JP6692108B2 - Analysis device and analysis system - Google Patents

Description

  The present invention relates to an analysis device and an analysis system.

  In recent years, it has been found that the state of the substance in the sub-surface is rate-limiting for various performances of the substance. The sub-surface means a region for a few atomic layers just below the surface of the substance. As a means for analyzing the state of this subsurface, a high-resolution Rutherford backscattering analysis (HRBS) device and a high-resolution elastic recoil detection analysis device (HERDA) are used. It has been known. Here, the medium energy ion scattering (MEIS) device is regarded as a kind of HRBS, and HRBS is a predicate including MEIS.

  HRBS is an analysis method for identifying the composition (type of constituent element) of the sample surface by irradiating the sample surface with ions having a smaller atomic weight than the atoms to be quantified. When the surface of the sample is irradiated with helium ions or the like, the irradiated ions bounce backward due to elastic scattering with atomic nuclei in the sample. How the ions bounce back depends on the atomic weights of the constituent elements in the sample that is the object of collision. Therefore, the state of the subsurface of the sample can be measured by measuring the energy of the rebounded ions. For example, Non-Patent Document 1 describes an analyzer using HRBS.

  HERDA is an analysis method in which the sample surface is irradiated with ions having a larger atomic weight than the atoms to be quantified, and recoil particles ejected from the sample surface are detected. For example, among the constituent elements of the sample, a hydrogen element having a smaller atomic weight than the ion to be irradiated is ejected forward by the ion irradiation. By detecting the ejected hydrogen, the hydrogen content in the sample can be quantified. For example, Non-Patent Document 2 describes an analyzer using HERDA.

  In both the HRBS and HERDA analysis methods, it is required to increase the detection sensitivity. For example, in Non-Patent Document 3, a filter is provided in front of the detector to remove stray ions that enter the detector (also referred to as ions that enter while colliding on the chamber wall surface, stray particles) and are generated by the detector. It is described that the detection sensitivity of an analyzer using HRBS is increased by suppressing the dark current that occurs.

K. Kimura, M .; Mannami, Nuclear Instruments and Methods in Physics Research B, 113 (1996) 270-274. K. Kimura, K .; Nakajima, H .; Imura, Nuclear Instruments and Methods in Physics Research B, 140 (1998) 397-401. H. Hashimoto et al. , Review of Scientific Instruments, 82, 063301 (2011).

However, in the analyzers using HRBS and HERDA described in Non-Patent Documents 1 to 3, the detection sensitivity was about 10 ¹⁴ / cm ² , and the detection sensitivity was not sufficient.

For example, in semiconductor devices such as MOSFETs, nanoscale oxides are formed. Hydrogen in the oxide and at the interface between the oxide and the semiconductor has a great influence on the channel mobility of the transistor. Therefore, there is an increasing demand for quantitatively measuring the hydrogen content. However, this hydrogen exists only in an extremely small amount of 10 ¹² / cm ² , and accurate quantitative analysis cannot be performed with the detection sensitivity of the analyzers described in Non-Patent Documents 1 to 3.

  There is also an analyzer using a secondary ion mass spectrometry (SIMS) only for the purpose of increasing the detection sensitivity. However, SIMS destroys the sample because it measures while scraping the sample. Therefore, there is an urgent need for an analyzer that is nondestructive and has high detection sensitivity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an analyzer and an analysis system capable of nondestructively and highly sensitively analyzing the state near the surface of a sample.

As a result of intensive studies, the present inventor has thought that the conventional method using a microchannel plate as a detector of an analyzer may have a limit in detection sensitivity. Therefore, instead of a microchannel plate capable of only position detection, a position-sensitive semiconductor detector capable of performing energy analysis in addition to position detection was used in the analyzer. As a result, the present inventors have found that an unexpected effect that the detection sensitivity can be improved by two digits or more is exhibited, and completed the present invention.
The present invention provides the following means in order to solve the above problems.

(1) An analyzer according to one aspect of the present invention is installed in a chamber having an installation part on which an object to be measured can be installed, a conduit for guiding an ion beam generated by an accelerator toward the installation part, and the installation part. An analysis in which a magnetic field or an electric field is applied to recoil particles recoiled by irradiating the measured object with the ion beam, and the traveling direction of the recoil particles is changed to a direction corresponding to the energy of the recoil particles. And a position-sensitive semiconductor detector that has a detection unit that extends in a direction perpendicular to a plane parallel to the trajectory of the recoil particles and that can detect the recoil particles in each traveling direction thereof, and the position. And a measuring instrument connected to the sensitive semiconductor detector and digitizing and measuring charges generated in the position sensitive semiconductor detector.

(2) An analyzer according to one aspect of the present invention is installed in a chamber having an installation part on which an object to be measured can be installed, a conduit for guiding an ion beam generated by an accelerator toward the installation part, and the installation part. A magnetic field or an electric field is applied to scattered ions among the ion beams irradiated to the DUT, and an analysis unit that changes the traveling direction of the scattered ions in a direction corresponding to the energy of the scattered ions, A position-sensitive semiconductor detector that extends in a direction perpendicular to a plane parallel to the trajectory of scattered ions and has a detection unit that can detect the scattered ions in each traveling direction, and is connected to the position-sensitive semiconductor detector. And a measuring instrument which digitizes and measures the electric charge generated in the position sensitive semiconductor detector.

