阅读说明：本技术 图像传感器中的辐射检测器的封装 (Packaging of radiation detectors in image sensors ) 是由 曹培炎 刘雨润 宋崇申 于 2018-01-24 设计创作，主要内容包括：本文所公开的是一种图像传感器,其包括：第一封装(200),包括安装在印刷电路板(PCB 400)上的多个辐射检测器(100)；其中,第一封装(200)的静区(488)没有在多个辐射检测器(100)之中的相邻辐射检测器(100)之间延伸；辐射检测器(100)没有保护环或侧壁掺杂。(Disclosed herein is an image sensor, including: a first package (200) comprising a plurality of radiation detectors (100) mounted on a printed circuit board (PCB 400); wherein the quiet zone (488) of the first package (200) does not extend between adjacent radiation detectors (100) among the plurality of radiation detectors (100); the radiation detector (100) is free of guard rings or sidewall doping.)

1. An image sensor, comprising:

a first package comprising a plurality of radiation detectors mounted on a Printed Circuit Board (PCB);

wherein a quiet zone of the first package does not extend between adjacent radiation detectors among the plurality of radiation detectors;

wherein the radiation detector is free of guard rings or sidewall doping.

2. The image sensor of claim 1, wherein the first package is mounted on a system PCB by a plug and socket.

3. The image sensor of claim 2, wherein the first package is tilted with respect to the system PCB.

4. The image sensor of claim 1, wherein the first package is mounted on a system PCB by wire bonding.

5. The image sensor of claim 1, further comprising a second package, wherein the quiet zone of the first package is obscured by the second package.

6. The image sensor of claim 5, wherein the quiet zone of the first package is obscured by a working zone of the second package.

7. The image sensor of claim 1, wherein the first package is rectangular in shape.

8. The image sensor of claim 1, wherein the first package is hexagonal in shape.

9. The image sensor of claim 1, wherein a gap between two adjacent radiation detectors is no wider than pixels of the two adjacent radiation detectors.

10. The image sensor of claim 1, wherein at least one of the radiation detectors does not include a peripheral region along at least three sides of the at least one radiation detector.

11. The image sensor of claim 1, wherein at least one of the radiation detectors comprises a radiation absorbing layer and an electron shell;

wherein the radiation absorbing layer comprises an electrode;

wherein the electron shell comprises an electron system;

wherein the electronic system comprises:

a first voltage comparator configured to compare a voltage of the electrode with a first threshold;

a second voltage comparator configured to compare the voltage with a second threshold;

a counter configured to record the number of radiation particles that reach the radiation absorbing layer;

a controller;

wherein the controller is configured to start a time delay from a time when the first voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold;

wherein the controller is configured to activate the second voltage comparator during the time delay;

wherein the controller is configured to increment the value recorded by the counter by one when the second voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold.

12. The image sensor of claim 11, wherein the electronic system further comprises a capacitor module electrically connected to the electrode, wherein the capacitor module is configured to collect carriers from the electrode.

13. The image sensor of claim 11, wherein the controller is configured to activate the second voltage comparator at the beginning or expiration of the time delay.

14. The image sensor of claim 11, wherein the electronic system further comprises a voltmeter, wherein the controller is configured to cause the voltmeter to measure the voltage upon expiration of the time delay.

15. The image sensor of claim 11, wherein the controller is configured to determine a radiation particle energy based on the value of the voltage measured at the expiration of the time delay.

16. The image sensor of claim 11, wherein the controller is configured to connect the electrode to electrical ground.

17. The image sensor of claim 11, wherein the rate of change of the voltage is substantially zero upon expiration of the time delay.

18. The image sensor of claim 11, wherein the rate of change of the voltage is substantially non-zero upon expiration of the time delay.

19. A system comprising the image sensor of claim 1 and a radiation source, wherein the system is configured to perform radiography of a human thorax or abdomen.

20. A system comprising the image sensor of claim 1 and a radiation source, wherein the system is configured to perform radiography of a human oral cavity.

21. A cargo scanning or non-invasive inspection (NII) system comprising the image sensor of claim 1 and a radiation source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image using backscattered radiation.

22. A cargo scanning or non-invasive inspection (NII) system comprising the image sensor of claim 1 and a radiation source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image using radiation transmitted through an object under inspection.

23. A whole-body scanner system comprising the image sensor of claim 1 and a radiation source.

24. A radiation computed tomography (radiation CT) system comprising the image sensor of claim 1 and a radiation source.

25. An electron microscope comprising the image sensor of claim 1, an electron source, and an electron optical system.

26. A system comprising the image sensor of claim 1, wherein the system is a radiation telescope or a radiation microscope, or the system is configured to perform mammography, industrial defect detection, micro-radiography, casting inspection, welding inspection, or digital subtraction angiography.

[ technical field ] A method for producing a semiconductor device

The present disclosure relates to radiation detectors, and in particular to packaging of radiation detectors.

