rate of the neutralizing electrons, and reduce the probability of electrons escaping from the exit.

[0116] S3: injecting neutralizing electrons into the ion beam in a neutralization region surrounding the ion beam transmission path in a direction perpendicular to the ion beam transmission path;

[0117] Specifically, in a neutralization region surrounding the ion beam transmission path, neutralizing electrons are injected into the ion beam in a direction perpendicular to the ion beam transmission path to neutralize the positively charged ions in the ion beam. The neutralizing electrons can be generated by an electron generating device in the prior art, for example, the electron generating device can be a plasma gun. When set, the electron output end of the plasma gun can correspond to the ion beam in the neutralization region, so that the ion beam and the electrons are neutralized in the neutralization region.

[0118] S4: measuring the current in the electron absorption layer to obtain the amount of remaining free electrons other than the neutralized ion beam;

[0119] The total amount of neutralized electrons includes the amount of electrons in the neutralized ion beam and the amount of free electrons. The amount of current in the electron absorption layer is measured to obtain the amount of electrons absorbed by the electron absorption layer, that is, the amount of free electrons remaining after the neutralized electrons except for the neutralized ion beam. Optionally, a current monitoring device can be connected to measure the amount of current generated by the flow of electrons in the electron absorption layer, thereby obtaining the amount of free electrons.

[0120] S5: measures the total generation of neutralized electrons;

[0121] Measuring the total amount of neutralized electrons generated. Specifically, a current monitoring device may be connected to the electron generating device, and the current monitoring device may be used to measure the amount of electrons generated by the electron generating device.

[0122] S6: Calculate the amount of electrons actually neutralizing the ion beam based on the total amount of neutralizing electrons produced and the amount of free electrons;

[0123] Based on the amount of free electrons and the total amount of neutralized electrons obtained in steps S4 and S5, the difference between the total amount of neutralized electrons and the amount of free electrons is calculated to be the actual amount of electrons in the neutralized ion beam.

[0124] S7: adjusting the total amount of neutralizing electrons generated according to the amount of electrons actually neutralizing the ion beam.

[0125] After calculating and obtaining the actual amount of electrons in the neutralized ion beam, the total amount of neutralized electrons generated is compared with the actual amount of electrons in the neutralized ion beam. When the difference between the two is large or the amount of free electrons is large, the total amount of neutralized electrons generated is reduced to the same as the actual amount of electrons in the neutralized ion beam or the difference is less than a preset value. This can not only avoid the influence of free electrons on subsequent measurements, but also monitor the actual amount of electrons in the neutralized ion beam to avoid oversaturation of the total amount of neutralized electrons and reduce energy consumption.

[0126] Example 2

[0127] This embodiment provides an ion beam neutralization device, which is arranged before the ion beam bombards the target workpiece and is used to inject neutralizing electrons into the ion beam. The ion beam neutralization device can be used in the ion beam neutralization method in the above embodiment 1. The ion beam neutralization device includes a neutralization chamber, an electron absorption layer and a first current monitoring device. Figure 3 The neutralization chamber 100 includes an intermediate wall 101 that is annularly closed around the neutralization region of the ion beam transmission path, and a neutralization electron inlet 1011 is provided on the intermediate wall 101. An ion beam inlet 1021 is provided at one end of the intermediate wall 101, and an ion beam outlet 1022 is provided at the other end of the intermediate wall 101. The ion beam inlet 1021 and the ion beam outlet 1022 are coaxially arranged. Figure 4 Or 5, the electron absorption layer is disposed in the neutralization cavity 100, and is at least disposed on the middle wall 101 in the neutralization cavity 100, and is in contact with the inner surface of the middle wall 101. Figure 7 , the first current detection device 301 is connected to the electron absorption layer to monitor the amount of current in the electron absorption layer. Therefore, in this embodiment, a neutralization chamber 100 is set in the neutralization area between the ion beam and the neutralizing electrons, and an electron absorption layer is set in the neutralization chamber 100 to absorb the free electrons that are not involved in the neutralization of the ion beam. The electron absorption layer is connected to the first current detection device 301, and the amount of free electrons is obtained through the measurement value of the first current detection device 301. The difference between the total amount of neutralized electrons and the amount of free electrons is used to calculate the amount of neutralized electrons in the neutralized ion beam, thereby realizing monitoring of the amount of neutralized electrons in the neutralized ion beam to avoid oversaturation of the total amount of neutralized electrons. At the same time, free electrons can also be absorbed to prevent free electrons from being freed to other positions of the machine and affecting ion injection.

