TW202321735A - Image sensors with shielded electronics layers - Google Patents

Abstract

Disclosed herein is an imaging system, comprising an image sensor which comprises: a stack of M radiation detectors each of which comprises (A) a radiation absorption layer and (B) an electronics layer configured to process electrical signals generated in the radiation absorption layer, M being an integer greater than 1; and M collimator regions respectively for the M electronics layers of the M radiation detectors, wherein there is a reference straight line for the image sensor such that for each electronics layer of the M electronics layers, every straight line intersecting said each electronics layer and being parallel to the reference straight line intersects the corresponding collimator region, and wherein for each radiation absorption layer of the M radiation absorption layers, every straight line intersecting said each radiation absorption layer and being parallel to the reference straight line does not intersect any collimator region of the M collimator regions.

Description

Image sensor with masked electronics layer

The invention relates to an image sensor with a layer covering electronic devices.

Radiation detectors are devices that measure the properties of radiation. Examples of such properties may include the spatial distribution of the intensity, phase and polarization of the radiation. The radiation measured by the radiation detector may be radiation that has passed through the object. The radiation measured by the radiation detector may be electromagnetic radiation, such as infrared light, visible light, ultraviolet light, X-rays or gamma rays. Radiation can be of other types, such as alpha and beta rays. An imaging system may include one or more image sensors, each of which may have one or more radiation detectors.

Disclosed herein is an imaging system comprising an image sensor comprising: a stack of M radiation detectors each comprising (A) a radiation absorbing layer and (B) an electronic device layer configured to process electrical signals generated in said radiation absorbing layer, M being an integer greater than 1; and M of the M electronic device layers respectively used for said M radiation detectors a collimator region, wherein there is a reference line for the image sensor such that, for each of the M electronic device layers, intersects the each electronic device layer and is parallel to the Each of the reference straight lines intersects the corresponding collimator region, and wherein for each radiation absorbing layer in the M radiation absorbing layers, each of the radiation absorbing layers intersects and is parallel to the reference straight line Each straight line of does not intersect any of the M collimator regions.

In one aspect, the M collimator regions are respectively located on the M electronic device layers.

In an aspect, the imaging system further includes a radiation source, wherein each of the M collimator regions completely shields a corresponding electronics layer from the radiation source.

In an aspect, each of the M collimator regions has the shape of a plate having the same thickness as the corresponding electronics layer.

In one aspect, the M radiation absorbing layers and the M electronics layers are arranged in an alternating manner.

In one aspect, the M collimator regions comprise tungsten.

In an aspect, for each of said M radiation detectors, said radiation absorbing layer of said each radiation detector is configured to generate an electrical signal in response to incident X-ray photons, and wherein said The electronics layer of each radiation detector is configured to process the generated electrical signals.

In one aspect, each radiation absorbing layer of the M radiation absorbing layers comprises a plurality of sensing elements arranged in a plurality of sensing element columns, wherein for each radiation absorbing layer of the M radiation absorbing layers For each sensing element column of the layer, the imaging system is configured to sum the final voltages of the sensing elements in each sensing element column whose voltage exceeds a predetermined threshold voltage, and wherein parallel to the reference line The straight line of is intersected with all the sensing elements of each sensing element column.

In an aspect, the first sense element whose final voltage in each sense element column exceeds the final voltage of the second sense element in each sense element column by at least a predetermined voltage tolerance value is not performed. The addition of the final voltage, wherein the first sensing element is adjacent to the second sensing element, and wherein the second sensing element is located between the first sensing element and the M between the collimator regions.

In an aspect, said finalizing is not performed on first sense elements in said each sense element column whose final voltage exceeds the final voltage of a second sense element of an adjacent sense element column by at least a predetermined voltage tolerance value. said addition of voltages, wherein a straight line perpendicular to said reference straight line intersects both said first sensing element and said second sensing element.

In one aspect, each radiation absorbing layer of the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, wherein the sensing element columns of the image sensor arranged in a plurality of sensing element column groups of adjacent sensing element columns, wherein for each sensing element column group of the image sensor, the imaging system is configured to Adding final voltages of sensing elements whose voltages exceed a predetermined threshold voltage in element column groups, wherein each sensing element column group includes N sensing element columns, N is an integer greater than 1, and wherein for the For each sensing element row in each sensing element row group, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element row.

