Apparatus, System, and Method for an Energy Spread Ion Beam

Abstract

To generate a spread of ion energies without using a sawtooth absorbing filter in ion implant operation.SOLUTION: An ion implanter may include an ion source arranged to generate a continuous ion beam, a DC acceleration system to accelerate the continuous ion beam, and an AC linear accelerator to receive the continuous ion beam and to output a bunched ion beam. The ion implanter may also include an energy spreading electrode assembly to receive the bunched ion beam and to apply an RF voltage between a plurality of electrodes of the energy spreading electrode assembly along a local direction of propagation of the bunched ion beam.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001]

[0001] This disclosure generally relates to ion implantation devices, and more particularly to high energy beam line ion implantation devices.

Background Art

[0002]

[0002] Currently, certain devices such as insulated gate bipolar transistors (IGBTs), CMOS image sensors, and other semiconductor devices are manufactured using multiple ion implantations. By using multiple ion implantations, it becomes easier to generate a smooth dopant profile having a target shape as a function of depth within a semiconductor substrate. This approach is particularly useful for relatively deep ion implantation profiles. In current practice, this target shape can be achieved by implanting relatively small amounts of ions at various ion energies. For example, in the current state of the art of CMOS image sensor (CIS) devices, 20 discrete energies in the range from 500 keV to over 10 MeV are sometimes used at doses from 1E10 to 1E12 / cm 2 but in sensing at shorter wavelengths required for automotive and other applications, the number of implantation steps can double or more.

[0003]

[0003] Rather than using multiple implantations to generate ion energy spread in a given ion implantation operation, it has been proposed to use a sawtooth absorption filter. However, this approach involves risks of contamination, particles, and filter life, and these risks may limit this approach in an actual production environment.

[0004]

[0004] This disclosure is presented in relation to the above considerations and other considerations.

Summary of the Invention

[0005]

[0005] In one embodiment, the ion implantation apparatus may include an ion source configured to generate a continuous ion beam, a DC acceleration system configured to accelerate the continuous ion beam, and an AC linear accelerator configured to receive the continuous ion beam and output a focused ion beam. The ion implantation apparatus may further include an energy diffusion electrode assembly configured to receive the focused ion beam and apply an RF voltage across a plurality of electrodes of the energy diffusion electrode assembly along a local propagation direction of the focused ion beam.

[0006]

[0006] In another embodiment, an ion implantation apparatus is provided, the ion implantation apparatus including an ion source configured to generate an ion beam as a continuous ion beam, and a linear accelerator configured to focus the continuous ion beam and output the ion beam as a focused ion beam. The ion implantation apparatus may include a scanner configured to receive the focused ion beam propagating along a first direction and scan the focused ion beam along a second direction perpendicular to the first direction. The ion implantation apparatus may further include a collimator disposed downstream of the scanner, the collimator configured to receive the focused ion beam and output the focused ion beam as a ribbon beam. The ion implantation apparatus may further include an energy diffusion electrode assembly disposed downstream of the linear accelerator, the energy diffusion electrode assembly configured to apply an AC voltage across a plurality of electrodes of the energy diffusion electrode assembly along a local direction of propagation of the ribbon beam.

[0007]

[0007] In another embodiment, the beam conditioning device may further include a scanner configured to receive a focused ion beam propagating along a first direction and scan the ion beam along a second direction perpendicular to the first direction. The beam conditioning device may further include a collimator disposed downstream of the scanner, the collimator receiving the focused ion beam and outputting the focused ion beam as a ribbon beam. The beam conditioning device may further include an energy spread electrode assembly disposed downstream of the linear accelerator, the energy spread electrode assembly configured to apply an AC voltage between a plurality of electrodes of the energy spread electrode assembly along a local direction of propagation of the ribbon beam. The beam conditioning device may additionally include a controller configured to control the scanner and the energy spread electrode assembly to generate a uniform energy spread of the ribbon beam across the width of the ribbon beam along a direction perpendicular to the local propagation direction of the ribbon beam.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009]

[0012] The drawings are not necessarily to scale. The drawings are merely illustrative and are not intended to represent specific parameters of the present disclosure. The drawings are intended to show exemplary embodiments of the present disclosure and should not be regarded as limiting the scope. In the drawings, like numbers represent like elements.