(3) In the analyzer according to any one of (1) and (2), a direction perpendicular to an extending direction of the detection unit and a direction in which the recoil particles or the scattered ions collide with the detection unit. In addition, it may have a configuration in which the detection unit moves in parallel.

(4) In the analyzer according to any one of (1) and (2) above, a direction perpendicular to the extending direction of the detection unit and the direction in which the recoil particles or the scattered ions collide with the detection unit. In addition, a plurality of the detection units may be arranged in parallel.

(5) In the analyzer described in (4) above, the ratio of the width d of the slit formed between the adjacent detection units and the pitch p of the adjacent detection units is d: p = 0.5. The relationship of: 10 to 2:10 may be satisfied.

(6) In the analyzer according to any one of (1) to (5), the thickness of the dead layer of the semiconductor used in the position-sensitive semiconductor detector may be 10 nm or more and 500 nm or less.

(7) In the analyzer according to any one of (1) to (6), the semiconductor used for the position-sensitive semiconductor detector is a pn junction type in which a dopant element is ion-implanted into an n-type semiconductor. It may be a semiconductor.

(8) In the analyzer according to any one of (1) to (6), the semiconductor used for the position-sensitive semiconductor detector is a Schottky barrier type semiconductor in which a metal film is laminated on the semiconductor. May be

(9) In the analyzer according to any one of (1) to (8) above, it is appropriate that the measuring instrument measures a time during which a peak of a potential generated by the electric charge exceeds a predetermined threshold value. A distinct signal may be distinguished from an inappropriate signal.

(10) In the analyzer according to (9), the measuring instrument may include a threshold value increasing unit that increases the predetermined threshold value in synchronization with a timing when a peak of a potential generated by the electric charge exceeds a predetermined threshold value. Good.

(11) An analysis system according to an aspect of the present invention includes the analysis device according to any one of (1) to (10) above, and an accelerator that supplies an ion beam to the analysis device.

  By using the analysis device and the analysis system according to one embodiment of the present invention, the state near the surface of the sample can be analyzed nondestructively and with high sensitivity.

It is the figure which showed typically the analyzer which used HERDA concerning one aspect of this invention. It is the figure which showed typically the 1st example of the position sensitive semiconductor detector in the analysis device which concerns on 1 aspect of this invention. It is the figure which showed typically the 2nd example of the position sensitive semiconductor detector in the analyzer which concerns on one aspect of this invention. It is sectional drawing which cut | disconnected the 2nd example of a position sensitive semiconductor detector by the AA surface of FIG. It is a circuit diagram of a processing circuit using the dTOT method. It is explanatory drawing explaining the timing which makes the increase threshold value Vref increase. 5 is a diagram showing the results of measuring the amount of hydrogen in amorphous carbon by the method of Example 1. FIG. 5 is a diagram showing the results of measuring the amount of hydrogen in amorphous carbon by the method of Comparative Example 1. FIG.

Hereinafter, an analyzer and an analysis system to which the present invention is applied will be described in detail with reference to the drawings as appropriate.
In the drawings used in the following description, in order to make the features of the present invention easier to understand, the features may be enlarged for convenience, and the dimensional ratios of the respective components may differ from the actual ones. Sometimes. Further, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented within the scope of the invention.

(Analyzer, analysis system: HERDA)
FIG. 1 is a diagram schematically showing an analyzer using HERDA according to one embodiment of the present invention.
The analysis apparatus 100 includes a chamber 10, a conduit 20, an analysis unit 30, a position-sensitive semiconductor detector 40, and a measuring instrument 50. In HERDA, recoil particles recoiled about 30 ° forward by injecting a beam of ⁴ He ⁺ or ¹⁶ O ⁺ accelerated by an electrostatic accelerator into the sample surface at an oblique incidence (about 15 ° from the surface). The number and energy of (eg, protons) are measured. Hereinafter, the principle of measurement will be described together with the configuration of each member based on FIG.

  Hereinafter, the direction from the back surface of the paper to the front surface is the z direction, the direction in which recoil particles are incident on the position sensitive semiconductor detector 40 is the y direction, and the direction perpendicular to the z direction and the y direction is the x direction.

  The chamber 10 has an installation unit 11 on which the object to be measured S can be installed. The installation unit 11 is fixed at any place in the chamber 10 so that the object S to be measured does not move during measurement. A known material can be used for the chamber 10, and for example, stainless steel or the like can be used.

  During use, the chamber 10 is evacuated by a vacuum pump (not shown). A known pump can be used as the vacuum pump.

  The chamber 10 has a plurality of connecting portions 12. As the connecting portion 12, a known flange or the like can be used. A conduit 20 is connected to any of the connecting portions 12.

  The conduit 20 guides an ion beam generated by an accelerator (not shown) to the object to be measured S installed in the installation unit 11 in the chamber 10. As the conduit 20, a known conduit can be used.

  The analysis unit 30 is connected to the chamber 10 via a connection 12 different from the conduit 20. In the analyzer using HERDA, the recoil particles recoiled by about 30 ° forward by the ion beam obliquely incident at about 15 ° are detected, and therefore the analysis unit 30 is connected to the chamber 10 according to the angle.

