The present invention relates to an X-ray detector and an X-ray measurement device using the same.
An XRF (X-Ray Fluorescence analyzer, fluorescent X-ray detector) is a device not only capable of performing qualitative and quantitative analysis of a substance, but also capable of evaluating a thickness, a laminated state, and the like of the substance by irradiating the substance with an X-ray and detecting a fluorescent X-ray generated from the substance. Currently, as improvement of an X-ray detector progresses, a fluorescent X-ray detector small enough to use on a desk and having high sensitivity has been popularized. A semiconductor detector (Silicon Drift Detector: SDD) which detects the X-ray contributed to miniaturization of the XRF. The largest characteristic of the SDD is that the SDD does not only have high detection sensitivity and a small size, but also does not require a large cooling device. In the X-ray detector, it is desirable that the detection sensitivity is high in a wide energy band ranging from low energy to high energy.
In JP-A-2014-21000 (PTL 1), disclosed is a radioactive ray detector of a structure in which a signal line connects a substrate, a radioactive ray detection element, and a preamplifier through a through hole provided on the substrate such as a wiring substrate, and the like.
PTL 1: JP-A-2014-21000
In the above-mentioned X-ray detector, detection efficiency deteriorates as an X-ray becomes high energy, depending on a thickness of a Si substrate forming the X-ray detector. In an SDD manufactured with a Si substrate having a standard thickness of 0.5 mm, when incident energy exceeds 10 keV, the detection efficiency dramatically deteriorates. For this reason, there exists a method of increasing the thickness of the Si substrate as away of improving the detection efficiency of the X-ray having X-ray energy equal to or greater than 10 keV.
However, to manufacture the SDD with the thick Si substrate, there exist problems such as demand of developing and purchasing a dedicated device, decrease of a window region having high detection efficiency as the Si substrate becomes thicker, and demand of a separate high-voltage circuit. On the other hand, there exists a method of making a multi-detector by arranging or laminating a plurality of SDDs without changing the substrate thickness of the SDD. However, as the number of SDDs increases, there exist problems that an occupancy area and a volume of the X-ray detector are increased, and the cost is also increased by the increased number of amplifiers and circuits.
Patent Literature 1 does not particularly describe the energy sensitivity of radioactive ray detected by the radioactive ray detection element.
An object of the present invention is to provide a technology capable of improving the detection efficiency of the X-ray while maintaining high resolution.
The object and new features of the present invention will become apparent from descriptions of this specification and the accompany drawings thereof.
Among the embodiments disclosed in this application, an outline of the representative embodiment will be briefly described as follows.
A representative X-ray detector includes a first semiconductor chip that detects an X-ray generated from a sample with a first energy sensitivity, and a second semiconductor chip that detects the X-ray with a second energy sensitivity different from the first energy sensitivity. The representative X-ray detector further includes a first signal line electrically connected to the first semiconductor chip, a second signal line electrically connected to the second semiconductor chip, and an amplifier that is electrically connected to the first signal line and the second signal line and amplifies a signal.
A representative X-ray measurement device includes a stage that holds a sample, an X-ray generation source that irradiates an X-ray on the sample, an X-ray detector that detects an X-ray generated from the sample, and a first processing part that edits a signal transmitted from the X-ray detector. Here, the X-ray detector includes a first semiconductor chip that detects the X-ray generated from the sample with a first energy sensitivity, and a second semiconductor chip that detects the X-ray generated from the sample with a second energy sensitivity different from the first energy sensitivity. The X-ray detector further includes a first signal line electrically connected to the first semiconductor chip, a second signal line electrically connected to the second semiconductor chip, and an amplifier that is electrically connected to the first signal line and the second signal line and amplifies a signal.
Among the inventions disclosed in this application, effects acquired by the representative invention will be briefly described as follows.
An X-ray detector and an X-ray measurement device including the X-ray detector are capable of improving detection efficiency of an X-ray while maintaining high resolution. It is possible to improve the detection efficiency of the X-ray by preventing an increase in cost without increasing an occupancy area and a volume of the X-ray detector.
As illustrated in
To describe a configuration of the X-ray detector 12, the X-ray detector 12 includes a first SDD chip (first semiconductor chip) 1 that irradiates a sample (specimen) 24 illustrated in
The X-ray detector 12 includes a first signal line 3 electrically connected to the first SDD chip 1, a second signal line 4 electrically connected to the second SDD chip 2, and an amplifier 5 that is electrically connected to the first signal line 3 and the second signal line 4 and amplifies a signal.