Disclosed herein is a method comprising: receiving incident radiation with an image sensor of an imaging system, the image sensor comprising: a stack of M radiation detectors, each comprising ( A) a radiation absorbing layer and (B) an electronics layer configured to process electrical signals generated in said radiation absorbing layer, M being an integer greater than 1; and M for said M radiation detectors, respectively M collimator regions of the electronic device layer, wherein there is a reference line for the image sensor, such that for each of the M electronic device layers, with each of the electronic device layers intersect and each line parallel to the reference line intersects the corresponding collimator region, and wherein for each radiation absorbing layer in the M radiation absorbing layers, intersects each of the radiation absorbing layers and Each straight line parallel to the reference straight line does not intersect any of the M collimator areas.

In one aspect, the M collimator regions are respectively located on and in the M electronic device layers.

In an aspect, each of the M collimator regions completely shields the corresponding electronics layer with respect to the same radiation source.

In an aspect, each of the M collimator regions has the shape of a plate having the same thickness as the corresponding electronics layer.

In one aspect, the M radiation absorbing layers and the M electronics layers are arranged in an alternating manner.

In one aspect, the M collimator regions comprise tungsten.

In an aspect, for each of said M radiation detectors, said radiation absorbing layer of said each radiation detector is configured to generate an electrical signal in response to incident X-ray photons, and wherein said The electronics layer of each radiation detector is configured to process the generated electrical signals.

In one aspect, each radiation absorbing layer of the M radiation absorbing layers comprises a plurality of sensing elements arranged in a plurality of sensing element columns, wherein the method further comprises: for the M radiation absorbing layers For each sensing element column in each radiation absorbing layer, the imaging system is used to add the final voltages of the sensing elements in each sensing element column whose voltage exceeds a predetermined threshold voltage, and wherein parallel to The straight line of the reference straight line intersects all the sensing elements of each sensing element row.

In an aspect, the first sense element whose final voltage in each sense element column exceeds the final voltage of the second sense element in each sense element column by at least a predetermined voltage tolerance value is not performed. The addition of the final voltage, wherein the first sensing element is adjacent to the second sensing element, and wherein the second sensing element is located between the first sensing element and the M between the collimator regions.

In an aspect, said finalizing is not performed on first sense elements in said each sense element column whose final voltage exceeds the final voltage of a second sense element of an adjacent sense element column by at least a predetermined voltage tolerance value. said addition of voltages, wherein a straight line perpendicular to said reference straight line intersects both said first sensing element and said second sensing element.

In one aspect, each radiation absorbing layer of the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, wherein the sensing element columns of the image sensor arranged in a plurality of sensing element column groups of adjacent sensing element columns, wherein the method further includes: for each sensing element column group of the image sensor, using the imaging system to image the The final voltages of the sensing elements whose voltage exceeds a predetermined threshold voltage in each sensing element column group are summed, wherein each sensing element column group includes N sensing element columns, N is an integer greater than 1, and Wherein, for each sensing element row in each sensing element row group, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element row.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

radiation detector

Fig. 1 schematically shows a radiation detector 100 as an example. Radiation detector 100 may include an array of pixels 150 (also referred to as sensing elements 150 ). The array may be a rectangular array (as shown in Figure 1), a honeycomb array, a hexagonal array, or any other suitable array. The array of pixels 150 in the example of FIG. 1 has 4 rows and 7 columns; however, in general, the array of pixels 150 can have any number of rows and any number of columns.

Each pixel 150 may be configured to detect radiation incident thereon from a radiation source (not shown), and may be configured to measure a characteristic of the radiation (eg, energy, wavelength, and frequency of the particles). Radiation can include particles such as photons and subatomic particles. Each pixel 150 may be configured to count the number of radiation particles having energies incident thereon that fall within a plurality of energy bins over a period of time. All pixels 150 may be configured to count the number of radiation particles incident thereon in multiple energy intervals during the same time period. When the incident radiation particles have similar energies, the pixels 150 may only be configured to count the number of radiation particles incident thereon over a period of time without measuring the energy of individual radiation particles.

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, or an analog signal representing the total energy of multiple incident radiation particles. The signal is digitized into a digital signal. Pixels 150 may be configured to operate in parallel. For example, while one pixel 150 is measuring an incident radiation particle, another pixel 150 may be waiting for the radiation particle to arrive. Pixels 150 may not necessarily be individually addressable.

