Periodic pulse high-energy ion implanter

Abstract

A periodic pulse high-energy ion implanter, which relates to the technical field of semiconductor ion implantation. A particular embodiment of the periodic pulse high-energy ion implanter comprises: a periodic pulse ion source (101) periodically generating a high-density plasma; ion beams are extracted by means of an extraction suppression electrode (102) and a three-coordinate extraction electrode (103); the ion beams are subjected to mass screening of a mass analyzer (104) and are then transmitted to a periodic pulse radio-frequency acceleration system (105); a pulse period of a radio-frequency pulse of the periodic pulse radio-frequency acceleration system (105) is synchronized with a pulse period of an ion source pulse of the periodic pulse ion source (101); the ion beams that have been subjected to mass screening are accelerated to a high-energy state; the accelerated ion beams are transmitted to an energy analyzer (106) for energy screening; the ion beams that have been subjected to energy screening are spread by means of an ion beam scanning apparatus (107); parallel ion beams are generated by means of a beam parallelization lens (108); and finally the parallel ion beams are transmitted to a target chamber (109) to complete implantation. Therefore, the energy consumption and area of a machine can be reduced, and the energy of implanted ions can be increased.

Description

A periodic pulse high-energy ion implanter

[0001] This application claims priority to the Chinese application filed with the Patent Office of China on November 27, 2023, with application number CN202311591526.7 and application name “A Periodic Pulse High Energy Ion Implantation Machine”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the technical field of semiconductor ion implantation, and in particular to a periodic pulse high-energy ion implanter. Background Art

[0003] A key step in semiconductor device manufacturing is the implantation of ions into a semiconductor wafer in a vacuum, introducing impurities into the wafer's crystal lattice and altering its conductivity. This process is performed using an ion implanter, which typically ionizes semiconductor impurity atoms into ions, accelerates them, and then implants them into the semiconductor wafer.

[0004] With the high integration of semiconductor components, it is necessary to implant high-energy ions deeper into the semiconductor wafer. The corresponding device is called a high-energy ion implanter. The components used for ion beam acceleration in high-energy ion implanters usually use a tandem electrostatic accelerator. The structure of the electrostatic accelerator gradually increases in complexity as the voltage increases. The gradually increasing insulation distance will significantly increase the physical size of the equipment. At the same time, the acceleration voltage is generally less than 500kV. For processes that require high-energy MeV (Million Electron Volts) injection, the electrostatic accelerator cannot meet the energy requirements of different scenarios. Therefore, linear accelerators that use the radio frequency acceleration principle and can accelerate ions to MeV energy (Patent.No.US4667111) have gradually become widely used. When a high-energy ion implanter uses an RF acceleration system, various ions generated by the ion source are extracted by an extraction voltage, filtered by a mass analyzer, and then enter the RF acceleration system to accelerate as many ion beams as possible to the required energy. The ions with the required energy are then filtered by the energy analyzer, scanned and parallelized, and injected into the wafer in the target chamber.

[0005] In the manufacture of high-quality imaging devices such as CCDs, the deeper the ion implantation, the higher the resolution and sensitivity. Consequently, there is a growing demand for ultra-high-energy ion implantation. Existing high-energy ion implanters utilize a continuous-wave ion source, which can meet the needs of most scenarios. However, as ion energies exceed 10 MeV, the corresponding machine energy consumption and floor space become extremely large. This results in extremely high machine power consumption (typically exceeding 100 kW), posing the risk of power shortages. In other words, given a given plant's power supply, the number of machines that can be accommodated is significantly reduced.

[0006] Summary of the Invention

[0007] In view of this, the embodiments of the present disclosure provide a periodic pulse high-energy ion implanter that can solve the problems of large machine energy consumption and floor space, extremely high machine room energy consumption, and the risk of insufficient power supply.

[0008] To achieve the above objectives, the present disclosure provides a periodic pulse high-energy ion implanter, comprising:

[0009] Periodic pulse ion source, extraction suppression electrode, three-coordinate extraction electrode, mass analyzer, periodic pulse radio frequency acceleration system, energy analyzer, ion beam scanning device, beam parallelization lens and target chamber, including:

[0010] The periodic pulse ion source periodically generates high-density plasma, and the extraction suppression electrode and the three-coordinate extraction electrode extract an ion beam, which is then mass-screened by the mass analyzer and transmitted to the periodic pulse RF acceleration system. The pulse period of the RF pulse of the periodic pulse RF acceleration system is synchronized with the pulse period of the ion source pulse of the periodic pulse ion source. The periodic pulse RF acceleration system accelerates the mass-screened ion beam to a high-energy state, and the accelerated ion beam is transmitted to the energy analyzer for energy screening. The ion beam after energy screening is expanded in at least one direction by the ion beam scanning device, and then a parallel ion beam is generated by the beam parallelization lens, and finally transmitted to the target chamber to complete the injection.