[0010]

[0013] Here, the apparatus, system, and method according to the present disclosure will be described in more detail below with reference to the accompanying drawings showing embodiments of the system and method. The system and method may be embodied in many different forms and should not be construed as limited to the embodiments presented herein. Instead, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the system and method to those skilled in the art.

[0011]

[0014] As used herein, terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "lateral," and "longitudinal" may be used to describe the relative placement and orientation of components of a semiconductor manufacturing device and the parts that make up these components with respect to the shape dimensions and orientation as seen in the figures. The terms may include the specifically recited words, their derivatives, and words of similar import.

[0012]

[0015] Here, an element or operation following the articles "a" or "an" which are recited in the singular is understood to potentially include a plurality of elements or operations. Further, reference to "one embodiment" of the present disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0013]

[0016] Here, an approach for an improved ion implantation system and components based on a beamline architecture, specifically for high-energy ion implantation devices such as ion implantation apparatuses based on linear accelerators, is provided. For the sake of brevity, the ion implantation system may also be referred to herein as an "ion implantation apparatus." Various embodiments involve a novel approach for generating a bunched ribbon ion beam for processing in a linear accelerator or LINAC.

[0014]

[0017] In various embodiments, the electrode assembly is provided downstream of the LINAC and uses an AC signal supplied to the electrode assembly at a high frequency to modify the energy of the bunched ion beam. In various embodiments where the substrate and / or the ion beam are scanned to process the substrate, the frequency of the energy variation may be set much faster than the scan of the substrate, such that the energy variations generated by the electrode assembly appear at each point on the substrate as a controlled and repeatable energy spread.

[0015]

[0018] FIG. 1 shows an ion implantation apparatus 100 according to an embodiment of the present disclosure. The ion implantation apparatus 100 includes an ion source 102 configured to generate a continuous ion beam shown as an ion beam 120. The ion implantation apparatus 100 may include an AC linear accelerator represented as a linear accelerator 104 disposed downstream of the ion source 102 to receive the ion beam 120. The linear accelerator 104 may include a buncher (not shown separately) known in the art to modify the ion beam 120 such that a bunched ion beam 122 is generated. According to various non-limiting embodiments, at multiple stages of the linear accelerator 104, the energy of the bunched ion beam 122 can be increased to a target ion energy such as 1 MeV, 2 MeV, 5 MeV, or other suitable ion energy.

[0016]

[0019] According to some non-limiting embodiments of the present disclosure, the ion implantation apparatus 100 may include additional components disposed downstream of the linear accelerator 104 for shaping, collimating, filtering, or scanning the bunched ion beam 122, or performing any combination of these operations. These additional components are indicated by the downstream component 106, which is disposed intermediate the linear accelerator 104 and the energy spread electrode assembly 108. The energy spread electrode assembly 108 is configured to receive the bunched ion beam 122, modulate the energy of the bunched ion beam 122, and output an energy spread ion beam 124 to the substrate 110.

