Instruments, systems, and techniques for mass spectrometry ion beams

Abstract

The apparatus may include an electrodynamic mass spectrometry (EDMA) assembly located downstream of the focused ion beam assembly. The EDMA assembly may include a first stage comprising a first upper electrode positioned above the beam axis and a first lower electrode positioned below the beam axis opposite the first upper electrode. The EDMA assembly may also include a second stage located downstream of the first stage, comprising a second upper electrode positioned above the beam axis and a second lower electrode positioned below the beam axis. The EDMA assembly may further include a deflection assembly located between the first and second stages, comprising a blocker positioned along the beam axis, an upper deflection electrode positioned on a first side of the blocker, and a lower deflection electrode positioned on a second side of the blocker.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims priority to U.S. Patent Application No. 18 / 131,271, filed on 5 April 2023. The contents of said U.S. Patent Application are incorporated herein by reference in their entirety.

[0002]

[0002] This disclosure relates more broadly to ion beam apparatus, and more particularly to ion implantation apparatus having mass spectrometry capabilities. [Background technology]

[0003]

[0003] Ion implantation is the process of introducing dopants or impurities into a substrate via collision. An ion implantation system ("ion implantation apparatus") may comprise an ion source and a substrate stage or process chamber that houses the substrate to be implanted. The ion source may comprise a chamber from which ions are generated. A beamline ion implantation apparatus may comprise a series of beamline components, such as a mass spectrometer, a collimator, and various components for accelerating or decelerating the ion beam.

[0004]

[0004] A useful function of an ion implanter beamline is to separate ions of different masses. This allows for the formation of an ion beam containing the desired ions for processing a workpiece or substrate, while unwanted ions are blocked within the beamline components and do not reach the substrate. In known systems, this mass spectrometry function is provided by an analytical magnet. This analytical magnet bends the beam of ions, all of the same energy, in a curve whose radius depends on the mass, thereby achieving the required separation. However, this type of magnet is large, expensive, and heavy, and accounts for a significant portion of the cost and power consumption of the ion implanter.

[0005]

[0005] Compact ion beam systems have been developed for relatively low-energy ion implantation, such as energies below approximately 50 keV. These ion beam systems may include a plasma chamber that acts as an ion source and may be located adjacent to a process chamber that houses the substrate to be implanted. The ion beam may be extracted from the plasma chamber using an extraction grid or other extraction optics to provide the substrate with an ion beam having a desired beam shape, such as a ribbon beam. In these latter systems, mass spectrometry may be omitted because of the size / space required to install the aforementioned magnet analyzer, as well as the cost. Therefore, the use of such compact ion beam systems may be limited to applications where the purity of the implanted species is not strictly required.

[0006]

[0006] Recently, an approach has been proposed for ion beam processing systems. In this approach, an electrodynamic mass spectrometry (EDMA) component is used to generate a mass-analyzed ion beam in an ion beam processing device that is more compact than known beamline ion implanters. This approach applies a high-frequency electric field to remove ions of undesirable mass. However, EDMA designs devised to date may not be able to generate an acceptable flux for ions of target mass, especially when operating at high beam currents overall.

[0007]

[0007] This disclosure is presented in connection with the above considerations and other considerations. [Overview of the project]

[0008]

[0008] In one embodiment, an apparatus is provided which may include an electrodynamic mass spectrometry (EDMA) assembly located downstream of a focused ion beam assembly. The EDMA assembly may include a first stage comprising a first upper electrode located above the beam axis and a first lower electrode located below the beam axis opposite the first upper electrode. The EDMA assembly may also include a second stage located downstream of the first stage, comprising a second upper electrode located above the beam axis and a second lower electrode located below the beam axis. The EDMA assembly may further include a deflection assembly located between the first and second stages, comprising a blocker located along the beam axis, an upper deflection electrode located on a first side of the blocker, and a lower deflection electrode located on a second side of the blocker.

[0009]

[0009] In another embodiment, an ion beam processing system is provided which includes an ion source chamber for generating an ion beam as a continuous ion beam, a focused beam assembly for outputting the ion beam as a focused ion beam along the beam axis, and an electrodynamic mass spectrometry (EDMA) assembly. The EDMA assembly may include a first stage for receiving the focused ion beam and applying a first RF signal between a first upper electrode and a first lower electrode, and a second stage located downstream of the first stage for applying a second RF signal between a second upper electrode and a second lower electrode. The EDMA assembly may also include a deflection assembly located between the first and second stages, comprising a blocker located along the beam axis, an upper deflection electrode located on a first side of the blocker, and a lower deflection electrode located on a second side of the blocker.

[0010]

[0010] In another embodiment, the method may include guiding an ion beam as a continuous ion beam along a beam axis into a first stage of an electro-dynamic mass analyzer (EDMA) assembly. The method may include deflecting the ion beam along a trajectory that is not parallel to the beam axis in the first stage of the EDMA assembly using a first AC voltage signal applied at a first frequency. The method may also include blocking the path of a first portion of the ion beam along the beam axis at a blocker disposed downstream of the first stage of the EDMA assembly. In that case, a second portion of the ion beam passes through the beam blocker as a bundled ion beam. The method may further include deflecting the bundled ion beam in a second stage of the EDMA assembly downstream of the blocker using a second AC voltage signal applied at the first frequency. In that case, a third portion of the beam exits the EDMA assembly.