[ background of the invention ]

A radiation detector is a device that measures properties of radiation. Examples of properties may include the spatial distribution of intensity, phase and polarization of the radiation. The radiation may be radiation that interacts with the subject. For example, the radiation measured by the radiation detector may be radiation that penetrates the subject or is reflected from the subject. The radiation may be electromagnetic radiation, such as infrared light, visible light, ultraviolet light, X-rays or gamma rays. The radiation may be of other types, such as alpha rays and beta rays.

One type of radiation detector is based on the interaction between radiation and a semiconductor. For example, this type of radiation detector may have a semiconductor layer that absorbs radiation and generates carriers (e.g., electrons and holes) and a circuit for detecting the carriers.

[ summary of the invention ]

Disclosed herein is an image sensor, including: a first package comprising a plurality of radiation detectors mounted on a Printed Circuit Board (PCB); wherein the quiet zone of the first package does not extend between adjacent radiation detectors among the plurality of radiation detectors; the radiation detector is free of guard rings or sidewall doping.

According to an embodiment, the first package is mounted on the system PCB by means of a plug and a socket.

According to an embodiment, the first package is tilted with respect to the system PCB.

According to an embodiment, the first package is mounted on the system PCB by wire bonding.

According to an embodiment, the image sensor further comprises a second package, wherein the dead space of the first package is shielded by the second package.

According to an embodiment, the dead space of the first package is shielded by the active area of the second package.

According to an embodiment, the first package is rectangular in shape.

According to an embodiment, the first package is hexagonal in shape.

According to an embodiment, the gap between two adjacent radiation detectors is no wider than the pixels of the two adjacent radiation detectors.

According to an embodiment, at least one of the radiation detectors does not comprise a peripheral region along at least three sides of the at least one radiation detector.

According to an embodiment, at least one of the radiation detector packages comprises a radiation absorbing layer and an electron shell; wherein the radiation absorbing layer comprises an electrode; the electron shell comprises an electron system; wherein the electronic system comprises: a first voltage comparator configured to compare a voltage of the electrode with a first threshold; a second voltage comparator configured to compare the voltage with a second threshold; a counter configured to record the number of radiation particles that reach the radiation absorbing layer; a controller; wherein the controller is configured to start the time delay from a time when the first voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold; the controller is configured to activate the second voltage comparator during the time delay; the controller is configured to increase the number recorded by the counter by one when the second voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold.

According to an embodiment, the electronic system further comprises a capacitor module electrically connected to the electrodes, wherein the capacitor module is configured to collect carriers from the electrodes.

According to an embodiment, the controller is configured to start the second voltage comparator at the beginning or at the expiration of the time delay.

According to an embodiment, the electronic system further comprises a voltmeter, wherein the controller is configured to cause the voltmeter to measure the voltage upon expiration of the time delay.

According to an embodiment, the controller is configured to determine the radiation particle energy based on a value of the voltage measured at the expiration of the time delay.

According to an embodiment, the controller is configured to connect the electrode to electrical ground.

According to an embodiment, the rate of change of the voltage is substantially zero at the expiration of the time delay.

According to an embodiment, the rate of change of the voltage is substantially non-zero upon expiration of the time delay.

Disclosed herein is a system comprising an image sensor disclosed herein and a radiation source, wherein the system is configured to perform radiography of a human thorax or abdomen.

Disclosed herein is a system comprising an image sensor disclosed herein and a radiation source, wherein the system is configured to perform radiography of a human oral cavity.

Disclosed herein is a cargo scanning or non-invasive inspection (NII) system comprising an image sensor disclosed herein and a radiation source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image using backscattered radiation.

Disclosed herein is a cargo scanning or non-invasive inspection (NII) system comprising an image sensor disclosed herein and a radiation source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image using radiation transmitted through an object under inspection.

Disclosed herein is a whole-body scanner system comprising an image sensor disclosed herein and a radiation source.

Disclosed herein is a radiation computed tomography (radiation CT) system including an image sensor disclosed herein and a radiation source.

Disclosed herein is an electron microscope including the image sensor disclosed herein, an electron source, and an electron optical system.

Disclosed herein is a system comprising the image sensor disclosed herein, wherein the system is a radiation telescope or a radiation microscope, or wherein the system is configured to perform mammography, industrial defect detection, micro-radiography, casting inspection, welding inspection, or digital subtraction angiography.

[ description of the drawings ]

Fig. 1A schematically shows a cross-sectional view of a radiation detector according to an embodiment.

Fig. 1B schematically shows a detailed cross-sectional view of a radiation detector according to an embodiment.

Fig. 1C schematically shows an alternative detailed cross-sectional view of a radiation detector according to an embodiment.

Fig. 2 schematically illustrates that a radiation detector may have an array of pixels, according to an embodiment.

FIG. 3 schematically shows a cross-sectional view of an electron shell in a radiation detector according to an embodiment.

