Spectroscopy-based safety system for nuclear reaction detection in ion implantation systems

Abstract

Ion implantation systems include spectroscopy-based safety systems for nuclear reaction detection. A spectroscopy analysis and safety system is disclosed herein. Related methods with the system include processing data received from a photon energy-resolved spectrometer to identify detected photon energies and issue an alert to an operator and / or shut down the system accordingly.

Description

[0001] Cross Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 620,193, filed January 12, 2024, entitled “SPECTRUM-BASED SAFETY SYSTEM FOR NUCLEAR REACTION DETECTION IN ION IMPLANT SYSTEMS,” the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present disclosure relates generally to ion implantation systems, and more particularly to nuclear reaction monitoring in ion implantation systems. BACKGROUND

[0003] Ion implantation systems are used to dope workpieces, such as semiconductor wafers, with ions from an ion beam to produce n-type or p-type doped materials, or to form passivation layers during the manufacture of integrated circuits. Such beam processing is typically used to selectively implant a specified dopant material into a wafer at a predetermined energy level and controlled concentration to produce a semiconductor material during the manufacturing process of an integrated circuit. When used to dope a semiconductor wafer, an ion implantation system implants a selected ion species into a workpiece to produce a desired extrinsic material. When implanting ions into a silicon wafer, for example, ions produced from source materials such as antimony, arsenic, or phosphorous result in “n-type” extrinsic material wafers, while “p-type” extrinsic material wafers are typically produced from ions produced from source materials such as boron, gallium, or indium. When implanting ions into silicon carbide (SiC) wafers, for example, nitrogen (n-dopant) and aluminum (p-dopant) are commonly used as ion species. Additionally, light ions, such as hydrogen or helium, are being used as implants to reduce minority carrier lifetime, increase switching speed, and reduce switching losses in insulated-gate bipolar transistors (IGBTs).

[0004] In an ion implanter, an ion source produces 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 energize and direct a stream of ions from the ion source, forming an ion beam. The desired ions are separated from the ion beam in a mass analysis device, which is typically a magnetic dipole that mass disperses or separates the extracted ion beam. A beam transport device, typically a vacuum system containing a series of focusing and acceleration / deceleration devices, transports the analyzed ion beam to a wafer processing device while maintaining the desired characteristics of the ion beam. Finally, semiconductor wafers or other targets for implantation are moved into and out of the wafer processing apparatus via a wafer handling system, which can include one or more robotic arms for placing wafers to be processed in front of the analyzed ion beam and removing processed wafers from the ion implanter.

[0005] For many ion implantation systems, the physical size of the ion beam is smaller than the target workpiece, whereby the ion beam is scanned in one or more directions to fully cover the surface of the target workpiece. Typically, electrostatic or magnetic based beam scanners scan the ion beam in the fast scan direction and mechanical means move the target workpiece in the slow scan direction to provide full coverage of the ion beam on the workpiece surface.

[0006] Ion implantation systems can generate unwanted beam hits on internal components of the system. This can result in particle emissions that generate ionizing radiation and breakdown of the liner or the chamber wall itself in certain chambers. Ion implantation systems are highly tuned instruments that require high precision, and, if not carefully tuned, unwanted beam hits can occur at certain times. Furthermore, if incorrect materials, such as heavy metals, are mistakenly inserted into the system, for example into the end chamber, or used as Faraday cups, or as a liner, unwanted reactions from the beam can be induced. For example, if a titanium material is hit by hydrogen ions with an energy higher than 800 keV, a fusion reaction with gamma-ray photon emission will occur. SUMMARY

[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, the monitoring system can be used during operation of the ion implantation system to quickly shut down the system when a threshold is exceeded. This helps to better protect the operator from radiation exposure and to prevent damage to the equipment.

[0008] The following presents a simplified summary of the disclosure to provide a basic understanding of some aspects of the disclosure. This summary is not an extensive overview of the disclosure. Neither is it intended to identify key or critical elements of the invention nor to delineate the scope of the invention. Its purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

[0009] In some aspects, the technology described herein relates to an ion implantation system comprising: an ion source that generates ions and an ion beam along a beamline, wherein the ions are selected from elements having an atomic number of 1 to 11; a mass analyzer downstream of the ion source, the mass analyzer generating a magnetic field; an ion accelerator downstream of the mass analyzer; and a first photon energy resolving spectrometer associated with a component of the ion implantation system.

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

[0011] In some aspects, the technology described herein relates to an ion implantation system, comprising: an ion source that generates ions and generates an ion beam along a beamline, wherein the ions are selected from elements of atomic number 11 or less; a mass analyzer located downstream of the ion source that generates a magnetic field; an ion accelerator located downstream of the mass analyzer; 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; a processor configured to receive input signals from the first, second, and third photon energy resolving spectrometers; process the input signals to identify detected photon energies as known or unknown photon energies; and transmit an alert to a display and / or shut down the ion implantation system if a threshold of unknown or specific known photon energies is identified. The processor is configured to process the input signals from the first, second, and third photon energy resolving spectrometers to identify a source location of the detected photon energies.

[0012] The foregoing overview is intended to provide a summary of some features of some embodiments of the present disclosure and other embodiments can include additional and / or different features than those described above. In particular, this overview should not be construed to limit the scope of this application. Thus, for implementing the foregoing and related aspects, the present disclosure includes the following described and claimed features. The following description and the appended figures describe certain illustrative embodiments of the disclosure in detail. These embodiments are indicative, however, of but a few of the various ways in which the principles of the disclosure can be employed. Other objects, advantages and novel features of the disclosure will become apparent from the following detailed description of the disclosure when considered in conjunction with the drawings. Further, features of various embodiments and examples described herein can be combined, unless otherwise specifically noted. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a simplified top view showing an ion implantation system according to an aspect of the present disclosure.