Brief Description of the Drawings

[0011] [Figure 1A]

[0011] An ion beam processing system operating according to a first scenario according to various embodiments of the present disclosure is shown. [Figure 1B]

[0012] Another ion beam processing system according to multiple other embodiments of the present disclosure is shown. [Figure 1C]

[0013] A computer simulation of an ion beamlet representing B+ ions transported through the ion beam processing system of FIG. 1B is shown. [Figure 1D]

[0014] FIGS. 1D, 1E, 1F, and 1G show computer simulations of ion species transport under the conditions of FIG. 1C for four different ions. [Figure 1E] FIGS. 1D, 1E, 1F, and 1G show computer simulations of ion species transport under the conditions of FIG. 1C for four different ions. [Figure 1F]Figures 1D, 1E, 1F, and 1G show computer simulations of ion species transport under the conditions of Figure 1C for four different ions. [Figure 1G] Figures 1D, 1E, 1F, and 1G show computer simulations of ion species transport under the conditions of Figure 1C for four different ions. [Figure 2A]

[0015] This shows one specific embodiment of a focused ion beam assembly. [Figure 2B]

[0016] Another embodiment of a focused ion beam assembly is shown. [Figure 3A]

[0017] Further embodiments of the present disclosure illustrate EDMA assemblies. [Figure 3B]

[0018] This shows an operational scenario for an EDMA assembly combined with an electrostatic energy filter. [Figure 4]

[0019] An exemplary simulated beam profile is shown, illustrating the beam current as a function of time for an ion beam generated by an EDMA assembly arranged according to this embodiment. [Figure 5A]

[0020] This shows the energy spread of a boron ion beam within an EDMA assembly without asymmetric deflection assembly. [Figure 5B]

[0021] This embodiment shows the energy spread of a boron ion beam within an EDMA assembly having an asymmetric deflection assembly. [Figure 6A]

[0022] This invention illustrates the operation of an EDMA assembly under one scenario according to one embodiment of the present disclosure. [Figure 6B] This invention illustrates the operation of an EDMA assembly under one scenario according to one embodiment of the present disclosure. [Figure 6C] This invention illustrates the operation of an EDMA assembly under one scenario according to one embodiment of the present disclosure. [Figure 6D]

[0023] Figure 6A shows the operation of EDMA under the second scenario. [Figure 6E] Figure 6A shows the operation of EDMA under the second scenario. [Figure 6F] Figure 6A shows the operation of EDMA under the second scenario. [Figure 7A]

[0024] Figure 6A shows one embodiment of the operation of EDMA under the third scenario. [Figure 7B] Figure 6A shows one embodiment of the operation of EDMA under the third scenario. [Figure 7C] Figure 6A shows one embodiment of the operation of EDMA under the third scenario. [Figure 8A]

[0025] Figure 6A shows the operation of a modified EDMA in which the length of the RF electrode in the first stage is different from the length of the RF electrode in the second stage. [Figure 8B] Figure 6A shows the operation of a modified EDMA in which the length of the RF electrode in the first stage is different from the length of the RF electrode in the second stage. [Figure 8C] Figure 6A shows the operation of a modified EDMA in which the length of the RF electrode in the first stage is different from the length of the RF electrode in the second stage. [Figure 9A]

[0026] One embodiment is shown in which the parameters for the simulation in Figure 9A are the same as those specified for Figure 6A, except that the length of the second stage is adjusted. [Figure 9B] One embodiment is shown in which the parameters for the simulation in Figure 9A are the same as those specified for Figure 6A, except that the length of the second stage is adjusted. [Figure 9C] One embodiment is shown in which the parameters for the simulation in Figure 9A are the same as those specified for Figure 6A, except that the length of the second stage is adjusted. [Figure 10]

[0027] Process flows according to several embodiments of this disclosure are presented. [Figure 11]

[0028] This disclosure presents alternative process flows according to several other embodiments of this disclosure. [Figure 12]

[0029] Further embodiments of this disclosure present alternative process flows. [Modes for carrying out the invention]

[0012]

[0030] The drawings are not necessarily to scale. The drawings are for illustrative purposes only and are not intended to represent any particular parameter of the disclosure. The drawings are intended to illustrate exemplary embodiments of the disclosure and should therefore not be considered limiting. In the drawings, similar numbering represents similar elements.

[0013]

[0031] The apparatus, systems, and methods relating to this disclosure will be fully described below with reference to the accompanying drawings illustrating embodiments of the systems and methods. The systems and methods may be implemented in many different forms and should not be construed as being limited to the embodiments specified herein. Rather, these embodiments are provided to make this disclosure detailed and complete and to fully convey the scope of the systems and methods to those skilled in the art.

[0014]

[0032] Here, any element or operation following the singular form of “one” or “a” (a, an) is understood to potentially include multiple elements or operations. Furthermore, any reference to “one embodiment” in this disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the enumerated features.

[0015]

[0033] An approach for a mass spectrometry ion implantation system using a novel EDMA instrument is provided herein.