Fig. 4A schematically shows a top view of a package comprising a radiation detector and a Printed Circuit Board (PCB).

Fig. 4B and 4C each schematically show a cross-sectional view of an image sensor with the multiple packages of fig. 4A mounted to a system PCB.

Fig. 5A and 5B schematically illustrate a large area arrangement of the package of fig. 4A in an image sensor, according to an embodiment.

Fig. 6A and 6B each illustrate a component diagram of an electronic system of the radiation detector in fig. 1B or 1C, according to an embodiment.

Fig. 7 schematically shows a temporal variation of a current flowing through an electrode of a diode or an electrical contact of a resistor of a radiation absorbing layer exposed to radiation (upper curve) and a corresponding temporal variation of a voltage of the electrode (lower curve), the current being induced by carriers generated by radiation particles incident on the radiation absorbing layer, according to an embodiment.

Fig. 8 schematically illustrates a temporal change in current flowing through an electrode (upper curve) and a corresponding temporal change in voltage of the electrode (lower curve) caused by noise (e.g., dark current) in an electronic system operating in the manner illustrated in fig. 7, according to an embodiment.

Fig. 9 schematically illustrates a system according to an embodiment comprising an image sensor as described herein, suitable for medical imaging such as chest radiography, abdominal radiography, and the like.

Fig. 10 schematically illustrates a system according to an embodiment, comprising an image sensor as described herein, suitable for dental radiography.

Figure 11 schematically illustrates a cargo scanning or non-intrusive inspection (NII) system including an image sensor as described herein, according to an embodiment.

Figure 12 schematically illustrates another cargo scanning or non-intrusive inspection (NII) system including an image sensor as described herein, according to an embodiment.

Fig. 13 schematically illustrates a whole-body scanner system including an image sensor as described herein, in accordance with an embodiment.

Fig. 14 schematically illustrates a radiation computed tomography (radiation CT) system including an image sensor as described herein, in accordance with an embodiment.

Fig. 15 schematically illustrates an electron microscope including an image sensor as described herein, in accordance with an embodiment.

[ detailed description ] embodiments

Fig. 1A schematically shows a cross-sectional view of a radiation detector 100 according to an embodiment. The radiation detector 100 may comprise a radiation absorbing layer 110 and an electronics layer 120 (e.g. an ASIC) for processing or analyzing electrical signals generated in the radiation absorbing layer 110 by incident radiation. In an embodiment, the radiation detector 100 does not include a scintillator. The radiation absorbing layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof. Semiconductors may have a high quality attenuation coefficient for the radiant energy of interest.

As shown in the detailed cross-sectional view of the radiation detector 100 in fig. 1B, the radiation absorbing layer 110 may include one or more diodes (e.g., p-i-n or p-n) formed by one or more discrete regions 114 of the first doped region 111 and the second doped region 113, according to embodiments. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete regions 114 are separated from each other by the first doped region 111 or the intrinsic region 112. The first and second doped regions 111 and 113 have opposite type doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type). In the example of fig. 1B, each of the discrete regions 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. That is, in the example of fig. 1B, the radiation absorbing layer 110 has a plurality of diodes having the first doped region 111 as a shared electrode. The first doped region 111 may also have a discrete region.

When radiation particles irradiate the radiation absorbing layer 110 (which includes a diode), the radiation particles may be absorbed by the radiation absorbing layer 110, and one or more carriers may be generated in the radiation absorbing layer 110 by a number of mechanisms. The radiation particles may generate 10 to 100000 carriers. The carriers may drift under the electric field to the electrode of one of the diodes. The electric field may be an external electric field. Electrical contacts 119B may comprise discrete portions that each make electrical contact with discrete regions 114. In an embodiment, the carriers may drift in a direction such that the carriers generated by a single radiating particle are not substantially shared by two different discrete regions 114 ("substantially not shared" here means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow into a discrete region 114 of the discrete regions 114 that is different from the rest of the carriers). Carriers generated by radiation particles incident around the footprint of one of the discrete regions 114 are not substantially shared with another of the discrete regions 114. The pixel 150 associated with the discrete region 114 may be a region around the discrete region 114 in which substantially all (more than 98%, more than 99.5%, more than 99.9%, or more than 99.99%) of the carriers generated by the radiation particles incident thereon flow to the discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of these carriers flow out of the pixel.

As shown in the alternative detailed cross-sectional view of the radiation detector 100 of FIG. 1C, the radiation absorbing layer 110 may include a resistor of semiconductor material (e.g., silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof) but no diode, according to an embodiment. Semiconductors may have a high quality attenuation coefficient for the radiant energy of interest.

