Spectroscopic safety system for detecting nuclear reactions in ion implantation systems

Abstract

The ion implantation system includes a spectroscopic-based safety system for detecting nuclear reactions. Spectral analysis and a safety system are disclosed herein. A related methodology for use with said system includes processing data received from a photon energy resolving spectrometer to identify detected photon energies, notify an operator, and / or stop said system.

Description

Technology Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 620,193, filed January 12, 2024, titled “Spectroscopic-based safety system for detecting nuclear reactions in ion implantation systems,” the entire contents of which are incorporated herein by reference.

[0002] The present disclosure generally relates to ion implantation systems, and more specifically to monitoring nuclear reactions in ion implantation systems. Background Technology

[0003] Ion implantation systems are used to create n-type or p-type doped materials or to form passivation layers by doping a workpiece, such as a semiconductor wafer, with ions from an ion beam during integrated circuit manufacturing. This beam processing is commonly used to selectively implant specific dopant materials into the wafer at predetermined energy levels and controlled concentrations to create semiconductor materials during integrated circuit manufacturing. When used to dope a semiconductor wafer, the ion implantation system implants selected ion species into the workpiece to create the desired extrinsic material. When implanting ions into a silicon wafer, ions generated from source materials, such as antimony, arsenic, or phosphorus, create an "n-type" extrinsic material wafer, whereas "p-type" extrinsic material wafers are commonly created from ions generated from source materials, such as boron, gallium, or indium. For example, when implanting ions into silicon carbide (SiC) wafers, nitrogen (n-type dopant) and aluminum (p-type dopant) are typically used as ion species. Additionally, light ions such as hydrogen or helium are used as implantation species in Insulated-Gate Bipolar Transistors (IGBTs) to reduce minority carrier lifetime, improve switching speed, and decrease switching losses.

[0004] In an ion implanter, an ion source generates ions of a desired atomic or molecular dopant species. These ions are extracted from the ion source by an ion extraction device, which is typically a set of electrodes that apply energy to the flow of ions from the ion source and direct that flow to form an ion beam. The desired ions are separated from the ion beam by a mass spectrometer, which is typically a magnetic dipole that performs mass dispersion or separation of the extracted ion beam. The beam transport device is typically a vacuum system comprising a series of focusing devices and acceleration / deceleration devices, which transports the analyzed ion beam to the wafer processing device while maintaining the desired characteristics of the ion beam. Finally, the semiconductor wafer or other implantation target is brought into and taken out of the wafer processing device via a wafer handling system, which may include one or more robotic arms used to place the wafer to be processed in front of the analyzed ion beam and to remove the processed wafer from the ion implanter.

[0005] In many ion implantation systems, the physical size of the ion beam is smaller than that of the target workpiece, and accordingly, the ion beam is scanned in one or more directions to sufficiently cover the surface of the target workpiece. Typically, an electrostatic or magnetic beam scanner scans the ion beam in a high-speed scanning direction, and a mechanical device moves the target workpiece in a low-speed scanning direction to provide sufficient coverage of the ion beam over the entire surface of the workpiece.

[0006] An ion implantation system can cause unwanted beam collisions to internal components of the system. This can lead to the emission of particles that generate ionizing radiation and damage to specific chamber linings or the chamber walls themselves. An ion implantation system is a highly tuned instrument requiring high precision, and if not carefully tuned, unwanted beam collisions may occur at some point. Additionally, if inappropriate materials, such as heavy metals, are incorrectly inserted into the system—for example, by inserting them into the end chamber or using them as a Faraday cup or liner—unwanted reactions from the beam may occur. For example, if titanium material collides with hydrogen ions with energies exceeding 800 keV, a nuclear fusion reaction accompanied by gamma-ray photon emission will occur.

[0007] The present disclosure provides a system and method for detecting and monitoring photon energy and ionizing radiation in an ion implantation system. In particular, such a monitoring system can be used to rapidly stop the system when a threshold is exceeded during the operation of the ion implantation system. This improves the prevention of radiation exposure to operators and the prevention of damage to equipment.

[0008] Accordingly, a simplified summary of the present disclosure is presented below to provide a basic understanding of some aspects of the present disclosure. This summary is not a comprehensive overview of the present disclosure. This summary is not intended to specify the essential or important elements of the invention or to limit the scope of the invention. The purpose of this summary is to present some concepts of the present disclosure in a simplified form as an introduction to the more detailed description to be presented later.

[0009] In some embodiments, the technology described herein relates to an ion implantation system comprising: an ion source that generates ions along a beamline and produces an ion beam—the ions being selected from elements with atomic numbers 1 to 11; a mass spectrometer located downstream of the ion source and generating a magnetic field; an ion accelerator located downstream of the mass spectrometer; and a first photon energy resolving spectrometer associated with the components of the ion implantation system.

[0010] In some embodiments, the technology described herein relates to a method for performing an ion implantation operation comprising the steps of: exciting ions of atomic number 1 to 11 and accelerating said ions to an energy of 10 keV to 30 MeV; detecting a photon in a first photon energy decomposition spectrometer and transmitting a first signal to a processor; receiving said first signal from said photon energy decomposition spectrometer in said processor; and processing said first signal to determine the type of photon energy when a threshold is exceeded.

[0011] In some embodiments, the technology described herein relates to an ion implantation system comprising: an ion source that generates ions along a beam line and produces an ion beam—the ions are selected from elements with atomic number 11 or less; a mass spectrometer located downstream of the ion source and generating a magnetic field; an ion accelerator located downstream of the mass spectrometer; a first photon energy decomposition spectrometer associated with a first component of the ion implantation system; a second photon energy decomposition spectrometer associated with a second component of the ion implantation system; a third photon energy decomposition spectrometer associated with a third component of the ion implantation system; and a processor configured to receive input signals from the first, second, and third photon energy decomposition spectrometers; to process the input signals to identify the detected photon energy as known or unknown photon energy; and to transmit an alarm to a display and / or stop the ion implantation system when a threshold of unknown or specific known photon energy is identified. The processor is configured to process input signals from the first, second, and third photon energy decomposition spectrometers to identify the source location of the detected photon energy.