[0016]

[0034] Figure 1A shows an ion beam processing system 10 according to various embodiments of the present disclosure. The ion beam processing system 10 includes an ion source chamber 12 for generating an ion beam 14 as a continuous ion beam, an EDMA assembly 20 arranged to receive the ion beam 14 and generate a mass spectrometry ion beam, and an electrostatic energy filter, shown as an electromagnetic energy filter 60, arranged to generate an energy-filtered mass spectrometry ion beam that is guided to a substrate 70 shown as an ion beam 14A. Since the structure and operation of electrostatic energy filters are well known, details of the electrostatic energy filter 60 will be omitted herein. The basic operation of such an energy filter employs a set of electrodes 62 arranged around the ion beam path. In this case, the electrodes 62 apply a series of target DC (static) voltages to deflect the ion beam and to accelerate and / or decelerate the ion beam. In doing so, the electric field generated within the electrostatic energy filter 60 removes unwanted ion species and high-energy neutral species that have energies different from the target energy or target range of energy. The general function of the EDMA assembly 20 is to remove unwanted ions (impurity ion species) and deliver target ion species of the target mass into the energy filter 60.

[0017]

[0035] According to various embodiments of the present disclosure, the EDMA assembly 20 may include a first stage 30 for receiving an ion beam 14. When received, the ion beam 14 may have a trajectory along the beam axis, i.e., along the Z-axis in the illustrated Cartesian coordinate system. The first stage 30 may apply a first RF signal between a first upper electrode 22 and a first lower electrode 24. In various non-limiting embodiments, suitable frequencies for the RF signal of the present disclosure may be in the range of 200 kHz to 100 MHz.

[0018]

[0036] As will be detailed in the following discussion, the first RF signal deflects the ion beam 14 in a manner that assists mass filtering. The EDMA assembly 20 may further include a second stage 40 positioned downstream of the first stage 30 to apply a second RF signal between a second upper electrode 42 and a second lower electrode 44. This second stage 40 may be positioned similarly to the first stage 30 in some embodiments, but in some other embodiments, the second stage 40 may differ from the first stage 30 in at least one embodiment.

[0019]

[0037] In some embodiments, the electrodes of the first stage 30 and the second stage 40 are elongated along the electrode axis (represented by the X-axis), and the electrode axis extends perpendicular to the beam axis. This configuration may be particularly suitable for processing ribbon beams, which are characterized by a long axis in the cross-section extending along the X-axis. However, in other embodiments, the electrodes of the first stage 30 and the second stage 40 may be shaped to process spot beams or pencil beams having a more equiaxial shape in the cross-section.

[0020]

[0038] The EDMA assembly 20 is positioned between the first stage 30 and the second stage 40 and may further include a deflection assembly 50 comprising a blocker 56. As shown in Figure 1A, the blocker 56 may be positioned along a beam axis 57, which, according to some embodiments, may represent a midline between the upper electrodes of the first stage 30 and the second stage 40 and the lower electrodes of the first stage 30 and the second stage 40. In some embodiments, the deflection assembly 50 may include an upper deflection electrode 52 positioned on the first side of the blocker 56 and a lower deflection electrode 54 positioned on the second side of the blocker 56. Note that for illustrative clarity, certain walls forming part of the EDMA assembly 20 or a similar EDMA apparatus are omitted in Figure 1A and several other drawings.

[0021]

[0039] As shown in FIG. 1A, during operation, the EDMA assembly 20 deflects the constituent ions of the ion beam 14 along different trajectories so as to block ions whose mass does not correspond to the target ion mass while sending ions of the target mass through the energy filter 60, thereby performing a mass filtering operation on the ion beam 14. In FIG. 1A, a computer simulation of an ion beamlet is shown, with three different ion species having different masses (in this case, B + ions, F + ions, and BF + ions), and the target ions for implantation into the substrate 70 are B + ions. The incident ion beam, i.e., the ion beam 14, may include portions of each of these ion species before entering the EDMA assembly 20. After passing through the EDMA assembly 20, most of the F + ions and BF + ions are deflected in such a way that these ions are blocked by components within the EDMA assembly 20 so as not to be sent to the energy filter 60. In the simulation shown, an input B + current of 3 mA, 20 kV is filtered so that a transmission of approximately 50% of the B + current is achieved at the substrate 70. In other words, B + ions move around the blocker 56 and approximately 50% of the B + ions are deflected in such a way that they exit the EDMA assembly 20 at a position close to the beam axis 57 without being blocked by structures such as the exit tunnel 58. At the same time, as shown in FIG. 1A, the ions of the ion beam 14 may exit the EDMA assembly 20 in multiple bundles rather than as a continuous ion beam after encountering the blocker 56.

[0022]

[0040] It should be noted that the ion beam 14 is created by individual ions moving at a velocity determined by their energy and mass. In this case, in the embodiment of Figure 1A, multiple ions move generally along the beam axis 57 as they enter the first stage 30. During the operation of the EDMA assembly 20, an AC (RF) voltage signal is applied to the first stage 30 to generate a time-dependent electric field that changes sinusoidally in the vertical direction (Y-axis) with a given maximum amplitude. The AC signal is applied in such a manner that, in any given instance, the first upper electrode 22 is driven by a first voltage signal at the first lower electrode 24 that is out of phase with a second voltage signal. The phase shift between the first voltage signals is ideally 180 degrees, or close to 180 degrees, according to some non-limiting embodiments, and may be, for example, 175 degrees, 178 degrees, or 179 degrees. This phase shift establishes a time-dependent electric field along the Y-axis. In other words, these equipotential lines of the electric field generally traverse parallel to the x-z plane in the illustrated Cartesian coordinate system. A similar scenario occurs with the second upper electrode 42 and the second lower electrode 44. As illustrated by the various bundles of ion beams representing different arrival times corresponding to different phases of the AC signal, portions of the ion beam 14, regardless of the phase (arrival time) of the different ions, return to their original flight path and angle directed along the beam axis 57, or return close enough to their original trajectory along the beam axis 57 and the Z-axis, and exit the EDMA assembly 20. + Ions and F + The remaining portions of the ion beam 14, which represent ions, are deflected to positions and / or orbits in which these remaining portions are captured within the EDMA assembly 20.