[0014] Figure 2is a cross-sectional view of an example of a portion of an ion implantation system according to an aspect of the present disclosure.

[0015] Figure 3 is a cross-sectional view of an example dedicated liner 400.

[0016] Figure 4 is a flowchart of an example method for operating an example ion implantation system, the method including detecting high-energy photons in the ion implantation system and processing signals received therefrom.

[0017] Figure 5 is an example flowchart of ion implantation and spectrometer operation at the system level.

[0018] Figure 6 is an example of a photon energy attenuation spectrum using calibration isotopes Cs-137 and Co-60. Each long scale on the horizontal axis indicates an interval of 1000 keV from the next long scale, and the long scale on the vertical axis indicates an interval of 20 counts / keV from the next long scale. DETAILED DESCRIPTION

[0019] In an example, a semiconductor manufacturing system includes an energy sensitive photon energy resolving spectrometer, such as a gamma ray detector associated with different locations in the system. The detector can be used to produce a spectral fingerprint that can be matched to a known sample of nuclear ion radiation. In addition, the system includes a controller that will shut down the system if a threshold level of harmful nuclear radiation is detected.

[0020] As ion implantation systems operate at higher energies and with lighter ion species, the risk of an operator accidentally producing a nuclear reaction in a liner or other material in the beamline also increases. This can be due to misadjustment of system components by the operator and / or the use of an inappropriate material in a particular location.

[0021] For example, operation of an ion implantation system using a high energy beam has the potential to erode or sputter away a protective liner within the beamline. A liner is often used to prevent a semiconductor wafer from being exposed to unwanted contaminants (especially metals) sputtered from the beamline walls, typically extending along a portion of the beamline in a chamber of the ion implantation system. In the case of a high energy beam, the liner can also be used to prevent nuclear reactions between the light high energy ion species (e.g., hydrogen) and other elements such as graphite or aluminum. Erosion of the liner exposing the undesired elements can result in unwanted nuclear reactions from beamline material collisions.

[0022] The ion implantation system disclosed herein equipped with a spectrometer uses a photon energy resolving crystal detector that is installed with the necessary electronics for signal processing and detection. The technology disclosed herein combines state-of-the-art energy spectroscopy techniques with high energy low atomic weight ion implantation systems.

[0023] In one example, the detection system is installed near multiple erosion sites and through continuous monitoring, detection of unwanted nuclear reactions can be quickly resolved and identified, thereby identifying the likelihood of failed liner / beamline material due to ion beam impact. Unique liners can be inserted under the beamline impact surface to create unique photon "fingerprint" signatures to facilitate detection. Additionally, if an incorrect workpiece, such as a metal wafer, is injected instead of a silicon wafer, or a silicon wafer with a device containing low atomic weight (low Z) elements, this can also be quickly detected by the spectrometer detector system.

[0024] Semiconductor manufacturing systems, such as ion implantation systems, include chambers that are under vacuum and bombarded by particle streams or other operations during use. The advantage of using a high-energy photon energy-resolved spectrometer is that the difficulty of monitoring internal radiation sources is avoided because such high-energy photons (e.g., gamma rays and X-rays) have enough energy to penetrate the walls of the system.

[0025] The present disclosure relates generally to various apparatuses, systems, and methods associated with ion implantation of workpieces or other semiconductor manufacturing processes. 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 and sounding an alarm and shutting down the system when a threshold condition is reached.

[0026] Accordingly, the present technology is described with reference to the drawings, in which like reference numerals are used to refer to like elements throughout. It is understood that the descriptions of these aspects are merely illustrative and are not to be construed as limiting. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the technology described herein. Furthermore, the scope of the present application is not intended to be limited by the embodiments or examples described below, but is intended to include all embodiments and examples that are within the scope of the appended claims and their equivalents.

[0027] It is also noted that the drawings may schematically illustrate some aspects of the embodiments of the present disclosure and are therefore not to be considered in a limiting sense, for the drawings are merely used to illustrate certain aspects of the many embodiments of the present disclosure and are not to be considered to be detailed representations of structures or compositions of the present disclosure. Specifically, the elements in the drawings are not necessarily to scale with one another, and the placement of various elements in the drawings has been determined for the purpose of providing an understanding of certain embodiments of the present disclosure and are not intended to be construed as definitive or limiting of the relative positions and / or orientations of the various elements in the claims.

[0028] It should also be understood that any direct or indirect connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the attached figures or described herein also can be implemented by indirect connections or couplings. Moreover, it should be understood that the functional blocks or units shown in the attached figures can be implemented as separate features or components in one embodiment, and also can or alternatively be implemented in whole or part as common features or components in another embodiment.

[0029] The terms "workpiece" and "workpiece support" are used herein, with the recognition that a workpiece (e.g., a silicon wafer) will be used in the operation, but the workpiece support is used to hold and position the workpiece. Further, an ion implantation system can be equipped with a workpiece support configured to hold a workpiece, but is not typically manufactured or sold with the workpiece. Accordingly, discussion of a workpiece, and how the beams or components of the ion implantation systems disclosed herein relate to the workpiece, should also be understood to be disclosed with respect to the workpiece support. The term "workpiece target" is used herein to refer to the workpiece (when the workpiece is in place on the workpiece support), or to the position in which the workpiece is configured to be held by the workpiece support.