The radiation detector 100 described herein may have features such as X-ray telescopes, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray non-destructive testing, X-ray Applications such as welding inspection, X-ray digital subtraction angiography, etc. It may be appropriate to use the radiation detector 100 in place of a photographic plate, photographic film, PSP plate, X-ray image intensifier, scintillator, or other semiconductor X-ray detector.

Figure 2 schematically illustrates a simplified cross-sectional view of the radiation detector 100 of Figure 1 along line 2-2, according to an embodiment. Specifically, the radiation detector 100 may include a radiation absorbing layer 110 and an electronics layer 120 (which may include one or more ASICs or application specific integrated circuits) for processing or analyzing electrical signals generated in the radiation absorbing layer 110 by incident radiation. ). The radiation detector 100 may or may not include a scintillator (not shown). The radiation absorbing layer 110 may include a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. Semiconductor materials can have high quality attenuation coefficients for the radiation of interest.

As an example, FIG. 3 schematically shows a detailed cross-sectional view of the radiation detector 100 of FIG. 1 along line 2-2. Specifically, the radiation absorbing layer 110 may include one or more diodes (eg p-i-n or p-n) formed by the first doped region 111 , one or more discrete regions 114 of the second doped region 113 . The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112 . The discrete regions 114 may be separated from each other by the first doped region 111 or the intrinsic region 112 . The first doped region 111 and the second doped region 113 may have opposite types of doping (eg, 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. 3 , each discrete region 114 of the second doped region 113 forms a diode with the first doped region 111 and an optional intrinsic region 112 . That is, in the example of FIG. 3, the radiation absorbing layer 110 has a plurality of diodes (more specifically, 7 diodes correspond to 7 pixels 150 in a row in the array of FIG. Only 2 of these pixels 150 are marked in 3). Multiple diodes may have electrical contact 119A as a common (common) electrode. The first doped region 111 may also have discrete portions.

The electronics layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by radiation incident on the radiation absorbing layer 110 . Electronic system 121 may include analog circuits such as filter networks, amplifiers, integrators, and comparators, or digital circuits such as microprocessors and memory. Electronic system 121 may include one or more ADCs (analog-to-digital converters). Electronics system 121 may include components that are shared by pixels 150 or components that are specific to a single pixel 150 . For example, electronic system 121 may include an amplifier dedicated to each pixel 150 and a microprocessor shared among all pixels 150 . Electronic system 121 may be electrically connected to pixel 150 through via 131 . The spaces between the via holes may be filled with a filling material 130 , which may increase the mechanical stability of the connection of the electronic device layer 120 to the radiation absorbing layer 110 . Other bonding techniques can connect electronics 121 to pixel 150 without using via 131 .

When radiation from a radiation source (not shown) strikes the radiation absorbing layer 110 comprising diodes, radiation particles may be absorbed and generate one or more charge carriers (eg, electrons, holes) through a variety of mechanisms. Charge carriers can drift to the electrodes of one of the diodes under the electric field. The electric field may be an external electric field. Electrical contacts 119B may include discrete portions each in electrical contact with a discrete region 114 . The term "electrical contact" may be used interchangeably with the word "electrode". In an embodiment, the charge carriers may drift in all directions such that the charge carriers generated by a single radiation particle are not substantially shared by two distinct discrete regions 114 (herein "substantially not. … .shared means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow to a different discrete area 114). Charge carriers generated by radiation particles incident around the footprint of one of the discrete regions 114 are substantially not shared with the other of the discrete regions 114 . Pixels 150 associated with discrete region 114 may be the area surrounding 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 charge carriers flow to discrete regions 114 . That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of the charge carriers flow through the pixel 150 .

FIG. 4 schematically illustrates a detailed cross-sectional view of the radiation detector 100 of FIG. 1 along line 2 - 2 according to an alternative embodiment. More specifically, the radiation absorbing layer 110 may include resistors of semiconductor materials such as silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof, but not diodes. Semiconductor materials can have high quality attenuation coefficients for the radiation of interest. In one embodiment, the electronics layer 120 of FIG. 4 is similar in structure and function to the electronics layer 120 of FIG. 3 .