[0128] Specifically, refer to Figure 3, the neutralization chamber 100 is a hollow cover or cage structure. The neutralization chamber 100 includes an intermediate wall body 101 that is annularly closed around a neutralization area on the ion beam transmission path. The intermediate wall body 101 can be a cylindrical structure or a structure with a square or rectangular cross-section. A neutralization electron entrance 1011 is provided on the intermediate wall body 101, an ion beam entrance 1021 is provided at one end of the intermediate wall body 101, and an ion beam exit 1022 is provided at the other end of the intermediate wall body 101. The ion beam entrance 1021 and the ion beam exit 1022 are coaxially arranged. In the present embodiment, a first end wall 102 is provided at one end of the neutralization chamber 100, and the ion beam entrance 1021 is provided on the first end wall 102. A second end wall 103 is provided at the other end of the neutralization chamber 100, and the ion beam exit 1022 is provided on the second end wall 103. The middle wall 101, the first end wall 102 and the second end wall 103 serve as the support frame of the neutralization chamber 100, and the material thereof may be metal, such as aluminum or other stainless steel materials. An insulating mounting block 220 is also provided on the middle wall 101 of the neutralization chamber 100, and the electron absorption layer on the inner wall of the neutralization chamber 100 may be connected by a wire later, and the wire may be led out to the current monitoring device through the insulating mounting block 220. The insulating mounting block 220 may also be used for the subsequent insulating connection between the entire ion neutralization device and the cavity of the ion implantation machine, and such an electrical insulating setting may realize the separate measurement of free electrons and improve the accuracy of the measurement.

[0129] Reference Figure 4 and 5 , the electron absorption layer is arranged in the neutralization cavity 100, and is at least arranged on the middle wall 101 in the neutralization cavity 100, and is in contact with the inner surface of the middle wall 101. In this embodiment, the electron absorption layer includes a first electron absorption layer 201, a second electron absorption layer 202 and a third electron absorption layer 203. The first electron absorption layer 201 is in contact with the inner surface of the first end wall 102 of the neutralization cavity 100. The second electron absorption layer 202 is in contact with the inner surface of the second end wall 103 of the neutralization cavity 100. The third electron absorption layer 203 is in contact with the inner surface of the middle wall 101 of the neutralization cavity 100. The first electron absorption layer 201, the second electron absorption layer 202 and the third electron absorption layer 203 can be in contact with each other, and the third electron absorption layer 203 can be isolated from the first electron absorption layer 201 and the second electron absorption layer 202 respectively later, so as to form an anti-electron escape electric field using this structure.

[0130] In one example, the third electron absorption layer 203 is isolated from the first electron absorption layer 201 and the second electron absorption layer 202. Figure 5 or Figure 8The first electron absorption layer 201 and the third electron absorption layer 203, and the second electron absorption layer 202 and the third electron absorption layer 203 are isolated by an insulating isolation layer 210. The first electron absorption layer 201, the second electron absorption layer 202 and the third electron absorption layer 203 are all graphite layers, and the insulating isolation layer 210 is a commonly used insulating material, such as silicon dioxide. Figure 8 , the first electron absorption layer 201 and the second electron absorption layer 202 are both connected to the first constant voltage source 302, the third electron absorption layer 203 is electrically connected to the second constant voltage source 301, and the input voltage of the first constant voltage source 302 is less than the input voltage of the second constant voltage source 301. Fig.10 Thus, the first electron absorption layer 201 and the third electron absorption layer 203 can form the first electric field in Example 1 at the ion beam entrance end, and the second electron absorption layer 202 and the third electron absorption layer 203 can form the second electric field at the ion beam exit end. The first electric field points from a low potential to a high potential along the direction from the ion beam entrance end to the ion beam exit end (that is, from the first electron absorption layer 201 to the third electron absorption layer 203), and the second electric field points from a high potential to a low potential along the direction from the ion beam entrance end to the ion beam exit end (that is, from the third electron absorption layer 203 to the second electron absorption layer 202). Fig. 9 and 10 As shown, electron 2 moves in a spiral motion toward ion beam entrance 1021 or ion beam exit 1022 under the action of the electric field, and is continuously decelerated in the electric field. Since the voltage of the electric field is greater than the initial voltage of the electron, electron 2 will not escape from the exit. Fig.10 The solid line motion trajectory in the figure changes to a dotted line motion trajectory, and the final destination is only to be taken away by the ion beam for neutralization or reach the graphite, thus solving the electron escape problem and preventing the escape of free electrons.