[0012] The above summary is merely intended to provide a brief overview of some features of some embodiments of the present disclosure, and other embodiments may include features that differ from or are in addition to those mentioned above. In particular, this summary should not be construed as limiting the scope of the present application. Accordingly, to achieve the foregoing and related purposes, the present disclosure includes features described below and specifically indicated in the claims. The following description and accompanying drawings provide detailed specific exemplary embodiments of the present disclosure. However, these embodiments represent some of the various ways in which the principles of the present disclosure may be applied. Other purposes, advantages, and novel features of the present disclosure will become apparent from the following detailed description of the present disclosure, which is taken into account in conjunction with the drawings. Furthermore, the features of the various embodiments and examples described herein may be combined with one another unless otherwise specifically stated. Brief explanation of the drawing

[0013] FIG. 1 is a simplified plan view illustrating an ion implantation system according to one embodiment of the present disclosure. FIG. 2 is a cross-sectional view of an example of a part of an ion implantation system according to one embodiment of the present disclosure. FIG. 3 is a cross-sectional view of an example of a special liner (400). FIG. 4 is a flowchart of an exemplary method for operating an exemplary ion implantation system, comprising detecting high-energy photons in the ion implantation system and processing the signal received therefrom. Figure 5 is an exemplary flowchart of ion implantation and spectrometer operation at the system level. Figure 6 is an example of photon energy decay spectra using calibration isotopes Cs-137 and Co-60. Each long scale on the horizontal axis represents an interval of 1000 keV to the next long scale, and each long scale on the vertical axis represents an interval of 20 counts / keV to the next long scale. Specific details for implementing the invention

[0014] In one example, a semiconductor manufacturing system includes energy-sensitive photon energy-resolved spectrometers, such as gamma-ray detectors, associated with different locations within the system. The detectors can be used to generate a spectroscopic fingerprint that can be matched with a known sample of nuclear ion radiation. Additionally, the system includes a controller that shuts down the system when a critical level of harmful nuclear radiation is detected.

[0015] As the ion implantation system operates at higher energies using lighter species, the risk of the operator unintentionally causing a nuclear reaction in the liner or other materials within the beam line increases. This may be caused by errors in adjusting the system components by the operator and / or the use of inappropriate materials at specific locations.

[0016] For example, the operation of an ion implantation system using a high-energy beam may cause the protective liner within the beam line to be eroded or removed by sputtering. To prevent semiconductor wafers from being exposed to unwanted contaminants sputtered from the beam line walls (particularly metals), a liner extending along a portion of the beam line within the chamber of the ion implantation system is commonly used. In the case of high-energy beams, the liner may also be used to prevent nuclear reactions between light high-energy ion species (e.g., hydrogen) and other elements such as graphite or aluminum. Erosion of the liner, which exposes unwanted elements, can cause unwanted nuclear reactions resulting from collisions with the beam line material.

[0017] In the disclosure of the present invention, the ion implantation system equipped with a spectrometer uses a photon-energy resolving crystal detector equipped with electronic devices necessary for signal processing and detection. The technology disclosed herein combines state-of-the-art energy spectroscopy technology with a high-energy, low-atomic-weight ion implantation system.

[0018] In one example, the detection system is mounted near multiple erosion sites and, through continuous monitoring, the detection of unwanted nuclear reactions can be rapidly deconstructed and identified, thereby identifying the possibility that the liner / beam line material is damaged by ion beam collisions. A unique liner may be inserted beneath the beam line collision surface to generate a unique photon "fingerprint" signature for easy detection. Additionally, if an incorrect workpiece, such as a metal wafer instead of a silicon wafer, is injected, or if a silicon wafer containing devices with low atomic weight (low Z) elements is injected, this can also be rapidly detected by the spectrometer detector system.

[0019] For example, semiconductor manufacturing systems, such as ion implantation systems, include a chamber that is under vacuum during use and is subjected to impact by particle streams or other actions. The advantage of using a high-energy photon energy-resolved spectrometer is that, since these high-energy photons—such as gamma rays and X-rays—are energized enough to pass through the walls of the system, the difficulty in monitoring the formation of internal radiation sources can be avoided.

[0020] The present disclosure generally relates to various apparatuses, systems, and methods associated with ion implantation or other semiconductor manufacturing processes for a workpiece. More specifically, the present disclosure relates to a semiconductor manufacturing system having a high-energy photon energy-resolved spectrometer and a method for detecting high-energy photons, generating an alarm when a critical condition is reached, and stopping said system.

[0021] Accordingly, the present technology is described with reference to the drawings, and similar reference numerals may be used throughout to refer to similar elements. It should be understood that the description of such embodiments is merely illustrative and should not be interpreted in a limiting sense. In the following description, numerous specific details are presented for the purpose of explanation to provide a sufficient understanding of the technology described in this specification. Furthermore, the scope of the present invention is not intended to be limited by the embodiments or examples described below with reference to the accompanying drawings, but only by the appended claims and their equivalents.

[0022] In addition, it should be noted that the drawings are provided to illustrate some aspects of the embodiments of the present disclosure and should therefore be regarded as exemplary only. In particular, the elements depicted in the drawings are not necessarily drawn to scale with respect to one another, and the arrangement of various elements within the drawings is chosen to provide a clear understanding of each embodiment and should not be interpreted as necessarily representing the actual relative positions of the various components for all embodiments included in the present disclosure.