When radiation strikes the radiation absorbing layer 110, which includes a resistor but does not include a diode, it can be absorbed and generate one or more charge carriers through a variety of mechanisms. Radiation particles can generate anywhere from 10 to 100,000 charge carriers. Charge carriers can drift to electrical contacts 119A and 119B under the electric field. The electric field may be an external electric field. Electrical contacts 119B may include discrete portions. In an embodiment, the charge carriers may drift in all directions such that the charge carriers generated by a single radiation particle are not substantially shared by two different discrete portions of the electrical contact 119B (herein "substantially not. .....shared means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers compared to the rest of the charge carriers flow to a different discrete segment). Charge carriers generated by radiation particles incident around the footprint of one of the discrete portions of electrical contact 119B are substantially not shared with the other of the discrete portions of electrical contact 119B. A pixel 150 associated with a discrete portion of electrical contact 119B may be an area around the discrete portion in which substantially all (more than 98%, more than 99.5%, more than 99.9%) of the radiation produced by radiation particles incident therein or more than 99.99%) of the charge carriers flow to discrete portions of the electrical contacts 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of the charge carriers flow through pixels associated with a discrete portion of electrical contact 119B.

Imaging Systems and Image Sensors

Fig. 5 schematically shows an imaging system 500 according to an embodiment. In an embodiment, the imaging system 500 may include an image sensor 510 , a computer 520 and a radiation source 530 .

In an embodiment, radiation source 530 may send radiation beam 532 to object 540 and then to image sensor 510 . In other words, the object 540 is located between the radiation source 530 and the image sensor 510 . Radiation beam 532 may include X-rays.

In an embodiment, image sensor 510 may include a stack of five radiation detectors 100 . In an embodiment, five radiation absorbing layers 110 and five electronics layers 120 of five radiation detectors 100 may be arranged in an alternating manner as shown. In other words, from right to left is the radiation absorbing layer 110, then the electronics layer 120, then the radiation absorbing layer 110, then the electronics layer 120, and so on.

In an embodiment, the image sensor 510 may further include 5 collimator regions 515 for the 5 electronic device layers 120 respectively. In an embodiment, five collimator regions 515 may be respectively located on five electronic device layers 120 as shown. In an embodiment, five collimator regions 515 may be respectively located on and in direct physical contact with five electronic device layers 120 as shown. In an embodiment, the collimator region 515 may comprise a material that blocks and absorbs X-rays, such as tungsten.

In an embodiment, there is a reference straight line 519 for the image sensor 510 such that for each of the five electronic device layers 120, the reference straight line 519 intersects said each electronic device layer Any (ie, every) straight line of , intersects the corresponding collimator region 515 .

For example, for the electronics layer 120.1 of the radiation detector 100.1, any line that intersects the electronics layer 120.1 and is parallel to the reference line 519 intersects the corresponding collimator region 515.1. As a result, radiation of the radiation beam 532 from the radiation source 530 parallel to the reference line 519 and aimed at the electronics layer 120.1 is blocked by the collimator region 515.1 and thus prevented from hitting the electronics layer 120.1.

In an embodiment, for each of the five radiation absorbing layers 110, any (ie, each) line that intersects each of the radiation absorbing layers and is parallel to the reference line 519 is not collimated with the five Any collimator regions intersecting the collimator region 515.

For example, for radiation absorbing layer 110.1 of radiation detector 100.1, any line that intersects radiation absorbing layer 110.1 and is parallel to reference line 519 does not intersect any of the five collimator areas 515. As a result, radiation of the radiation beam 532 from the radiation source 530 parallel to the reference line 519 and aimed at the radiation absorbing layer 110.1 is not blocked by any of the collimator regions 515 (including the collimator region 515.1) and can thus strike the radiation absorbing layer 110.1.

In an embodiment, the computer 520 may be electrically connected to the five electronics layers 120 of the image sensor 510 . In an embodiment, computer 520 may receive and process data from electronics layer 120 to generate an image of object 540 .

The term "image" in this specification is not limited to the spatial distribution of radiation properties such as intensity. For example, the term "image" may also include the spatial distribution of the density of a substance or element.

Operation of the Imaging System

In an embodiment, imaging system 500 may operate as follows. In an embodiment, radiation source 530 may send radiation beam 532 to object 540 and then to image sensor 510 . In an embodiment, radiation beam 532 may include X-rays parallel to reference line 519 .

As a result, the collimator region 515 prevents the radiation beam 532 from entering the five electronics layers 120 but does not prevent the radiation beam 532 from impinging on the five radiation absorbing layers 110 . Incident radiation striking the five radiation absorbing layers 110 generates electrical signals in the five radiation absorbing layers 110 . In response, in an embodiment, the five electronics layers 120 may monitor and process these electrical signals and generate data accordingly. In response, in an embodiment, computer 520 may receive and process data generated by five electronics layers 120 and generate an image of object 540 .