  A magnetic field is applied to the inside of the analysis unit 30 by a magnet. Although an electric field can be used, an example using a magnetic field will be described below. Recoil particles having an electric charge undergo Lorentz force due to a magnetic field, and their traveling directions are bent and changed. At this time, the low-energy recoil particles are largely bent in the traveling direction by the magnetic field. On the other hand, high-energy particles have a smaller change in traveling direction than low-energy recoil particles. That is, by passing through the analysis unit 30, the traveling direction of the recoil particles can be changed to the direction corresponding to the energy of the recoil particles.

  The magnetic field generated by the magnet is applied in the z direction in FIG. When an electric field is used, the electric field is applied in a direction perpendicular to the traveling direction of the recoil particles and not in the z direction. The recoil particles recoiled from the object S to be measured bend along the curve of the analysis unit 30. Therefore, the energy of the recoil particles becomes higher as going from the inner side to the outer side of the curve of the analysis unit 30.

  In the analysis unit 30, not only recoil particles whose traveling direction has changed according to the energy amount of the recoil particles but also stray particles are generated. Stray particles are recoil particles that have collided with the wall surface of the analysis unit 30 or the like. The stray particles change their traveling direction by colliding with the wall surface. Therefore, the stray particles after passing through the analysis unit 30 are not guided to the position corresponding to the energy amount. That is, the stray particles are one of the causes of noise in the analyzer. In order to increase the detection sensitivity of the analytical device, it is necessary to appropriately separate these stray particles.

  The position-sensitive semiconductor detector 40 is connected to the analysis unit 30. Recoil particles whose traveling direction has changed in the analysis unit 30 enter the position-sensitive semiconductor detector 40. The position-sensitive semiconductor detector 40 is a detector that is position-sensitive and can perform energy analysis. Position-sensitive means that it is possible to determine at which position of the detector an incident particle (here, a recoil particle) is incident. That is, the position-sensitive semiconductor detector 40 can determine at which position the recoil particles have been incident, and at the same time, determine whether the recoil particles that are incident are appropriate or improper. It can be sorted according to the amount of energy.

The position-sensitive semiconductor detector 40 has a detection unit that extends in a direction perpendicular to a plane parallel to the trajectory of recoil particles or scattered ions and can detect recoil particles or scattered ions in each traveling direction. .. Here, "the recoil particles or scattered ions can be detected in each traveling direction" means that the recoil particles or scattered ions can be detected along the amount of energy of the recoil particles or scattered ions.
Specifically, for example, the following two can be raised. FIG. 2 is a diagram schematically showing a first example of the position-sensitive semiconductor detector in the analyzer according to the aspect of the present invention. 3 and 4 are diagrams schematically showing a second example of the position-sensitive semiconductor detector in the analyzer according to the aspect of the present invention. FIG. 4 is a cross section taken along plane AA of the position sensitive semiconductor detector of FIG.

The position-sensitive semiconductor detector 41 of the first example shown in FIG. 2 has one detection unit 42 extending in the z direction and a slider 43 for moving the detection unit 42 in the x direction. The detection unit 42 need only be able to move in parallel in the x direction, and the slider 43 may be omitted.
When recoil particles are incident on the detection unit 42, electric charges are induced in the detection unit 42. This electric charge is digitized by the measuring device 50 and measured as a signal having one peak intensity.

  The recoil particles that enter the position-sensitive semiconductor detector 41 are analyzed by the magnet of the analysis unit 30, and the amount of energy that they have at each position in the x direction is different. Therefore, it is possible to assume at what position the detection unit 42 is arranged to obtain a peak of which intensity. For example, in the case where the detection unit 42 is arranged at the leftmost side in FIG. 2, the recoil particles incident on the detection unit 42 are mainly recoil particles that have passed around the analysis unit 30. That is, recoil particles of low energy mainly enter. On the other hand, in FIG. 2, the recoil particles that enter the detection unit 42 have high energy as the detection unit 42 is translated rightward. When the detection unit 42 is arranged on the far right, the recoil particles incident on the detection unit 42 have the highest energy.

  When the detection unit 42 is set at a predetermined position, the recoil particles incident on the detection unit 42 collide with the recoil particles appropriately analyzed by the analysis unit 30 and collide with the wall surface to become stray particles. It is a jump particle. At this time, the amount of energy of the recoil particles that have become stray particles is different from the amount of energy of the recoil particles that have been appropriately analyzed by the analysis unit 30. Therefore, the position-sensitive semiconductor detector 41 can clearly determine the recoil particles that have been properly analyzed by the analysis unit 30 and the recoil particles that have become stray particles by colliding with the wall surface or the like. That is, the recoil particles that have become stray particles can be processed as noise by the measuring device 50.

  In a conventional position-sensitive microchannel plate or the like, it is only possible to determine that particles have entered, and therefore it is not possible to distinguish between recoil particles that have been appropriately analyzed by the analysis unit 30 and recoil particles that have become stray particles. It was That is, the desired data and noise were both read as the same data by the measuring instrument 50 and could not be separated. On the other hand, since the position-sensitive semiconductor detector 41 can determine how much energy is incident, the measuring instrument 50 can separate desired data and noise. Therefore, since the position-sensitive semiconductor detector 41 is a detector that is position-sensitive and capable of performing energy analysis, the number of recoil particles generated from the measured object S can be detected with higher accuracy.