[0023] Additionally, it should be understood that any direct connection or combination between functional blocks, devices, components, or other physical or functional units illustrated in the drawings or described in this specification may also be implemented by indirect connection or combination. Furthermore, it should be recognized that functional blocks or units illustrated in the drawings may be implemented as distinct features or components in one embodiment, and wholly or partially as common features or components in another embodiment.

[0024] The terms “workpiece” and “workpiece support” are used herein with the recognition that a workpiece, such as a silicon wafer, will be used during operation, while the workpiece support is used to hold and position said workpiece. Additionally, an ion implantation system may be manufactured with a workpiece support configured to hold the workpiece, but is not typically manufactured or sold together with the workpiece. Therefore, any discussion of the workpiece and how the beam or component of the ion implantation system disclosed herein relates to the workpiece should be understood as also being disclosed in relation to said workpiece support. The term “workpiece target” is used herein to mean either said workpiece when placed on said workpiece support or a position configured to hold said workpiece support.

[0025] In ion implantation, dopant atoms / molecules are ionized and separated, sometimes accelerated or decelerated, formed into a beam, and scanned across a workpiece or wafer. The dopant ions physically impact the workpiece to enter the surface and typically settle within the crystal lattice structure beneath the workpiece surface. In light ion, high-energy ion implantation, the ions are selected from elements with atomic number 11 or lower, for example, 7 to 2 or 3 to 1. For example, ions such as H, He, Li, Be, and B may be generated from the ion source. In examples of heavier mass beam species, C, N, O, F, Ne, P, and As may also be generated from the ion source. These ions are accelerated to high energy states of 300 keV or higher, for example, 400 keV to 15 MeV, 500 keV to 10 MeV, or 1 MeV to 5 MeV.

[0026] Accelerator systems conducting higher-energy beams, such as the acceleration of ion beams exceeding 400 keV, may utilize LINAC structures employing resonator, cavity, and / or RF gap systems, or may utilize tandem acceleration schemes or radio frequency quadrupole (RFQ) acceleration. The use and implementation of such devices typically employ an energy separation slit or ERS coupled with a magnet to separate the final energy emanating from the device's acceleration structure. A combination of a LINAC block with an ERS for energy separation and a magnet is commonly used in high-energy systems.

[0027] Now, referring to the drawings, according to one exemplary embodiment of the present disclosure, FIG. 1 illustrates an exemplary hybrid parallel scan single-wafer ion implantation system (100). The ion implantation system (100) is also referred to as a post-acceleration implanter because the main accelerator (113) is positioned after the mass analyzer (104) and before the energy filter (130). This type of ion implantation system (100) often has the energy filter (130) after the main accelerator (113) (i.e., at a location further from the ion source (102) along the beam line) to remove unwanted energy spectrum from the output of the main accelerator (113) (as illustrated).

[0028] In this exemplary ion implantation system (100), an ion beam (101) generated from the ion source (102) is accelerated by an optional pre-mass spectrometer accelerator (105) located prior to the mass spectrometer (104) to produce an accelerated and analyzed ion beam (108). Downstream, the accelerated and analyzed ion beam (108) may be further accelerated by a plurality of accelerator stages within the main accelerator (113). For example, each accelerator stage may include a resonator (such as in an RF accelerator) to generate an RF acceleration field within it and may output a further accelerated accelerated ion beam (110). After passing through the energy filter (130), the filtered ion beam (111) passes through a beam scanner (119) and an angle corrector lens (120) to convert the filtered ion beam (111) into a parallel-shifted ion beam (115).

[0029] In order to uniformly irradiate the entire surface of the workpiece (134), in the hybrid scanning method, the workpiece (134) is moved in a direction orthogonal to the parallel-shifted ion beam (115) (shown as moving in and out of the drawing). Other types of scanning methods may also be used in the monitoring and related technologies described herein. As described above, various aspects of the present disclosure may be implemented in relation to any type of ion implantation system, including but not limited to the exemplary ion implantation system (100) of FIG. 1.

[0030] Now, the components of FIG. 1 will be described in more detail. The source chamber assembly (112) comprises the ion source (102) and an ion extraction electrode assembly (121) for extracting and accelerating ions to intermediate energy. To generate the ions, a gas of the dopant material to be ionized is located within the ion generation chamber (not shown) of the ion source (102). Other sources of dopants and forms of dopants may be used, for example, the dopant may be introduced by sputtering (e.g., aluminum nitride) or as a vapor (e.g., aluminum chloride). The dopant gas may be supplied to the source chamber assembly (112), for example, from a gas source (not shown). It will be understood that one or more suitable mechanisms (not shown) for exciting free electrons may be used, such as, for example, RF or microwave excitation sources, electron beam injection sources, electromagnetic sources, and / or a cathode that generates an arc discharge within a chamber. The excited electrons collide with the dopant gas molecules, thereby generating ions. Typically, positive ions are generated, but the details disclosed herein are also applicable to systems in which negative ions are generated.

[0031] The ions are controlledly extracted through a slit within the ion extraction electrode assembly (121). The ion extraction electrode assembly (121) includes a plurality of extraction electrodes and / or suppression electrodes. The ion extraction electrode assembly (121) may include a separate extraction power supply (not shown) for accelerating ions from the source chamber assembly (112), for example, by applying a bias to the extraction electrodes and / or suppression electrodes. It may be understood that since the ion beam (101) contains particles with the same charge, the beam may have a tendency to expand radially outward as the particles with the same charge repel each other. It may also be understood that beam expansion may be exacerbated in a low-energy, high-current (high perveance) beam, where a plurality of particles with the same charge (e.g., high current) move relatively slowly (e.g., low energy) in the same direction, so that the repulsion between the particles is abundant but there is little particle momentum to move the particles in the beam path direction. Accordingly, the ion extraction electrode assembly (121) is generally configured so that the beam is extracted at high energy so that the beam does not expand excessively (e.g., so that the particle has enough momentum to overcome the repulsive force that could cause beam expansion), and such excessive expansion of the beam can result in beam current loss.