[0131] Moreover, since the two electric fields are connected to the same voltage source, the potential difference between the two electric fields is also the same. Fig.11 When the ion beam reaches the first electric field at the ion beam entrance, the energy is reduced due to the reverse voltage. Later, when it reaches the second electric field at the ion beam exit, it becomes a forward voltage and the energy increases. The two voltage potentials are the same, so the setting of the two electric fields has no effect on the ion beam energy.

[0132] Optionally, the first constant voltage source 302 can be provided by grounding, or it can be connected to other voltage sources. In the present embodiment, the first constant voltage source 302 can be provided by grounding. Optionally, the providing device of the second constant voltage source 301 can be a voltage source or a source meter. When the providing device of the second constant voltage source 301 is a source meter, it can not only provide a constant voltage source for the device, but also realize the current monitoring function of the electron absorption layer. That is, the source meter can also be used as the first current detection device 301, and realize the provision of voltage source and current monitoring at the same time. In the present embodiment, the providing device of the second constant voltage source 301 is a source meter.

[0133] The first current detection device 301 is connected to the electron absorption layer to monitor the current in the electron absorption layer. Optionally, the first current detection device 301 can be an ammeter or a source meter. In this embodiment, the first current detection device 301 is a source meter.

[0134] In one example, refer to Figure 7 or Figure 8 The ion beam neutralization device further includes an electron generator 500. The electron generator 500 is located at the neutralization electron inlet 1011 and is electrically insulated from the neutralization chamber 100. The electron emission end of the electron generator 500 corresponds to the neutralization electron inlet 1011 of the middle wall 101 of the neutralization chamber 100. The electron generator 500 is used to generate neutralization electrons. In this example, referring to Figure 6 , the electron generating device 500 includes a plasma gun 1 and a second current monitoring device 502. The plasma gun 1 includes an arc power supply 5011 and a filament power supply 5012, wherein the filament power supply 5012 provides heat for the cathode (tungsten filament) to emit electrons, and the arc power supply 5011 uses these electrons to form and maintain an arc, reacting with the introduced gas to generate plasma, wherein the introduced gas can be xenon. The change in the current of the arc power supply 5011 is used to control the amount of neutralized electrons generated by the plasma flow gun, and the amount of electrons generated in the plasma flow gun can be obtained by monitoring the current of the arc power supply 5011. In addition, the plasma flow gun also includes other conventional structures, which will not be repeated here. The second current monitoring device 502 is electrically connected to the arc power supply 5011 to monitor the current in the plasma flow gun. Optionally, the voltage difference between the second constant voltage source 301 and the first constant voltage source 302 is greater than the voltage of the arc power source 5011, that is, greater than the initial suction voltage of the electrons, and is a forward voltage to prevent the electrons from escaping in the electric field formed by the second constant voltage source 301 and the first constant voltage source 302. Optionally, the voltage difference between the second constant voltage source 301 and the first constant voltage source 302 is 1.1 to 10 times the voltage provided by the arc power source 501, for example, 2 times.