Flowchart outlining operations

FIG. 6 shows a flowchart 600 outlining the operation of the imaging system 500 of FIG. 5 described above, according to an embodiment. In step 610, an image sensor of an imaging system receives incident radiation. For example, in the embodiments described above, with reference to FIG. 5 , image sensor 510 of imaging system 500 receives incident radiation of radiation beam 532 .

Furthermore, in step 610, the image sensor comprises a stack of M radiation detectors, each radiation detector comprising (A) a radiation absorbing layer and (B) a radiation detector configured to process electrical signals generated in the radiation absorbing layer The electronic device layer, M is an integer greater than 1. For example, in the embodiment described above, referring to FIG. 5 , the image sensor 510 includes a stack of five radiation detectors 100, each radiation detector 100 including (A) a radiation absorbing layer 110 and (B) configured to process Electronics layer 120 for electrical signals generated in radiation absorbing layer 110 (here, M=5>1).

In addition, in step 610, the image sensor further includes M collimator regions for the M electronic device layers of the M radiation detectors, respectively. For example, in the above embodiment, referring to FIG. 5 , the image sensor 510 further includes 5 collimator regions 515 for the 5 electronic device layers 120 of the 5 radiation detectors 100 respectively.

Furthermore, in step 610, there is a reference straight line for the image sensor such that for each of the M electronic device layers, any The straight lines all intersect the corresponding collimator regions. For example, in the above embodiments, referring to FIG. 5 , for the electronics layer 120.1, any straight line that intersects the electronics layer 120.1 and is parallel to the reference straight line 519 intersects the corresponding collimator region 515.1.

Furthermore, in step 610, for each of the M radiation absorbing layers, any straight line that intersects said each radiation absorbing layer and is parallel to the reference straight line is not collimated with any of the M collimator regions area intersects. For example, in the above embodiments, referring to FIG. 5 , for the radiation absorbing layer 110.1, any straight line that intersects the radiation absorbing layer 110.1 and is parallel to the reference straight line 519 does not intersect any of the five collimator regions 515.

other embodiments

Collimator area fully shields electronics layers

In an embodiment, referring to FIG. 5 , the image sensor 510 and radiation source 530 may be such that each of the five collimator regions 515 completely shields the corresponding electronics layer 120 from the radiation source 530 . In other words, each of the five collimator regions 515 completely shields the corresponding electronics layer 120 from radiation from the radiation source 530 . For example, the collimator region 515.1 completely prevents radiation from the radiation source 530 from striking the corresponding electronics layer 120.1.

Collimator Area - Shape and Thickness

In an embodiment, referring to FIG. 5 , each of the five collimator regions 515 has the shape of a plate having the same thickness as the corresponding electronics layer 120 . For example, the collimator region 515.5 has the shape of a plate having the same thickness 515w as the thickness 120w of the corresponding electronics layer 120.5.

Image generation - summing the final voltages

In an embodiment, referring to FIG. 5 , imaging system 500 may generate an image of object 540 as follows. Specifically, radiation source 530 may send radiation beam 532 to object 540 and then to image sensor 510 .

In an embodiment, with respect to the radiation detector 100.1, the electronics layer 120.1 may monitor the voltage of each sensing element 150 of the corresponding radiation absorbing layer 110.1. The voltage of sensing element 150 may be the voltage of electrical contact 119B of sensing element 150 ( FIGS. 3 and 4 ).

In an embodiment, if the electronics layer 120.1 finds that the voltage of the sensing element 150 of the radiation absorbing layer 110.1 exceeds a predetermined threshold voltage Vt at a time point T1, the electronics layer 120.1 may measure the voltage of the sensing element 150 at a time point T2. voltage, the time point T2 is delayed by a predetermined time after T1. This measured voltage may be referred to as the final voltage. After the measurement of the final voltage of the sensing element 150 , the charge carriers in the sensing element 150 that generated the final voltage of the sensing element 150 may be discharged.

In an embodiment, the computer 520 may sum the measured final voltages of the sensing elements 150 of the same sensing element column. Note that the voltages of these sensing elements 150 exceed the predetermined threshold voltage Vt.