  When the recoil particles are, for example, protons, the protons are derived from hydrogen in the object S to be measured. Therefore, by detecting the number of protons incident on the position-sensitive semiconductor detector 41 with high accuracy, the object S to be measured can be detected. It is possible to more accurately determine the amount of hydrogen.

  The position-sensitive semiconductor detector 44 of the second example has a plurality of detectors 45 extending in the z direction and arranged in parallel. A plurality of slits 46 are provided between the detectors 45. The groove-shaped slit 46 is for enhancing the position sensitivity and is not always essential. Only a plurality of electrodes may be installed in parallel. When the slit 46 is provided, as shown in FIG. 4, the slit 46 only needs to be able to separate the insensitive layers 47 of the position-sensitive semiconductor detector 44 in its cross section, and it is necessary to penetrate the entire thickness direction of the semiconductor. There is no. The dead layer 47 will be described later.

  The slit 46 can be formed by using dry etching or the like. For example, by dry etching, a groove having a high aspect ratio with a slit width of less than 10 μm and a depth of 100 μm or more can be formed.

  The position-sensitive semiconductor detector 44 has a plurality of detection units 45, which are divided. Since the recoil particles that enter each detection unit 45 are analyzed by the magnet of the analysis unit 30, the amount of energy differs depending on the position. Therefore, the amount of energy of the recoil particles that enter each detection unit 45 can be estimated. Therefore, the position-sensitive semiconductor detector 44 of the second example, like the position-sensitive semiconductor detector 41 of the first example, includes recoil particles appropriately analyzed by the analysis unit 30 in each detection unit 45, The recoil particles that collided with the wall surface and became stray particles can be clearly determined. That is, the position sensitive semiconductor detector 44 can perform position sensitive and energy analysis. That is, the number of recoil particles, such as protons, incident on the position-sensitive semiconductor detector 44 can be detected with high accuracy, and in this example, the amount of hydrogen in the measured object S can be more accurately quantified.

  In the position-sensitive semiconductor detector 44, the ratio of the width d of the slit 46 formed between the adjacent detection units 45 and the pitch p of the adjacent detection units 45 is d: p = 0.5: 10 to 2: It is preferable to satisfy the relationship of 10. Here, the pitch of the adjacent detection units 45 means the distance from the end of one detection unit 45 to the corresponding end of the adjacent detection unit 45, as shown in FIG.

  If the width d of the slit 46 and the pitch p of the adjacent detection units 45 satisfy the above relationship, the sensitive area of the position-sensitive semiconductor detector 44 can be increased. The sensitive area means the area of the detection unit 45 in the position-sensitive semiconductor detector 44. If the sensitive area can be widened, recoil particles incident on the position-sensitive semiconductor detector 44 can be measured with high efficiency, and more precise measurement can be performed. For example, it is preferable that the pitch p is 100 μm and the width d of the slit is 10 μm.

  In both the position-sensitive semiconductor detector 41 of the first example and the position-sensitive semiconductor detector 44 of the second example, the thickness of the dead layer 47 of the detection units 42 and 45 is preferably 10 nm or more and 100 nm or less. ..

  The induction of electric charges by the incident recoil particles occurs at the interface of the pn junction of the semiconductor and the interface of the Schottky junction when the semiconductor and the metal are joined. Therefore, the dead layer 47 means a layer up to these bonding interfaces. For example, in the case of pn junction, the p-type semiconductor formed on the n-type semiconductor becomes the insensitive layer 47. In the case of Schottky junction, the metal layer laminated on the semiconductor becomes the dead layer 47.

  Recoil particles generated from the object S to be measured in an analyzer using HERDA are about several hundred keV, and the energy is small in the field of electron beams. Therefore, in order for the incident recoil particles to induce electric charges, it is preferable that the thickness up to the bonding interface (that is, the thickness of the dead layer 47) is thin. The thickness of the dead layer 47 is preferably as thin as possible, but is preferably 10 nm or more from the viewpoint of controllability.

The dead layer 47 can be formed by the following means.
When forming a pn junction, a dopant element can be injected into an n-type semiconductor to form a p-type semiconductor. For example, the n-type semiconductor can be Si, and the dopant element added thereto can be boron.

As a method of implanting the dopant element, there are a thermal diffusion method and an ion beam implantation method. From the viewpoint of depth controllability, an ion beam implantation method is preferable.
When forming a Schottky junction, a metal film can be laminated on the semiconductor by sputtering or the like. From the viewpoint of film thickness controllability and cost, the semiconductor used for the position sensitive semiconductor detectors 41 and 44 is preferably a Schottky barrier type semiconductor.

  As described above, since the position-sensitive semiconductor detector is a detector that is position-sensitive and can perform energy analysis, it is possible to separate stray particles and perform detection with less noise. In addition to this, compared with the microchannel plate, it also has an advantage that a false signal due to thermal fluctuation does not occur. The microchannel plate measures the recoil particles that have entered by the electron multiplication method using a high voltage. Therefore, a false signal is likely to occur due to thermal fluctuation. In order to remove this spurious signal, the microchannel plate requires various mechanisms such as taking coincidence with the secondary electron signal at the time of recoil particle incidence. On the other hand, the position-sensitive semiconductor detectors 41 and 44 have a low bias voltage of about 20 V, so that false signals due to thermal fluctuation do not occur in the first place, and high-accuracy measurement can be easily performed. Further, there is no fear of failure due to sudden discharge due to high voltage.

