JP2013156180A - Ion beam measuring apparatus, ion beam measuring method and ion implantation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide non-contact type ion beam measurement.SOLUTION: An ion beam measuring apparatus 10 includes an optical fiber 22 arranged so as to circle a periphery of an ion beam route 14, a light source 20 for applying incident light to the optical fiber 22, a detector 24 for detecting outgoing light from the optical fiber 22, and an arithmetic processing unit 32 for providing an ion beam measurement result on the basis of a deviation of polarization states between the incident light and the outgoing light. The optical fiber 22 may be arranged so as to surround a scanning range 19 of an ion beam 12.

Description

  The present invention relates to an ion beam measurement apparatus, an ion beam measurement method, and an ion implantation apparatus.

  An ion beam irradiation apparatus for irradiating an object with an ion beam is known. For example, there is an ion implantation apparatus for implanting a desired ion species into a semiconductor substrate. In general, an ion implantation apparatus is provided with a measuring instrument, such as a Faraday cup, for directly receiving an ion beam and performing beam measurement.

JP 2008-262748 A JP 2000-111942 A JP-A-7-153416

  In so-called contact-type beam measurement in which such an ion beam is directly received, the measuring device occupies the beam during the measurement, and thus the workpiece cannot be irradiated with the ion beam during the measurement. Similarly, measurement cannot be performed when the workpiece is irradiated with an ion beam. Therefore, there is a trade-off relationship between increasing the throughput of the irradiation process on the object to be processed and ensuring the beam quality by the high frequency measurement of the ion beam. In addition to the original purpose of irradiating the irradiated object, extra ionic material is consumed for measurement.

  One exemplary object of an aspect of the present invention is to provide a so-called non-contact measurement that enables measurement while irradiating an object with an ion beam.

  One embodiment of the present invention is an ion beam measurement apparatus. The apparatus includes an optical fiber arranged to circulate around an ion beam path, a light source for providing incident light to the optical fiber, a detector for detecting light emitted from the optical fiber, A calculation unit for providing an ion beam measurement result based on a deviation in polarization state between the incident light and the emitted light.

  Another aspect of the present invention is an ion beam measurement method. The method includes providing an ion beam and measuring Faraday rotation of electromagnetic waves in the material in a magnetic field from the ion beam.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, non-contact ion beam measurement is provided.

It is a figure which shows typically the ion beam measuring device which concerns on one Embodiment of this invention. It is a figure which shows typically the ion beam measuring device which concerns on one Embodiment of this invention.

  FIG. 1 is a diagram schematically showing an ion beam measurement apparatus 10 according to an embodiment of the present invention. The ion beam measurement apparatus 10 is configured to measure the Faraday rotation of an electromagnetic wave in a substance in a magnetic field from the ion beam 12. Specifically, for example, the ion beam measurement apparatus 10 is configured to measure the Faraday rotation of light passing through an optical fiber that circulates around the ion beam path 14.

  The ion beam 12 is supplied to the processing chamber 16 along a predetermined ion beam path 14 (indicated by a one-dot chain line in FIG. 1). The ion beam 12 is generated by, for example, an ion beam generator (not shown) including an ion source and a beam line. A processing object 18 is accommodated in the processing chamber 16. The processing chamber 16 includes a support portion (not shown) that supports the workpiece 18 so as to be movable or stationary with respect to the ion beam 12. In this way, the ion beam 12 is irradiated onto the workpiece 18 disposed on the ion beam path 14.

  The workpiece 18 may be irradiated with the ion beam 12 along the fixed ion beam path 14. Alternatively, the ion beam 12 may be scanned over a scanning range 19 (indicated by an arrow in FIG. 1) in a direction perpendicular to the ion beam path 14 (ie, the ion beam 12 may reciprocate through the scanning range 19). The cross section of the ion beam 12 perpendicular to the ion beam path 14 may be a spot shape (for example, a circle) or a shape extending in a longitudinal direction (a direction perpendicular to the ion beam path 14).

  The ion beam measurement apparatus 10 is configured to be incorporated as a subsystem for measuring the ion beam 12 in an ion beam irradiation system (for example, an ion implantation apparatus or a particle beam therapy apparatus) for irradiating the ion beam 12. Also good. Alternatively, the ion beam measurement apparatus 10 may be configured as a stand-alone measurement apparatus that is a stand-alone type.

  When the ion beam measurement apparatus 10 is incorporated into an ion implantation apparatus, the workpiece 18 is, for example, a semiconductor substrate (for example, a silicon wafer). The processing chamber 16 is sometimes called an end station. The ion implantation apparatus includes an ion beam control device (not shown) for controlling the ion beam 12.