[0030] In ion implantation, dopant atoms / molecules are ionized and isolated, sometimes accelerated or decelerated, formed into a beam, and swept across a workpiece or wafer. The dopant ions physically bombard the workpiece, enter the surface, and typically lodge in the crystal lattice structure beneath the workpiece surface. In light ion, high energy ion implantation, the ions are selected from elements with atomic numbers of 11 or less, such as 7 to 2, or 3 to 1. For example, ions such as H, He, Li, Be, and B can be produced in an ion source. In examples of higher mass beam species, C, N, O, F, Ne, P, and As can also be produced in an ion source. These ions are accelerated to high energy states, such as at 300 keV or above, such as 400 keV to 15 MeV, 500 keV to 10 MeV, or 1 MeV to 5 MeV.

[0031] Accelerator systems that deliver higher energy beams, such as ion beams above 400 keV, can utilize linear accelerator (LINAC) structures that use resonators, cavities, and / or radio frequency (RF) gap systems; they can also utilize tandem acceleration schemes or radio frequency quadrupole (RFQ) acceleration. The use and implementation of these devices employ energy resolving slits (ERSs) (typically coupled with magnets) to isolate the final energy from the machine acceleration structure. In high energy systems, LINAC blocks are typically used in combination with ERSs and magnets for energy resolution.

[0032] Referring now to the drawings, in accordance with one exemplary aspect of the present disclosure, Figure 1An exemplary hybrid parallel scanning single-wafer ion implantation system 100 is illustrated. This ion implantation system 100 is also referred to as a post-accelerator 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 typically (as shown) has an energy filter 130 after the main accelerator 113 (i.e., further away from the ion source 102 along the beamline) to remove unwanted energy spectra from the output of the main accelerator 113.

[0033] In this exemplary ion implantation system 100, an ion beam 101 generated by an ion source 102 is accelerated by an optional pre-mass analyzer accelerator 105 located before a mass analyzer 104 to produce an accelerated and analyzed ion beam 108. Downstream, the accelerated and analyzed ion beam 108 can be further accelerated in a main accelerator 113 via multiple accelerator stages therein. For example, each accelerator stage may include a resonator (like an RF accelerator) to generate an RF accelerating field and output a further accelerated ion beam 110. After passing through an energy filter 130, the filtered ion beam 111 passes through a beam scanner 119 and then through an angle corrector lens 120, converting the filtered ion beam 111 into a parallel-shifted ion beam 115.

[0034] In the hybrid scanning scheme, the workpiece 134 is moved orthogonally to the parallel-shifted ion beam 115 (shown as moving into and out of the paper) to uniformly irradiate the entire surface of the workpiece 134. Other types of scanning can also be used in conjunction with the monitoring and related techniques described herein. As mentioned above, various aspects of this disclosure can be implemented in conjunction with any type of ion implantation system, including but not limited to... Figure 1 An exemplary ion implantation system 100.

[0035] The following describes it in more detail. Figure 1 The source chamber assembly 112 includes an ion source 102 and an ion extraction electrode assembly 121 for extracting ions and accelerating them to intermediate energies. To generate ions, a dopant material gas to be ionized is located within the ion generation chamber (not shown) of the ion source 102. Other sources and forms of dopant may also be used; for example, the dopant may be sputtered (e.g., aluminum nitride) or introduced in vapor form (e.g., aluminum chloride). For example, the dopant gas may be supplied to the source chamber assembly 112 from a gas source (not shown). It should be understood that one or more suitable mechanisms (not shown) may be used to excite free electrons, such as RF or microwave excitation sources, electron beam injection sources, electromagnetic sources, and / or a cathode that generates an arc discharge within the chamber. The excited electrons collide with dopant gas molecules, thereby generating ions. Positive ions are typically generated, but the disclosure herein also applies to systems that generate negative ions.

[0036] Ions are controllably extracted through a slit in the ion extraction electrode assembly 121. The ion extraction electrode assembly 121 comprises a plurality of extraction and / or suppression electrodes. The ion extraction electrode assembly 121 can comprise, for example, a separate extraction power supply (not shown) to bias the extraction and / or suppression electrodes to accelerate ions from the source chamber assembly 112. It will be appreciated that since the ion beam 101 comprises particles of the same charge, the beam can have a tendency to expand radially outwards as the like-charged particles repel each other. It will also be appreciated that in low energy, high current (high conductance) beams, the beam expansion is exacerbated, where many like-charged particles (e.g. high current) move relatively slowly (e.g. low energy) in the same direction, such that there is a significant amount of repulsive force between the particles, but insufficient momentum for the particles to move in the direction of the beam path. Therefore, the ion extraction electrode assembly 121 is typically configured to extract the beam at a high energy, such that the beam does not expand excessively (e.g. such that the particles have sufficient momentum to overcome the repulsive forces that can cause beam expansion), otherwise beam current loss can result.

[0037] The pre-mass analyser accelerator 105 further accelerates the ions, and is an optional component that can not be required for certain operations.