  Returning to FIG. 1, the measuring device 50 converts a current-voltage conversion circuit that converts a current pulse composed of charges induced by the position-sensitive semiconductor detector 40 into a voltage pulse, and an analog signal (voltage pulse) from the current-voltage conversion circuit. And a processing circuit for processing.

  In the measuring instrument 50, the method of processing the analog signal by the processing circuit differs depending on whether the position-sensitive semiconductor detector 41 of the first example or the position-sensitive semiconductor detector 44 of the second example is selected.

First, the case of using the position sensitive semiconductor detector 41 of the first example will be described.
The position-sensitive semiconductor detector 41 has only one detection unit 42. Therefore, only one analog-digital (AD) converter that converts the analog signal (voltage pulse) from the current-voltage conversion circuit into a digital signal is sufficient. As a method of obtaining the peak value by the AD converter, a filter integration method, a digital integration method expression or the like can be used. In addition to this, a TOT (Time over threshold) type AD converter may be used (see International Publication No. 2011/039819). These are properly used depending on the type of amplifier placed before inputting the signal to the AD converter and the input frequency of the signal.

  The filter integration method is a voltage pulse whose pulse wavelength, which is the sum of pulse rise time and decay time, of several tens of nanoseconds is shaped by a filter (CR integration) up to several μsec. Is a method of obtaining the peak value of the voltage pulse by sample-holding when a certain time (for example, 500 nsec) has passed after the threshold voltage exceeds the threshold voltage and AD-converting the peak value only once.

  The digital integration method is a voltage pulse whose pulse wavelength, which is the sum of pulse rise time and decay time, of several tens of nanoseconds is shaped by a filter (CR integration) up to several μsec. Is a method of calculating the peak value of the voltage pulse by performing AD conversion, for example, eight times at a constant time (for example, 20 nsec) after exceeding the threshold voltage, and adding all the peak values obtained by this AD conversion.

  In the TOT method, a voltage pulse whose pulse wavelength, which is the sum of the pulse rise time and the decay time, is several tens of nanoseconds is waveform-shaped by a filter (CR integration) up to several μsec. This is a method of obtaining the peak value of a voltage pulse by measuring the pulse time width from when the voltage exceeds the threshold voltage until it returns to the same threshold voltage.

  In the position sensitive semiconductor detector 41 of the first example, one AD converter is sufficient. Therefore, the control circuit and the processing circuit do not become complicated. Therefore, it is preferable to measure the crest value using a normal filter integration method or digital integration method. However, the position-sensitive semiconductor detector 41 needs to perform measurement while moving the detection unit 42. Therefore, it is necessary to collect data one by one, and it takes time to measure all the data.

Next, the case of using the position-sensitive semiconductor detector 44 of the second example will be described.
The position-sensitive semiconductor detector 44 has a plurality of detection units 45. Therefore, it is necessary to process the data from the plurality of detection units 45 in parallel. In this case, the filter integration method and the digital integration method require an enormous number of comparators including operational amplifiers. For example, considering a 1000-channel detector in which the detectors 45 are arranged in parallel at a pitch of 100 μm in a position-sensitive semiconductor detector 44 having a total length of 100 mm, the number of input channels of the AD converter is also 1000. A filter integration type or digital integration type AD converter having about 1000 input channels requires a huge number of comparators and is expensive. In addition, the processing circuit and the control circuit may be complicated.

  Therefore, in a multi-channel application such as the position sensitive semiconductor detector 44, it is preferable to use a TOT type processing circuit. In the TOT method, only one comparator is required for each channel of the AD converter, so that it is possible to avoid a large scale of equipment.

  In order to further improve the measurement accuracy in the processing circuit, it is more preferable to adopt the dTOT (dynamic Time over threshold) method. The dTOT method is a measurement method which is a modification of the TOT method in which the predetermined threshold value is increased in synchronization with the timing when the potential peak generated by the electric charge exceeds the predetermined threshold value. Therefore, the processing circuit of the dTOT system includes a threshold value increasing unit that increases the predetermined threshold value in synchronization with the timing when the peak of the potential generated by the electric charge exceeds the predetermined threshold value. Although the dTOT method has been proposed in the field of nuclear medicine diagnostic equipment as proposed in WO 2011/039819, it is not known in the field of polar surface analysis such as HERDA and HRBS. No examples have been used.

  FIG. 5 is a circuit diagram of a processing circuit using the dTOT method. The processing circuit 51 includes a comparator 52, a reference pulse generator 53, an initial threshold power supply 54, resistors 55 and 56, a capacitor 57, and a counter circuit 58.