The X-ray detector 12 includes a Peltier 10 that absorbs heat of each element (each semiconductor chip), and a thermistor 8 which is a temperature sensor that detects a temperature of each element (each semiconductor chip) is mounted thereon.
The X-ray detector 12 is provided with a control part 11 that is electrically connected to each semiconductor chip, the Peltier 10, the thermistor 8, and the like, and controls power supply control, temperature control, signal processing, and the like.
In the X-ray detector 12, the first SDD chip 1 and the second SDD chip 2 are disposed to be laminated, and the first SDD chip 1 is disposed on an incident side of the X-ray 6, whereas the second SDD chip 2 is disposed on a side opposite to the incident side of the X-ray 6. That is, in the X-ray detector 12, the first SDD chip 1 and the second SDD chip 2 are disposed in order from the incident side of the X-ray 6. Accordingly, a surface (window surface) 1a of the first SDD chip 1 faces the incident side of the X-ray 6, and a rear surface (ring surface) 1b of the first SDD chip 1 and a surface 2a of the second SDD chip 2 are facing each other.
An insulating spacer 9 is interposed between the first SDD chip 1 and the second SDD chip 2. In other words, the first SDD chip 1 is laminated on the second SDD chip 2 via the spacer 9.
The second SDD chip 2 disposed on the side opposite to the incident side is provided with a through hole (space part) 2e that is opened on the surface 2a thereof and the rear surface 2b thereof at a center part of a chip plane (surface 2a), and the second signal line 4 electrically connected to the second SDD chip 2 is disposed in the through hole 2e.
A wiring layer 1d that is provided with a circuit for extracting a signal of the first SDD chip 1 outside is formed on the rear surface 1b of the first SDD chip 1, whereby the signal of the first SDD chip 1 is extracted outside via an internal wiring of the wiring layer 1d.
In the same manner, a wiring layer 2d that is provided with a circuit for extracting a signal of the second SDD chip 2 outside is formed on the rear surface 2b of the second SDD chip 2, whereby the signal of the second SDD chip 2 is extracted outside via an internal wiring of the wiring layer 2d. A thin film wiring substrate and the like may be adopted as the wiring layer 1d and the wiring layer 2d.
The amplifier 5, which is electrically connected to both the first signal line 3 and the second signal line 4, is provided on the wiring layer 1d provided on the rear surface 1b of the first SDD chip 1.
Specifically, one end of the first signal line 3 is electrically connected to the first SDD chip 1 via an anode electrode (first charge collection electrode) 1c provided at a center part of the rear surface 1b of the first SDD chip 1, and the other end of the first signal line 3 is electrically connected to the amplifier 5 provided on the wiring layer 1d on a side of the rear surface 1b of the first SDD chip 1.
On the other hand, one end of the second signal line 4 is electrically connected to the second SDD chip 2 via an anode electrode (second charge collection electrode) 2c provided at a center part of the rear surface 2b of the second SDD chip 2, the second signal line 4 is disposed in the through hole 2e, and the other end of the second signal line 4 is electrically connected to the amplifier 5 via the through hole 2e.
Here, in the X-ray detector 12 of the embodiment, a thickness of the second SDD chip 2 disposed on the side opposite to the incident side of the X-ray 6 is thicker than a thickness of the first SDD chip 1 disposed on the incident side. As an example, the thickness of the first SDD chip 1 is about 0.5 mm, and the thickness of the second SDD chip 2 is about 1.0 mm.
Next, referring to
As illustrated in
On the other hand, on an uppermost layer on the side of the rear surface (ring surface) 1b of the SDD chip, the plurality of ring-shaped wirings 1f made of aluminum and the like are formed, and the anode electrode 1c is formed at a center part thereof. The boron layer 1g is formed on an upper part of each ring-shaped wiring 1f in the same manner as that on the side of the surface 1a, and the insulating film 1h is formed between the ring-shaped wirings 1f, respectively. The plurality of ring-shaped wirings 1f are the plurality of ring-shaped wirings 1f formed having a same center at equal intervals.
Phosphorus is injected between the respective boron layers 1g of the Si substrate on the side of the surface 1a and the side of the rear surface 1b. The inside of the Si substrate is a depletion layer.