[0023]

[0041] In particular, as the ion beam 14 crosses the first stage 30, the positions and trajectories of the constituent ions of the ion beam 14 will vary according to the magnitude and frequency of the applied AC(RF) signal. In embodiments of the sinusoidal RF signal, the ion beam 14 may take on a sinusoidal or wavy shape in the first stage. Different portions of the ion beam are characteristic of different species with different masses and tend to propagate as waves with different amplitudes, and some of the waves are blocked by the blocker 56. As a result, the ion beam 14 tends to be arranged in bundles after passing through the blocker 56, as shown in the figure. Furthermore, the EDMA assembly 20 may be configured to favor the propagation of bundles associated with ion species of target mass, as will be further detailed in the following discussion.

[0024]

[0042] Advantageously, the power supply 32 for the first stage may be configured to apply a first RF voltage signal between the first upper electrode 22 and the first lower electrode 24, while the power supply 34 for the second stage may be configured to apply a second RF voltage signal between the second upper electrode 42 and the second lower electrode 44. The controller 38 may also be provided to independently vary the first magnitude of the first RF voltage signal with respect to the second magnitude of the second RF voltage signal. The controller 38 may also be configured to vary the first phase of the first RF voltage signal with respect to the second phase of the second RF voltage signal. This flexibility allows the characteristics of the ion beam processed by the EDMA assembly 20 to be tuned on an application-specific basis to improve, for example, current yield, mass filtering, and / or the energy spread of the delivered ions.

[0025]

[0043] One challenge encountered when operating the system in Figure 1A is that, when parallel ion beams with roughly parallel ion orbitals are guided into the EDMA assembly 20, as the beam current increases, the space charge effect tends to reduce the EDMA assembly 20's ability to deliver ions of the target mass. The 15 mA, 20 kV input B guided into the EDMA assembly 20 +One simulation of a current ion beam showed that the resulting ion beam exhibited only 20% of the original beam current, and the F in the delivered ion beam + Relatively high ion transmission was observed.

[0026]

[0044] Referring back to Figure 1B, another ion beam processing system, shown as ion beam processing system 100, is shown according to several other embodiments of the present disclosure. In this embodiment, in addition to the aforementioned components of the embodiment in Figure 1A, which include the electrostatic energy filter 60 and the EDMA assembly 20, the ion beam processing system 100 includes a focused ion beam assembly 102. The focused ion beam assembly 102 is arranged to generate a focused ion beam that is received by the EDMA assembly 20. The advantages of this configuration will be further explained with respect to Figure 1C.

[0027]

[0045] In various embodiments, a deflection power supply 36 may be provided. The deflection power supply 36 is arranged to apply a static bias voltage between the blocker 56 of the deflection assembly 50 and the upper deflection electrode 52 and the lower deflection electrode 54. For example, the blocker 56 may be set to ground or a negative potential, while both the upper deflection electrode 52 and the lower deflection electrode 54 are set to a positive potential relative to ground, e.g., +1kV, +1.5kV, +2kV, or any appropriate potential based on the mass and energy of the ion species induced through the EDMA assembly 20.

[0028]

[0046] Referring back to Figure 1C, a computer simulation of the ion beamlet is shown. This is the B transported through the ion beam processing system 100. + This represents ions. In this simulation, B is 18mA, 20kV. + The ion beam is guided from the focused ion beam assembly 102 into the EDMA assembly 20 as a focused ion beam 66. The ion beam is "B + It is called an "ion beam," but ion beams have BF + BF2+ F + It also includes the B of the beam. + Please note that only the ingredients are listed.

[0029]

[0047] A first RF voltage signal is applied between the first upper electrode 22 and the first lower electrode 24 with a frequency of 4 MHz and a peak amplitude of 7.5 kV. A second RF voltage signal is also applied between the second upper electrode 42 and the second lower electrode 44, also with a frequency of 4 MHz and a peak amplitude of 7.5 kV. Note that in this embodiment, the phases of the first RF voltage signal and the second RF voltage signal are as follows: the potential at the first upper electrode 22 is always the same as the potential at the second upper electrode 42, while the potential at the first lower electrode 24 is always the same as that at the second lower electrode 44. Again, the phases of the first and second RF signals received by the first upper electrode 22 and the second upper electrode 42 are shifted by 180 degrees from the phases of the first and second RF signals received by the first lower electrode 24 and the second lower electrode 44. A deflection voltage of +1.5kV is applied to the upper deflection electrode 52 and the lower deflection electrode 54, and the blocker 56 is grounded. An instantaneous depiction of the generated electric field is shown as equipotential lines 64.