  The comparator 52 compares the waveform-shaped analog pulse Pa with the initial threshold value Vth or the increase threshold value Vref corresponding to the reference voltage. The reference pulse generator 53 is a pulse generator that generates the reference pulse Pm having a predetermined peak value for a predetermined time when the analog pulse Pa is larger than the initial threshold value Vth. The initial threshold power supply 54 outputs an initial threshold Vth corresponding to the reference voltage to the comparator 52. The resistor 55 is connected between the initial threshold power supply 54 and the comparator 52. The capacitor 57 and the resistor 56 are used to increase the increase threshold Vref. The counter circuit 58 measures the peak value of the digital pulse Pd output from the comparator 52. Here, the capacitor 57 and the resistor 56 correspond to the threshold increasing means.

  The comparator 52 turns on the output when the voltage pulse applied to the signal input (plus side) terminal exceeds a predetermined threshold value set for the reference voltage input (minus side), and the voltage pulse is set as the reference voltage. When it falls below a predetermined threshold, the output is turned off. That is, when the analog pulse Pa exceeds the initial threshold value Vth set as the reference voltage, the comparator 52 turns on the output of the digital pulse Pd. Then, when the analog pulse Pa falls below the increase threshold Vref set as the reference voltage while being attenuated after passing the peak value, the comparator 52 turns off the output. The comparator 52 outputs the digital pulse Pd to the reference pulse generator 53 and the counter circuit 58.

  The initial threshold value Vth is a constant voltage value. The initial threshold value Vth is preferably a low voltage value. This is because the higher the peak value of the voltage pulse, the shorter the time until it exceeds the initial threshold Vth, and the lower the peak value, the longer the time until it exceeds the initial threshold Vth. As a result, if voltage pulses with different peak values are measured at the same time, the voltage pulse with the higher peak value is earlier in the timing of exceeding the initial threshold value Vth. Therefore, by setting the initial threshold value Vth as low as possible, it is possible to suppress the variation in the rising timing.

  The reference pulse generator 53 generates a reference pulse Pm having a predetermined time width and a predetermined crest value, triggered by the rising when the digital pulse Pd is turned on. The reference pulse generator 53 is composed of a one-shot multivibrator circuit (monostable multivibrator circuit) having a capacitor 59 and a resistor 60. The reference pulse Pm is given to the capacitor 57 and the resistor 56. The reference pulse generator 53 does not output another reference pulse Pm even if another pulse is input during turning on of the reference pulse Pm. The predetermined time width of the reference pulse Pm is determined by the time constant determined by the product of the capacitance of the capacitor 59 and the value of the resistor 60 that form the reference pulse generator 53. The predetermined peak value of the reference pulse Pm is a fixed voltage value. The peak value when the reference pulse Pm is OFF is the same voltage value as the initial threshold value Vth.

  The capacitor 57 accumulates electric charges while the reference pulse Pm is applied to the capacitor 57. The capacitor 57 raises the reference voltage set in the comparator 52 due to the accumulation of charges. As a result, the capacitor 57 increases the increase threshold value Vref over the predetermined time width of the reference pulse Pm. The time constant determined by the product of the capacitance of the capacitor 57 and the value of the resistor 56 is set according to the time when the increase threshold Vref increases, that is, the predetermined time width of the reference pulse Pm.

  In this way, when the reference pulse Pm is fed back as the reference voltage of the comparator 52 via the resistor 56 and the capacitor 57, the increase threshold Vref rises with time after exceeding the initial threshold Vth. The voltage value of the increase threshold Vref is determined by Vm × (1−exp (−t / τ)). Here, Vm is the peak value of the reference pulse Pm. t is the time after the increase threshold Vref exceeds the initial threshold Vth. τ is a time constant determined by the product of the capacitance of the capacitor 11 and the value of the resistor 12. The increase threshold Vref exponentially increases as the value of t increases, and approaches the peak value Vm. As the time constant τ increases, the time to approach the crest value Vref becomes longer, and as the time constant τ decreases, the time to approach the crest value Vref becomes shorter. Therefore, the time constant τ can be freely set by the combination of the capacitor 57 and the resistor 56 within the range of the pulse time width Tm of the reference voltage Pm.

  The counter circuit 58 measures the pulse crest value by measuring the pulse time width of the digital pulse Pd. That is, the counter circuit 58 generates the counter pulse in synchronization with the rising edge of the digital pulse Pd, and stops the counter pulse in synchronization with the falling edge of the digital pulse Pd. Then, the peak value of the analog pulse Pa is measured according to the number of pulses counted during this period.

  As described above, since the dToT circuit is as simple as one ToT and has only one comparator, an application specific integrated circuit (ASIC) with a size of about 10 millimeters square has several dozen channels of AD converters. Is suitable for parallel processing of multiple data.

  Next, the timing of increasing the increase threshold Vref will be described with reference to FIG. FIG. 6 is a timing chart in which the vertical axis represents the pulse peak value and the horizontal axis represents the pulse time width. Pa1, Pa2, and Pa3 are analog pulses input to the comparator 52. Pd1, Pd2 and Pd3 are digital pulses output from the comparator 52. Wtot1, Wtot2, and Wtot3 are pulse widths of Pd1, Pd2, and Pd3. Pm is a reference pulse output from the reference pulse generator 53. Tm is the pulse width of the reference pulse Pm, and Vm is the peak value of the reference pulse Pm. The increase threshold Vref increases so as to approach the peak value Vm of the reference pulse.