[0017]

[0020] In various embodiments, it is possible to modulate the energy of the bunched ion beam 122 by applying a high-frequency voltage across the energy spread electrode assembly 108. This voltage may generate a corresponding high-frequency electric field along the propagation direction of the bunched ion beam 122, which is represented as the Z-axis in the illustrated Cartesian coordinate system. Specifically, in this embodiment and other subsequent embodiments, the energy spread electrode assembly 108 may be configured as a hollow electrode that conducts the bunched ion beam 122 while applying a high-frequency electric field along the propagation direction. In this way, variable energy can be applied to the bunched ion beam 122 as it passes through the energy spread electrode assembly. For example, an RF power supply 130 can be utilized to generate an AC voltage signal (the term "AC voltage" or "AC voltage signal" as used herein may encompass any suitable frequency range including 1 kHz, 1 MHz, etc.) between various electrodes within the energy spread electrode assembly 108 at an appropriate frequency above 1 MHz. In various non-limiting embodiments, examples of suitable acceleration frequencies for driving the acceleration stage of the linear accelerator and the energy spread electrode assembly 108 include frequencies between 13.56 MHz and 40 MHz.

[0018]

[0021] According to various embodiments of the present disclosure, the AC voltage supplied to the energy spread electrode assembly 108 may have an amplitude suitable for generating a target energy spread within the energy spread ion beam 124 supplied to the substrate 110. For example, according to some non-limiting embodiments, the energy spread ion beam 124 may have an energy distribution with a full width at half maximum (FWHM) equal to 1% of the nominal ion beam energy, 2% of the nominal energy, 5% of the nominal energy, 10% of the nominal energy, or 20% of the nominal energy. Thus, the nominal ion beam energy can be greater than 500 keV, greater than 1 MeV, greater than 2 MeV, or greater than 5 MeV in different embodiments. In this way, at a given nominal ion beam energy, the energy spread ion beam 124 can be implanted into the substrate 110 to provide a wider implantation profile compared to the implantation profile generated by a single energy ion beam having the same nominal ion beam energy.

[0019]

[0022] FIG. 2 shows an ion implantation apparatus 200 according to an additional embodiment of the present disclosure. Similar to the ion implantation apparatus 100, the ion implantation apparatus 200 includes an ion source 102 and a linear accelerator 104 disposed downstream of the ion source 102.

[0020]

[0023] The ion implantation apparatus 200 may include a beam conditioning apparatus 220 disposed downstream of the linear accelerator 104 and including a scanner 202, a collimator 204, and an energy spread electrode assembly 208.

[0021]

[0024] The linear accelerator 104 may include a buncher (not shown) that generates a bunched ion beam 122 from the ion beam 120. This ion beam may enter the linear accelerator 104 as a continuous ion beam. The scanner 202 is configured to receive the bunched ion beam 122 (schematically shown as an ion beam represented by a solid ellipse), and is configured to supply a scan signal as defined by a scan cycle, and scans the bunched ion beam 122 between a first beam line side and a second beam line side. In this embodiment, the bunched ion beam 122 may be a pencil beam or a spot ion beam, and the bunched ion beam 122 is scanned in the illustrated X-Z plane. For example, the scan generator 230 may supply a scan signal such as an oscillating voltage to a pair of electrode plates that generate an oscillating electric field at a scan frequency (in the kHz range such as 1 kHz, 2 kHz, 5 kHz, etc.) according to some non-limiting embodiments. Thus, when averaged over a time scale longer than the period of the scan generator 230 for a given scan frequency, the scanned bunched ion beam may fan out to form an elongated cross-section along the X-axis. In the present embodiment, the energy spread electrode assembly 208 includes a series of AC electrodes connected to a phase control system that uses information on the scan position of the bunched ion beam 122 to select an appropriate phase to achieve the desired energy spread of the bunched ion beam 122.

[0022]

[0025] The collimator 204 is disposed downstream of the scanner 202, and in this case, receives the bunched ion beam 122 in the form of a fan-shaped beam. The collimator 204 may be configured to shape and output the bunched ion beam 122 as a ribbon beam 222 extending along the X-axis. As further shown in FIG. 2, the energy spread electrode assembly 208 is disposed downstream of the collimator 204 and receives the ribbon beam 222. As will be described in detail below, the energy spread electrode assembly 208 is configured to apply an RF voltage between a plurality of electrodes along the propagation direction of the ribbon beam to generate an energy spread.