[0030]

[0048] As shown in Figure 1C, the ion beam is guided as a focused ion beam 66, and this shape compensates for space charge blow-up in the first stage 30 of the EDMA assembly 20, especially for higher beam currents such as 18 mA in the illustrated embodiment. In many cases, B generated from the ion source + The beam is F + Seeds, and BF + This will include species. These species (F + Seeds and BF +It should be noted that heavier species tend to be present in greater quantities in the first stage 30 and generate the strongest space charge effect. These heavy / space charge contributing species tend to be removed to a considerable extent by the deflection assembly 50, which includes the blocker 56. In addition, the bias of the blocker 56 on the upper deflection electrode 52 and the lower deflection electrode 54 in the first stage 30 + This can provide the ability to adjust for excessive deflection of desired ion species due to space charge drive, such as B. + The beam transmittance may be improved compared to the embodiment shown in Figure 1A.

[0031]

[0049] Referring back to Figures 1D, 1E, 1F, and 1G, we see that B + F + BF + , and BF2 + For the corresponding boron ion beam and constituent species, computer simulations of ion species transport under the conditions shown in Figure 1C above are illustrated. As qualitatively illustrated, B + A relatively large proportion of the ion current is transported to the substrate 70 (see Figure 1C for individual elements with reference numbers, which are omitted here for clarity). + Regarding ion species, a relatively large proportion of the incident current passes into the second stage 40 (see Figure 1C). However, B + F + Due to its heavy mass, the electric field within the EDMA is as follows: That is, F + The ionic current is deflected in a way that prevents it from entering the electrostatic energy filter 60. Heavier ionic species (BF2) primarily contribute to the space charge effect. + and BF + As for the majority of ions, most of these ions are removed in the first stage 30. For example, BF2 + The current is not substantially deflected in the Y direction. As a result, the current is essentially completely blocked by the blocker 56.

[0032]

[0050] With respect to the focused ion beam assembly 102, in various embodiments, this assembly can be constructed according to any suitable known apparatus for generating a focused ion beam. Figure 2A shows one particular embodiment of a focused ion beam assembly 200 formed from a tetrode assembly. The focused ion beam assembly 200 may include a first electrode 202, such as a plate of ion source. This plate is biased with the final beam energy. A suppression electrode 204 is negatively biased with respect to the first electrode 202 to extract the ion beam. A "defocus" electrode 206 is positively biased with respect to the suppression electrode 204 to slow the ion beam and increase the beam vertical size, and a "ground" electrode 208 is provided at the beamline potential to generate the focused ion beam 260 entering the EDMA assembly 20.

[0033]

[0051] It should be noted that this configuration differs from known tetrode extraction assemblies in which a defocus electrode similar to the defocus electrode 206 is maintained negatively relative to the beamline to maintain beamline neutralization. However, such neutralization is not necessary for the operation of the EDMA assembly 20.

[0034]

[0052] In another embodiment shown in Figure 2B, the focused ion beam assembly 250 may be configured as an Einzel lens having three sets of electrodes as shown. In this case, the central electrode is biased relative to the first and last electrodes to generate the focused ion beam 260.

[0035]

[0053] Figure 3A shows an EDMA assembly 20A according to several further embodiments of the present disclosure. In this embodiment, the first stage 30 and the second stage 40 may be configured as described above. A deflection assembly 50A is provided. The center C of the blocker 56A is located downstream of the upper deflection electrode 52A and the lower deflection electrode 54A. In this embodiment, the upper deflection electrode 52A and the lower deflection electrode 54A may be configured as rods (elongated in the X direction) having an elliptical cross-section as shown. The blocker 56A may also be configured as a rod (elongated in the X direction) having an elliptical cross-section as shown. In this case, the center C of the ellipse is located downstream of the upper deflection electrode 52A and the lower deflection electrode 54A. Figure 3A also shows the electric field 302 present when there is a potential difference of 0V between the first upper electrode 22 and the first lower electrode 24. Ion deflection in this scenario is sometimes called asymmetric deflection. This is due to the asymmetry of the blocker 56A with respect to the positions of the upper deflection electrode 52A and the lower deflection electrode 54A. In particular, an electrostatic field will exist even when an RF potential is present. This is because it is assumed that heavy ion species introduce potentials up to 1 kV along the axis of symmetry A, which was previously called the beam axis. Therefore, when an instantaneous RF voltage of 0 V is applied between the first upper electrode 22 and the first lower electrode 24, an electric field of 1 kV exists in the center between these electrodes, as shown in the figure. This potential is B compared to the case where there is no space charge. + This gives the ions an extra kick in the up and down direction.

[0036]

[0054] Next, referring back to Figure 3B, a scenario of operation of the EDMA assembly in conjunction with the electrostatic energy filter 60 is shown. In this case, the input B is 21kV, 18mA. +The beam is guided from the focused ion beam assembly into the EDMA assembly 20. A first 4 MHz RF voltage signal is applied between the first upper electrode 22 and the first lower electrode 24 with a maximum amplitude of 4 kV. Similarly, a first 4 MHz RF voltage signal is applied between the second upper electrode 42 and the second lower electrode 44 with a maximum amplitude of 4 kV. A potential of +525 V is applied to the upper deflection electrode 52A and the lower deflection electrode 54A while the blocker 56A is maintained at a potential of -525 V.