[0135] In one example, refer to Figure 7 Or 8, the ion beam neutralization device further includes a first pair of magnets 401 and a second pair of magnets 402, wherein the first pair of magnets 401 is used to generate the first magnetic field in Example 1, and the second pair of magnets 402 is used to generate the second magnetic field in Example 1. In this example, the first pair of magnets 401 is arranged on the outer wall of the intermediate wall 101 and is arranged close to the ion beam entrance 1021, and the first pair of magnets 401 includes a first magnet 410 and a second magnet 420, and the first magnet 410 and the second magnet 420 are separately arranged on opposite sides of the ion beam transmission path, and the polarities of the relative positions of the first magnet 410 and the second magnet 420 are opposite to each other, so as to form a first electric field in the ion beam transmission path. The second pair of magnets 402 is arranged on the outer wall of the middle wall 101 and is arranged near the exit of the ion beam. The second pair of magnets 402 includes a third magnet 430 and a fourth magnet 440. The third magnet 430 and the second magnet 440 are separately arranged on opposite sides of the ion beam transmission path. The polarity of the relative positions of the third magnet 430 and the fourth magnet 440 is opposite to form a second electric field in the ion beam transmission path. The direction of the magnetic field formed by the first pair of magnets 401 is opposite to the direction of the magnetic field formed by the second pair of magnets 402. The first pair of magnets 401 and the second pair of magnets 402 are installed relative to each other according to polarity, and the magnetism of the first magnet and the second magnet are both weak magnets, and the two pairs of magnets have the same length and the same magnetic flux.

[0136] It can be seen from the left-hand rule that charged ions will change their paths in a magnetic field. Since the magnets that form the two magnetic fields are both weak, they have almost no effect on the paths of the positive ions with larger mass, that is, the ion beam. However, with the application of high-end supports, the angle accuracy of the ion beam is getting higher and higher. This tiny effect is also taken into consideration and solved in the present invention. Fig.12 As shown, after the two pairs of magnets are installed relative to each other according to polarity, the ion beam 3 will be slightly deflected to one side after passing through the first pair of magnets 401 ( Fig.12 After passing through the second pair of magnets 402, the ion beam 3 will be deflected in the opposite direction to the previous direction due to the change in the polarity of the magnets ( Fig.12 The dotted line trajectory in the figure) is used to correct the path of the ion beam 3 back to the initial path and angle. Since the magnetic flux of the two pairs of magnets is the same, the deflection amounts are also the same. For electrons, the setting of the two pairs of magnets also changes the trajectory and path of the electron 2, so that the dotted line trajectory of the electron 2 that could have hit the graphite (the third electron absorption layer 203) quickly is changed to a solid line trajectory (spiral trajectory), and the path to the graphite is longer, which increases the probability of being carried away by the ion beam 3, thereby increasing the utilization rate of the neutralized electrons and reducing the probability of the electrons escaping from the exit.

[0137] In this embodiment, refer to Figure 8One of the magnets of the first pair of magnets 401 or the second pair of magnets 402 is arranged on one side of the ion beam and on the same side as the neutralizing electron entrance 1011, and the other magnet is arranged on the other side of the ion beam opposite to the magnet. Arranging one generating end of the magnetic field on the same side as the neutralizing electron entrance 1011 can have an effect on most of the directly incident neutralizing electrons, increase the movement trajectory and path of the directly incident neutralizing electrons, and is more conducive to increasing the probability of more neutralizing electrons being taken away by the ion beam, improving the utilization rate of neutralizing electrons, and reducing the probability of electrons escaping from the exit.

[0138] When using this embodiment Figure 7 When the ion neutralization device shown in FIG. 8 performs ion neutralization, the current value I displayed in the first current detection device 301 is p That is, the current formed by the electrons neutralized by the electron absorption layer, and refer to Figure 6 , the current value I displayed in the second current monitoring device 502 e is the total amount of electrons emitted by the plasma gun 1. From this, the size of the electrons carried away by the ion beam to neutralize the positive ions in the ion beam is calculated as: e -I p , that is, the amount of electrons generated by the plasma gun 1 to neutralize the ion beam is I b =I e -I p Subsequently, the amount of electrons emitted by the plasma gun 1 can be adjusted by monitoring the size of the electrons used to neutralize the ion beam, so as to monitor the amount of electrons used to neutralize the ion beam while avoiding the generation of excessive free electrons and reducing energy consumption.