When a radiation particle strikes the radiation absorbing layer 110 (which includes a resistor but does not include a diode), it may be absorbed by the radiation absorbing layer 110, and one or more carriers may be generated in the radiation absorbing layer 110 by a number of mechanisms. The radiation particles may generate 10 to 100000 carriers. The carriers may drift under the electric field to electrical contacts 119A and 119B. The electric field may be an external electric field. Electrical contact 119B includes discrete portions. In an embodiment, the carriers may drift in a direction such that carriers generated by a single radiating particle are not substantially shared by two different discrete portions of electrical contact 119B ("substantially not shared" here means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to a discrete portion of the discrete portion that is different from the rest of the carriers). Carriers generated by radiation particles incident around the footprint of one of these discrete portions of electrical contact 119B are not substantially shared with another of these discrete portions of electrical contact 119B. The pixel 150 associated with the discrete portion of electrical contact 119B may be a region around the discrete portion in which substantially all (more than 98%, more than 99.5%, more than 99.9%, or more than 99.99%) of the carriers generated by the radiation particles incident thereon flow to the discrete portion of electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow out of the pixel associated with a discrete portion of electrical contact 119B.

The electron layer 120 may comprise an electron system 121 adapted to process or interpret signals generated by radiation particles incident on the radiation absorbing layer 110. Electronic system 121 may include analog circuits (e.g., filter networks, amplifiers, integrators, and comparators) or digital circuits (e.g., microprocessors and memories). The electronic system 121 may include components that are shared by pixels or components that are dedicated to individual pixels. For example, the electronic system 121 may include an amplifier dedicated to each pixel and a microprocessor shared among all pixels. The electronic system 121 may be electrically connected to the pixels through vias 131. The space between the vias may be filled with a filler material 130, which may increase the mechanical stability of the connection of the electron layer 120 to the radiation absorbing layer 110. Other bonding techniques are possible to connect the electronic system 121 to the pixels without using vias.

Fig. 2 schematically illustrates that the radiation detector 100 may have an array of pixels 150, according to an embodiment. The array may be a rectangular array, a honeycomb array, a hexagonal array, or any other suitable array. Each pixel 150 may be configured to detect radiation particles incident thereon, measure the energy of the radiation particles, or both. For example, each pixel 150 may be configured to count the number of radiation particles incident thereon having energies falling into a plurality of bins within a certain time period. All of the pixels 150 may be configured to count the number of radiation particles incident thereon within multiple bins of energy within the same time period. Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident radiation particle into a digital signal. The ADC may have a resolution of 10 bits or more. Each pixel 150 may be configured to measure its dark current, e.g., before or concurrently with each radiation particle incident thereon. Each pixel 150 may be configured to subtract a contribution of dark current from the energy of the radiation particles incident thereon. The pixels 150 may be configured to operate in parallel. For example, while one pixel 150 measures incident radiation particles, another pixel 150 may wait for radiation particles to arrive. The pixels 150 may be, but need not be, individually addressable. The radiation detector 100 may not have guard rings that include the pixels 150. The radiation detector 100 may be free of sidewall doping configured to reduce leakage current on the sidewalls of the radiation absorbing layer 110.

Fig. 3 schematically shows an electronics layer 120 according to an embodiment. The electronics layer 120 includes a substrate 122 having a first surface 124 and a second surface 128. As used herein, a "surface" need not be exposed, but can be completely or partially buried. The electronics layer 120 includes one or more electrical contacts 125 on the first surface 124. One or more electrical contacts 125 can be configured to electrically connect to one or more electrical contacts 119B of radiation absorbing layer 110. The electronic system 121 may be in or on a substrate 122.

Substrate 122 may be a thinned substrate. For example, the substrate may have a thickness of 750 microns or less, 200 microns or less, 100 microns or less, 50 microns or less, 20 microns or less, or 5 microns or less. The substrate 122 may be a silicon substrate or a substrate or other suitable semiconductor or insulator. The substrate 122 may be created by grinding a thicker substrate to a desired thickness.

One or more of the electrical contacts 125 may be a metal or doped semiconductor layer. For example, electrical contact 125 may be gold, copper, platinum, palladium, doped silicon, and the like.

Fig. 3 schematically shows the junction between the radiation absorbing layer 110 and the electron shell 120 at electrical contact 119B of the radiation absorbing layer 110 and electrical contact 125 of the electron shell 120. Bonding may be performed by a suitable technique, such as direct bonding or flip chip bonding.

Direct bonding is a wafer bonding process without any additional intermediate layers (e.g., solder bumps). The bonding process is based on chemical bonding between two surfaces. The direct bonding may be at an elevated temperature, but need not be.

Flip chip bonding uses solder bumps 199 deposited onto contact pads (e.g., electrical contacts 119B or electrical contacts 125 of radiation absorbing layer 110). Either the radiation absorbing layer 110 or the electron layer 120 is flipped over and the electrical contact 119B of the radiation absorbing layer 110 is aligned to the electrical contact 125. The solder mass 199 can fuse to solder the electrical contact 119B and the electrical contact 125 together. Any void spaces between the solder masses 199 may be filled with an insulating material.