[0023]

[0026] In the embodiment of FIG. 2, the energy spread electrode assembly 208 includes a first ground electrode 212 and a second ground electrode 216, and an electrode 214 powered between the two ground electrodes is disposed therebetween. The RF power supply 234 may supply an RF power signal at an appropriate frequency to the powered electrode 214. For example, the RF power supply 234 may induce an RF signal to a resonator (not shown separately) that supplies an RF voltage signal to the powered electrode 214. Accordingly, an RF voltage is generated between the powered electrode 214 and the first ground electrode 212 and the second ground electrode 216. And the RF voltage generates an oscillating electric field along the Z-axis in the propagation direction of the ribbon beam 222 having a frequency corresponding to the frequency of the RF voltage signal.

[0024]

[0027] According to various embodiments of the present disclosure, the energy spread electrode assembly 208 may be configured as a series of a plurality of hollow conductive cylinders having an elongated cross-section (along the X-axis) designed to encompass the ribbon beam 222. In this way, the energy spread electrode assembly 208 may exhibit some characteristics of a known drift tube assembly used to bunch or accelerate ion beams in a linear accelerator. When the ribbon beam 222 passes through a given hollow electrode of the energy spread electrode assembly, the ribbon beam 222 will encounter a drift region within the hollow electrode where there is no electric field. An oscillating electric field is generated between the first ground electrode 212 and the powered electrode 214, but an oscillating electric field is also generated between the powered electrode 214 and the second ground electrode 216. In this way, the energy spread electrode assembly 208 may define a so-called double-gap configuration characterized by two acceleration gaps. According to various embodiments of the present disclosure, in order to obtain the desired effect of ion energy spread, the frequency and phase of the oscillating voltage applied to the energy spread electrode assembly 208 are selected in consideration of several factors. These factors include the velocity of the ions, the spread of the phase in the ion beam, and the length between the two gaps of the double-gap configuration.

[0025]

[0028] When the ribbon beam 222 enters the acceleration gap in the energy spread electrode assembly 208, the timing of entry of a given ion beam of the ribbon beam 222 affects how the ions are accelerated or decelerated across the gap. For example, a sinusoidal RF voltage signal may be applied to the electrode 214 to which power is supplied, in which case a sinusoidal electric field is generated across the acceleration gap. Depending on the instantaneous amplitude and sign of the electric field as the ions cross the acceleration gap, the ions are accelerated or decelerated, more or less. Thus, in a given ion beam passing through the acceleration gap, the ions at the front end of the beam are accelerated or decelerated to a different extent than the ions at the rear end of the beam, resulting in an energy spread of the ions of the ribbon beam 222 as it passes through the energy spread electrode assembly 208.

[0026]

[0029] According to an embodiment of the present disclosure, the energy spread electrode assembly 208 can broaden or spread the energy of the ribbon beam 222 by a target amount in order to supply an energy spread ion beam 224 (shown as a more elongated filled ellipse to indicate energy spread) having a desired range of ion energy to the substrate 110. For example, in one case, the linear accelerator 104 imparts an ion energy of 1 MeV to the ribbon beam 222, while an RF voltage signal with an amplitude of 80 keV is supplied to the electrode 214 to which power is supplied. Assuming that the ribbon beam 222 is initially of a single energy, the 80 kV signal can cause the energy spread ion beam 224 to impinge on the substrate 110 with an average energy of 1 MeV and a FWHM of up to 160 keV.