[0139] Example 3

[0140] The present embodiment provides an ion implantation device, which includes an ion beam providing device, an ion beam neutralization device and a target workpiece. Among them, the ion beam providing device is used to provide an ion beam. The ion beam neutralization device receives the ion beam emitted by the ion beam providing device and neutralizes the received ion beam. The ion beam neutralization device is the ion beam neutralization device in Example 2. The target workpiece is bombarded by the ion beam neutralized by the ion beam neutralization device to complete ion implantation in the target workpiece. The ion implantation device in this embodiment includes the ion beam neutralization device in Example 2, and also has the technical effect of the ion beam neutralization device in Example 2.

[0141] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An ion beam neutralization method, characterized in that: include: providing an ion beam, wherein the ion beam is used to bombard a target workpiece to implant ions into the target workpiece; Before the ion beam bombards the target workpiece, an electron absorption layer is arranged at least at the periphery of a neutralization region surrounding the ion beam transmission path, the electron absorption layer is used to absorb free electrons that are not involved in the neutralization of the ion beam, and the two ends of the neutralization region are respectively an ion beam entrance end and an ion beam exit end; Injecting neutralizing electrons into the ion beam in a neutralization region surrounding the ion beam transport path in a direction perpendicular to the ion beam transport path; Measuring the amount of current in the electron absorption layer to obtain the amount of remaining free electrons of the neutralized electrons excluding the neutralized ion beam; measuring the total generation of said neutralized electrons; Calculating the amount of electrons actually neutralizing the ion beam based on the total amount of neutralizing electrons produced and the amount of free electrons; The total amount of neutralizing electrons generated is adjusted according to the amount of electrons that actually neutralize the ion beam.

2. The ion beam neutralization method according to claim 1, characterized in that: The step of providing an electron absorption layer around a neutralization region of an ion beam transmission path includes: A first electron absorption layer is provided at the ion beam inlet end of the neutralization region, and an ion beam inlet is provided on the first electron absorption layer; A second electron absorption layer is arranged at the ion beam outlet end of the neutralization region, an ion beam outlet is arranged on the second electron absorption layer, and the ion beam inlet and the ion beam outlet are arranged coaxially; A third electron absorption layer is disposed around the neutralization region.

3. The ion beam neutralization method according to claim 1, characterized in that: After the step of disposing an electron absorption layer at least at the periphery of a neutralization region surrounding the ion beam transmission path, and before the step of injecting neutralizing electrons into the ion beam in the neutralization region surrounding the ion beam transmission path in a direction perpendicular to the ion beam transmission path, the method further includes: A first electric field is formed at the ion beam entrance end of the neutralization region, and a second electric field is formed at the ion beam exit end of the neutralization region. The first electric field points from a low potential to a high potential along the direction from the ion beam entrance end to the ion beam exit end, and the second electric field points from a high potential to a low potential along the direction from the ion beam entrance end to the ion beam exit end.

4. The ion beam neutralization method according to claim 3, characterized in that: The potential difference of the first electric field is equal to the potential difference in the second electric field.

5. The ion beam neutralization method according to claim 1, characterized in that: Before the step of injecting neutralizing electrons into the ion beam in a neutralization region surrounding the ion beam transmission path in a direction perpendicular to the ion beam transmission path, the method further comprises: forming a first magnetic field in the neutralization region near the ion beam entrance end; A second magnetic field is formed in the neutralization region near the ion beam outlet end. The first magnetic field and the second magnetic field form a magnetic field that intersects the ion beam transmission path. The first magnetic field and the second magnetic field are arranged in parallel and in opposite directions.

6. The ion beam neutralization method according to claim 5, characterized in that: The first magnetic field generating end of the first magnetic field or the second magnetic field is arranged on one side of the ion beam and on the same side as the entrance of the neutralized electrons, and the second magnetic field generating end is arranged on the other side of the ion beam opposite to the first magnetic field generating end.