Fig. 4A schematically illustrates a top view of a package 200 including a radiation detector 100 and a Printed Circuit Board (PCB)400, in accordance with an embodiment. The term "PCB" as used herein is not limited to a particular material. For example, the PCB may include a semiconductor. The radiation detector 100 is mounted to the PCB 400. PCB 400 may have a plurality of radiation detectors 100. PCB 400 may have an area 405 that is not covered by radiation detector 100 for receiving bonding wire 410. The radiation detector 100 may have an active area 190, which is where the pixels 150 are located. According to an embodiment, at least one of the radiation detectors 100 has an active area 190 that extends to at least 3 sides of the radiation detector 100. That is, at least one of the radiation detectors 100 does not include a peripheral region on those sides of the radiation detector 100. The peripheral region 195 is a zone of the radiation detector 100 that does not detect radiation particles. One side of that radiation detector 100 may have a peripheral region 195 to receive a bonding wire 410.

Radiation incident on the peripheral region 195 of the radiation detector 100 or on the region 405 of the PCB 400 cannot be detected by the package 200. A quiet zone 488 of a package (e.g., package 200) is defined as an area of the radiation-receiving surface of the package where incident radiation particles cannot be detected by a radiation detector in the package. In this example shown in fig. 4A, quiet zone 488 of package 200 includes peripheral zone 195 and area 405. Quiet zone 488 of package 200 does not extend between adjacent radiation detectors among the plurality of radiation detectors 100 of package 200. For example, as shown in fig. 4A, any gap between two adjacent radiation detectors is no wider than the pixels of the two adjacent radiation detectors.

Fig. 4B and 4C each schematically illustrate that radiation originally incident at a quiet zone 488 of package 200 may be detected by another package (whose active zone obscures quiet zone 488), according to an embodiment. The plurality of packages 200 may be arranged such that they are tilted with respect to the system PCB 450. The quiet zone 488 of one package 200 is hidden under an adjacent package such that the quiet zone 488 is obscured by the working area of the adjacent package. Package 200 and its one or more adjacent packages may be arranged in close proximity to each other such that the entirety of quiet zone 488 of package 200 is obscured by the one or more adjacent packages. Fig. 4B and 4C also show that the package 200 can be mounted (electrically and mechanically) to the system PCB450 via a plug 451 and a socket 452. The plug 451 may be an integral part of the PCB 400 and the receptacle 452 may be an integral part of the system PCB450 (as shown in fig. 4B), or vice versa (as shown in fig. 4C). The socket 452 may be a hole through the system PCB450 or PCB 400 to receive solder.

Fig. 5A and 5B schematically illustrate a large-area arrangement of a package 200 in an image sensor according to an embodiment. In this embodiment, the package 200 may be mounted to the system PCB450 by a plug and socket. The shape of the package 200 may be rectangular (as shown in fig. 5A) or the shape may be hexagonal (as shown in fig. 5B). The dead space of one package is shielded by the active area of one or more adjacent packages. The gap between packages may be negligible in imaging using the image sensor.

Fig. 6A and 6B each show a component diagram of an electronic system 121 of the radiation detector 100 according to an embodiment. Electronic system 121 may include a first voltage comparator 301, a second voltage comparator 302, a counter 320, a switch 305, a voltmeter 306, and a controller 310.

The first voltage comparator 301 is configured to compare the voltage of the electrode of the diode 300 with a first threshold value. The diode may be a diode formed by the first doped region 111, one of the discrete regions 114 of the second doped region 113, and the optional intrinsic region 112. Alternatively, first voltage comparator 301 is configured to compare the voltage of an electrical contact (e.g., a discrete portion of electrical contact 119B) to a first threshold. The first voltage comparator 301 may be configured to monitor the voltage directly or to calculate the voltage by integrating the current flowing through the diode or the electrical contact for a certain period of time. The first voltage comparator 301 may be controllably activated or deactivated by the controller 310. The first voltage comparator 301 may be a continuous comparator. That is, the first voltage comparator 301 may be configured to be continuously enabled and continuously monitor the voltage. The first voltage comparator 301, configured as a continuous comparator, reduces the chance of the system 121 missing the signal generated by the incident radiation particle. The first voltage comparator 301, configured as a continuous comparator, is particularly suitable when the intensity of the incident radiation is high. The first voltage comparator 301 may be a clocked comparator, which has the beneficial effect of lower power consumption. A voltage comparator 301 configured as a clocked comparator may cause the system 121 to miss some of the signals generated by incident radiation particles. When the intensity of the incident radiation is low, the chance of missing the incident radiation particle is low because the time interval between two consecutive photons is long. Therefore, the first voltage comparator 301 configured as a clocked comparator is particularly suitable when the incident radiation intensity is low. The first threshold may be 5-10%, 10-20%, 20-30%, 30-40% or 40-50% of the maximum voltage that an incident radiation particle can generate in a diode or resistor. The maximum voltage may depend on the energy of the incident radiation particles (i.e., the wavelength of the incident radiation), the material of the radiation absorbing layer 110, and other factors. For example, the first threshold may be 50mV, 100mV, 150mV, or 200 mV.