[0032] The above preliminary analyzer accelerator (105) further accelerates the ions and is an optional component that may not be necessary in some operations.

[0033] The mass spectrometer (104) generates a magnetic field according to a selected charge-to-mass ratio and performs angle adjustment for the ion beam (101). In this example, the mass spectrometer (104) is configured to deflect the ion beam (101) at an angle of approximately 90 degrees and includes one or more magnets (not shown) that serve to form a (dipole) magnetic field within it. As the ion beam (101) enters the mass spectrometer (104), it is deflected by the magnetic field in response so that ions with an inappropriate charge-to-mass ratio are excluded. More specifically, ions with a charge-to-mass ratio that is too large or too small are deflected toward the sidewalls of the mass spectrometer (104). In this way, the mass spectrometer (104) allows ions within the ion beam (101) with a desired charge-to-mass ratio to pass through, and in one example, are discharged through a mass separation opening to further adjust the ion beam (101). It will be understood that collisions between the ion beam (101) and other particles within the ion implantation system (100) can degrade beam integrity. Therefore, one or more pumps (not shown) may be included to exhaust parts of the system, such as the mass spectrometer (104), for example.

[0034] The main accelerator (113) accelerates the ions to higher energy and may be, for example, an RF linear particle accelerator (LINAC) in which the ions are repeatedly accelerated by an RF electric field, or a DC accelerator (for example, a tandem electrostatic accelerator) that accelerates the ions with a static DC high voltage. The main accelerator (113) is further described in relation to FIG. 2 below.

[0035] After the accelerated ion beam (110) is discharged from the main accelerator (113), it is further adjusted by an energy resolving slit (ERS) (137). The ERS (137) is a structure and method for collimating the energy distribution of transported accelerated particles discharged from a LINAC block assembly. The energy resolution of a given beam can be adjusted by the width of the slit and selected amplitude and phase in the presence of the beam. It is often combined with a dipole bending magnet, in which case the trajectory of higher energy ions within a given accelerated beam has less curvature than that of lower energy ions. By using this, an allowable range can be introduced to make the energy distribution a fixed value. For example, the width of the "standard" ERS may be an energy distribution / resolution of ±5% of the desired acceleration beam energy, and the operator may change the resolution to 10% or 0.05% depending on the relative slit width of the allowable beam coming from the dipole magnet from the LINAC.

[0036] The beam scanner (119) typically scans the accelerated ion beam (110) from left to right using an electrostatic or electromagnetic method and sends it to the angle correction lens (120), and the angle correction lens (120) converts the filtered ion beam (111) into the parallel-shifted ion beam (115).

[0037] The angle correction lens (120) changes the path of the filtered ion beam (111) so that the ion beam travels parallel to the beam axis regardless of the scan angle. As a result, the injection angle becomes relatively uniform across the entire workpiece (134) and is normalized to eliminate vertical deviation of the beam, causing it to move nearly horizontally toward the final destination. The angle correction lens (120) may be an electromagnetic magnet as illustrated, but may also be an electrostatic type, for example. The final parallel-shifted ion beam (115) generated from the angle correction lens (120) is directed toward the workpiece (134).

[0038] The workpiece (134) is supported by a workpiece support (175) that, if absent (as further described above), occupies the same space as the workpiece target and can be accommodated in a process chamber or an end station (not shown). It is acknowledged that various types of end stations and workpiece supports (175) may be used in the ion implantation system (100). For example, a “batch” type end station may support multiple workpieces (134) simultaneously on a rotating workpiece support structure, in which case the workpieces are rotated through the path of an ion beam (115, also referred to as a beam line) until all workpieces are fully implanted. Such a “batch” type implanter does not require a scanner and a calibration lens. On the other hand, a “serial” type end station supports a single workpiece (134) along the path of the ion beam (115) for injection, in which case multiple workpieces are injected one by one in a serial manner, and each workpiece is fully injected before the injection of the next workpiece begins. In a hybrid system, in order to apply the parallel-shifted ion beam (115) to the entire workpiece (134), the workpiece (134) may be mechanically moved in a first direction (y direction, so-called “low-speed scan” direction) while the ion beam (115) is scanned in a second direction (x direction, so-called “high-speed scan” direction).

[0039] FIG. 2 illustrates an example of a part of an ion implantation system according to one aspect of the present disclosure. An accelerator (200), which may be the main accelerator (113) of FIG. 1, may include an RF accelerator illustrated in FIG. 2 as an example of one embodiment and may include a plurality of accelerator stages (e.g., 202, 204, 208, 210, and 212). Each of the accelerator stages (202, 204, 208, 210, and 212) may include at least one accelerator electrode (214) driven by an RF resonator to generate an RF accelerating field, for example, on both sides (not shown). An ion beam (201) of charged particles having a charge state (e.g., net electric charge or valence) may sequentially pass through the openings of the accelerator electrodes (214).

[0040] Beam focusing may be provided by a lens (234) (e.g., an electrostatic or magnetic quadrupole) included within the accelerator (200). In one embodiment, the accelerator (200) may accelerate charged ions to a kinetic energy level of 10 keV or more or 300 keV or more when the accelerated beam is ejected from the accelerator (200). In one example, the lens (234) is included in each accelerator stage (202, 204, 208, 210, and 212).

[0041] The present disclosure is not limited to a specific accelerator or LINAC type. The number of stages is not limited to the illustration in FIG. 2 and may be, for example, 1 to 50, for example, 2 to 10, or 3 to 6 accelerator stages. Additionally, the accelerator may be a tandem accelerator or an RFQ.