For example, referring to Fig. 5, assume that Vt = 2V, and that X-ray photons (not shown) of radiation beam 532 enter the rightmost column of sensing elements of radiation absorbing layer 110.1. The rightmost sensing element column includes seven sensing elements 150(4,7)-150(4,1). Assume further that the charge carriers generated by photons in sense elements 150(4,7), 150(4,6), 150(4,5) and 150(4,4) of the rightmost sense element column It is enough to make the voltage of these 4 sense elements exceed Vt. As a result, the electronics layer 120.1 measures the 4 final voltages of the 4 sensing elements 150(4,7), 150(4,6), 150(4,5) and 150(4,4). Assume that the measured final voltages of sensing elements 150(4,7), 150(4,6), 150(4,5) and 150(4,4) are 6V, 5V, 8V and 3V, respectively. Then, the computer 520 adds together the four final voltages to obtain the photon voltage value. Specifically, the photon voltage value of the photon and the rightmost sensing element column is 6V+5V+8V+3V=22V.

Suppose another X-ray photon later enters the same rightmost column of sensing elements. In an embodiment, imaging system 500 may perform the same operations described above and determine another photon voltage value for the photon and the rightmost column of sensing elements.

In an embodiment, for an exposure time period, the computer 520 may sum the rightmost column of sensing elements and all photon voltage values of all photons that entered the rightmost column of sensing elements during the exposure time period. As a result, the sum of all these photon voltage values represents the total energy of all photons that hit the rightmost column of sensing elements during the exposure period.

For example, assume that during the exposure period, 30 photons of radiation beam 532 enter the rightmost column of sensing elements one after the other. As a result, imaging system 500 determines 30 photon voltage values for the 30 photons. The sum of all 30 photon voltage values represents the total energy of all 30 photons that entered the rightmost column of sensing elements during the exposure time.

In an embodiment, the imaging system 500 can perform the same operations as above for the other 19 sensing element columns of the image sensor 510 . As a result, since the image sensor 510 has 5×4=20 sensing element columns, the 20 sums of the 20 sensing element columns represent the values of the 20 image elements of the object 540 image. Please note that each column of sensing elements of the image sensor 510 corresponds to an image element of the image of the object 540 .

Ignore Bad Sensing Element—Compare with Immediately Above Sensing Element in Same Column

In an embodiment, the above-described final voltage summation of sense elements in the same sense element column may not be applicable to bad sense elements. In an embodiment, a sensing element 150 may be considered a bad sensing element if its final voltage exceeds the final voltage of the immediately above sensing element 150 in the same sensing element column by at least a predetermined voltage tolerance value. element.

For example, assume that the predetermined voltage tolerance value is 1V, and assume that the final voltages of sensing elements 150(4,7), 150(4,6), 150(4,5), and 150(4,4) are 6V, 5V, 8V and 3V. Since the final voltage of sense element 150 should decrease as the depth of the sense element increases, sense element 150(4,5) would be considered a bad sense element because its final voltage (8V) exceeds the rightmost The final voltage (5V) of the sense elements 150 (4, 6) directly above in the sense element column is at least 1V.

In an embodiment, the final voltage of a bad sense element 150 may be ignored when summing the final voltages of the columns of sense elements. In the above example, the computer 520 may add 6V+5V+3V=14V for the rightmost column of sense elements (ie, the final voltage (8V) of the bad sense element 150 (4,5) is ignored).

alternative embodiment

Bad sensing element—compare to adjacent sensing elements at the same depth

In the embodiments described above, a sensing element 150 is considered bad if its final voltage exceeds the final voltage of the immediately above sensing element in the same sensing element column by at least a predetermined voltage tolerance value. In an alternative embodiment, a sense element 150 may be considered defective if its final voltage exceeds the final voltage of sense elements in adjacent columns of sense elements at the same depth by at least a predetermined voltage tolerance value. of.

In the above example, it is assumed that the predetermined voltage tolerance value is 1V, and the final voltage of the sensing element 150(3,5) is 4V. Sensing element 150 ( 4 , 5 ) can then be considered a bad sensing element because its final voltage (8V) exceeds the final voltage (4V) of sensing element 150 ( 3 , 5 ) by at least 1V. Note that sensing element 150(3,5) belongs to an adjacent sensing element column and is at the same depth as sensing element 150(4,5). Note also that since sensing elements 150(3,5) and 150(4,5) are at the same depth, there is a lines that intersect.