[0011] One or more technical solutions provided in the embodiments of the present application can achieve the following technical effects through a periodic pulsed ion source and a periodic pulsed radio frequency acceleration system with synchronized pulse periods:

[0012] (1) Introducing pulse technology into high-energy ion implantation machines provides a periodic pulse high-energy ion implantation machine with high implanted ion energy, small machine energy consumption and area, which greatly reduces the energy consumption of the radio frequency acceleration unit, thereby reducing the machine energy consumption and reducing the machine cost; in other words, under the same implanted ion energy index, the radio frequency acceleration unit can be saved, the machine footprint can be reduced, and the machine cost can be reduced.

[0013] (2) Like traditional high-energy ion implanters, the extraction electrode of the periodic pulse high-energy ion implanter is the structure closest to the ion source, and is adjustable in three directions along the coordinate axis, which can optimize the shape and size of the extracted beam. The extraction suppression electrode is used to suppress the secondary electrons from bombarding the ion source. The mass analyzer can screen the required ion types and valence states, and its function will not change depending on whether the ions arrive continuously or in a pulsating manner. The mass analyzer is a high-energy consuming component, but it is not easy to generate pulses with good waveforms. Therefore, in the periodic pulse high-energy ion implanter, the extraction suppression power supply and the mass analyzer power supply still use DC working mode.

[0014] (3) The ion beam entering the periodic pulse RF acceleration system presents a pulsed mode, "working" for a short time and "resting" for a long time. The time span within the pulse is on the order of hundreds of microseconds, while the RF operating frequency of the RF power supply is generally several MHz to tens of MHz. Under the time span of the corresponding RF cycle (tens of nanoseconds to hundreds of nanoseconds), there will be thousands of RF cycles within a pulse, and the time span required for ions to accelerate from the keV level to the MeV level is a few microseconds. Therefore, the working mode of the RF acceleration system within the pulse is not much different from that of the continuous wave RF acceleration system. The periodic pulse RF acceleration system includes multiple RF acceleration units. Under the premise of pulse synchronization, each RF power supply needs to achieve frequency lock and precise phase shift within the pulse.

[0015] (4) The RF sinusoidal voltage of the RF power supply is changing. The inductance L and capacitance C in the RF acceleration unit are relatively large. If the ion beam arrives during the establishment and dissipation process of the resonance constructed by the inductance L and capacitance C, the expected acceleration effect cannot be achieved. Therefore, through pulse delay technology, it is ensured that most of the ions arrive in the flat top area of ​​the RF pulse to achieve the expected acceleration effect. Analogous to the microwave cavity in the electron accelerator, its equivalent inductance L and equivalent capacitance C are relatively small. The establishment time and dissipation time of the resonant energy balance under the pulse working mode can be reduced to the order of hundreds of nanoseconds. That is, the higher the frequency, the shorter the establishment and dissipation time of the energy balance in the RF acceleration unit. Therefore, a higher RF operating frequency of the RF power supply can be selected to reduce the establishment and dissipation time of the energy balance in the RF acceleration unit, making the rising and falling edges of the RF pulse steeper, reducing the invalid ratio of the pulse width, and further increasing the electrical breakdown threshold when the pulse period and pulse width remain unchanged.

[0016] (5) When a high-power pulse is fed into the RF acceleration unit, the rising and falling edges of the pulse are not steep enough due to the large capacitance C and inductance L in the RF acceleration unit. Since the ion beam cannot be fully accelerated at the rising and falling edges of the RF pulse, the present disclosure adopts a "trapping pulse" approach. By adjusting the pulse widths of the ion source pulse and the RF pulse, and the relative delays of each RF power supply, the ion source pulse is completely "trapped" within the RF pulse and located in the flat top region within the RF pulse.

[0017] (6) The RF acceleration unit of the periodic pulse RF acceleration system has the same structure as the RF acceleration unit in the continuous wave RF acceleration system. In the continuous wave mode, it can reach an acceleration voltage of about 90kV. In the periodic pulse mode, if the RF pulse duty ratio is 1%-10%, the acceleration voltage inside the pulse can reach about 180kV-270kV, reducing the risk of electrical breakdown and increasing the ion acceleration energy. The same number of RF acceleration units connected in series can achieve 2-3 times the acceleration energy. If the total power of a traditional continuous wave high energy ion implanter is 30-100kW, using the pulse mode and the RF pulse duty ratio is 10%, the power of the periodic pulse RF acceleration system will be one-tenth of that of the continuous wave RF acceleration system, so that the total power of the periodic pulse high energy ion implanter can achieve the same ion implantation energy with a total power of 10-20kW, which greatly reduces the power demand for the factory.