  The digital pulse Pd1 rises in synchronization with the timing when the analog pulse Pa1 exceeds the initial threshold Vth, and the digital pulse Pd1 falls in synchronization with the timing when the analog pulse Pa1 falls below the increase threshold Vref. The reference pulse Pm rises with the rising of the digital pulse Pd1 as a trigger, and the reference pulse Pm falls after a lapse of a predetermined time Tm. The increase threshold value Vref increases in synchronization with the rising of the reference pulse Pm. The increase threshold Vref increases even after exceeding the cross point potential Vcp1 with the analog pulse Pa1 and attenuates to the initial threshold Vth in synchronization with the fall of the reference pulse Pm. Since Pa2 and Pa3 are the same as Pa1, the description thereof will be omitted.

Crosspoint potentials Vcp1 ′, Vcp2 ′, Vcp3 ′ between the analog pulses Pa1, Pa2, Pa3 and the initial threshold value Vth are generated in a short time, but the crosspoint potentials Vcp1, Vcp2, Vcp3 are Vcp1 ′, Vcp2 ′, The time interval is sufficiently wider than that of Vcp3 '. The pulse time widths Wtot1, Wtot2, Wtot3 are sufficiently different corresponding to the pulse crest values of the analog pulses Pa1, Pa2, Pa3.
That is, by using the dTOT method as compared with the TOT method, it is possible to accurately convert the pulse time width into a peak value.

  Unlike the semiconductor detector 41 of the first example, the semiconductor detector 44 of the second example processes data in parallel. Therefore, the data can be processed at higher speed. Also, by using the dTOT method, it is possible to avoid making the device large and to perform accurate measurement.

(Analyzer, analysis system: HRBS)
The measuring apparatus using the HRBS of the present invention includes a chamber having an installation part on which an object to be measured can be installed, a conduit for guiding an ion beam generated by an accelerator toward the installation part, and an object to be measured installed on the installation part. A magnetic field is applied to scattered scattered ions in the irradiated ion beam to change the traveling direction of the scattered ions in a direction corresponding to the energy of the scattered ions, and a plane parallel to the trajectory of the scattered ions. A position-sensitive semiconductor detector having a detector extending in a vertical direction, and a measuring device connected to the position-sensitive semiconductor detector for measuring electric charges generated in the position-sensitive semiconductor detector by digitizing the electric charges are provided.

  The analysis device 100 is the same as the above-described analysis device 100 using HERDA, except that the components separated by the analysis unit and the components detected by the position-sensitive semiconductor detector are changed from recoil particles to scattered ions.

  Therefore, there is almost no difference in configuration between the analyzer using HRBS and the analyzer using HERDA. The structural difference between the analyzer using the HRBS and the analyzer 100 using the HERDA is that the chamber 10 and the analyzer 30 are connected via the connector 12 closer to the conduit 20 in FIG.

This different connection portion 12 is used because HERDA measures recoil particles ejected from the measured object S, whereas HRBS measures scattered ions elastically scattered by the measured object S. In the HRBS, the ion beam incident from the conduit 20 is backscattered by the object S to be measured, so that the analysis unit 30 is connected to the conduit 20 side as compared with the case of HERDA.
Other configurations can be the same as the configuration of the analyzer 100 using the HERDA described above, and thus description thereof will be omitted.

  The analysis device of the present invention (the analysis device using HERDA and the analysis device using HRBS) has a position-sensitive semiconductor detector capable of performing position-sensitive and energy analysis. Therefore, the detection accuracy can be improved by two digits as compared with the conventional analyzer. As a result, the analyzer using HERDA can quantitatively analyze the light elements in the sample, and the analyzer using HRBS can more accurately analyze the composition of the elements in the sample. For example, it is possible to quantify the content of a very small amount of hydrogen such as hydrogen in the oxide of a semiconductor device such as MOSFET and at the interface between the oxide and the semiconductor. The brittleness of steel can also be measured by measuring the amount of hydrogen in the steel. In addition, it is possible to confirm the contamination of the fuel cell.

(Analysis system)
An analysis system of the present invention includes the above-described analysis device and an accelerator that supplies an ion beam to the analysis device. The ion beam is delivered from the accelerator to the analyzer conduit.
The accelerator is not particularly limited as long as it can output energy of about 1 MV. For example, a known tandem accelerator or the like can be used.
Since the analysis system of the present invention has the above-mentioned analysis device, it can analyze the state near the surface of the sample nondestructively and with high sensitivity.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the gist of the present invention described in the claims. Can be modified and changed.

  Examples of the present invention will be described below. The present invention is not limited to the following examples.

(Example 1)
An analyzer having the configuration shown in FIG. 1 was prepared. Amorphous carbon containing hydrogen was set as the object to be measured in the installation section. This hydrogen-containing amorphous carbon was irradiated with 500 keV ¹⁶ O ⁺ as an ion beam by an accelerator.
Then, the protons ejected from the amorphous carbon by the ion beam were detected by the semiconductor detector. At this time, the analysis unit used a 90 ° magnet that curves 90 ° from the entrance to the exit. As the semiconductor detector, the first semiconductor detector shown in FIG. 2 was used. The detection unit had a width of 1 mm and a length of 8 mm, and was moved in parallel in the width direction to perform detection 21 times. The result is shown in FIG. 7. In FIG. 7, the vertical axis represents the number of hydrogen signal counts, and the horizontal axis represents the energy intensity of hydrogen.