  The processing chamber 16 is in a desired vacuum state at least when the ion beam 12 is irradiated. In order to evacuate the processing chamber 16, an evacuation device (for example, a cryopump or other vacuum pump (not shown)) is attached to the processing chamber 16. Therefore, the processing chamber 16 is also called a vacuum chamber. Here, the vacuum chamber refers to any structure surrounding the vacuum environment for the ion beam 12, and may be, for example, a vacuum vessel, a vacuum chamber, a vacuum chamber, or a vacuum duct.

  The ion beam measurement apparatus 10 includes a light source 20, an optical fiber 22, and a detector 24. The light source 20 is provided to give incident light to the optical fiber 22. The optical fiber 22 is arranged so as to go around the ion beam path 14. The detector 24 is provided to detect light emitted from the optical fiber 22.

  The light source 20 is, for example, a laser light source. The light source 20 is configured to emit light having a wavelength that can be transmitted through the optical fiber 22 (for example, visible light, ultraviolet light, or infrared light). The light source 20 is configured to emit light having a desired polarization state (for example, circularly polarized light or linearly polarized light). The light source 20 may include a polarization controller (not shown) for making light incident on the optical fiber 22 into a desired polarization state. The light source 20 is disposed outside the processing chamber 16.

  One end 26 and the other end 28 of the optical fiber 22 are disposed outside the processing chamber 16, and an intermediate portion 30 connecting the one end 26 and the other end 28 is disposed inside the processing chamber 16. One end 26 and the other end 28 of the optical fiber 22 penetrate the wall of the processing chamber 16 and protrude outside. The intermediate portion 30 of the optical fiber 22 surrounds the ion beam path 14 in a ring shape, and is wound many times in a coil shape, for example. Therefore, hereinafter, the intermediate portion 30 may be referred to as an optical fiber coil 30. The light source 20 is connected to one end 26 of the optical fiber 22, and the detector 24 is connected to the other end 28 of the optical fiber 22. In this way, light is inserted from the light source 20 into the optical fiber 22, and the light is detected by the detector 24 via the optical fiber 22.

  The optical fiber coil 30 is disposed so as to surround the scanning range 19 of the ion beam 12. In other words, the optical fiber coil 30 is provided so that the ion beam path 14 passes inside the optical fiber coil 30. Thus, the optical fiber coil 30 includes the entire scanning range 19 of the ion beam 12.

  The detector 24 is provided to detect the polarization state of the light emitted from the optical fiber 22. As the detector 24, a polarization detector having a known configuration for detecting the polarization state can be appropriately employed. For example, when the incident light to the optical fiber 22 is circularly polarized light, the detector 24 is configured to detect a phase shift of the emitted light with respect to the incident light. When the incident light to the optical fiber 22 is linearly polarized light, the detector 24 is configured to detect the rotation angle of the electric field vector of the emitted light. The detector 24 is disposed outside the processing chamber 16. The detector 24 is connected to the arithmetic processing unit 32 so as to output a signal representing the detection result.

  The ion beam measurement apparatus 10 includes an arithmetic processing unit 32. The arithmetic processing unit 32 may be an arithmetic device such as a known personal computer provided separately from the detector 24. The arithmetic processing unit 32 may be integrally mounted on the detector 24.

  The arithmetic processing unit 32 is provided to provide an ion beam measurement result based on the deviation of the polarization state between the light incident on the optical fiber 22 and the light emitted from the optical fiber 22. The arithmetic processing unit 32 calculates the magnetic field which acts on the optical fiber 22 from the detection result by the detector 24 like the so-called optical CT (Current Transformer). The arithmetic processing unit 32 converts the calculated magnetic field into a beam current of the ion beam 12 using a known relationship between the magnetic field and the current.

  The arithmetic processing unit 32 is configured to output a calculation result. The arithmetic processing unit 32 outputs an ion beam measurement result to a display means (for example, a display etc.) as needed. Alternatively, the arithmetic processing unit 32 outputs an ion beam measurement result to the control device in order to control the ion beam 12 by a control device (not shown) of the ion beam 12.

  In addition, the ion beam measurement apparatus 10 may include a magnetic shield (not shown) in order to suppress the influence of a magnetic field from the outside of the processing chamber 16 on the measurement, for example. The magnetic shield is provided, for example, inside the processing chamber 16 and is configured to surround the optical fiber 22 and the ion beam path 14. An opening for passing the ion beam 12 is formed at a portion intersecting the ion beam path 14 of the magnetic shield. The magnetic shield is also formed with an opening for passing one end 26 and the other end 28 of the optical fiber 22.

  Preprocessing for ion beam measurement will be described. The preprocessing includes calibration processing of the detector 24 by the arithmetic processing unit 32. The calibration process includes detecting the light emitted from the optical fiber 22 by the detector 24 when the ion beam 12 is not supplied to the processing chamber 16. That is, the calibration process includes detecting the polarization state of the light incident on the optical fiber 22.

  A measurement operation of the ion beam measurement apparatus 10 will be described. When the preprocessing is completed, the ion beam measurement apparatus 10 can start measurement. An ion beam 12 to be measured is supplied to the ion beam path 14. The workpiece 18 is irradiated with the ion beam 12. The optical fiber 22 is given light from the light source 20.