[0018] (7) Since a large internal pulse beam current is required to ensure that the average ion beam current and ion injection dose meet the expectations, the difficulty of lateral focusing of the ion beam increases in the narrow and long RF acceleration channel. Conventional continuous wave electrostatic quadrupole lenses also have voltage resistance issues, and the voltage cannot be too high, resulting in limited lateral focusing ability. In scenarios where the internal pulse beam current is large, a periodic pulse method is used. The quadrupole lens electrode structure remains unchanged, and the electrical breakdown threshold is increased several times, which can improve the voltage resistance and increase the voltage and lateral focusing ability within the pulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0020] FIG1 shows a schematic diagram of a periodic pulse high energy ion implanter according to an exemplary embodiment of the present disclosure;

[0021] FIG2 shows a schematic diagram of a periodic pulsed radio frequency acceleration system according to an exemplary embodiment of the present disclosure;

[0022] FIG3 shows a schematic diagram of a signal waveform of a radio frequency sinusoidal voltage generated by a radio frequency power supply according to an exemplary embodiment of the present disclosure;

[0023] FIG4 is a schematic diagram showing the envelope relationship between an ion source pulse and a radio frequency pulse according to an exemplary embodiment of the present disclosure;

[0024] FIG5 shows a schematic diagram of synchronization between a working pulse width and a scanning period according to an exemplary embodiment of the present disclosure;

[0025] FIG6 shows a schematic diagram comparing energy consumption of a continuous wave high energy ion implanter and a periodic pulse high energy ion implanter according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] The following describes embodiments of the present disclosure in more detail with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0027] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to". The term "based on" means "at least partially based on". The term "in an embodiment of the present disclosure" means "at least one embodiment"; the term "another exemplary embodiment" means "at least one other embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0028] It should be noted that the modifications of "one" and "multiple" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0029] Aspects of the present disclosure are described below with reference to the accompanying drawings.

[0030] Figure 1 shows a schematic diagram of a periodic pulse high-energy ion implanter according to an exemplary embodiment of the present disclosure. As shown in Figure 1, the periodic pulse high-energy ion implanter of the present disclosure includes: a periodic pulse ion source 101, an extraction suppression electrode 102, a three-coordinate extraction electrode 103, a mass analyzer 104, a periodic pulse radio frequency acceleration system 105, an energy analyzer 106, an ion beam scanning device 107, a beam parallelization lens 108 and a target chamber 109.

[0031] A high-density plasma is periodically generated from a periodic pulsed ion source 101. An ion beam 110 is extracted by an extraction suppression electrode 102 and a three-coordinate extraction electrode 103 in a pulsed state. After mass screening by a mass analyzer 104, it is transmitted to a periodic pulsed radio frequency acceleration system 105. The periodic pulsed radio frequency acceleration system 105 accelerates the mass-screened ion beam 110 to a high energy state. An energy analyzer 106 performs energy screening on the ion beam 110 accelerated by the periodic pulsed radio frequency acceleration system 105. The energy-screened ion beam 110 is expanded in at least one direction (e.g., the X direction) by an ion beam scanning device 107. A parallel ion beam is then generated by a beam parallelizing lens 108, and finally transmitted to a target chamber 109 for implantation. The ion source pulses extracted from the periodic pulsed ion source 101 by the three-coordinate extraction electrode 103 are synchronized with the pulse period of the radio frequency pulses of the periodic pulsed radio frequency acceleration system 105.

[0032] Furthermore, unlike the continuous wave operating mode, the periodic pulse operating mode causes the main components of the high-energy ion implanter, such as the periodic pulse ion source 101 and the periodic pulse RF acceleration system 105, to periodically switch between "operating" and "resting" operating states. When in the "operating" state, an ion beam 110 is extracted from the periodic pulse ion source 101 by the extraction suppression electrode 102 and the three-coordinate extraction electrode 103. After mass screening by the mass analyzer 104, it enters the periodic pulse RF acceleration system 105. After being accelerated to a high energy state, the energy analyzer 106 selects a beam with a predetermined energy. The beam is then transmitted to the target chamber 109 through the ion beam scanning device 107 and the beam parallelization lens 108, completing the ion beam implantation. When in the "resting" state, no ions are extracted from the periodic pulse ion source 101, and the periodic pulse RF acceleration system 105 and the periodic pulse ion source 101 "rest" synchronously, saving RF energy loss.