(Comparative Example 1)
Comparative Example 1 differs from the analyzer of Example 1 only in that the semiconductor detector is changed to a microchannel plate. Other configurations and measurement conditions were the same. The measurement result is shown in FIG. In FIG. 8, the vertical axis is the number of hydrogen signal counts, and the horizontal axis is the position in the width direction where hydrogen is incident.

  As shown in FIGS. 7 and 8, the hydrogen signal-to-noise intensity ratio in Example 1 is 1000: 1, whereas the hydrogen signal-to-noise intensity ratio in Comparative Example 1 is 10: 1. That is, when the analysis is performed under the same conditions, it can be confirmed that the analyzer of Example 1 has a two-digit higher sensitivity than the analyzer of Comparative Example 1.

  The horizontal axes in FIGS. 7 and 8 are different because Comparative Example 1 does not have energy analysis capability and can only perform position analysis. In any case, noise is detected when the count number is near zero.

  10 ... Chamber, 11 ... Installation part, 12 ... Connection part, 20 ... Conduit, 30 ... Analysis part, 40 ... Semiconductor detector, 41 ... First semiconductor detector, 42 ... Detection part, 43 ... Slider, 44 ... 2 semiconductor detector, 45 ... Detection part, 46 ... Slit, 47 ... Insensitive layer, 48 ... Semiconductor, 50 ... Measuring instrument, 51 ... Processing circuit, 52 ... Comparator, 53 ... Reference pulse generator, 54 ... Initial threshold value Power source, 55, 56, 60 ... Resistor, 57, 59 ... Capacitor, 58 ... Counter circuit, 100 ... Analytical device

Claims (9)

A chamber having an installation part on which an object to be measured can be installed,
A conduit for guiding the ion beam generated by the accelerator toward the installation section,
A magnetic field or an electric field is applied to the recoil particles recoiled by irradiating the object to be measured installed in the installation section with the ion beam, and the recoil particles have a direction corresponding to the energy of the recoil particles. An analysis unit that changes the direction of travel,
A position-sensitive semiconductor detector that has a plurality of detection units that extend in a direction perpendicular to a plane parallel to the trajectory of the recoil particles and that can detect the recoil particles in each traveling direction thereof,
A measuring instrument that is connected to the position-sensitive semiconductor detector and that digitizes and measures the electric charge generated in the position-sensitive semiconductor detector ;
The plurality of detection units are a plurality of detection units arranged in a direction perpendicular to the extending direction of the plurality of detection units and the recoil particles colliding with the plurality of detection units,
The measuring instrument includes an AD converter,
The AD converter includes a plurality of input channels,
The plurality of input channels have different threshold voltages,
The analyzer in which each of the plurality of detection units is set to a different input channel . A chamber having an installation part on which an object to be measured can be installed,
A conduit for guiding the ion beam generated by the accelerator toward the installation section,
A magnetic field or an electric field is applied to scattered ions scattered out of the ion beam with which the object to be measured installed in the installation unit is changed, and the traveling direction of the scattered ions is changed to a direction corresponding to the energy of the scattered ions. An analysis section to
A position-sensitive semiconductor detector that extends in a direction perpendicular to a plane parallel to the trajectory of the scattered ions, and has a plurality of detection units that can detect the scattered ions in each traveling direction thereof,
A measuring instrument that is connected to the position-sensitive semiconductor detector and that digitizes and measures the electric charge generated in the position-sensitive semiconductor detector ;
The plurality of detection units are a plurality of detection units arranged in a direction perpendicular to the extending direction of the plurality of detection units and the collision direction of the scattered ions to the plurality of detection units,
The measuring instrument includes an AD converter,
The AD converter includes a plurality of input channels,
The plurality of input channels have different threshold voltages,
The analyzer in which each of the plurality of detection units is set to a different input channel . Wherein the plurality of the width d of the slit formed between the detection portion you adjacent ones of the detecting portion, the ratio of the pitch p of the detection unit adjacent, d: p = 0.5: 10~2 : 10 The analysis device according to claim 1 or 2 , wherein the relationship is satisfied. The thickness of the insensitive layer of the semiconductor used for the said position sensitive semiconductor detector is 10 nm or more and 500 nm or less, The analysis apparatus as described in any one of Claims 1-3 . The location semiconductor used in sensitive semiconductor detector, n-type semiconductor with respect to analyzer according to any one of claims 1 to 4, characterized in that the dopant element is a semiconductor ion implanted pn junction .. The location semiconductor used in sensitive semiconductor detector, analyzer according to any one of claims 1 to 4, characterized in that a metal film on a semiconductor is a semiconductor of the Schottky barrier type stacked. Claim 1-6, wherein the instrument, the peak of the potential generated by the charge is characterized by distinguishing between improper signal and appropriate signal to measure the time exceeding the predetermined said threshold voltage The analyzer according to any one of 1. The instrument, according to claim 7 in which the peak of the potential generated by the charge, characterized in that it comprises a threshold voltage increasing means for increasing said predetermined the threshold voltage in synchronism with the timing above a predetermined said threshold voltage Analyzer. An analyzer according to any one of claims 1 to 9 ,
And an accelerator for supplying an ion beam to the analyzer.

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