7. An ion beam neutralization device, characterized in that: The ion beam neutralization device is arranged before the ion beam bombards the target workpiece, and is used to inject neutralizing electrons into the ion beam. The ion beam neutralization device comprises: A neutralization chamber, comprising an intermediate wall body annularly closed around a neutralization region of an ion beam transmission path, wherein a neutralization electron inlet is arranged on the intermediate wall body; an ion beam inlet is arranged at one end of the intermediate wall body, and an ion beam outlet is arranged at the other end of the intermediate wall body, wherein the ion beam inlet and the ion beam outlet are arranged coaxially; An electron absorption layer is disposed in the neutralization cavity and at least disposed on a middle wall in the neutralization cavity and is in contact with an inner surface of the middle wall; The first current monitoring device is connected to the electron absorption layer to monitor the current in the electron absorption layer.

8. The ion beam neutralization device according to claim 7, characterized in that: The neutralization chamber also includes: A first end wall, arranged at one end of the intermediate wall body, and the ion beam inlet is arranged on the first end wall; A second end wall, arranged at the other end of the intermediate wall body, and the ion beam outlet is arranged on the second end wall; The electron absorption layer comprises: A first electron absorption layer is in contact with the inner surface of the first end wall of the neutralization cavity; A second electron absorption layer is in contact with the inner surface of the second end wall of the neutralization cavity; The third electron absorption layer is in contact with the inner surface of the intermediate wall.

9. The ion beam neutralization device according to claim 8, characterized in that: The first electron absorption layer, the second electron absorption layer and the third electron absorption layer are all graphite layers.

10. The ion beam neutralization device according to claim 8, characterized in that: The ion neutralization device also includes: A first constant voltage source is electrically connected to the first electron absorption layer and the second electron absorption layer respectively; The second constant voltage source is electrically connected to the third electron absorption layer. The input voltage of the first constant voltage source is lower than the input voltage of the second constant voltage source. The third electron absorption layer is isolated from the first electron absorption layer and the second electron absorption layer respectively.

11. The ion beam neutralization device according to claim 10, characterized in that: The first current monitoring device is a source meter, and the second constant voltage source providing device and the first current detection device are the same source meter.

12. The ion beam neutralization device according to claim 10, characterized in that: The ion beam neutralization device also includes: The electron generating device is located at the neutralizing electron inlet, and the electron emitting end of the electron generating device corresponds to the neutralizing electron inlet.

13. The ion beam neutralization device according to claim 12, characterized in that: The electron generating device comprises: A plasma gun, comprising an arc power supply, wherein the change in the current of the arc power supply is used to control the amount of neutralizing electrons generated by the plasma gun; The second current monitoring device is electrically connected to the arc power supply to monitor the current of the plasma gun.

14. The ion beam neutralization device according to claim 13, characterized in that: A voltage difference between the second constant voltage source and the first constant voltage source is greater than a voltage of the arc power source.

15. The ion beam neutralization device according to claim 7, characterized in that: The ion beam neutralization device also includes: A first pair of magnets is disposed on the outer wall of the intermediate wall and is disposed near the ion beam entrance, the first pair of magnets comprising a first magnet and a second magnet, the first magnet and the second magnet are separately disposed on opposite sides of the ion beam transmission path, and the relative positions of the first magnet and the second magnet have opposite polarities; A second pair of magnets is arranged on the outer wall of the middle wall body and is arranged near the exit of the ion beam. The second pair of magnets includes a third magnet and a fourth magnet. The third magnet and the fourth magnet are separately arranged on two opposite sides of the ion beam transmission path. The polarities of the relative positions of the third magnet and the fourth magnet are opposite. The direction of the magnetic field formed by the first pair of magnets is opposite to the direction of the magnetic field formed by the second pair of magnets.

16. An ion implantation device, characterized in that: include: An ion beam providing device, used for providing an ion beam; an ion beam neutralization device, receiving the ion beam emitted by the ion beam providing device and neutralizing the received ion beam, wherein the ion beam neutralization device is the ion beam neutralization device according to any one of claims 7 to 15; The target workpiece is bombarded by the ion beam neutralized by the ion beam neutralization device to perform ion implantation.

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