  The ion beam 12 generates a concentric magnetic field having the ion beam path 14 as a central axis. When this magnetic field acts on the optical fiber 22, Faraday rotation occurs in the light passing through the optical fiber 22. The outgoing light whose polarization state has changed due to the Faraday rotation is detected by the detector 24.

  The arithmetic processing unit 32 calculates the magnetic field acting on the optical fiber 22 from the deviation of the polarization state between the incident light to the optical fiber 22 and the outgoing light from the optical fiber 22. The arithmetic processing unit 32 calculates the beam current of the ion beam 12 from the magnetic field acting on the optical fiber 22.

  In this manner, the ion beam measurement apparatus 10 measures the magnetic field from the ion beam 12 using the Faraday effect, and obtains the ion beam current from the magnetic field by calculation. Therefore, according to the ion beam measuring apparatus 10, it is possible to perform non-contact measurement at an arbitrary timing while irradiating the workpiece 18 with the ion beam 12.

  The optical fiber 22 is disposed so as to surround the scanning range 19 of the ion beam 12. The magnetic field from the ion beam 12 acts on the optical fiber 22 regardless of the position of the ion beam 12 in the scanning range 19. Therefore, even when the ion beam 12 is scanned over the scanning range 19, the ion beam 12 can be measured in a non-contact manner over the scanning range 19.

  The optical fiber 22 is provided in the processing chamber 16 for irradiating the workpiece 18 with the ion beam 12. In a typical ion implantation apparatus, a contact type detector (for example, a Faraday cup) is provided outside the workpiece 18 and it is practically essential to irradiate the contact type detector with an ion beam for measurement. It is said that. However, according to one embodiment of the present invention, it is not necessary to irradiate the ion beam 12 outside the workpiece 18 for measurement of the ion beam 12. Therefore, the irradiation area of the ion beam 12 can be reduced in accordance with the inside of the workpiece 18. Thus, an improvement in the throughput of the ion beam 12 irradiation process and a reduction in the amount of ion material consumed are realized.

  Further, the light source 20 and the detector 24 are provided outside the processing chamber 16. In this way, a general-purpose light source and detector that are not necessarily compatible with the vacuum environment in the processing chamber 16 can be used.

  FIG. 2 is a diagram schematically showing an ion beam measurement apparatus 10 according to an embodiment of the present invention. The ion beam measurement apparatus 10 shown in FIG. 2 is different from the ion beam measurement apparatus 10 shown in FIG. 1 in that the optical fiber coil 30 is mounted on the final stage aperture 34. FIG. 2 is a plan view of the workpiece 18 viewed along the traveling direction of the ion beam 12. In the following description, the same portions of the ion beam measurement apparatus 10 shown in FIGS. 1 and 2 are omitted as appropriate in order to avoid redundancy.

  The optical fiber coil 30 is mounted on the final stage aperture 34 as described above. The last stage aperture 34 is a member arranged for beam shaping just before the workpiece 18 in the ion beam path 14. The final stage aperture 34 is, for example, a plate having an opening 36 corresponding to the scanning range 19 of the ion beam 12, and is supported in the vicinity of the workpiece 18 in the processing chamber 16. The optical fiber coil 30 surrounds the opening 36 of the final stage aperture 34. According to the ion beam measuring apparatus 10 shown in FIG. 2, the ion beam 12 can be measured in the vicinity of the workpiece 18.

  In the above, this invention was demonstrated based on the Example. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention. By the way.

  For example, the ion beam measurement apparatus 10 may measure the relative fluctuation of the ion beam 12. For example, the ion beam measurement apparatus 10 may measure the presence or absence of the ion beam 12. The arithmetic processing unit 32 may determine whether or not the ion beam intensity has decreased by comparing the detected magnetic field with a predetermined threshold value.

  10 ion beam measuring device, 12 ion beam, 14 ion beam path, 16 processing chamber, 19 scanning range, 20 light source, 22 optical fiber, 24 detector, 30 optical fiber coil, 32 arithmetic processing unit.

Claims (5)

An optical fiber arranged to circulate around the ion beam path;
A light source for providing incident light to the optical fiber;
A detector for detecting light emitted from the optical fiber;
An ion beam measurement apparatus comprising: an arithmetic unit for providing an ion beam measurement result based on a deviation in polarization state between the incident light and the emitted light.   The ion beam measurement apparatus according to claim 1, wherein the optical fiber is disposed so as to surround a scanning range of the ion beam.   The ion beam measuring apparatus according to claim 1, wherein the optical fiber is provided in a processing chamber for irradiating an object with an ion beam.   An ion implantation apparatus comprising the ion beam measurement apparatus according to claim 1. Supplying an ion beam;
Measuring an Faraday rotation of an electromagnetic wave in a substance in a magnetic field from the ion beam.

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