When a voltage is applied to an inner electrode 1i and an outer electrode 1j with respect to such an SDD chip, since the plurality of ring-shaped wirings 1f are spirally formed having same center at equal intervals on the side of the rear surface 1b, an electric field is formed toward a center of the Si substrate. The X-ray 6 is collected by this electric field. In the SDD chip illustrated in
The X-ray detector 12 of the embodiment adopts the SDD chip of the structure illustrated in
Accordingly, it is not required to handle a Si substrate having a large thickness, whereby an area and a volume of the detector are not increased, and detection efficiency of the X-ray 6 can be improved while resolution thereof is maintained without requiring a plurality of amplifiers and post-stage circuits.
Next, a structure of two SDD chips incorporated in the X-ray detector 12 of the embodiment will be described.
Out of the two SDD chips laminated in the X-ray detector 12 of the embodiment, the SDD chip illustrated in
Specifically, as illustrated in
The SDD chip illustrated in
As described above, the X-ray detector 12 of the embodiment is formed by laminating the first SDD chip 1 and the second SDD chip 2, and detects the respective signals by one amplifier 5. That is, the SDD operation is executed by a single circuit. For example, the respective signals detected by the amplifier 5 are extracted outside of the chip via the internal wiring of the wiring layer 1d illustrated in
In the second SDD chip 2, the space part (gap) such as the through hole 2e is formed to connect the signal line (second signal line 4) to the amplifier 5 provided on the rear surface 1b of the first SDD chip 1. In other words, as illustrated in
As illustrated in
The anode electrode (second charge collection electrode) 2c is provided along a long side of the vertically elongated rectangular shape of an opening part of the through hole 2e on the rear surface 2b, and the second signal line 4 is electrically connected to the anode electrode 2c.
On the rear surface 2b of the second SDD chip 2, a plurality of wirings 2f are formed having approximately the same center at equal intervals surrounding the anode electrode 2c and the through hole 2e while the anode electrode 2c and the through hole 2e are disposed at the center part.
Here, in the X-ray detector 12 of the embodiment, since the first SDD chip 1 and the second SDD chip 2 are disposed to be laminated in the incident direction of the X-ray 6, the first energy sensitivity for detecting the fluorescent X-ray 7 of the first SDD chip 1 is different from the second energy sensitivity for detecting the fluorescent X-ray 7 of the second SDD chip 2. That is, the second SDD chip 2 disposed on the rear side regarding the incident direction of the X-ray 6 has the energy sensitivity inevitably different from that of the first SDD chip 1 on the incident side. In other words, the sensitivity of the two SDD chips is different as the two SDD chips are laminated. In this case, the second SDD chip 2 on the rear side has higher energy sensitivity compared with the first SDD chip 1 on the incident side.
Therefore, for example, the X-ray 6 having energy equal to or greater than 10 keV can be detected by the second SDD chip 2 on the rear side, and the X-ray 6 having energy not exceeding 10 keV can be detected by the first SDD chip 1 on the incident side.
The thickness of the second SDD chip 2 in the X-ray detector 12 of the embodiment is thicker than that of the first SDD chip 1. For example, the thickness of the first SDD chip 1 is about 0.5 mm, and the thickness of the second SDD chip 2 is about 1.0 mm. However, the thickness of the first SDD chip 1 and the thickness of the second SDD chip 2 may be same.
In the X-ray detector 12 of the embodiment, the first SDD chip 1 and the second SDD chip 2 are laminated, and the signal line of the second SDD chip 2 passes through the space part provided in the second SDD chip 2, thereby making it possible to detect the respective signals of both SDD chips by one amplifier 5. As a result, since there is no need to increase an occupancy area and a volume of the X-ray detector 12, miniaturization of the X-ray detector 12 can be achieved.
When attempting to detect the X-ray 6 having energy equal to or greater than 10 keV, in the Si substrate, there exists a characteristic that the sensitivity of the X-ray 6 dramatically deteriorates. As a countermeasure for increasing the detection sensitivity of the X-ray 6 having high energy, simply increasing the thickness of the Si substrate maybe considered. However, when the Si substrate is thickened, some problems occur such as the followings. (1) When the SDD chip is manufactured, it becomes difficult to handle and convey the Si substrate. (2) A leakage current affecting the resolution of the SDD chip increases. (3) An effective area of the window surface (window region) on which the X-ray 6 is incident becomes small in inverse proportion to the thickness of the Si substrate.
Here, the X-ray detector 12 of the embodiment does not simply thicken the thickness of the SDD chip, but laminates the first SDD chip 1 and the second SDD chip 2 which are two SDD chips. Accordingly, occurrence of the above-mentioned problems from (1) to (3) when simply thickening the thickness of the SDD chip can be avoided.