[0033] Furthermore, the periodic pulsed ion source 101 is maintained at an extraction voltage potential via an isolation transformer, generating a high-density plasma internally in a pulsed manner. The ion beam 110 extracted from the ion source by the three-coordinate extraction electrode 103 is a positive ion beam. The extraction suppression electrode 102 is used to prevent ejected secondary electrons from bombarding the ion source. The extraction suppression electrode 102 and the three-coordinate extraction electrode 103 are structurally bound together, and their positions in the X, Y, and Z directions can be adjusted. Mass screening refers to the mass analyzer 104 selecting the required ion species from the extracted ion beam 110. Its operating method and design are the same as those of a continuous wave high-energy ion implanter. The structure of the chamber, RF acceleration unit, and quadrupole lens of the periodic pulsed RF acceleration system 105 can keep the dimensions of the continuous wave high-energy ion implanter almost unchanged. The energy analyzer 106, ion beam scanning device 107, beam parallelization lens 108, and target chamber 109 are essentially the same as those of a continuous wave high-energy ion implanter.

[0034] In the embodiment of the present disclosure, as shown in Figure 1, different from the DC power supply that extracts a uniform continuous wave ion beam, the periodic pulse ion source 101 can generate high-density plasma within the pulse and the plasma density outside the pulse quickly decreases to zero. That is, the periodic pulse ion source 101 can generate high-density plasma in the "working" state and the plasma density quickly decreases to zero in the "resting" state. Therefore, under the extraction effect of the DC voltage of the three-coordinate extraction electrode 103, periodic ion source pulses can be generated on the time axis to achieve periodic extraction of the ion beam.

[0035] Furthermore, the periodic pulse ion source 101 may be implemented by using an indirect heating ion source (also called an IHC ion source), a microwave ion source, a radio frequency ion source, or a pulsed vacuum arc ion source.

[0036] The indirect heating ion source includes hardware such as the hot filament, bias, source magnetic field, and arc chamber. The hot filament voltage and current maintain continuous wave heating, and the bias and source magnetic field also maintain continuous working mode. The arc chamber voltage adopts a periodic pulse working mode to achieve periodic ion source pulses. The ultra-high transient arc voltage causes the plasma density of the ion beam inside the periodic pulse to increase instantly.

[0037] The microwave ion source includes a microwave amplifier, a microwave pre-stage, a microwave chamber, etc. The microwave amplifier power supply adopts a continuous working mode, and the microwave pre-stage adopts a pulsed working mode. Periodic arcing in the microwave chamber generates high-density plasma to achieve periodic ion source pulses.

[0038] The RF ion source includes an RF power supply, a plasma arc chamber, and an RF cavity. The RF power supply operates in a continuous mode, and the plasma arc chamber operates in a pulsed mode. Periodic arcing in the RF cavity generates high-density plasma, thereby achieving periodic ion source pulses.

[0039] The pulsed vacuum arc ion source includes a metal cathode, an arc starting electrode, etc. The metal cathode maintains a continuous power-on working mode, and the arc starting electrode applies periodic pulse high voltage. Periodic arc starting generates high-density plasma to achieve periodic ion source pulses.

[0040] Furthermore, or alternatively, the periodic ion source pulse generation method can be a combination of a conventional continuous wave ion source and a three-coordinate extraction electrode 103 that applies a periodic pulse extraction voltage. The greater the extraction voltage, the greater the extraction current. The extraction voltage of the periodic pulse (200kV) is much higher than the traditional DC extraction voltage (80kV), but it is still possible to maintain no electrical breakdown and increase the ion source beam current inside the pulse. Since the working mode is between the "working" and "resting" working states, and since the plasma density in the ion source does not change, the extraction current inside the pulse does not increase much. It should be noted that those skilled in the art can select an appropriate generation method according to the actual production environment to ensure that the periodic pulse ion source can generate periodic ion source pulses.

[0041] In the embodiment of the present disclosure, as shown in FIG2 , the periodic pulsed RF acceleration system 105 includes a RF acceleration electrode 1501, a quadrupole lens 1502, a RF acceleration unit 1503, a RF power supply 1504, and a command center 1505. The RF acceleration electrode 1501, the quadrupole lens 1502, the RF acceleration unit 1503, and the RF power supply 1504 correspond to each other, and the number can be selectively set as needed. The command center 1505 controls the start and stop of the RF sinusoidal voltage 1506 generated by each RF power supply 1504, and generates periodic RF pulses on the RF acceleration electrode 1501 after the resonant voltage transformation processing of the RF acceleration unit 1503. The waveform of the RF sinusoidal voltage 1506 is shown in FIG3 .