[0042] A control system (168) (also referred to as a controller) is further provided to control, communicate with, and / or adjust the ion source (102), the preliminary analyzer accelerator (105), the mass spectrometer (104), the main accelerator (113), the ERS (137), the beam scanner (119), and the angle correction lens (120). Although connections are not shown in FIG. 1, the controller is typically connected to the various components it controls via communication cables.

[0043] The control system (168) may also be coupled with one or more power supplies for the components. The control system (168) may also be coupled with one or more photon energy decomposition spectrometers (e.g., photon energy decomposition spectrometers (191, 192, 193)) associated with the ion implantation system (100).

[0044] The control system (168) may include a computer having a processor and a data storage unit and may be operable to acquire measurements of the characteristics of the ion beam and adjust parameters accordingly. Additionally, it may be configured, for example by software or hardware, to receive and process signals from the photon energy decomposition spectrometers (191, 192, 193) and generate reports and alarms to an operator via a display. Additionally, the control system (168) may be configured to process signals from the photon energy decomposition spectrometers (191, 192, 193) to determine whether there is a threshold level of unknown radiation or known but unwanted radiation, as further disclosed below. The control system (168) may also control a power supply or other components to stop the beam line operation when a threshold level of radiation is reached.

[0045] The ion implantation system (100) comprises a plurality of high-energy photon energy-resolved spectrometers (191, 192, 193). For example, two to six or three to five detectors may be used in the ion implantation system (100). In one embodiment, a single detector may be used.

[0046] The determination of known or unknown radiation can be made by comparing one or more signal spectra with a database of known safe and unsafe X-ray or gamma-ray signatures, for example, the National Nuclear Material and Signature Database. Additionally, signals from the photon energy-resolved spectrometers (191, 192, 193) can be processed to determine the location where high-energy emission occurs within the ion implantation system (100). The photon energies detected by the photon energy-resolved spectrometers may include photons in the X-ray range, such as energies of 100 eV to 100 keV. Additionally, for most applications, photons in the gamma-ray energy range of 1 keV to 20 MeV, e.g. 10 keV to 15 MeV, or 50 keV to 5 MeV are sufficient.

[0047] When using multiple photon energy resolving spectrometers, the photon energy resolving spectrometers may be spaced apart from each other and positioned in close proximity to the area of ​​the ion implantation system most likely to generate high-energy radiation, such as X-rays or gamma rays. In one example, the photon energy resolving spectrometers are spaced apart from each other by at least 1 foot, for example, 1.5 to 30 feet, 2 to 15 feet, or 2.5 to 5 feet. In one embodiment, each photon energy resolving spectrometer of the system is spaced apart from any other photon energy resolving spectrometer in the system by at least 1 foot, for example, 1.5 to 30 feet, 2 to 15 feet, or 2.5 to 5 feet.

[0048] Since the high-energy radiation of interest is not blocked by the walls or chamber lining of the ion implantation system, the photon energy resolution spectrometer can still be associated with the photon energy of interest even if it is located outside the walls of the system. However, the photon energy resolution spectrometer must be positioned near the components of the system or the outer wall of the chamber, such as from a position in direct contact with the outer wall of the chamber of the system to 3 feet from the outer wall of the chamber of the system, 0.1 feet to 2.5 feet, or 0.5 feet to 1 foot from the outer wall of the chamber of the system.

[0049] At various locations within the ion implantation system (100), different materials may be removed by sputtering upon impact from particle beam collisions. The three locations illustrated in FIG. 1 represent photon energy resolving spectrometers near the LINAC main accelerator (113), the ERS (137), and the beam scanner (119). In one example, the first, second, and third photon energy resolving spectrometers (191, 192, 193) are located outside and adjacent (either side, top, or bottom) the beam scanner (119), the LINAC main accelerator (113), and the ERS (137), respectively. In one example, each photon energy resolving spectrometer is spaced closer to the LINAC main accelerator (113), the ERS (137), or the beam scanner (119) than any other component of the system. In another example, the photon energy resolving spectrometer is located near an end terminal where a workpiece (134) and a workpiece support (175) may be present. In yet another example, the photon energy resolving spectrometer is located near a Faraday cup, a dose cup, a bending magnet, or other structure that may be struck by the beam or cause deflection of the beam.

[0050] The plurality of photon energy decomposition spectrometers (191, 192, 193) are coupled to a control system (168) configured to process input signals from the photon energy decomposition spectrometers through a processor and a data storage unit. By knowing the intensity of the signal and the location of the photon energy decomposition spectrometer, the controller is configured to determine the location where the system is experiencing a radiation event (detected photon energy). Additionally, the controller can interpret the signal from the photon energy decomposition spectrometer to determine the type of radiation, such as X-rays or gamma rays, or specific spectral data that matches known spectral data. The controller can store this information in the data storage unit and provide this information to an operator through a graphical user interface on a display. Additionally, the controller can stop the system when a critical level of radiation is detected, as further described below.

[0051] The photon energy resolving spectrometer and stop control disclosed in this specification are described as being used primarily in ion implantation systems, but may also be used in other devices such as high-energy particle accelerators.

[0052] In one example, the photon energy-resolved spectrometer is a solid-state scintillator-type spectrometer. A scintillator is a material that emits a scintillation or optical pulse when interacting with ionizing radiation. Scintillation crystals are used in radiation detectors for gamma rays, X-rays, cosmic rays, and particles characterized by energy levels exceeding about 1 keV.

[0053] A spectrometer comprises the scintillating crystal (or other scintillator) along with an element (e.g., a photodetector) for detecting light generated by the crystal that interacts or "scints" when exposed to a radiation source. The photodetector generates an electrical signal proportional to the intensity of the scintillation (or a light pulse received from the scintillator material). The electrical signal is then processed in various ways to provide data regarding the radiation.

[0054] In one example, the photon energy resolving spectrometer used in this specification may be a scintillation crystal element such as a NaI crystal doped with thallium, germanium, cesium bromide, or lanthanum bromide.