[0027]

[0030] According to various non-limiting embodiments of the present disclosure, the energy spread electrode assembly can process an ion beam to spread the ion energy (FWHM) from 1% to 30% for an initial ion energy in the range of 1 MeV to 10 MeV. As described above, the ribbon beam 222 enters the energy spread electrode assembly as a bunched ion beam (i.e., a discrete series of ion packets or ion bunches) that are separated from each other in time and space. This bunching operation is performed by a drift tube device. The drift tube device can operate in a manner similar to the operation of the energy spread electrode assembly 108 in which an RF signal is applied to at least one powered electrode in a series of drift tube electrodes. These drift tube assemblies of the buncher will generate two or more acceleration gaps. These two or more acceleration gaps tend to accelerate or decelerate different ions in the ion beam differently depending on the timing at which the various ions pass through the acceleration gap as the RF electric field oscillates across the acceleration gap. Further, according to various embodiments of the present disclosure, the bunched ion beam (ribbon beam 222) can be bunched at a bunch frequency equal to the spreading frequency output by the RF power supply 234. In this way, the arrival timing of the ion bunches of the ribbon beam 222 can be synchronized with the electric field generated across the energy spread electrode assembly 208.

[0028]

[0031] In certain embodiments, when the diffusion frequency of the energy diffusion electrode assembly 208 (e.g., on the order of several MHz or several tens of MHz) can be much higher than the scanning frequency of the scanner 202 (e.g., on the order of 1 kHz), energy diffusion can be provided to various bunches of the energy diffusion ion beam 224 uniformly and repeatedly. For example, while the ribbon beam 222 extends along the lateral direction (X-axis) perpendicular to the propagation direction (Z-axis), the energy diffusion electrode assembly 208 can provide uniform energy diffusion to the bunched ribbon beam (ribbon beam 222) for various ion bunches across the width of the bunched ribbon beam along the X-axis. This uniformity of energy diffusion can be achieved by keeping the phase relationship between the RF signal output from the RF power supply 234 to the energy diffusion electrode assembly 208 and the arrival time of the bunch groups in the ribbon beam constant.

[0029]

[0032] In one embodiment, the ion implantation apparatus 200 may include a detector 210 and a phase measurement component 232 for measuring the phase of the ion bunches of the ribbon beam 222 at the entrance to the energy diffusion electrode assembly 208. As shown in FIG. 2, the ion implantation apparatus 200 may further include a controller 236 that synchronizes this phase information with the RF power supply 234. Alternatively, the controller 236 can acquire or receive a signal from the scan generator 230 to determine the instantaneous scan position (along the X-axis) of the ion bunches of the ribbon beam 222. Knowing the instantaneous scan position of the ion bunches enables synchronization of the RF signal generated by the RF power supply 234, ensuring that a given ion bunch passes through the energy diffusion electrode assembly 208 at appropriate intervals and that the targeted energy diffusion occurs.

[0030]

[0033] FIG. 3 shows an ion implantation apparatus 300 configured according to a further embodiment of the present disclosure. Similar to the ion implantation apparatus 100 and the ion implantation apparatus 200, the ion implantation apparatus 300 includes an ion source 102 and a linear accelerator 104 disposed downstream of the ion source 102. In this embodiment (as well as variations of the embodiments of FIGS. 1, 2, and 4), before further acceleration of the ion beam is performed by the linear accelerator 104, according to some non-limiting embodiments, the ion implantation apparatus may further include a DC acceleration system 103 for accelerating the ion beam 120 to an appropriate energy, such as from 250 keV to 500 keV.

[0031]

[0034] In this embodiment, the energy spread device may include a power supply connected to an energy spread electrode assembly 310. In this case, the energy spread electrode assembly 310 is embodied as a diode set including an upstream electrode 312 and a downstream electrode 314. According to some embodiments, an AC voltage may be applied between the upstream electrode 312 and the downstream electrode 314. As shown in FIG. 3, the upstream portion 322 of the beamline is electrically insulated from the downstream portion 324 of the beamline. According to different embodiments, the upstream portion 322 of the beamline, including an end station (not shown) that houses the substrate 110, may be electrically floating, or the downstream portion 324 may be electrically floating. To list the advantages of this approach, in this example, the energy spread electrode assembly 310 does not need to receive an RF voltage signal set to the same frequency as the RF voltage applied to the linear accelerator 104. In the embodiment of FIG. 3, there is only one gap in the energy spread electrode assembly 310, and the frequency of energy oscillation can be freely selected from a fairly wide range without causing other problems, so in some aspects it is simpler than the embodiment of FIG. 2. However, the embodiment of FIG. 3 has a more complex mechanical design and requires separating a large assembly from the ground potential and attaching the assembly to an insulator.