[0038] The mass analyser 104 generates a magnetic field according to a selected mass-to-charge ratio, and angularly adjusts the ion beam 101. In this example, the mass analyser 104 is configured to bend the ion beam 101 through an angle of about 90 degrees, and comprises one or more magnets (not shown) for establishing a (dipole) magnetic field therein. When the ion beam 101 enters the mass analyser 104, it is correspondingly bent by the magnetic field, such that ions of an inappropriate mass-to-charge ratio are repelled. More specifically, ions of too great or too small a mass-to-charge ratio are deflected into the side walls of the mass analyser 104. In this way, the mass analyser 104 primarily allows ions of a desired mass-to-charge ratio in the ion beam 101 to pass through, and in one example, exit through a mass resolution aperture, which can further condition the ion beam 101. It will be appreciated that collisions of the ion beam 101 with other particles in the ion implantation system 100 can degrade the integrity of the beam. Therefore, one or more pumps (not shown) can be included to evacuate portions of the system, such as the mass analyser 104.

[0039] The main accelerator 113 accelerates the ions to a higher energy, and can be, for example, an RF linear particle accelerator (LINAC), in which the ions are repeatedly accelerated by an RF field, or a DC accelerator (e.g. a tandem electrostatic accelerator), which accelerates the ions using a fixed DC high voltage. The main accelerator 113 will be described further below with reference to Figure 2 The main accelerator 113 will be described further below with reference to

[0040] After the accelerated ion beam 110 exits the main accelerator 113, it is further conditioned by an energy-resolving slit (ERS) 137. The ERS 137 is a structure and method for collimating the energy distribution of the transmitted accelerated particles exiting from the LINAC module assembly. The energy resolution of a given beam can be adjusted by the width of the slit when the beam is present, as well as the chosen amplitude and phase. The slit is typically coupled with a dipole bending magnet, where within a given accelerated beam, the trajectory curvature of high-energy ions is less than that of low-energy ions. With this, an acceptance can be introduced to make the energy distribution a fixed value. For example, the width of a "standard" ERS can be an energy distribution / resolution of + / - 5% of the desired accelerated beam energy, which can be changed by the operator to 10% or 0.05% depending on the relative slit width when the beam exits the dipole magnet from the LINAC.

[0041] The beam scanner 119 electrostatically or electromagnetically scans the accelerated ion beam 110 (typically from left to right) into an angle corrector lens 120, which converts the filtered ion beam 111 into a parallel-shifted ion beam 115.

[0042] The angle corrector 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 implantation angle is relatively uniform across the workpiece 134 and is normalized to eliminate the vertical deviation of the beam so that it moves almost horizontally to its final destination. As shown, the angle corrector lens 120 can be an electromagnetic magnet, but can also be electrostatic, for example. The resulting parallel-shifted ion beam 115 produced by the angle corrector lens 120 is directed to the workpiece 134.

[0043] The workpiece 134, if present, occupies the same space as the workpiece target (as explained further above) and is held by a workpiece support 175, which can be housed in a process chamber or end station (not shown). It should be appreciated that different types of end stations and workpiece supports 175 can be employed in the ion implantation system 100. For example, a "batch" type end station can simultaneously support multiple workpieces 134 on a rotating workpiece support structure, where the workpieces are rotated through the path of the ion beam 115 (also referred to as the beamline) until all workpieces are fully implanted. Such a "batch" type implanter does not require a scanner and a correction lens. On the other hand, a "serial" type end station supports a single workpiece 134 along the path of the ion beam 115 for implantation, where multiple workpieces are implanted one at a time in a serial fashion, with each workpiece being fully implanted before the next workpiece begins implantation. In a hybrid system, the workpieces 134 can be mechanically translated in a first direction (the y-direction or so-called "slow scan" direction), while the ion beam 115 is scanned in a second direction (the x-direction or so-called "fast scan" direction) to impart the parallel-shifted ion beam 115 across the workpiece 134.

[0044] Figure 2 One example of a portion of an ion implantation system is shown in accordance with one aspect of the present disclosure. Accelerator 200 (which can be a main accelerator 113 of Figure 1 is shown as an example of one embodiment in Figure 2 and can include multiple accelerator stages (e.g., 202, 204, 208, 210, and 212). Acceleration stages 202, 204, 208, 210, and 212 can each include at least one acceleration electrode 214, for example driven by an RF resonator, for producing an RF acceleration field (not shown) on both sides. Ion beam 201 of charged particles having a charge state (e.g., net charge or valence) can continuously pass through the aperture of acceleration electrode 214.

[0045] Beam focusing can be provided by lenses 234 (e.g., electrostatic or magnetic quadrupoles) incorporated within accelerator 200. In one embodiment, accelerator 200 can accelerate the charged ions to a kinetic energy level of 10 keV or more, or 300 keV or more as the accelerated beam exits accelerator 200. In one example, lenses 234 are included in each of acceleration stages (202, 204, 208, 210, and 212).

[0046] The present disclosure is not limited to one particular accelerator or LINAC type. The number of stages is not limited to Figure 2 the illustration, for example, can be 1 to 50 accelerator stages, for example, 2 to 10, or 3 to 6. Further, the accelerator can also be a tandem accelerator or an RFQ.

[0047] A control system 168 (also referred to as a controller) is also provided to control, communicate with, and / or regulate ion source 102, pre-analyzer accelerator 105, mass analyzer 104, main accelerator 113, ERS 137, beam scanner 119, and angle corrector lens 120. While Figure 1 connections are not shown in

[0048] Control system 168 can also be coupled to one or more power supplies for the components. Control system 168 can also be coupled to one or more photon energy resolving spectrometers (e.g., photon energy resolving spectrometers 191, 192, 193) associated with ion implantation system 100.