[0037]

[0055] In Figure 3B, the voltage applied to the deflection assembly 50A is used to generate B, which is generated by the space charge from heavy ions, as detailed in Figure 3A, particularly in the first stage 30. + This compensates for the extra "kick" to the ions. Note that when the configuration in Figure 1C is used, in which the blocker 56 is not positioned downstream of the upper deflection electrode 52 and the lower deflection electrode 54, this "symmetrical" deflection was observed to overcompensate for the "kick" from the spatial potential at the second stage 40. In contrast, in Figure 3B, asymmetric deflection is generated. This asymmetric deflection is primarily due to the focused ion beam 66 reaching the second stage 40 before the focused B + The trajectory and position of the beam (ion beam 310) are corrected. As a result, in addition to excellent mass filtering, the EDMA assembly 20A provides a relatively high transmittance of the ion beam 310 to the substrate 70 compared to a configuration with a symmetrical deflection assembly as shown in Figure 1C.

[0038]

[0056] Referring back to Figure 4, an exemplary simulated beam profile is shown, illustrating the beam current as a function of time for ion beams generated by EDMA assemblies arranged according to multiple embodiments. The beam current changes as a function of time as pulses reflecting the deflection of a continuous ion beam deflected to different trajectories and positions, as shown in Figure 3B. This current represents a current yield of over 50% relative to the input beam current into the EDMA assembly.

[0039]

[0057] While EDMA configurations can offer a compact and convenient way to perform mass spectrometry, one challenge encountered when using EDMA assemblies is the energy spread of the filtered ions for a given target mass. Figure 5A shows the energy spread for a boron ion beam in an EDMA assembly without an asymmetric deflection assembly. In this case, the maximum-to-minimum energy spread is 6.5 kV.

[0040]

[0058] Figure 5B shows the energy spread for a boron ion beam in an EDMA assembly with an asymmetric deflection assembly according to this embodiment. In this case, the maximum to minimum energy spread is 3.4 kV. The simulated conditions in Figures 5A and 5B are for a 21 kV input ion beam and 18 mA of B + , 18mA BF + , 18mA BF2+, and 8mA F + It is composed of the following. The graph shows the energy distribution of the boron beam component after passing through EDMA. Thus, multiple embodiments facilitate the ability to achieve substantially smaller energy spread for filtered ion beams.

[0041]

[0059] As described above, several embodiments have been considered, namely, the amplitude of a first RF voltage signal applied to the first stage 30 can change independently of the second RF voltage signal applied to the second stage 40. Thereafter, the amplitude and / or phase of the first RF voltage signal can change with respect to the amplitude and / or phase of the second RF voltage signal.

[0042]

[0060] Figures 6A to 6C show the results of operation of an EDMA assembly under one scenario according to one embodiment of the present disclosure. Figures 6D to 6F show the results of operation of the EDMA assembly 20A of Figure 6A under a second scenario. In this case, the operating conditions are the same as those of Figure 6A, except that the voltage at the RF electrode in the first stage 30 is set to a maximum amplitude different from the maximum amplitude of the voltage at the RF electrode in the second stage 40.

[0043]

[0061] In Figure 6A, input B is 21 keV and 18 mA. + The focused beam 602 is guided through the EDMA assembly 20A. In this case, a 4kV maximum amplitude RF voltage signal is supplied to the first stage 30, and similarly, a 4kV maximum amplitude RF voltage signal is applied to the second stage 40. Two different RF voltage signals are supplied with a zero-degree phase shift between them. In this embodiment, the length of both the first stage 30 and the second stage 40 along the Z axis is 12.5 cm. The focused ion beam is F as shown in the computer simulation in Figure 6A. + and BF + B containing component + This is an ion beam. Figure 6B shows the current density as a function of ion energy, illustrating the energy spread at 3.5 keV. Figure 6C shows the current as a function of time in the substrate. This current corresponds to 9 mA, and therefore the current yield is approximately 50%.

[0044]

[0062] In Figure 6D, input B is 21 keV and 18 mA. +The focused beam 602 is guided through an EDMA assembly controller. In this case, a 4kV maximum amplitude RF voltage signal is supplied to the first stage 30, while a 1kV maximum amplitude RF voltage signal is applied to the second stage 40. Two different RF voltage signals are supplied with a zero-degree phase shift between them. A 600V DC deflection is supplied in the deflection assembly. In this embodiment, the lengths of both the first stage 30 and the second stage 40 along the Z-axis are 12.5 cm. Figure 6E shows the current density as a function of ion energy, exhibiting an energy spread of 3.0 keV. Figure 6F shows the current as a function of time in the substrate. This current corresponds to 9 mA, and thus the current yield is approximately 50%. Therefore, by lowering the maximum voltage of the second stage 40, the energy spread for the filtered boron ion beam may be reduced, at least under specified conditions.