In the X-ray detector 12, since the energy sensitivity of each of the two SDD chips is different from each other by laminating the first SDD chip 1 and the second SDD chip 2, as a result, the detection efficiency of the X-ray 6 can be improved while maintaining the high resolution in the X-ray detection. It is possible to increase the detection efficiency of the X-ray 6 by preventing an increase in cost.
In the X-ray detector 12 of the embodiment, the thickness of the second SDD chip 2 on the rear side is thicker than the thickness of the first SDD chip 1 on the incident side. Thus, the second SDD chip 2 on the rear side can be used exclusively for the detection of the X-ray having the high energy. In this case, by setting the thickness of the second SDD chip 2 to, for example, about 1.0 mm, the occurrence of the problems when thickening the Si substrate can be avoided.
Next, modified examples of the X-ray detector 12 of the embodiment will be described.
Since a structure of the first SDD chip 1 in the X-ray detector 12 of the first modified example illustrated in
In the second SDD chip 2 illustrated in
On the rear surface 2b of the second SDD chip 2, the plurality of wirings 2f are formed having approximately the same center at equal intervals surrounding the anode electrode 2c and the through hole 2e while the anode electrode 2c and the through hole 2e are disposed at the center part.
In the X-ray detector 12 illustrated in
Since the structure of the first SDD chip 1 in the X-ray detector 12 of the second modified example illustrated in
As illustrated in
As illustrated in
Therefore, the circular opening part of the through hole 2e, the circular anode electrode 2c formed along the opening part, and the plurality of ring-shaped wirings 2f are formed having same center.
As illustrated in
In the X-ray detector 12 illustrated in
Since the structure of the first SDD chip 1 in the X-ray detector 12 of the third modified example illustrated in
The second SDD chip 2 illustrated in
On the rear surface 2b illustrated in
The plurality of ring-shaped wirings 2f are formed having same center at equal intervals on the rear surface 2b of the second SDD chip 2.
As illustrated in
In the X-ray detector 12 illustrated in
Since the structure of the first SDD chip 1 in the X-ray detector 12 of the fourth modified example illustrated in
As illustrated in
The X-ray detector 12 illustrated in
That is, the X-ray detector 12 has a structure in which the anode electrode 2c is formed on the respective rear surfaces 2b of the two second SDD chips 2, the two second signal lines 4 connected to the respective anode electrodes 2c pass through the space part between the two second SDD chips 2, and each of the two second signal lines 4 is electrically connected to the amplifier 5 mounted on the rear surface 1b of the first SDD chip 1.
In the X-ray detector 12 illustrated in
Next, an X-ray measurement device according to the embodiment will be described.
An X-ray measurement device 20 of the embodiment illustrated in
When a configuration of the X-ray measurement device 20 illustrated in
Here, in the X-ray measurement device 20 illustrated in
The X-ray detector 12 is same as the X-ray detector 12 illustrated in
The X-ray measurement device 20 includes a driving driver 22 that drives the stage 21 and is provided with a power source 23 that supplies a power source to the driving driver 22 and the X-ray generation source 25.
The control PC (second processing part) 27 is connected to the X-ray measurement device 20 as described above. As illustrated in
Next, general operations of the X-ray measurement device 20 illustrated in
Next, “irradiate X-ray” indicated at step S2 is performed. At step S2, the stage 21 is first moved to a predetermined position by the driving driver 22. Thereafter, a predetermined portion of the sample 24 is irradiated with the X-ray 6 from the X-ray generation source 25.
Next, “measure fluorescent X-ray” indicated at step S3 is performed. At step S3, the fluorescent X-ray 7 generated from the sample 24 is detected by the X-ray detector 12. In the X-ray detector 12, when the fluorescent X-ray 7 is incident, a pair of “e” and “Hole” depending on the energy of the X-ray 6 is internally generated, the amplifier 5 amplifies a current value corresponding to the number of the generation and converts the amplified current value into a voltage, and the converted voltage is output as a pulse signal (waveform).
Next, “create fluorescent X-ray spectrum” indicated at step S4 is performed. At step S4, the pulse signal transmitted from the X-ray detector 12 is edited by the DPP 26, thereby creating a fluorescent X-ray spectrum (fluorescent X-ray intensity).
Next, “quantitative calculation” indicated at step S5 is performed. At step S5, in the control PC 27, analysis (calculation) is performed by a dedicated program incorporated therein, based upon a numerical value transmitted from the DPP 26.