[0049] The control system 168 can include a computer with a processor and data storage and be operable to take measurements of ion beam characteristics and adjust parameters accordingly. It can also be configured, e.g., by software or hardware, to receive signals from the photon energy resolving spectrometers 191, 192, 193 and process them to produce reports and alerts to an operator through a display. In addition, the control system 168 can be configured to process signals from the photon energy resolving spectrometers 191, 192, 193 and determine whether there is a threshold level of unknown radiation or known and unwanted radiation, as disclosed further below. The control system 168 can also control power supplies or other components to shut down beamline operation in the event that a threshold level of radiation is reached.

[0050] The ion implantation system 100 includes multiple high-energy photon energy resolving spectrometers 191, 192, 193. For example, two to six or three to five detectors can be used in the ion implantation system 100. In one embodiment, a single detector can also be used.

[0051] By comparing one or more signal spectra to a database of known safe and unsafe X-ray or gamma-ray signatures (e.g., the National Nuclear Materials and Signature Database), unknown or known radiation can be determined. In addition, signals from the photon energy resolving spectrometers 191, 192, 193 can be processed to determine where high-energy emissions originate from in the ion implantation system 100. The photon energies detected by the photon energy resolving spectrometers can include photons in the X-ray range, e.g., 100 eV to 100 keV in energy. In addition, for photons in the gamma-ray energy range, 1 keV to 20 MeV (e.g., 10 keV to 15 MeV, or 50 keV to 5 MeV) can be sufficient for most applications.

[0052] With multiple photon energy resolving spectrometers, the photon energy resolving spectrometers can be spaced apart and near regions in the ion implantation system that are most likely to produce high-energy radiation (e.g., X-rays or gamma-rays). In an example, the photon energy resolving spectrometers are spaced apart (from each other) by at least 1 foot, e.g., 1.5 feet to 30 feet, 2 feet to 15 feet, or 2.5 feet to 5 feet. In an embodiment, each photon energy resolving spectrometer in the system is spaced apart from any other photon energy resolving spectrometer in the system by at least 1 foot, e.g., 1.5 feet to 30 feet, 2 feet to 15 feet, or 2.5 feet to 5 feet.

[0053] Because the high energy radiation of interest is not contained by the walls or chamber linings of the ion implantation system, the photon energy resolving spectrometers can be located outside the walls of the system and still be associated with the photon energies of interest. However, these photon energy resolving spectrometers should be placed near the outer walls of the components or chambers of the system, for example, in immediate contact with the outer walls of the system chambers to 3 feet, 0.1 to 2.5 feet from the outer walls of the system chambers, or 0.5 to 1 feet from the outer walls of the system chambers.

[0054] At various locations in the ion implantation system 100, different materials can be sputtered off after being bombarded by the particle beam. Figure 1 The three locations shown in FIG. 1 illustrate photon energy resolving spectrometers near the LINAC main accelerator 113, the ERS 137, and the beam scanner 119. In an example, the first, second, and third photon energy resolving spectrometers 191, 192, 193 are located outside and adjacent to (next to, above, or below) the beam scanner 119, the LINAC main accelerator 113, and the ERS 137, respectively. In an 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 spectrometers are located near the end of the end of the workpiece 134 and the workpiece support 175. In another example, the photon energy resolving spectrometers are located near the Faraday cup, the dose cup, the bending magnet, or other structures that can be affected by the beam or cause deflection.

[0055] The plurality of photon energy resolving spectrometers 191, 192, 193 are coupled to a control system 168 configured to process the input signals from the photon energy resolving spectrometers by a processor and a data storage. By the intensity of the signals and knowing the location of the photon energy resolving spectrometers, the controller is configured to determine the location of the system that is experiencing a radiation event (detected photon energy). In addition, the controller can interpret the signals from the photon energy resolving spectrometers to determine the type of radiation (e.g., X-ray or gamma ray), or specific spectral data that matches known spectral data. The controller can cause this information to be stored in the data storage and provided to an operator through a graphical user interface on a display. In addition, if a threshold level of radiation is detected, the controller can cause the system to shut down, as further described below.

[0056] While the photon energy resolving spectrometers and shutdown control disclosed herein are primarily described for use in ion implantation systems, they can also be used in other devices, such as high energy particle accelerators.

[0057] In an example, the photon energy resolving spectrometer is a solid state scintillator type spectrometer. Scintillators are materials that emit a flash or pulse of light when they interact with ionizing radiation. Scintillator crystals are used in radiation detectors for gamma rays, X-rays, cosmic rays, and particles with energy levels greater than about 1 keV.

[0058] The spectrometer includes a scintillation crystal (or other scintillator) and a component for detecting the light produced by the crystal when it interacts or “scintillates” upon exposure to a radiation source, such as a photodetector. The photodetector produces an electrical signal proportional to the intensity of the scintillation (or light pulse received from the scintillator material). This electrical signal is then processed in various ways to provide data about the radiation.

[0059] In an example, the photon energy resolving spectrometer used herein can be a scintillation crystal device, such as a NaI crystal doped with thallium, germanium, cesium bromide, or lanthanum bromide.

[0060] In an example, a dedicated liner can be placed in the chambers most likely to have beam impingement, such as LINAC accelerator 113, ERS 137, and beam scanner 119. Although it is normal to place protective liners inside the beamline to prevent unwanted nuclear reactions, a dedicated additional liner under the beam impingement protection plate can be used in place of or in addition to these liners. In combination with the photon energy resolving spectrometer, the dedicated liner provides additional analysis and alarm capabilities before any unwanted nuclear reactions occur.