[0032]

[0035] In an embodiment where an AC voltage is applied between the upstream electrode 312 and the downstream electrode 314, in order to avoid aliasing between the scanning frequency and / or bunch frequency of the RF voltage applied to the linear accelerator 104 (including the buncher) and the AC voltage, it is necessary to carefully select the AC voltage frequency. Since the bunch frequencies applied in multiple stages of the linear accelerator 104 are estimated to be above several MHz, the scanning frequency of the scanner 202 may be in the range of 1 kHz or less. According to some embodiments, an AC voltage frequency in the range of 100 kHz or less (for example, in the range of 50 kHz to 500 kHz) may be used for the energy diffusion electrode assembly 310. As shown in the embodiment of FIG. 3, the first power supply 332 may be connected to the upstream portion 322, or alternatively the power supply 334 may be connected to the downstream portion 324, and each power supply may be connected to the controller 330. Since the latter frequency may be much lower (10 times or more lower) than the bunch frequency of the linear accelerator 104, each bunch of ions passing through the energy diffusion electrode assembly 310 will substantially undergo DC acceleration or deceleration. In other words, for example, in the case of an ion beam bunched at a frequency of 13.56 MHz, since the length of the ion beam passing through the energy diffusion electrode assembly 310, and thus the transit time, is sufficiently short, the effective magnetic field experienced by the beam appears to be quasi-constant due to the much lower (100 kHz or less) energy diffusion magnetic field frequency.

[0033]

[0036] FIG. 4 shows an ion implantation apparatus 400 configured according to a further embodiment of the present disclosure. Similar to the ion implantation apparatus 100, the ion implantation apparatus 200, and the ion implantation apparatus 300, the ion implantation apparatus 300 includes an ion source 102 and a linear accelerator 104 disposed downstream of the ion source 102. Different from the embodiments of FIGS. 2 and 3, in this embodiment, the ion implantation apparatus 400 generates a pencil beam (or spot beam) and directs it towards the substrate 110.

[0034]

[0037] According to various non - limiting embodiments, as in the above - described embodiments, at multiple stages of the linear accelerator 104, a focused ion beam 122 can be generated and accelerated to a target ion energy such as 1 MeV, 2 MeV, 5 MeV, or other suitable ion energies. Different from the above - described embodiments, components such as an energy - selection magnet 404 can be provided to process the focused ion beam 122 as a spot beam having a target value of ion energy before it collides with the substrate 110. The energy - selection magnet 404 (sometimes referred to as the "final - energy magnet") is responsible for individually measuring the energy of the ions at that point in the beamline. The ion implantation device 400 further includes an energy - spreading device embodied as a high - frequency power supply 412 and an energy - spreading electrode assembly 406. For simplicity, the energy - spreading electrode assembly 406 is shown as two electrodes. However, according to different embodiments, the energy - spreading electrode assembly 406 may be embodied as a double - gap drift - tube assembly, similar to the energy - spreading electrode assembly 208, or alternatively, as a triple - gap electrode assembly with two powered electrodes provided between two grounded electrodes. Thus, the high - frequency power supply 412 can generate an RF voltage at the same frequency as the power supply assembly 410 supplies RF voltages to the buncher and various stages of the linear accelerator 104. The advantage of the structure in FIG. 4 is that the path length of the ions of the focused ion beam 122 from the linear accelerator to the energy - spreading electrode assembly 406 is constant, so the phase relationship between the two is also constant. To achieve the desired and repetitive acceleration or deceleration of a series of ion bunches, the phase of the accelerating or decelerating AC magnetic field needs to match the arrival time of the ion bunch on which the AC magnetic field acts. In other words, each successive ion bunch arriving at the energy - spreading electrode assembly 406 should experience the same amplitude and phase as the applied AC magnetic field.Accordingly, by establishing the same frequency for the bunched signal generated by the power supply assembly 410 and the spread signal transmitted by the high-frequency power supply 412, and properly synchronizing the bunched signal and the spread signal, each successive ion beam along a given ion path will be similarly processed by the applied AC magnetic field from the energy spread electrode assembly. In the configuration of FIG. 2, this phase relationship changes as the path lengths of the various ion paths change according to the scanning angle at a given point in time, but in the configuration of FIG. 4, there is no high-speed scanning that changes the path length. Thus, the controller 414 can more easily synchronize the acceleration of the bunched ion beam 122 passing through the linear accelerator 104 and the energy spread performed by the energy spread electrode assembly 406.