Next, “output quantitative value” indicated at step S6 is performed. At step S6, the quantitative value processing of the detected element is performed by the control PC 27, and the quantitative value of the detected element is output.
According to the X-ray measurement device 20 of the embodiment, since the X-ray detector 12 of the embodiment is incorporated inside thereof, the detection efficiency of the X-ray can be improved while maintaining high resolution. Since the miniaturization of the X-ray detector 12 incorporated inside thereof can be achieved, the miniaturization of the X-ray measurement device 20 can also be achieved.
Since the X-ray detector 12 is incorporated therein, the detection efficiency of the X-ray 6 can be improved while preventing the increase in cost of the X-ray measurement device 20.
Next, a modified example of the X-ray measurement device 20 of the embodiment will be described.
The X-ray measurement device 20 of the modified example illustrated in
That is, in the X-ray measurement device 20 illustrated in
Accordingly, a function of the X-ray measurement device 20 can be improved. The detection efficiency of the X-ray 6 can be improved while preventing the increase in cost of the X-ray measurement device 20.
Next, referring to
On the other hand, as the Ka ray energy becomes greater than 10 KeV, the improvement rate becomes higher. The reason is that as the Ka ray energy becomes higher, it is easy to pass through the first detector (first SDD chip 1), and a ratio of being detected by a second detector (second SDD chip 2) is increased. Accordingly, the effect of the way of laminating the two SDD chips according to the embodiment is high, and as the X-ray becomes the higher energy, the effect becomes greater. From the above-mentioned result, it can be estimated that increasing the number of laminated SDD chips from two pieces to three pieces further increases the improvement rate.
When the X-ray detector 12 having high efficiency and high energy of the embodiment is applied to compositional analysis of environmental load substances regulated by the RoHS directive, it is possible to improve fluorescent X-ray intensity higher than 10 KeV compared with the comparative example. For example, Ka ray (23.1 KeV) intensity of Cd contained in Pb free solder can be 1.7 times, Kb ray (26.2 KeV) intensity can be 1.8 times, and Lb1 ray (12.6 KeV) intensity of Pb can be 1.2 times.
When detecting polybrominated biphenyl (PBB) contained in the printed substrate as Br, the Ka ray (11.9 KeV) intensity of Br can be 1.2 times and the Kb ray (13.3 KeV) intensity can be 1.3 times. Particularly, since a regulated value of Cd is ten times more strict than those of other substances (<100 ppm), the way of the embodiment has a great effect of improving the analysis accuracy of Cd.
As described above, the present invention is not limited to the above-mentioned embodiments, but includes various modifications. For example, the above-mentioned embodiments are described in detail to describe the present invention in an easy-to-understand manner, and are not necessarily limited to those including all of the configurations described herein.
A part of the configuration of one embodiment can be replaced with a configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. It is possible to add, delete, and replace another configuration regarding a part of the configuration of each embodiment. Each member and relative size described in the drawings are simplified and idealized to describe the present invention in an easy-to-understand manner, and a more complicated shape is achieved during the implementation.
For example, in the above-mentioned embodiments, two SDD chips laminated are described, but three or more SDD chips may be laminated.
In the above-mentioned embodiments, to laminate two SDD chips, two SDD chips having different thicknesses laminated are described, but two SDD chips having same thickness may be laminated, and two completely same SDD chips may be laminated.
1: first SDD chip (first semiconductor chip)
1
a: surface
1
b: rear surface
1
c: anode electrode (first charge collection electrode)
1
d: wiring layer
1
e: oxide film
1
f: wiring
1
g: boron layer
1
h: insulating film
1
i: inner electrode
1
j: outer electrode
2: second SDD chip (second semiconductor chip)
2
a: surface
2
b: rear surface
2
c: anode electrode (second charge collection electrode)
2
d: wiring layer
2
e: through hole (space part)
2
f: wiring
2
g: notch (space part)
3: first signal line
4: second signal line
5: amplifier
6: X-ray
7: fluorescent X-ray
8: thermistor
9: spacer
10: Peltier
11: control part
12: X-ray detector
13: adhesive material
20: X-ray measurement device
21: stage
22: driving driver
23: power source
24: sample (specimen)
25: X-ray generation source
26: DPP (first processing part)
27: control PC (second processing part)
28: control part (second processing part)
Number | Date | Country | Kind |
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2018-082253 | Apr 2018 | JP | national |