[0061] Figure 3 is a cross-sectional view of an example dedicated liner 400. Dedicated liner 400 can be used to coat a surface 415 along an ion beam 420. For example, if dipole bending magnets (typically made of soft magnetic steel) are the surface 415, these magnets typically have a nickel coating 410 on top of the surface. (Other surfaces 415 do not have a nickel coating on top.) In Figure 3 In, on top of the nickel coating 410 is a film 405. (In other example surfaces 415, there is no nickel layer, and film 405 directly covers the surface 415.) Film 405 can contain a low molecular weight substance, such as graphite, B, or an element with atomic number Z, where 3 < Z < 72 (e.g., 4 < Z < 30, or 5 < Z < 15). On top of film 405 is a top shielding layer 401, which can be a layer that includes a high-Z (high atomic number) element, such as 72 ≤ Z ≤ 83. The dedicated liner is different from a typical graphite liner, which does not provide detection and protection functions.

[0062] In an example operation, a misstrike of the ion beam 420 will only strike the top shielding layer 401, leaving the nickel coating 410 or surface 415 unstruck. If the top shielding layer 401 is penetrated by the beam, the film 405, which includes graphite, Be, and / or B, can be struck, or other beam species can be struck. This will produce a unique photon energy emission spectrum. The photon energy spectrometer and controller will be configured to identify that the film 405 has been struck within a short time window. An alarm can then be issued by the processor and display indicating that a portion of the top shielding layer 401 has been sputtered away.

[0063] In an embodiment, the top shielding layer 401 and film 405 will not produce dangerous radiation upon being struck by the beam, so long as a threshold level has not been reached. For example, the film 405 can produce photon energy, such as X-rays or less harmful gamma rays, which can be detected by the photon energy resolving spectrometer. This radiation can not be harmful in the short term and can provide the operator with sufficient time to address the issue and shut down the system before damage is caused. In an embodiment, the beamline will automatically shut down if any radiation signatures are detected that indicate a layer of the liner has been struck by the beam.

[0064] The specialized liner material of the film 405 should be selected based on the ion source and / or particle beam energy, as the exact decay properties of the nuclear reactions produced by the beam strike are determined by the quantum mechanical properties of the beam and the liner. Changing the beam species or liner combination will change the properties and energy of the photon decay signature. The kinetic energy of the particle beam also determines the probability of photon decay. Therefore, if the ion source / beam species or particle velocity changes, this information should be input into the system, informing the controller to look for different photon decay signatures.

[0065] In an example, the controller will receive input of the ion source or beam material composition, beam energy, and one or more liner types. The controller will process this information along with data from the photon energy resolving spectrometer with known and unknown radiation signatures for analysis and determination. For example, different liner materials can be used to identify different locations in the beamline, which will be easily identifiable due to the characteristic photon energy spectra associated with various nuclear reactions.

[0066] The system can also be used to determine if the wrong type of wafer has been injected. The same spectroscopic techniques can be used to identify the prompt and decay radiation of activated isotopes in the wafer.

[0067] Reference will now be made to Figure 4 Example methods related to the use of the photon energy resolving spectrometer in an ion implantation system will be further described. Figure 4 is a flowchart of an example method for detecting high energy photons in an ion implantation system, processing signals received therefrom, and operating the ion implantation system.

[0068] At operation 610, an ion implantation operation is performed, such as the above-described operations in systems such as those shown in FIGS. 1-3. Figure 1 Specifically, a light ion / high energy ion implantation is performed, which can be performed by exciting ions of atomic number 1-11 and accelerating the ions at an energy of 300 keV to 20 MeV. The systems and methods used herein can also be performed with ions accelerated at 10 keV to 30 MeV.

[0069] At operation 630, the processor receives first and second signals transmitted from the first and second photon energy-resolving spectrometers. The signals can be transmitted and received through a wired or wireless connection, although a wired connection can provide better reliability.

[0070] At operation 635, the processor determines whether a high-energy photon is detected by analyzing the signals from the first and second photon energy-resolving spectrometers. This can involve a first level determination of whether any high-energy photons have been detected. The process continues until a high-energy photon is detected.

[0071] At operation 640, the first and second signals are processed to determine the source location of the detected photon. This can be done when the processor compares the location information about the photon energy-resolving spectrometer to the detected photon energy levels at each detector. The location data can be provided to the processor by storing the coordinate (x, y, and optionally z) values of the photon energy-resolving spectrometer in a data store. The locations of the components of the ion implantation system can also be input in coordinate form into a data store accessible to the processor. Alternatively, the location information can be provided in the form of the proximity of the photon energy-resolving spectrometer to the various components of the ion implantation system.

[0072] At operation 642, the first and / or second signals are processed to determine the type of detected photon energy. This can be done by comparing the detected spectral data to known spectra of selected types of photon energies.

[0073] At operation 643, a determination is made as to whether the type of radiation requires an immediate shutdown. This can be based on a determination that the detected data matches a known (e.g., stored in system memory and accessible to the processor) photon energy spectrum to a certain level of certainty. The determination can also be that the detected data does not match a known photon energy spectrum and is therefore unknown. Optionally, once this determination is made, an alert signal can be transmitted to a display and / or the system can be shut down (operation 660).

[0074] At operation 644, the first signal and the second signal are processed to determine whether a threshold level of photon energy is exceeded. The threshold can be a certain level that is designated as dangerous over a certain time period, or a lower level.