The second voltage comparator 302 is configured to compare the voltage with a second threshold. The second voltage comparator 302 may be configured to monitor the voltage directly or calculate the voltage by integrating the current flowing through the diode or electrical contact for a certain period of time. The second voltage comparator 302 may be a continuous comparator. The second voltage comparator 302 may be controllably activated or deactivated by the controller 310. When the second voltage comparator 302 is disabled, the power consumption of the second voltage comparator 302 may be less than 1%, 5%, 10%, or 20% of the power consumption when the second voltage comparator 302 is enabled. The absolute value of the second threshold is greater than the absolute value of the first threshold. The term "absolute value" or "modulus" | x | of a real number x as used herein is a non-negative value of x regardless of its sign. That is to say that the first and second electrodes,

the second threshold may be 200% -300% of the first threshold. The second threshold may be at least 50% of the maximum voltage that an incident radiation particle can generate in the diode or resistor. For example, the second threshold may be 100mV, 150mV, 200mV, 250mV, or 300 mV. The second voltage comparator 302 and the first voltage comparator 310 may be the same component. That is, the system 121 may have one voltage comparator that is capable of comparing a voltage to two different thresholds at different times.

The first voltage comparator 301 or the second voltage comparator 302 may comprise one or more operational amplifiers or any other suitable circuit. The first voltage comparator 301 or the second voltage comparator 302 may have a high speed to allow the system 121 to operate at a high flux of incident radiation. However, having high speed often comes at the cost of power consumption.

The counter 320 is configured to record the number of radiation particles that reach the diode or resistor. The counter 320 may be a software component (e.g., a value stored in a computer memory) or a hardware component (e.g., 4017IC and 7490 IC).

The controller 310 may be a hardware component, such as a microcontroller or microprocessor. The controller 310 is configured to start the time delay from the time the first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold (e.g., the absolute value of the voltage increases from below the absolute value of the first threshold to a value equal to or above the absolute value of the first threshold). Absolute values are used here, since the voltage may be negative or positive, depending on whether the cathode or anode voltage of the diode or which electrical contact is used. The controller 310 may be configured to keep the second voltage comparator 302, the counter 320, and any other circuitry not required to disable the operation of the first voltage comparator 301 until such time as the first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold. The time delay may expire before or after the voltage has stabilized, i.e. the rate of change of the voltage is substantially zero. The phrase "the rate of change of the voltage is substantially zero" means that the temporal change of the voltage is less than 0.1%/ns. The phrase "the rate of change of the voltage is substantially non-zero" means that the time change of the voltage is at least 0.1%/ns.

The controller 310 may be configured to activate the second voltage comparator during the time delay (including start and expiration). In an embodiment, the controller 310 is configured to activate the second voltage comparator at the beginning of the time delay. The term "activate" means to bring a component into an operational state (e.g., by sending a signal such as a voltage pulse or logic level, by providing power, etc.). The term "disable" means to bring a component into a non-operational state (e.g., by sending a signal such as a voltage pulse or logic level, by cutting power, etc.). The operating state may have a higher power consumption (e.g., 10 times higher, 100 times higher, 1000 times higher) than the non-operating state. The controller 310 itself may be disabled until the output of the first voltage comparator 301 activates the controller 310 when the absolute value of the voltage equals or exceeds the absolute value of the first threshold.

The controller 310 may be configured to increment the number recorded by the counter 320 by one when the second voltage comparator 302 determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold during the time delay.

The controller 310 may be configured to cause the voltmeter 306 to measure the voltage upon expiration of the time delay. The controller 310 may be configured to connect the electrodes to electrical ground in order to reset the voltage and drain any carriers accumulated on the electrodes. In an embodiment, the electrode is connected to electrical ground after the time delay expires. In an embodiment, the electrode is connected to electrical ground for a limited reset period. Controller 310 may connect the electrodes to electrical ground by controlling switch 305. The switch may be a transistor (e.g., a Field Effect Transistor (FET)).

In an embodiment, system 121 does not have an analog filter network (e.g., an RC network). In an embodiment, system 121 has no analog circuitry.

The voltmeter 306 can feed the measured voltage to the controller 310 as an analog or digital signal.

The system 121 may include a capacitor module 309 electrically connected to an electrode or electrical contact of the diode 300, wherein the capacitor module is configured to collect carriers from the electrode. Capacitor moduleA capacitor in the feedback path of the amplifier can be included. An amplifier configured in this way is called a capacitive transimpedance amplifier (CTIA). CTIA has a high dynamic range by preventing the amplifier from saturating and improves the signal-to-noise ratio by limiting the bandwidth in the signal path. The carriers from the electrodes are for a certain period of time ("integration period") (e.g., at t, as shown in fig. 7, for example, at t₀And t₁Or t₁And t₂In between) is accumulated on the capacitor. After the integration period has expired, the capacitor voltage is sampled and then reset by the reset switch. The capacitor module can include a capacitor directly connected to the electrode.