[0055] In one example, a special liner may be placed in a chamber where beam collisions are most likely to occur, such as, for example, the LINAC accelerator (113), ERS (137), and beam scanner (119). While it is common to place a protective liner inside the beam line to prevent unwanted nuclear reactions, a special additional inner liner under the beam collision protection plate may be used to replace or in addition to it. Together with the photon energy resolution spectrometer, the special liner provides additional analysis and alarm functions before unwanted nuclear reactions occur.

[0056] FIG. 3 is a cross-sectional view of an example of a special liner (400). The special liner (400) can be used to coat the surface (415) of a component located along the ion beam (420). For example, if the surface (415) is the poles of a dipole bending magnet, which are typically made of soft magnetic steel, it typically has a nickel coating (410) on the surface. (Other surfaces (415) do not have a nickel coating on top.) In FIG. 3, a film (405) is positioned over the nickel coating (410). (In another example surface (415), the nickel layer is absent and the film (405) directly covers the surface (415).) The film (405) may contain low molecular weight species such as graphite, B, or an element having atomic number Z, where 3 < Z < 72, e.g., 4 < Z < 30 or 5 < Z < 15. The top shielding layer (401) covering the film (405) may be a layer containing a high Z (high atomic number) element, e.g., 72 ≤ Z ≤ 83. The special liner is distinguished from a conventional graphite liner that does not provide detection and protection functions.

[0057] In an exemplary operation, a misfire of the ion beam (420) does not strike the nickel coating (410) or surface (415) but strikes only the upper shielding layer (401). When the upper shielding layer (401) is penetrated by the beam, the film (405) containing graphite, Be and / or B, or other beam species may be struck. This will generate a unique photon energy emission spectrum. The photon energy spectrometer and the controller will be configured to identify within a short time that the film (405) has been struck. Subsequently, an alert that a portion of the upper shielding layer (401) has been sputtered and removed may be provided through the processor and display.

[0058] In one embodiment, the upper shielding layer (401) and the film (405) will not generate dangerous radiation even if struck by the beam unless a critical level is reached. For example, the film (405) may generate photon energy such as X-rays or less dangerous gamma rays that can be detected by the photon energy resolving spectrometer. Such radiation may not be harmful in the short term and may provide the operator with sufficient time to resolve the issue and stop the system before damage occurs. In one embodiment, the beam line will automatically stop if a radiation signature is detected indicating that the layer of the liner has been struck by the beam.

[0059] Since the precise decay characteristics of the nuclear reaction resulting from the beam collision are determined by the quantum mechanical properties of the beam and the liner, the special liner material of the film (405) must be selected based on the ion source and / or particle beam energy. Changing the beam type or liner combination changes the characteristics and energy of the photon decay signature. The kinetic energy of the particle beam also determines the photon decay probability. Therefore, if the ion source / beam type or the particle velocity is changed, this information must be entered into the system to inform the controller to search for a different photon decay signature.

[0060] In one example, the controller will receive input regarding the composition of the ion source or beam material, the energy of the beam, and the type or types of the liner. The controller processes, analyzes, and identifies this information together with data from the photon energy-resolved spectrometer, as well as known and unknown radiation signatures in the data storage. For example, different locations within the beam line can be identified using different liner materials, which can be easily identified due to characteristic photon spectra associated with various nuclear reactions.

[0061] This system can also be used to determine whether an incorrect type of wafer is being injected. The prompt radiation and decay radiation of the activated isotope within the wafer can be identified using the same spectroscopic technique.

[0062] Now, referring to FIG. 4, an exemplary methodology related to the photon energy-resolved spectrometer used in the ion implantation system will be further described. FIG. 4 is a flowchart of an exemplary method for detecting high-energy photons in an ion implantation system, processing the signal received therefrom, and operating the ion implantation system.

[0063] In operation (610), an ion implantation operation as described above is performed in a system as illustrated in FIG. 1. In particular, a light ion / high-energy ion implantation is performed, which can be performed by exciting ions of atomic numbers 1 to 11 and accelerating said ions to an energy of 300 keV to 20 MeV. The system and method used herein may also be performed with ions accelerated to 10 keV to 30 MeV.

[0064] In operation (630), the processor receives a first signal and a second signal transmitted from a first photon energy decomposition spectrometer and a second photon energy decomposition spectrometer. The signals may be transmitted and received via a wired or wireless connection, but a wired connection may provide better reliability.

[0065] In operation (635), the processor analyzes signals from the first photon energy decomposition spectrometer and the second photon energy decomposition spectrometer to determine whether high-energy photons are detected. This may include a first-level determination of whether any high-energy photon has been detected. This process continues until a high-energy photon is detected.

[0066] In operation (640), the first signal and the second signal are processed to determine the source location of the detected photon. This can be done by the processor comparing information about the location of the photon energy decomposition spectrometer with the level of photon energy detected at each detector. Location data can be provided to the processor by storing coordinate values ​​(x, y, and optionally z) in the data storage of the photon energy decomposition spectrometer. The locations of various components of the ion implantation system can also be entered into the data storage accessible to the processor in the form of coordinates. Alternatively, location information can be provided in the form of the proximity of the photon energy decomposition spectrometer to the various components of the ion implantation system.

[0067] In operation (642), the first signal and / or second signal is processed to determine the type of detected photon energy. This can be done by comparing the detected spectrum data with a known spectrum of a selected type of photon energy.

[0068] In operation (643), a determination is made as to whether the type of radiation requires immediate cessation. This may be based on a determination that the detected data matches with some degree of certainty a known photon energy spectrum (e.g., stored in a memory storage unit and accessible to the processor of the system). Alternatively, the determination may be that the detected data does not match a known photon energy spectrum and is therefore unknown. Optionally, if such a determination is made, an alarm signal may be immediately transmitted to a display and / or the system may be stopped (operation 660).