[0035]

[0038] As shown in FIG. 4, the ion implantation apparatus 400 may include a substrate stage 408 configured to rotate the substrate 110 about the Z-axis and move the substrate along a vertical axis such as the X-axis. In this way, the bunched ion beam 122 may irradiate only a portion of the substrate 110 at a given stage, but the entire substrate 110 or any target portion thereof may be exposed to the energy spread ion beam 420 by proper rotation and / or translation of the substrate 110.

[0036]

[0039] In view of the above, at least the following advantages are achieved by the embodiments disclosed herein. The first advantage provided by the ion implantation apparatus of this embodiment is the ability to achieve a wider implantation profile within a given implantation process than when using a known single-energy high-energy implantation apparatus. A further advantage is the ability to easily adjust the width of the implantation profile by simply adjusting the voltage applied to the energy spread component.

[0037]

[0040] While specific embodiments of the present disclosure are described herein, the present disclosure is not limited thereto. This is because the present disclosure is broad as permitted by the relevant art and can be interpreted similarly herein. Therefore, the above description should not be construed as limiting. Those skilled in the art will envision other modifications within the scope of the appended claims and the essence of the present disclosure.

Claims

1. An ion implantation apparatus comprising: an ion source configured to generate an ion beam; a scanner disposed downstream of the ion source in a moving direction of the ion beam; and an energy spread electrode assembly disposed downstream of the scanner, receiving the ion beam, and applying a time-varying voltage bias signal between a plurality of electrodes of the energy spread electrode assembly to generate energy spread of the ion beam. The ion implantation apparatus provided with the above components.

2. The ion implantation apparatus according to claim 1, wherein the energy spread depends on the time-varying voltage bias signal.

3. The ion implantation apparatus according to claim 1, wherein the energy spread results in a first implantation profile in a substrate with respect to a nominal ion energy, and the first implantation profile is wider than a second implantation profile in the substrate generated when a mono-energetic ion beam of the same nominal energy is directed at the substrate.

4. The ion implantation apparatus according to claim 1, wherein the energy spread has an energy distribution equal to 1% to 30% of an initial energy of the ion beam.

5. The ion implantation apparatus according to claim 1, wherein the time-varying voltage bias signal is an RF voltage.

6. The ion implantation apparatus according to claim 1, wherein the time-varying voltage bias signal is an alternating voltage.

7. The ion implantation apparatus according to claim 1, wherein the scanner operates to scan the ion beam at a first frequency, and the time-varying voltage bias signal is applied at a second frequency at least 10 times greater than the first frequency.

8. The ion beam is elongated along a lateral direction perpendicular to a local propagation direction of the ion beam, and the energy spread electrode assembly is configured to apply uniform energy spread to the ion beam along the lateral direction across a width of the ion beam. The ion implantation apparatus according to claim 7.

9. The ion implantation apparatus according to claim 1, further comprising a linear accelerator disposed between the ion source and the energy spread electrode assembly and configured to increase an energy of the ion beam.

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