[0075] Then, if it is determined that the threshold is exceeded, a signal is transmitted to shut down the system, and the system is shut down in operation 660. Shut down means that the beamline operation stops so that the beam impact causing the detected photon energy stops. In an example system, the beamline operation would automatically shut down immediately. However, in some cases, such as if the threshold is set to a level below dangerous, an alarm can be triggered and provided to an operator at operation 650, for example, through a display. The operator can then have an opportunity to manually shut down the operation, and in an example operation, if no further input is received from the operator within a certain time after the first alarm is transmitted, and / or if the detector continues to identify an excess of the threshold, the system can automatically trigger a shutdown.

[0076] At operation 660, one or more alarm signals can be transmitted to a display or other alarm device. These signals include: identification information that identifies the spectrum as being of a certain known type or an unknown type, a display of the detected spectral data, a location of the detected photon energy relative to possible components of the ion implantation system and / or the beam impact, information that identifies the layer of the liner that is being impacted, a total level and / or a level relative to the threshold, and a time until shutdown.

[0077] Figure 5 is a flowchart of the operation of the system-level spectrometer and ion implantation. Figure 5 The discussion below is relevant disclosure of the operation described above Figure 4 and in some cases is more detailed disclosure.

[0078] In Figure 5 , the photon energy resolving spectrometer 701 operates with power input 710 and input parameters 705. The data is then stored in memory 715 and processed 720 with calibration parameters. The raw data or the processed and calibrated data can be stored in memory and accessed by the processor in the processing data and calibration step 720. The photon energy resolving spectrometer 701 can include the memory and the processor physically coupled thereto, or the photon energy resolving spectrometer 701 can transmit the data to a remote computing device that includes the memory and the processor. The photon energy resolving spectrometer 701 can be one, at least one, multiple, or all of the photon energy resolving spectrometers.

[0079] The method continues with the computer processor analyzing the calibration data received from the photon energy resolving spectrometer to identify the reactant species 725. The calibrated spectral data is compared to known standards stored in memory. The controller parameters 723 are input to provide information about the ion implantation system. In an example, if there are multiple liners in the system, the controller will receive input parameters of the ion source or beam material composition, beam energy, and liner type or liner type. The controller processes this information along with data from the photon energy resolving spectrometer with data stores of known and unknown radiation signatures to analyze and determine one or more isotopes present in the spectrum.

[0080] Based on the analyzed data, the processor then determines if there is an unknown or disallowed photon radiation source in the calibration data 730. If the answer is no, the beamline operation continues 735. Optionally, if the answer is no, feedback is generated and reported to the user through, for example, a display 750. However, if the answer is yes, the processor will transmit a signal to a safety system 740.

[0081] For example, a disallowed photon radiation source can be any unidentified or radiation source with an energy at or above 100 keV. For example, 511 keV photons can be identified as evidence of a radioactive isotope decaying via beta decay. Another example of a disallowed photon radiation source can be a photon radiation source expected to be generated by a beam striking a liner layer (such as the specialized layers disclosed herein).

[0082] Figure 6 An example of a photon energy spectrometer output spectrum is shown in FIG. 6 for reference. The four peaks seen in the energy spectrum are the“fingerprints” of Cs137 (producing 662 keV gamma rays), Co-60 (producing 1173 and 1332 keV gamma rays), and a sum peak of the two Co-60 photon energies due to the overlap of the energy integration time of the recording spectrometer. The baseline in the photon spectrum represents the Compton scattering background estimate used to detect these events. This photon signature can be used in 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 prior to use, and thus a determination of known peaks from additional liners can be quickly identified.

[0083] In one example, throughout the process, an identification system (which would be integrated into the central safety system of the accelerator) would be refreshed and polled for results by the processor during beam operation. This identification system would be able to control the interlocked safety integrated system, essentially limiting access to the interior of the accelerator until a specified time or the radiation source has decayed to undetectable and / or to background levels. If there is an unknown or unpermitted spectral identification, the beamline would be forced to shut down at 745, for example by placing a Faraday / beam block module in the beam path upstream of the radiation source. One example is if a source is detected after a LINAC module, the Faraday cup before the LINAC would be activated, shutting down the beam from reaching that section of the beam path.

[0084] In one example method, the beamline operation would continue unless an unknown or unpermitted spectral feature is explicitly identified at a preset threshold. In another example method, the beamline operation would stop unless all detected spectral features are known and on a safety list, or do not exceed a threshold. While the threshold would be defined by the safety limits for a given location of the beamline. The threshold could be, for example, 100 or more counts in a particular photon energy range, such as 200 or more, or 300 or more counts.

[0085] In one example method, if the safety system shuts down the beamline operation, it would also generate and report feedback to the user, for example through a display 750. In one embodiment, the system would provide a real-time continuous monitoring display for one, multiple, or all of the photon energy resolving spectrometers 701 present within the system. For example, the display could be similar to an oscilloscope, where the recorded / captured spectra would form in real-time. This could be a histogram of recorded charge signal amplitudes, which are roughly converted to the energy of the photons.

[0086] Upon beam interaction, the detected transient radiation and possible decay radiation from activated materials would be used to analyze the radiation hazard during and after ion implanter operation. Thus, in one example, even after the beamline operation is shut down, the detection / analysis operation would continue to assess any residual hazard of the decay radiation.

[0087] While the disclosure has been illustrated and described with respect to certain applications and embodiments, it will be realized by those skilled in the art that equivalent alterations and modifications will occur to them upon reading and understanding this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, systems, etc.), the terms (including any reference to "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the disclosure. In this manner, it will be appreciated that equivalent alterations and modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In addition, where possible, identical reference numbers have been used, throughout the specification, to designate the same or similar elements.