[0045]

[0063] Referring also to Figures 6A to 6C, Figures 7A to 7C show one embodiment in which the phase of the voltage signal applied to the RF electrode in the first stage 30 is set to a different phase from the phase of the voltage signal applied to the RF electrode in the second stage 40. The parameters for the simulation in Figure 7A are the same as those specified for Figure 6A, except that the phase of the RF voltage signal applied to the second stage 40 is offset by 60 degrees from the phase of the RF voltage signal applied to the first stage 30. The filtering in Figure 7A, i.e., mass selection, is substantially the same as the filtering in the arrangement of Figure 6A. However, as shown in Figure 7B, the energy spread is reduced from 3.5 keV to 2.5 keV, while the throughput (Figure 7C) is increased to 10 mA, i.e., the transmittance is approximately 56%.

[0046]

[0064] Referring also to Figures 6A-6C, Figures 8A-8C show one embodiment in which the length of the RF electrode in the first stage 30 differs from the length of the RF electrode in the second stage 40. The simulation parameters in Figure 8A are the same as those specified for Figure 6A, except that the length of the second stage 40 is exactly 7.6 cm, unlike the length of the first stage 30 which is 12.5 cm. The filtering in Figure 8A, i.e., mass selection, is substantially the same as the filtering in the arrangement of Figure 6A. In this embodiment, as shown in Figure 8B, the energy spread increased from 3.5 keV to 4 keV, while the throughput (Figure 8C) increased to 11 mA, i.e., the transmittance was approximately 62%, which represents an improvement of more than 20% compared to the configuration in which the lengths of the first stage 30 and the second stage 40 are 12.5 cm.

[0047]

[0065] From the above, those skilled in the art will recognize that the EDMA configuration of this embodiment can be adjusted by a combination of physical changes to the electrodes of different stages and changes to the RF signals applied to different stages in order to adjust the parameters of the output ion beam.

[0048]

[0066] Referring also to Figures 6A to 6C, Figures 9A to 9C use the same parameters for the simulation in Figure 9A as those specified for Figure 6A, except that the length of the first stage 40 is exactly 7.6 cm, the maximum amplitude of the voltage applied to the second stage 40 is 1 kV, and there is a 60-degree phase difference between the RF voltage signal at the first stage 30 and the RF voltage signal at the second stage 40. In this embodiment, as shown in Figure 9B, the energy spread is slightly reduced from 3.5 keV to 2.5 keV, while the current (Figure 9C) is similarly reduced to 9 mA.

[0049]

[0067] Figure 10 shows a process flow 1000 according to several embodiments of the present disclosure. In block 1002, an ion beam is introduced into an electrodynamic mass spectrometry (EDMA) assembly as a focused ion beam. In block 1004, while the ion beam is being transported through the EDMA assembly, a first RF voltage is applied to a first stage of the EDMA assembly.

[0050]

[0068] In block 1006, while the ion beam is being transported through the EDMA assembly, a DC voltage is applied between the set of deflection electrodes and blockers of the deflection assembly located downstream of the first stage.

[0051]

[0069] In block 1008, while the ion beam is being transported through the EDMA assembly, a second RF voltage is applied to a second stage of the EDMA assembly downstream of the deflection assembly.

[0052]

[0070] Figure 11 shows a process flow 1100 according to several other embodiments of the present disclosure. In block 1102, the ion beam is led as a focused ion beam to an electrodynamic mass spectrometry (EDMA) assembly.

[0053]

[0071] In block 1104, while the ion beam is being transported through the EDMA assembly, a first RF voltage having a first maximum amplitude is applied to a first stage of the EDMA assembly.

[0054]

[0072] In block 1106, while the ion beam is being transported through the EDMA assembly, a second RF voltage having a second maximum amplitude different from the first maximum amplitude is applied to a second stage of the EDMA assembly located downstream of the first stage.

[0055]

[0073] Figure 12 shows a process flow 1200 according to several other embodiments of the present disclosure. In block 1202, an ion beam is introduced into an electrodynamic mass spectrometry (EDMA) assembly as a focused ion beam. In block 1204, while the ion beam is being transported through the EDMA assembly, a first RF voltage having a first phase is applied to a first stage of the EDMA assembly.

[0056]

[0074] In block 1206, while the ion beam is being transported through the EDMA assembly, a second RF voltage having a second phase different from the first phase is applied to a second stage of the EDMA assembly located downstream of the first stage.

[0057]

[0075] In view of the foregoing, the various embodiments disclosed herein provide at least the following advantages: The first advantage is achieved by providing a more compact mass spectrometry component for mass spectrometry of an ion beam. The second advantage is cost savings in providing an EDMA-type system for mass spectrometry. The third advantage is the ability to maintain a high degree of mass spectrometry of the ion beam processed within the EDMA system at relatively high beam currents exceeding several mA.

[0058]

[0076] While several specific embodiments of the present disclosure have been described herein, the present disclosure is in the broadest scope permitted by the art, and this specification can be read in the same manner as such, and is therefore not limited to these embodiments. Accordingly, the foregoing should not be construed as limiting. Those skilled in the art will anticipate other modifications within the scope of the claims and essence appended herein.

Claims

1. An apparatus comprising an electrodynamic mass spectrometry (EDMA) assembly, wherein the EDMA assembly is A first stage comprising a first upper electrode positioned above the beam axis and a first lower electrode positioned below the beam axis opposite the first upper electrode, A second stage located downstream of the first stage, comprising a second upper electrode located above the beam axis and a second lower electrode located below the beam axis, and A deflection assembly disposed between the first stage and the second stage, comprising a blocker disposed along the beam axis, an upper deflection electrode disposed on the first side of the blocker, and a lower deflection electrode disposed on the second side of the blocker.

