JP2884164B2 - Two-dimensional charged particle detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle detection device using a solid-state imaging device used for a secondary ion mass spectrometer or the like.

[Conventional technology]

Conventionally, a detector having a configuration as shown in FIG. 4 has been used in a secondary ion detector of a secondary ion mass spectrometer to measure the surface distribution of ions. That is, in the figure, 10
Reference numeral 1 denotes a multi-channel plate that plays a role of converting incident secondary ions into electrons. 102 is a fluorescent substance called P1, which converts incident electrons into light. Numeral 103 denotes a solid-state image sensor composed of a CCD or the like, which converts light into an electric signal. In the detector configured as described above, the secondary ions incident on the multi-channel plate 101 are converted into the fluorescent substance 102 and the solid-state image sensor 103.
And converted into an electric signal, and the surface distribution of secondary ions was measured.

[Problems to be solved by the invention]

By the way, the conventional secondary ion detector having the above configuration has a narrow dynamic range of about 200 per channel, and the dead time for the ion beam is 10 μsec because the multi-channel plate is an insulator.
Therefore, if two or more secondary ions are incident within 10 μsec, they are detected as one and a problem arises in quantitative performance. Further, there is a problem that the configuration of the device is complicated.

The present invention has been made in order to solve the above-mentioned problems in a charged particle detection device such as a conventional secondary ion detector, and has a wide dynamic range and a surface of a charged particle such as a secondary ion excellent in quantitative performance. It is an object of the present invention to provide a charged particle detection device having a simple configuration for measuring distribution.

[Means and Actions for Solving the Problems]

In order to solve the above problems, the present invention provides a two-dimensional charged particle detection device using a two-dimensional solid-state imaging device, which is isolated while maintaining ohmic contact with a PN junction of a light receiving unit of the solid-state imaging device. By providing the formed charged particle detection metal electrode, the charged particles are made incident on the charged particle detection metal electrode of the two-dimensional solid-state imaging device to change the charged state of the metal electrode, the PN junction of the PN junction It is configured to detect a charged particle by detecting a potential change.

In the two-dimensional charged particle detector configured as described above, charged particles such as an ion beam are charged to the charged particle detection metal electrode that is isolated while maintaining ohmic contact with the reverse-biased PN junction. Upon arrival, the charged state of the charged particle detection metal electrode changes due to secondary electron emission, charging by the charged particles themselves, and the like. A change in the potential of the PN junction in ohmic contact with the charged particle metal electrode due to the change in the charged state is read out, and detection can be performed by converting the charged particles into an electric signal.

In the two-dimensional charged particle detector configured as described above, the charged particles are incident on the charged particle detection metal electrode provided in the solid-state imaging device to detect the charged particles, and the charged particles are directly detected by the solid-state imaging device. Therefore, the solid-state imaging device is not damaged, and the life can be extended. Also, depending on the type of charged particles to be detected, the type of metal used for the charged particle detection metal electrode can be freely selected, and a highly versatile charged particle detection device can be easily obtained. Since the charged particle detector is used, the aperture ratio can be made close to 100%, and high sensitivity can be obtained. In addition, by increasing the thickness of the metal electrode for detecting charged particles, it is possible to strengthen the sputtering effect due to ion collision, and the light receiving portion composed of the PN junction of the solid-state imaging device is a metal electrode. Since it is covered, advantages such as elimination of light shielding means are obtained.

Further, since the multi-channel plate is not used, the configuration is simplified, the dead time is eliminated, and the surface distribution of the charged particles excellent in quantitative performance can be easily measured.

〔Example〕

Hereinafter, embodiments will be described. FIG. 1 is a schematic perspective view showing a first configuration example of a two-dimensional charged particle detection device related to the present invention. In the first configuration example, a fluorescent substance 2 is formed on the surface of a two-dimensional solid-state imaging device 1 to constitute a two-dimensional charged particle detection device. As the fluorescent substance 2, KBr,
A material that converts an ion beam into light, such as tantalum oxide or ZnO, is used. The solid-state imaging device 1 is required to have high sensitivity because the light incident from the fluorescent substance 2 is weak.
nsistor: SIT) or CMD (Charge Modulatio)
It is preferable to use an internal amplification type solid-state imaging device such as n Device).