[0042] Furthermore, the RF acceleration unit 1503 adopts a resonant transformer scheme, with a relatively large inductor L and capacitor C set inside. The RF power supply 1504 feeds an RF sinusoidal voltage 1506 to the corresponding RF acceleration unit 1503. The amplitude of the RF sinusoidal voltage 1506 is modulated by the pulse signal of the command center 1505, so that the RF acceleration unit 1503 outputs periodic RF pulses. Since the RF acceleration unit 1503 has a long response time during the start and stop process of the RF sinusoidal voltage 1506 signal (for example, the establishment and dissipation time is about 100μs), as shown in FIG4 , when it is reflected in the RF pulse 1507 generated by the RF acceleration unit 1503, the rising edge and falling edge of the pulse envelope are more obvious (the rising edge and falling edge indicate that the amplitude envelope of the RF sinusoidal voltage 1506 is constantly changing). Therefore, in order to ensure the expected pulsed energy acceleration, the ion source pulse 1101 of the ion beam 110 drawn out by the three-coordinate extraction electrode 103 needs to adopt the "nested pulse" method shown in FIG4 to avoid the rising edge and falling edge of the RF pulse 1507 drawn out by the RF acceleration electrode 1501, so that the effective ion beam appears at the flat top of the pulse envelope of the RF pulse 1507. Taking an application scenario as an example, the RF operating frequency f of the RF power supply 1504 is 射频工作13.56MHz, RF pulse duty ratio η 射频脉冲 The RF pulse frequency f generated by the RF acceleration unit 1503 is 4%. 射频脉冲 The RF pulse period is 200 Hz and T 射频脉冲 5ms, RF pulse width τ 射频脉冲 is 200μs, and the RF pulse duty ratio η 射频脉冲 4% (η 射频脉冲 =f 射频脉冲 ×τ 射频脉冲 ), it can be seen that the RF operating frequency f 射频工作 Far exceeds the RF pulse frequency f 射频脉冲 , that is, f 射频工作 >>f 射频脉冲 As shown in Figure 2, the RF pulse width τ 射频脉冲 (RF pulse width for short) includes a rising edge and a flat top, that is, the rising edge is about 100μs and the flat top is about 100μs inside the pulse, and the falling edge is about 100μs outside the pulse; among them, the flat top area of ​​the RF pulse width is the available time period of the RF pulse. The ion source pulse appears in this time period to achieve effective acceleration. The RF pulse width includes thousands of complete working cycles of the RF operating frequency. Therefore, the physical process within the RF pulse width is actually the same as that of a continuous wave.

[0043] Furthermore, the pulse periods of the ion source pulses drawn from the periodic pulse ion source 101 through the three-coordinate extraction electrode 103 and the RF pulses drawn from the RF acceleration unit 1503 through the RF acceleration electrode 1501 are synchronized. As shown in FIG4 , the ion source pulse frequencies f of the ion source pulses 1101 and the RF pulses 1507 are 离子源脉冲 and RF pulse frequency f 射频脉冲 The same, that is, f 射频脉冲 =f 离子源脉冲 , accordingly, the ion source pulse period T of the ion source pulse 1101 is 离子源脉冲 and the RF pulse period T of RF pulse 1507 射频脉冲 The same, that is, T 离子源脉冲 =T 射频脉冲 , when the relative delay is precisely adjustable, it can be achieved that each ion source pulse width of the ion source pulse 1101 is completely "enclosed" in the flat top area of ​​the RF pulse 1507. Therefore, for a periodic pulse high-energy ion implanter, the truly effective working pulse width is the RF pulse width τ of the RF pulse 1507. 射频脉冲 The flat top and the ion source pulse width τ of the ion source pulse 1101 离子源脉冲 Overlapping time period τ 交叠 . Among them, the ion source pulse width τ 离子源脉冲That is, the available time period of the ion source pulse, including the rising edge, flat top and falling edge. Although the ion source pulse 1101 also has a rising edge and a falling edge, it does not affect the acceleration effect, but only reflects the change in the number of ions accelerated to a certain energy; the rising edge and falling edge of the RF pulse 1507 will affect the ion acceleration energy, and the ions corresponding to the rising edge and falling edge time periods will eventually be eliminated by the energy analyzer 106, so the ion beam should be avoided in this interval.