2. The apparatus according to claim 1, wherein the center of the blocker is positioned downstream of the upper deflection electrode and the lower deflection electrode.

3. The apparatus according to claim 1, wherein the second upper electrode is shorter than the first upper electrode in a direction parallel to the beam axis, and the second lower electrode is shorter than the first lower electrode in a direction parallel to the beam axis.

4. The apparatus according to claim 1, further comprising a power supply for a first stage arranged to apply a first RF voltage signal between the first upper electrode and the first lower electrode, and a power supply for a second stage arranged to apply a second RF voltage signal between the second upper electrode and the second lower electrode.

5. The apparatus according to claim 1, further comprising a deflection power supply arranged to apply a static bias voltage between the blocker, the upper deflection electrode, and the lower deflection electrode.

6. The apparatus according to claim 4, further comprising a controller arranged to independently change the first magnitude of the first RF voltage signal with respect to the second magnitude of the second RF voltage signal, the controller arranged to change the first phase of the first RF voltage signal with respect to the second phase of the second RF voltage signal.

7. An ion beam processing system, Ion source chamber for generating an ion beam as a continuous ion beam, A focusing beam assembly for outputting the ion beam as a focused ion beam along the beam axis, and The system includes an electrodynamic mass spectrometry (EDMA) assembly, and the EDMA assembly is: A first stage for receiving the focused ion beam and applying a first RF signal between a first upper electrode and a first lower electrode, A second stage located downstream of the first stage, the second stage for applying a second RF signal between a second upper electrode and a second lower electrode, and An ion beam processing system comprising a deflection assembly disposed between the first stage and the second stage, the deflection assembly comprising a blocker disposed along the beam axis, an upper deflection electrode disposed on the first side of the blocker, and a lower deflection electrode disposed on the second side of the blocker.

8. The ion beam processing system according to claim 7, wherein the center of the blocker is located downstream of the upper deflection electrode and the lower deflection electrode.

9. The ion beam processing system according to claim 7, wherein the second upper electrode is shorter than the first upper electrode in a direction parallel to the beam axis, and the second lower electrode is shorter than the first lower electrode in a direction parallel to the beam axis.

10. The ion beam processing system according to claim 7, further comprising a power supply for a first stage arranged to apply the first RF signal between the first upper electrode and the first lower electrode, and a power supply for a second stage arranged to apply the second RF signal between the second upper electrode and the second lower electrode.

11. The ion beam processing system according to claim 7, further comprising a deflection power supply positioned between the blocker and the deflection assembly to apply a static bias voltage.

12. The ion beam processing system according to claim 10, further comprising a controller arranged to independently change the first magnitude of the first RF signal with respect to the second magnitude of the second RF signal, and further comprising a controller arranged to change the first phase of the first RF signal with respect to the second phase of the second RF signal.

13. The ion beam processing system according to claim 7, wherein the focusing beam assembly comprises an Einzel lens.

14. The ion beam processing system according to claim 7, wherein the focusing beam assembly comprises a tetrode assembly, and the third lens of the tetrode assembly is positively biased.

15. The ion beam processing system according to claim 7, further comprising an electrostatic energy filter positioned downstream of the EDMA assembly and comprising a plurality of electrodes for changing the propagation direction of the ion beam.

16. To guide the ion beam as a continuous ion beam along the beam axis into the first stage of the electrodynamic mass spectrometry (EDMA) assembly, Using a first AC voltage signal applied at a first frequency, the ion beam is deflected in the first stage of the EDMA assembly along a trajectory not parallel to the beam axis. In a blocker located downstream of the first stage of the EDMA assembly, blocking the path of a first portion of the ion beam along the beam axis, such that a second portion of the ion beam passes through the blocker as a bundled ion beam, and A method comprising deflecting the bundled ion beam at a second stage of the EDMA assembly downstream of the blocker using a second AC voltage signal applied at the first frequency, such that a third portion of the beam exits the EDMA assembly.

17. The method according to claim 16, further comprising applying a deflection voltage between the blocker and a pair of deflection electrodes arranged on both sides of the beam axis.

18. The method according to claim 16, wherein the first AC voltage signal has a first voltage amplitude, and the second AC voltage signal has a second voltage amplitude smaller than the first voltage amplitude.

19. The method according to claim 16, wherein the first AC voltage signal has a first phase, and the second AC voltage signal has a second phase smaller than the first phase.

20. The method according to claim 16, wherein the ion beam is provided to the first stage as a focused ion beam.

21. The method according to claim 16, wherein the first AC voltage signal is applied between the first upper electrode and the first lower electrode, the phase of the first AC voltage signal at the first upper electrode is shifted by 180 degrees from the phase of the first AC voltage signal at the first lower electrode, and the second AC voltage signal is applied between the second upper electrode and the second lower electrode, the phase of the second AC voltage signal at the second upper electrode is shifted by 180 degrees from the phase of the second AC voltage signal at the second lower electrode.

22. The method according to claim 16, wherein a target ion species having a first mass exits the EDMA assembly, an impurity ion species having a second mass different from the first mass does not exit the EDMA assembly along the beam axis, and the ion beam exits the EDMA assembly as a mass spectrometry ion beam.

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