In the two-dimensional charged particle detector configured as described above, when the ion beam 3 is incident on the fluorescent substance 2, light is generated, and the emitted light is detected by the solid-state imaging device 1. Thereby, the amount of incident ions can be detected. In this configuration example, the solid-state imaging device can be used as it is, so that it is easy to create a detection device. In addition, the versatility of the detection device can be expanded by appropriately selecting a fluorescent substance according to the type of ion beam. In addition, since the ion beam does not directly enter the solid-state imaging device, the solid-state imaging device is not damaged, and a long-life detection device can be obtained. Further, by using a cooling device to cool the solid-state imaging device, higher sensitivity can be realized.

FIG. 2A is a schematic perspective view showing a second configuration example of the two-dimensional charged particle detection device related to the present invention. In this configuration example, a charged particle detection device is configured with only the two-dimensional solid-state imaging device 10, and is configured to detect charged particles such as an ion beam directly incident on the solid-state imaging device 10.

In the case of a solid-state imaging device that detects ordinary light, the structure of a light receiving section in a unit pixel is configured as shown in FIG. 2 (B). That is, in FIG. 2B, reference numeral 11 denotes, for example, a P-type semiconductor substrate, and an N-type diffusion layer 12 is provided on the surface of the substrate 11.
Are formed by diffusion, and a transparent protective insulating film 13 is formed to cover the entire surface. As the light receiving operation,
When the incident light 14 reaches the positively reverse-biased diffusion layer 12, a hole-electron pair is generated, and electrons are accumulated in the diffusion layer, so that the potential of the diffusion layer 12 changes. By detecting this potential change, the amount of light is detected by photoelectric conversion.

On the other hand, the solid-state imaging device 10 used for detecting charged particles such as an ion beam has a configuration shown in FIG. 2 (C). In FIG. 2C, reference numeral 21 denotes, for example, an N-type semiconductor substrate, and a P-type diffusion layer 22 is provided on the surface of the semiconductor substrate 21.
Are formed by diffusion. On the surface, a diffusion layer 22
A transparent protective insulating film 23 whose window is opened is coated.

The operation of detecting charged particles such as an ion beam by the solid-state imaging device 10 configured as described above is performed when the incident ion beam 24 reaches the negatively-biased P-type diffusion layer 22 by secondary electron emission and ions themselves. The potential of the diffusion layer 22 changes due to charging, hole / electron pair generation, and the like. By detecting this potential change, detection is performed by converting charged particles such as ion beams into electric signals.

This configuration example can be easily manufactured because the configuration is further simplified, and can use not only secondary electron emission and charging by the ions itself, but also the generation of a hole-electron pair as a signal. Can be increased. Further, as in the first configuration example, the sensitivity is further improved by using an amplifying solid-state imaging device such as SIT or CMD as the solid-state imaging device, or by cooling the solid-state imaging device using a cooling device. Can be.

FIG. 3 is a diagram showing a schematic cross-sectional structure of an embodiment of the two-dimensional charged particle detection device according to the present invention. In this embodiment, similarly to the related second configuration example, the charged particle detection device is constituted only by the two-dimensional solid-state imaging device alone. Are different. That is, in FIG.
Reference numeral 31 denotes, for example, an N-type semiconductor substrate, on the surface of which a P-type diffusion layer 32 is formed by diffusion. On the surface thereof, a transparent protective insulating film 33 in which a window of the diffusion layer 32 is opened is formed, and further a metal made of aluminum or the like isolated so as to cover the window opening 33a of the protective insulating film 33. An electrode 34 is formed. The metal electrode 34 and the diffusion layer 32 are opened with a window 33a.
It is configured to make ohmic contact via the.