[0044] In the embodiment of the present disclosure, since the pulses of the periodic pulse ion source 101 and the RF power supply 1504 are both controllable, the ion source pulse width τ 离子源脉冲 and RF pulse width τ 射频脉冲 It can be selectively set as needed, and it is not necessary to require the periodic pulse ion source 101 and the periodic pulse radio frequency acceleration system 105 to start "working" or "resting" at the same time. In other words, the ion source pulse width τ 离子源脉冲 and RF pulse width τ 射频脉冲 Can be the same or different, but the ion source pulse width τ 离子源脉冲 and RF pulse width τ 射频脉冲 The flat-top areas must overlap in time, and the corresponding working pulse width τ 交叠 is the actual working time of the periodic pulse high energy ion implanter, so the RF pulse width τ 射频脉冲 Generally larger.

[0045] Furthermore, in the ion source pulse width τ 离子源脉冲 and RF pulse width τ 射频脉冲 Under the same conditions, the ion source pulse working ratio η using the "set pulse" working mode is 离子源脉冲 Less than or equal to RF pulse duty ratio η 射频脉冲 ,Right now:

[0046] η 离子源脉冲 ≤η 射频脉冲 Among them, η 离子源脉冲 =f 离子源脉冲 ×τ 离子源脉冲 .

[0047] Furthermore, the ion source pulse period T of the ion source pulse 离子源脉冲 and the RF pulse period T of the RF pulse 射频脉冲 1~10ms, ion source pulse duty ratio η 离子源脉冲 and RF pulse duty ratio η 射频脉冲 It is 1% to 20%.

[0048] In the embodiment of the present disclosure, the structure of the RF acceleration electrode 1501 and the quadrupole lens 1502 is the same as that of a conventional continuous wave high energy ion implanter. However, since the ion source pulse 1011 of the present disclosure is a periodic pulse, the peak value of the ion beam in the "working" state is much higher than that of a conventional continuous wave ion beam, and the spatial charge force between ions will increase accordingly. Therefore, the required lateral confinement is enhanced. The present disclosure applies a periodic pulse voltage to the lens power supply of the quadrupole lens 1502, so that the quadrupole lens 1502 generates a periodic quadrupole lens pulse. Without changing the structure of the quadrupole lens of the conventional continuous wave high energy ion implanter that applies DC high voltage, the pulse voltage of the periodic quadrupole lens pulse can greatly improve the peak withstand voltage limit of the quadrupole lens 1502, thereby meeting the demand for strong current lateral focusing.

[0049] Alternatively, a conventional DC voltage may be selected as the lens power supply of the quadrupole lens 1502 according to actual production costs.

[0050] Furthermore, the periodic pulses applied to the quadrupole lens 1502 are synchronized with the periodic pulses of the RF power supply 1504 and the periodic pulse ion source 101, that is, the lens pulse frequency f of the quadrupole lens pulse is 透镜脉冲 , ion source pulse frequency f 离子源脉冲 and RF pulse frequency f 射频脉冲 The following relationship is satisfied:

[0051] f 透镜脉冲 =f 离子源脉冲 =f 射频脉冲 .

[0052] In the embodiment of the present disclosure, when the RF power supply 1504 and the lens power supply of the quadrupole lens 1502 all adopt the periodic pulse working mode, each RF power supply 1504 not only requires pulse synchronization so that the RF pulses 1507 of each RF acceleration unit 1503 remain strictly synchronized, but also requires the internal RF sinusoidal voltage 1506 of the pulse to be phase-locked and accurately phase-shifted to ensure the normal operation of RF acceleration. Taking another application scenario as an example, the RF pulse frequency f of the RF pulse, ion source pulse, and quadrupole lens pulse is 射频脉冲 , ion source pulse frequency f 离子源脉冲 , lens pulse frequency f 透镜脉冲 All are 200Hz, and the corresponding RF pulse period is T 射频脉冲 , ion source pulse period T 离子源脉冲 , lens pulse period T 透镜脉冲 All are 5ms, and the RF pulse duty ratio is r 射频电源 4%, RF pulse width τ 射频脉冲The RF acceleration unit of the original continuous wave high energy ion implanter that worked at 90 kV is now capable of working at a peak RF voltage level of about 180 kV, which greatly improves the acceleration capability, while the average beam current is reduced to 4% or even less of that in the continuous wave state. In this case, the periodic pulse ion source 101 can increase the plasma peak density inside the pulse, increase the average beam current, save the injection time, and realize the periodic pulse high energy ion implanter to inject more quickly, efficiently and economically, reduce the time cost consumed by the machine, and reduce the injection cost of the machine; alternatively, the periodic pulse high energy ion implanter can also be applied to the production scenario of high energy and small beam flow to maximize the value of the periodic pulse high energy ion implanter.

[0053] Furthermore, or, since there is a time difference of μs between the first RF acceleration unit 1503 and the last RF acceleration unit 1503 when the ion beam 110 flies through the periodic pulse RF acceleration system 105, a slight time delay can also be set for each RF acceleration unit 1503.