Fig. 7 schematically shows the temporal variation of the current flowing through the electrodes (upper curve) and the corresponding temporal variation of the voltage of the electrodes (lower curve) caused by the carriers generated by the radiation particles incident on the diode or resistor. The voltage may be an integral of the current with respect to time. At time t₀The radiation particles irradiate the diode or the resistor, carriers are generated in the diode or the resistor, a current starts to flow through the electrodes of the diode or the resistor, and the absolute value of the voltage of the electrodes or the electrical contacts starts to increase. At time t₁The first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold V1, and the controller 310 starts the time delay TD1, and the controller 310 may deactivate the first voltage comparator 301 when TD1 starts. If at t₁Previously deactivating the controller 310, then at t₁The controller 310 is activated. During TD1, controller 310 activates second voltage comparator 302. The term "during" a time delay as used herein means beginning and expiration (i.e., ending) and any time therebetween. For example, the controller 310 may activate the second voltage comparator 302 when TD1 expires. If during TD1, second voltage comparator 302 determines the absolute value of the voltage at time t₂Equal to or exceeding the absolute value of the second threshold, the controller 310 increments the number recorded by the counter 320 by one. At time t_eAll carriers generated by the radiation particles drift out of the radiation absorbing layer 110. At time t_sTime delay TD1 expires. In the example of FIG. 24, time t_sAt time t_eThen; that is, TD1 expires after all carriers generated by the radiation particles drift out of radiation absorbing layer 110. Thus, the rate of change of voltage is at t_sIs substantially zero. Controller 310 may be configured to expire at TD1 or at t₂Or any time in between, disables the second voltage comparator 302.

The controller 310 may be configured to cause the voltmeter 306 to measure the voltage when the time delay TD1 expires. In an embodiment, the controller 310 causes the voltmeter 306 to measure the voltage after the rate of change of the voltage becomes substantially zero after the time delay TD1 expires. The voltage at this moment is proportional to the amount of carriers generated by the radiating particles, which is related to the energy of the radiating particles. The controller 310 may be configured to determine the energy of the radiation particles based on the voltage measured by the voltmeter 306. One way to determine the energy is by binning the voltage to determine the energy. The counter 320 may have a sub-counter per cell. When the controller 310 determines that the energy of the radiation particle falls into a bin, the controller 310 may increment the number recorded by the sub-counter for that bin by one. Thus, the system 121 may be capable of detecting radiation images and may be capable of resolving the radiation particle energy of each radiation particle.

After TD1 expires, controller 310 connects the electrodes to an electrical ground reset period RST to allow carriers accumulated on the electrodes to flow to ground and reset the voltage. After the RST, the system 121 is ready to detect another incident radiation particle. Implicitly, the velocity of the incident radiation particles that the system 121 can manipulate in the example of fig. 24 is limited by 1/(TD1+ RST). If the first voltage comparator 301 has been disabled, the controller 310 can enable it at any time before the RST expires. If the controller 310 has been deactivated, it may be activated before the RST expires.

Fig. 7 schematically shows the temporal variation of the current through the electrodes (upper curve) and the corresponding temporal variation of the voltage of the electrodes (lower curve) caused by noise (e.g. dark current, background radiation, scattered radiation, fluorescent radiation, shared charge from neighboring pixels) in a system 121 operating in the manner shown in fig. 7. At time t₀Noise openingAnd (6) starting. If the noise is not large enough to cause the absolute value of the voltage to exceed the absolute value of V1, the controller 310 does not activate the second voltage comparator 302. If the noise is at time t as determined by the first voltage comparator 301₁Large enough that the absolute value of the voltage exceeds the absolute value of V1, the controller 310 starts the time delay TD1 and the controller 310 may deactivate the first voltage comparator 301 when TD1 starts. During TD1 (e.g., upon expiration of TD 1), controller 310 enables second voltage comparator 302. The noise is unlikely to be large enough during TD1 to cause the absolute value of the voltage to exceed the absolute value of V2. Therefore, the controller 310 does not increment the number recorded by the counter 320. At time t_eAnd the noise ends. At time t_sTime delay TD1 expires. Controller 310 may be configured to disable second voltage comparator 302 when TD1 expires. If the absolute value of the voltage does not exceed the absolute value of V2 during TD1, controller 310 may be configured not to cause voltmeter 306 to measure the voltage. After TD1 expires, controller 310 connects the electrodes to an electrical ground reset period RST to allow carriers accumulated on the electrodes due to noise to flow to ground and reset the voltage. Thus, the system 121 may be extremely effective in noise suppression.