[0069] In operation (644), the first signal and the second signal are processed to determine whether a threshold level of photon energy has been exceeded. The threshold level may be any level designated as dangerous for a specific period or a level lower than that.

[0070] Subsequently, if it is determined that the threshold is exceeded, a signal is transmitted to stop the system, and the system is stopped in operation (660). Here, stopping means that the beamline operation is stopped so that the beam shock causing the detected photon energy is stopped. In an exemplary system, the beamline operation is stopped immediately and automatically. However, in some situations, such as when the threshold is set lower than a danger level, an alarm may be generated and provided to the operator, for example, via a display, in operation (650). The operator may then have the opportunity to manually stop the operation, and in an exemplary operation, if no additional input is received from the operator within a certain time after the initial alarm is transmitted and / or the detector continues to identify the threshold exceeding, the system may be triggered to stop automatically.

[0071] In operation (660), one or more alarm signals may be transmitted to a display or other alarm device. These signals include information identifying the spectrum as a specific known or unknown type, a display of the detected spectrum data, the location of the detected photon energy for the ion implantation system and / or the component where the beam collision appears to be occurring, information identifying the layer of the liner being impacted, a level related to the total level and / or threshold, and the time until imminent stop.

[0072] FIG. 5 is a flowchart of the spectrometer and ion implantation operations at the system level. FIG. 5 and the description below are relevant to the operations also described in FIG. 4 above, and provide, where applicable, more detailed disclosures.

[0073] In FIG. 5, the photon energy decomposition spectrometer (701) operates with a power input (710) and input parameters (705). The data is then stored in memory (715), and data processing using calibration parameters is performed (720). Raw data or processed and calibrated data may be stored in memory and may be accessed by a processor during the data processing and calibration step (720). The photon energy decomposition spectrometer (701) may include a memory and a processor physically coupled thereto, or the photon energy decomposition spectrometer (701) may transmit data to a remote computing device including the memory and the processor. The photon energy decomposition spectrometer (701) may be one, at least one, multiple, or all photon energy decomposition spectrometers.

[0074] The method continues by having a computer processor analyze the corrected data to identify the reaction species received from the photon energy-resolved spectrometer (725). The corrected spectral data is compared with a known standard stored in memory. Controller parameters are input to provide information about the ion implantation system (723). In one example, the controller will receive input parameters for the composition of the ion source or beam material, the energy of the beam, and, if multiple liners are present in the system, the type of liner or liner types. The controller processes this information together with the data from the photon energy-resolved spectrometer, along with a data storage of known and unknown radiation signatures, to analyze and identify the isotopes or isotopes present in the spectrum.

[0075] Based on the analyzed data, the processor then determines whether there is an unknown or unauthorized photon radiation source in the corrected data (730). If the answer is no, the beamline operation continues (735). Optionally, if the determination is no, feedback is generated and reported to the user, for example, via a display (750). However, if the determination is yes, the processor will transmit a signal to the safety system (740).

[0076] Unauthorized photon radiation sources may be, for example, any radiation source that is unidentified or has an energy of 100 keV or more. For example, a photon of 511 keV may be identified as evidence of radioactive isotope decay through beta decay. Other examples of unauthorized photon radiation sources may be those expected to arise from beam collisions on a layer of the liner, such as the special layer disclosed herein.

[0077] An example of a reference photon energy spectrometer output spectrum is shown in FIG. 6. The four peaks appearing in the energy spectrum are the "fingerprint" of Cs-137 generating gamma rays of 662 keV, Co-60 generating gamma rays of 1173 keV and 1332 keV, and the sum peak of two photon energies of Co-60 resulting from the energy integration time overlap of the recording spectrometer. The baseline of the photon spectrum represents the Compton scattering background estimation for the detection of these events. These photon signatures can be used for the calibration of the detector or as a stored known spectrum to identify detected isotopes in real time. Each combination of liner and beam species will produce a similar spectrum, which can be energy calibrated before use, so that the identification of known peaks from additional liners can be quickly identified.

[0078] In one example, throughout the entire process, an identification system to be integrated into the central safety system of the accelerator will continuously update and ping the processor to obtain results during beam operation. The identification system may control an interlock safety integrated system to substantially restrict access into the accelerator until a specified time or until the radiation source decays below the detection limit and / or to a background level. In the event of an unknown or unauthorized spectral identification, the beam line will be forcibly stopped during operation (745), for example, by placing a Faraday / beam blocking module in the beam path upstream of the radiation source. An example of this is that if the radiation source is detected after the LINAC module, a Faraday cup prior to the LINAC is activated to stop the beam to that section of the beam path.

[0079] In an exemplary method, the beamline operation will continue unless there is a clear identification of an unknown or unallowed spectral identification at a preset threshold. In another exemplary method, the beamline operation will stop unless all detected spectral signatures are known, in a safety list, or exceed a threshold. Here, the threshold will be defined by the safety limit of a given position of the beamline. The threshold may be, for example, 100 or more counts within a specific photon energy range, e.g., 200 or more, or 300 or more counts.

[0080] In an exemplary manner, if the safety system stops the beamline operation, it will also report to the user, for example, by generating feedback via a display (750). In one embodiment, the system will provide a real-time continuous monitoring display for one, many, or all of the photon energy decomposition spectrometers (701) present in the system. For example, the display may resemble an oscilloscope, in which case the recorded / captured spectrum will be formed in real time. This may be a histogram of the amplitude of the recorded charge signal, roughly converted into photon energy.

[0081] During beam interaction, the detected immediate radiation and potential decay radiation from the activated material will be used to analyze the radiation risk during and after the operation of the ion implanter. Therefore, in one example, to evaluate the residual risk of decay radiation, the detection / analysis operation will continue even after the beam line operation has stopped.