[0054] In the embodiment of the present disclosure, as shown in FIG5 , the ion beam scanning device 107 can adopt continuous scanning, and the scanning voltage is continuous and will not be interrupted. However, due to the scanning period T 扫描 The pulse width is similar in magnitude to the aforementioned pulse width. To maintain consistent operation of the ion implanter, avoid beam turbulence, and ensure optimal implantation results, it is preferred that the effective working period of the ion beam corresponds to an integer number of transverse scanning periods. The truly effective pulse width of the accelerated ion beam is the working pulse width τ corresponding to the intersection of the flat top of the RF pulse 1507 and the ion source pulse width of the ion source pulse 1101. 交叠 , so τ 交叠 and the scanning period T of the ion beam scanning device 107 扫描 The following relationship is satisfied:

[0055] τ 交叠 =nT 扫描 , (n=1,2,3,…).

[0056] In the above formula, n=1 is relatively easy to achieve, but in order to increase beam uniformity, it is preferred that n≥5. At the same time, in order to ensure consistent pace, the pulse period and the scanning period must be synchronized, and the pulse delay or the phase shift of the scanning voltage waveform can be finely adjusted. For the moving parts in the target chamber area, it is usually necessary to coordinate with the previous periodic pulse. The parts move when the ion beam is working and stop moving when the ion beam stops. However, in the single-wafer injection mode, the mechanical movement is much slower than the beam scanning (for example, the ion beam "works" for 1ms and "rests" for 9ms. In one cycle, the chip movement is only less than tens of microns, which is far less than the beam spot diameter of tens of millimeters). Therefore, the movement of the moving parts in the target chamber area can be the same as in the continuous wave mode, and there is no need to consider synchronization issues. If the chip movement needs to be accelerated, the pulse "rest" time can also be appropriately reduced. A compromise solution can be selected and selectively set according to actual production needs.

[0057] Among them, τ 交叠 If it is not an integer multiple of T 扫描 Every time a batch of accelerated ion beams arrives, the starting and ending points of the scan injection into the wafer are different due to the different scanning voltages. This is not a problem when the electrical scanning speed in one dimension is very different from the mechanical scanning speed in another dimension. However, once the speed difference between the two dimensions is small, the different starting and ending points of each scan may cause uneven injection on the wafer surface.

[0058] Furthermore, the ion beam of the high-energy ion implanter is pulsed and implanted into the wafer in batches, which can reduce the thermal effect of wafer implantation compared to traditional continuous wave implantation.

[0059] As shown in Figure 6, conventional continuous-wave high-energy ion implanters utilize a multipolar continuous-wave standing-wave acceleration scheme. The continuous continuous-wave injection makes these high-energy ion implanters energy-intensive. In a single, tens-of-kilowatt continuous-wave high-energy ion implanter, a dozen or so RF power supplies operating in continuous-wave mode account for 60%-90% of the power, resulting in extremely high power consumption. In the disclosed embodiments, the RF power supplies of the periodic pulse high-energy ion implanter all operate in pulsed mode, resulting in an instantaneous reduction in power consumption and, accordingly, a significant reduction in overall system power consumption. On the one hand, the periodic pulse high-energy ion implanter can achieve a high-efficiency improvement in ion energy injection without changing the overall structure of the machine and consuming the same energy as the traditional continuous wave high-energy ion implanter. Taking another application scenario as an example, the RF pulse working ratio of the RF power supply is 10%, and the withstand voltage of the RF acceleration electrode is increased by 2 times, that is, the power of the whole machine is reduced by 5-10 times, and the ion injection energy is increased by 2 times, with significant energy savings; on the other hand, the periodic pulse high-energy ion implanter can achieve the same injection energy as the traditional continuous wave high-energy ion implanter while reducing the number of RF power supplies and RF acceleration units, reducing the machine footprint, and greatly saving the machine cost.

[0060] Furthermore, the RF power supply of the periodic pulse high-energy ion implanter can continue to increase the peak power to further enhance the implantation energy.