[0088] In addition, while a particular feature of the disclosure can have been disclosed with respect to only one of several implementations, such feature can be combined with one or more other features of the other implementations as can be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "including", "includes", "having", "has", "united", "unites", "comprising", "comprises", and the like, are used in the detailed description and / or in the claims, such terms are intended to be inclusive (meaning as encompassed by) rather than exclusive and / or exhaustive (meaning each necessary component of a total recitation of elements in a claim are present).

Claims

1. An ion implantation system, comprising: an ion source that generates ions and generates an ion beam along a beamline, wherein the ions are selected from elements with an atomic number of 1 to 11; a mass analyzer located downstream of the ion source, the mass analyzer generating a magnetic field; an ion accelerator located downstream of the mass analyzer; and a first photon energy-resolved spectrometer associated with a component of the ion implantation system.

2. The ion implantation system according to claim 1, wherein, The ions include H ions, He ions, or both.

3. The ion implantation system according to claim 1, further comprising a second photon energy-resolved spectrometer associated with a different component of the ion implantation system and spaced at least 1 foot apart from the first photon energy-resolved spectrometer.

4. The ion implantation system according to claim 1, wherein, The ion accelerator is configured to accelerate the ions to an energy of 10 keV to 30 MeV.

5. The ion implantation system according to claim 1, wherein, The first photon energy-resolved spectrometer associated with the component of the ion implantation system is in contact with the outer wall of the chamber of the ion implantation system, or is within 1 foot of the outer wall of the chamber of the ion implantation system.

6. The ion implantation system according to claim 1, wherein, The first photon energy-resolved spectrometer is located outside and adjacent to a beam scanner, the ion accelerator, or an energy-resolving slit.

7. The ion implantation system according to claim 1, further comprising a liner extending along a portion of the beamline in the chamber of the ion implantation system, the liner comprising a film, the film comprising a material selected from the group consisting of: graphite, or an element having an atomic number Z, wherein 3<Z<72.

8. The ion implantation system according to claim 1, further comprising a liner extending along a portion of the beamline in the chamber of the ion implantation system, the liner comprising a top shielding layer containing an element with an atomic number Z, wherein 72≤Z≤83.

9. The ion implantation system according to claim 8, wherein the liner further comprises a film, the film comprising a material selected from the group consisting of: graphite, or an element having an atomic number Z, wherein 3<Z<72, wherein the top shielding layer covers the film.

10. The ion implantation system according to claim 1, further comprising a processor configured to receive an input signal from the photon energy-resolved spectrometer; process the input signal to identify the detected photon energy as known or unknown; and send an alert to a display and / or shut down the ion implantation system if a threshold for an unknown or specific known photon energy is identified.

11. The ion implantation system according to claim 10, further comprising a second photon energy-resolved spectrometer, wherein the processor is configured to process inputs from the first photon energy-resolved spectrometer and the second photon energy-resolved spectrometer to identify the source location of the detected photon energy.

12. The ion implantation system according to claim 1, further comprising a display configured to transmit an alert related to the detected photon energy based on the input signal from the first photon energy-resolved spectrometer.

13. The ion implantation system according to claim 1, wherein, The first photon energy-resolved spectrometer is a gamma-ray spectrometer.

14. A method for performing ion implantation, comprising the following operations: Ions with atomic numbers from 1 to 11 are excited and accelerated with energies from 10 keV to 30 MeV; Photons are detected at the first photon energy-resolved spectrometer, and the first signal is transmitted to the processor; The processor receives the first signal from the first photon energy-resolved spectrometer. as well as If the threshold is exceeded, the first signal is processed to determine the type of photon energy.

15. The method of claim 14, further comprising: If the threshold is exceeded, an alarm signal is transmitted.

16. The method of claim 14, further comprising: If the threshold is exceeded, the ion implantation operation is automatically shut down.

17. The method according to claim 14, wherein, The energy of the photons ranges from 100 eV to 20 MeV.

18. The method according to claim 14, wherein, The energy of the photon is 100 keV to 20 MeV or more than 100 keV to 20 MeV.

19. The method of claim 14, further comprising: Photons are detected at a second photon energy-resolved spectrometer, and a second signal is transmitted to the processor. The processor receives the second signal from the second photon energy-resolved spectrometer. as well as The first signal and the second signal are processed to determine the source location of the detected photon.

20. An ion implantation system, comprising: An ion source that generates ions and produces an ion beam along a beamline, wherein the ions are selected from elements with an atomic number of 11 or less. A mass analyzer, located downstream of the ion source, generates a magnetic field; An ion accelerator is located downstream of the mass analyzer; A first photon energy-resolved spectrometer is associated with a first component of the ion implantation system; A second photon energy-resolved spectrometer is associated with a second component of the ion implantation system; The third photon energy-resolved spectrometer is associated with the third component of the ion implantation system; as well as The processor is configured to: receive input signals from the first photon energy-resolved spectrometer, the second photon energy-resolved spectrometer, and the third photon energy-resolved spectrometer; and process the input signals to identify the detected photon energy as known or unknown photon energy. And if a threshold of unknown or specific known photon energy is identified, an alarm is transmitted to the display and / or the ion implantation system is shut down; The processor is configured to process input signals from the first photon energy-resolved spectrometer, the second photon energy-resolved spectrometer, and the third photon energy-resolved spectrometer to identify the source location of the detected photon energy.

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