Fig. 9 schematically illustrates a system including an image sensor 9000 as described with respect to fig. 4A-8. The system may be used for medical imaging such as chest radiography, abdominal radiography, and the like. The system comprises a radiation source 1201. Radiation emitted from radiation source 1201 penetrates subject 1202 (e.g., a body part such as a chest, limb, abdomen), is attenuated to varying degrees by internal structures of subject 1202 (e.g., bone, muscle, fat, organs, etc.), and is projected to image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of radiation.

Fig. 10 schematically illustrates a system including an image sensor 9000 as described with respect to fig. 4A-8. The system may be used for medical imaging, such as dental radiography. The system includes a radiation source 1301. Radiation emitted from radiation source 1301 penetrates subject 1302, which is part of the oral cavity of a mammal (e.g., a human). The object 1302 may include a maxilla, palatine, teeth, mandible, or tongue. The radiation is attenuated to varying degrees by different structures of the object 1302 and projected to the image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of radiation. Teeth absorb radiation more than cavities, infections, periodontal pockets. The dose of radiation received by a dental patient is typically small (about 0.150mSv for a full mouth series).

Fig. 11 schematically illustrates a cargo scanning or non-intrusive inspection (NII) system including an image sensor 9000 as described with respect to fig. 4A-8. The system may be used to inspect and identify goods in a transportation system (e.g., containers, vehicles, ships, luggage, etc.). The system includes a radiation source 1401. Radiation emitted from radiation source 1401 may be backscattered from object 1402 (e.g., container, vehicle, ship, etc.) and projected to image sensor 9000. Different internal structures of object 1402 may backscatter radiation differently. The image sensor 9000 forms an image by detecting the intensity distribution of the backscattered radiation and/or the energy of the backscattered radiation particles.

Fig. 12 schematically illustrates another cargo scanning or non-intrusive inspection (NII) system including an image sensor 9000 as described with respect to fig. 4A-8. The system can be used for baggage inspection at public transport stations and airports. The system includes a radiation source 1501. Radiation emitted from the radiation source 1501 may penetrate the baggage 1502, be attenuated differently by the contents of the baggage, and be projected to the image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of transmitted radiation. The system may reveal the contents of the baggage and identify prohibited goods for public transportation (e.g., firearms, narcotics, sharps, combustibles).

Fig. 13 schematically illustrates a whole-body scanner system including an image sensor 9000 as described with respect to fig. 4A-8. A whole-body scanner system can detect objects on a human body for security without physically removing clothing or making physical contact. The whole-body scanner system may be capable of detecting non-metallic objects. The whole body scanner system includes a radiation source 1601. Radiation emitted from radiation source 1601 may be backscattered from the human body 1602 under examination and the subject thereon and projected onto image sensor 9000. The object and the human body may backscatter radiation differently. The image sensor 9000 forms an image by detecting the intensity distribution of the backscattered radiation. The image sensor 9000 and the radiation source 1601 may be configured to scan a human body in a linear or rotational direction.

Fig. 14 schematically shows a radiation computed tomography (radiation CT) system. Radiation CT systems use computer processing of radiation to produce tomographic images (virtual "slices") of specific regions of a scanned object. Tomographic images can be used for diagnostic and therapeutic purposes in various medical disciplines or for flaw detection, fault analysis, metrology, assembly analysis, and reverse engineering. The radiation CT system includes an image sensor 9000 and a radiation source 1701 as described with respect to fig. 4A-8. The image sensor 9000 and the radiation source 1701 may be configured to rotate synchronously along one or more circular or helical paths.

Fig. 15 schematically shows an electron microscope. The electron microscope includes an electron source 1801 (also referred to as an electron gun) configured to emit electrons. The electron source 1801 may have various emission mechanisms, such as a thermionic, photocathode, cold emission, or plasma source. The emitted electrons pass through an electron optics system 1803, which may be configured to shape, accelerate, or focus the electrons. The electrons then reach the sample 1802, and an image detector may form an image therefrom. The electron microscope can include an image sensor 9000 as described with respect to fig. 4A-8 for performing energy dispersive X-ray spectroscopy (EDS). EDS is an analytical technique for elemental analysis or chemical characterization of a sample. When electrons are incident on the sample, they cause the emission of characteristic X-rays from the sample. The incident electron may excite an electron in the core layer of an atom of the sample, thereby dislodging the electron from the shell layer while creating an electron hole in which it resides. Electrons from the higher energy outer shell layer then fill the holes, and the difference in energy between the higher and lower energy shell layers can take the form of X-rays to be released. The number and energy of X-rays emitted from the sample can be measured by the image sensor 9000.

The image sensor 9000 described herein may find other applications, such as in radiation telescopes, radiation mammography, industrial radiation defect detection, radiation microscopy or micro radiography, radiation casting inspection, radiation non-destructive testing, radiation welding inspection, radiation digital subtraction angiography, and the like. This image sensor 9000 can be suitably used in place of a photographic plate, film, PSP plate, radiation image intensifier, scintillator or another semiconductor radiation detector.

While various aspects and embodiments are disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.