The charged particle detection operation in the charged particle detection device configured as described above is performed as follows. That is, the metal electrode 34 formed on the diffusion layer 32 reversely biased negatively
When the incident ion beam 35 arrives, secondary electron emission,
The potential of the diffusion layer 32 changes due to charging by the ions themselves. By detecting this potential change, it is possible to perform detection by converting the ion beam into an electric signal.

In this embodiment, since the ion beam does not directly enter the diffusion layer of the solid-state imaging device, a long-life detection device can be provided without damaging the diffusion layer. Further, the type of metal used for the metal electrode 34 can be freely selected according to the type of ion beam to be detected, and a highly versatile detection device can be easily obtained. Further, since the aperture ratio according to this embodiment can be made close to 100%, the sensitivity is high, and by increasing the thickness of the metal electrode 34, the sputtering effect due to ion collision can be enhanced. Further, since the light receiving portion is covered with the metal electrode, there is an advantage that light shielding is not required and the configuration is simplified. Further, in the present embodiment, as in the first configuration example, higher sensitivity can be achieved by using the amplification type solid-state imaging device and its cooling means.

In the above embodiment, the detection of an ion beam is described. However, the present invention can of course detect not only ions but also other charged particles such as electrons.

〔The invention's effect〕

As described above with reference to the embodiments, according to the present invention, since a multi-channel plate is not used, dead time is eliminated, and the surface distribution of charged particles excellent in quantitative performance can be measured. Also, by using an internal amplification type solid-state imaging device such as SIT or CMD as a two-dimensional solid-state imaging device, signal charges generated several times for one charged particle can be amplified to a detectable level. As a result, high sensitivity can be achieved. Further, since the wide dynamic range of the internal amplification type solid-state imaging device can be used as it is, there is obtained an advantage that the dynamic range of the detection device can be widened.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a first configuration example of a two-dimensional charged particle detection device related to the present invention, and FIG. 2 (A) is a schematic perspective view showing a second configuration example of the same. FIG. 2B is a schematic cross-sectional view showing a configuration of one pixel portion when the two-dimensional solid-state imaging device performs photoelectric conversion, and FIG. 2C is a diagram of the two-dimensional solid-state imaging device used in the second configuration example. FIG. 3 is a schematic cross-sectional view showing the configuration of one pixel portion. FIG. 3 is a schematic cross-sectional view showing the configuration of one pixel portion of a two-dimensional solid-state imaging device in the embodiment of the two-dimensional charged particle detection device according to the present invention. FIG. 1 is a schematic perspective view showing a configuration example of a conventional charged particle detector. In the figure, 1 is a two-dimensional solid-state imaging device, 2 is a fluorescent substance,
Reference numeral 3 denotes an incident ion beam, 10 denotes a two-dimensional solid-state imaging device, 21 denotes an N-type semiconductor substrate, 22 denotes a P-type diffusion layer, 23 denotes a transparent protective insulating film, and 34 denotes a metal electrode.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-48-86491 (JP, A) JP-A-56-61180 (JP, A) JP-A-63-86472 (JP, A) JP-A 47-8647 27076 (JP, A) JP-A-64-84176 (JP, A) JP-A-63-101788 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01T 1/00-7 / 12 H01L 31/00 H01L 27/14

Claims (2)

(57) [Claims] 1. A two-dimensional charged particle detection device using a two-dimensional solid-state imaging device, wherein a P-type light-receiving portion of the solid-state imaging device is provided.
A charged particle detection metal electrode formed in isolation while maintaining ohmic contact at the N junction is provided, and charged particles are made incident on the charged particle detection metal electrode of the two-dimensional solid-state imaging device to change the charged state of the metal electrode. The two-dimensional charged particle detection device is configured to detect a charged particle by detecting a potential change of the PN junction by changing the potential. 2. The two-dimensional charged particle detection device according to claim 1, wherein the metal constituting the charged particle detection metal electrode is selected and set according to the type of the charged particle to be detected.