[0082] Although the present disclosure has been illustrated and described in relation to specific applications and embodiments, it will be acknowledged by those skilled in the art that equivalent changes and modifications can be made by reading and understanding the present specification and the accompanying drawings. In particular, regarding the various functions performed by the components (assemblies, devices, circuits, systems, etc.) described above, the terms used to describe such components (including references to “means”) are intended to correspond to any component that performs (i.e., is functionally equivalent to) the specific function of the described component that performs the function in the exemplary embodiments illustrated in the present specification, even if it is not structurally equivalent to the structure disclosed, unless otherwise specified.

[0083] Furthermore, even if a specific feature of the present disclosure is disclosed in relation to only one of several embodiments, such feature may be combined with one or more other features of other embodiments as is desirable and advantageous for any given or specific application. Additionally, where the terms “includes,” “including,” “has,” “having,” and variations thereof are used in either the detailed description or the claims, these terms are intended to be inclusive in a manner similar to the term “comprising.”

Claims

Claim 1 An ion implantation system comprising: an ion source that generates ions along a beam line and produces an ion beam—the ions are selected from elements with atomic numbers 1 to 11—; a mass spectrometer located downstream of the ion source and generating a magnetic field; an ion accelerator located downstream of the mass spectrometer; and a first photon energy resolving spectrometer associated with one component of the ion implantation system. Claim 2 An ion implantation system according to claim 1, wherein the ions include H ions, He ions, or both. Claim 3 An ion implantation system according to claim 1, further comprising a second photon energy resolving spectrometer associated with another component of the ion implantation system and spaced at least 1 foot apart from the first photon energy resolving spectrometer. Claim 4 An ion implantation system according to claim 1, wherein the ion accelerator is configured to accelerate ions to an energy of 10 keV to 30 MeV. Claim 5 In claim 1, the first photon energy resolving spectrometer associated with a component of the ion implantation system is in contact with the outer wall of the chamber of the ion implantation system or is located within 1 foot of the outer wall of the chamber of the ion implantation system. Claim 6 In claim 1, the first photon energy resolving spectrometer is an ion implantation system located outside and adjacent to the beam scanner, the ion accelerator, or the energy resolving slit. Claim 7 An ion implantation system according to claim 1, further comprising a liner extending along a portion of the beam line within the chamber of the ion implantation system, wherein the liner comprises a film comprising a material selected from the group consisting of graphite or elements having an atomic number Z of 3 < Z < 72. Claim 8 An ion implantation system according to claim 1, further comprising a liner extending along a portion of the beam line within the chamber of the ion implantation system, wherein the liner comprises an upper shielding layer, and the upper shielding layer comprises an element having an atomic number Z of 72 ≤ Z ≤ 83. Claim 9 In claim 8, the liner further comprises a film comprising a material selected from the group consisting of graphite or an element having atomic number Z of 3 < Z < 72, and the upper shielding layer covers the film, an ion implantation system. Claim 10 An ion implantation system according to claim 1, further comprising a processor configured to receive an input signal from the photon energy decomposition spectrometer; process the input signal to identify the detected photon energy as known or unknown; and, if the unknown or a threshold of a specific known photon energy is identified, transmit an alarm to a display and / or stop the ion implantation system. Claim 11 An ion implantation system according to claim 10, further comprising a second photon energy decomposition spectrometer, wherein the processor is configured to process inputs from the first photon energy decomposition spectrometer and the second photon energy decomposition spectrometer to identify the source location of the detected photon energy. Claim 12 An ion implantation system according to claim 1, further comprising a display configured to transmit an alarm related to the photon energy detected based on an input signal from the first photon energy decomposition spectrometer. Claim 13 In claim 1, the ion implantation system, wherein the first photon energy decomposition spectrometer is a gamma ray spectrometer. Claim 14 A method for performing an ion implantation operation, comprising: an operation of exciting ions having atomic numbers 1 to 11 and accelerating said ions to an energy of 10 keV to 30 MeV; an operation of detecting a photon in a first photon energy decomposition spectrometer and transmitting a first signal to a processor; an operation of receiving said first signal from said first photon energy decomposition spectrometer in said processor; and an operation of processing said first signal to determine the type of photon energy when a threshold value is exceeded. Claim 15 A method according to claim 14, further comprising the operation of transmitting an alarm signal when the above threshold is exceeded. Claim 16 A method according to claim 14, further comprising an operation to automatically stop the ion implantation operation when the threshold value is exceeded. Claim 17 In claim 14, the method wherein the photon has an energy of 100 eV to 20 MeV. Claim 18 In claim 14, the method wherein the photon has an energy of 100 keV or more to 20 MeV. Claim 19 A method according to claim 14, further comprising: detecting a photon in a second photon energy decomposition spectrometer and transmitting a second signal to a processor; receiving the second signal from the first photon energy decomposition spectrometer in the processor; and processing the first signal and the second signal to determine the source location of the detected photon. Claim 20 As an ion implantation system, an ion source that generates ions along a beam line and produces an ion beam—said ions selected from elements with atomic number 11 or less—; a mass spectrometer located downstream of the ion source and generating a magnetic field; an ion accelerator located downstream of the mass spectrometer; a first photon energy resolving spectrometer associated with a first component of the ion implantation system; a second photon energy resolving spectrometer associated with a second component of the ion implantation system; a third photon energy resolving spectrometer associated with a third component of the ion implantation system; and receiving input signals from the first, second, and third photon energy resolving spectrometers; and processing the input signals to identify the detected photon energy as known or unknown photon energy; An ion implantation system comprising: a processor configured to transmit an alarm to a display and / or stop the ion implantation system when an unknown or specific known threshold of photon energy is identified; wherein the processor is configured to process input signals from the first, second, and third photon energy decomposition spectrometers to identify the source location of the detected photon energy.

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