Claims

1. A periodic pulse high energy ion implanter, characterized in that: include: A periodic pulse ion source (101), an extraction suppression electrode (102), a three-coordinate extraction electrode (103), a mass analyzer (104), a periodic pulse radio frequency acceleration system (105), an energy analyzer (106), an ion beam scanning device (107), a beam parallelization lens (108) and a target chamber (109), wherein: The periodic pulse ion source (101) periodically generates high-density plasma, and an ion beam (110) is extracted by the extraction suppression electrode (102) and the three-coordinate extraction electrode (103). After mass screening by the mass analyzer (104), the ion beam (110) is transmitted to the periodic pulse radio frequency acceleration system (105). The pulse period of the radio frequency pulse of the periodic pulse radio frequency acceleration system (105) is synchronized with the pulse period of the ion source pulse of the periodic pulse ion source (101). The periodic pulse radio frequency acceleration system (105) accelerates the mass-screened ion beam (110) to a high energy state, and the accelerated ion beam (110) is transmitted to the energy analyzer (106) for energy screening. The ion beam (110) after energy screening is expanded in at least one direction by the ion beam scanning device (107), and then a parallel ion beam (110) is generated by the beam parallelization lens (108). Finally, the ion beam is transmitted to the target chamber (109) to complete the injection.

2. The periodic pulse high energy ion implanter according to claim 1, characterized in that: The periodic pulse radio frequency acceleration system (105) comprises a plurality of radio frequency acceleration electrodes (1501), a plurality of quadrupole lenses (1502), a plurality of radio frequency acceleration units (1503) and a plurality of radio frequency power supplies (1504), wherein the pulse period of the radio frequency pulse of the periodic pulse radio frequency acceleration system (105) is synchronized with the pulse period of the ion source pulse of the periodic pulse ion source (101), and comprises: The ion source pulse frequency f of the ion source pulse extracted from the periodic pulse ion source (101) through the three-coordinate extraction electrode (103) is 离子源脉冲 , the radio frequency operating frequency f of the radio frequency power supply (1504) 射频工作 , and a radio frequency pulse frequency f of a radio frequency pulse obtained by amplitude modulation of the radio frequency power source (1504) through the radio frequency acceleration electrode (1501) 射频脉冲 Satisfies the following relationship: f 射频脉冲 =f 离子源脉冲 ; f 射频工作 >>f 射频脉冲 。 3. The periodic pulse high energy ion implanter according to claim 2, characterized in that: The ion source pulse frequency f of the ion source pulse 离子源脉冲 、Ion source pulse width τ 离子源脉冲 、Ion source pulse duty ratio η 离子源脉冲 , and the radio frequency pulse frequency f of the radio frequency pulse 射频脉冲 , RF pulse width τ 射频脉冲 , RF pulse duty ratio η 射频脉冲 Satisfies the following relationship: η 离子源脉冲 =f 离子源脉冲 ×τ 离子源脉冲 ; or 射频脉冲 =f 射频脉冲 ×t 射频脉冲 。 4. The periodic pulse high energy ion implanter as claimed in claim 3, characterized in that: The ion source pulse and the radio frequency pulse adopt a set pulse working mode, and the ion source pulse width τ of the ion source pulse 离子源脉冲 The radio frequency pulse width τ embedded in the radio frequency pulse 射频脉冲 inside the flat roof.

5. The periodic pulse high energy ion implanter as claimed in claim 4, characterized in that: The working pulse width of the periodic pulse high energy ion implanter is the ion source pulse width τ 离子源脉冲 and the RF pulse width τ 射频脉冲 The intersection of the flat tops τ 交叠 .

6. The periodic pulse high energy ion implanter as claimed in claim 3, characterized in that: or 离子源脉冲 ≤η 射频脉冲 。 7. The periodic pulse high energy ion implanter according to claim 6, characterized in that: The scanning period T of the ion beam scanning device (107) is 扫描 and the operating pulse width τ 交叠 Satisfies the following relationship: 交叠 =nT 扫描 , (n=1,2,3,…).

8. The periodic pulse high energy ion implanter according to claim 2, characterized in that: The voltage applied to the quadrupole lens (1502) is a direct current voltage or a pulse voltage.

9. The periodic pulse high energy ion implanter according to claim 8, characterized in that: When the voltage applied by the lens power supply to the quadrupole lens (1502) is a pulse voltage, the quadrupole lens pulse on the quadrupole lens (1502) is synchronized with the radio frequency pulse and the ion source pulse, wherein: The lens pulse frequency f of the quadrupole lens pulse 透镜脉冲 , the ion source pulse frequency f of the ion source pulse 离子源脉冲 and the radio frequency pulse frequency f of the radio frequency pulse 射频脉冲 Satisfies the following relationship: f 透镜脉冲 =f 离子源脉冲 =f 射频脉冲 。 10. The periodic pulse high energy ion implanter according to claim 1, characterized in that: The ion source pulse period T of the ion source pulse 离子源脉冲 and the RF pulse period T of the RF pulse 射频脉冲 is 1 to 10 ms, and the ion source pulse duty ratio η of the ion source pulse 离子源脉冲 and the radio frequency pulse duty ratio η of the radio frequency pulse 射频脉冲 It is 1% to 20%.

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