Column groups compared to individual columns

In the above-mentioned embodiment, the computer 520 sums the measured final voltages of the sensing elements 150 of the same sensing element row. In an alternative embodiment, all other things being equal, computer 520 may sum the resulting voltages measured for sense elements of the same sense element column group. A sensing element column group may include a plurality of adjacent sensing element columns of the radiation absorbing layer 110 .

For example, the 4 sensing element columns of the radiation absorbing layer 110.1 can be divided into 2 sensing element column groups, each sensing element column group has 2 adjacent sensing element columns. Specifically, the first sensing element column group may include left 2 sensing element columns, and the second sensing element column group may include right 2 sensing element columns. The other four radiation absorbing layers 110 of the image sensor 510 can be divided into sensing element column groups in a similar manner. As a result, the image sensor 510 has 2×5=10 sensor column groups in total, and each sensor column group has 2 adjacent sensor column groups. As a result, the resulting image of object 540 should have 2x5=10 image elements (each image element of the image corresponds to a sensing element column group).

Although various aspects and embodiments have been 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 appended claims.

100, 100.1: Radiation detectors 110, 110.1, 110.5: radiation absorbing layer 111: the first doped region 112: Intrinsic area 113: the second doped region 114: discrete area 119A, 119B: electrical contacts 120, 120.1, 120.5: Electronic device layer 120w, 515w: thickness 121: Electronic system 130: filling material 131: Through hole 150,150(3,5),150(4,1),150(4,4)-150(4,7): pixel (sensing element) 500: imaging system 510: image sensor 515, 515.1, 515.5: Collimator area 519: Reference line 520: computer 530: Radiation source 532: Radiation Beam 540: object 600: Flowchart 610: Step

Fig. 1 schematically shows a radiation detector according to an embodiment. Fig. 2 schematically shows a simplified cross-sectional view of a radiation detector according to an embodiment. Fig. 3 schematically shows a detailed cross-sectional view of a radiation detector according to an embodiment. Fig. 4 schematically shows a detailed cross-sectional view of a radiation detector according to an alternative embodiment. Fig. 5 schematically shows an imaging system including an image sensor according to an embodiment. Figure 6 shows a flowchart outlining the operation of the imaging system.

100.1: Radiation detectors

110.1, 110.5: Radiation absorbing layer

120.1, 120.5: Electronic device layer

120w, 515w: thickness

150(3,5), 150(4,1), 150(4,4)-150(4,7): sensing element

500: imaging system

510: image sensor

515, 515.1, 515.5: Collimator area

519: Reference line

520: computer

530: Radiation source

532: Radiation Beam

540: object

Claims (22)

An imaging system includes an image sensor, the image sensor includes: A stack of M radiation detectors, each of said radiation detectors comprising (A) a radiation absorbing layer and (B) an electronics layer configured to process electrical signals generated in said radiation absorbing layer, M being greater than 1 an integer of ; and M collimator regions for the M electronics layers of the M radiation detectors, respectively, Wherein, there is a reference straight line for the image sensor, so that for each electronic device layer in the M electronic device layers, the Each line intersects the corresponding collimator region, and Wherein, for each radiation-absorbing layer in the M radiation-absorbing layers, each straight line that intersects each radiation-absorbing layer and is parallel to the reference straight line does not collide with any of the M collimator regions. Collimator regions intersect. The imaging system according to claim 1, wherein the M collimator regions are respectively located on the M electronic device layers and are in direct physical contact with the M electronic device layers. The imaging system as described in claim 1, further comprising: A radiation source, wherein each of the M collimator regions completely shields a corresponding electronics layer with respect to the radiation source. The imaging system of claim 1, wherein each of the M collimator regions has a shape of a plate having the same thickness as the corresponding electronics layer. The imaging system of claim 1, wherein the M radiation absorbing layers and the M electronic device layers are arranged in an alternating manner. The imaging system of claim 1, wherein the M collimator regions comprise tungsten. The imaging system of claim 1, wherein, for each of the M radiation detectors, the radiation absorbing layer of each radiation detector is configured to generate an electrical signal in response to incident X-ray photons, and Wherein, the electronics layer of each radiation detector is configured to process generated electrical signals. The imaging system of claim 1, Wherein, each radiation absorbing layer in the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, Wherein, for each sensing element column of each radiation absorbing layer in the M radiation absorbing layers, the imaging system is configured to sense the voltage in each sensing element column exceeding a predetermined threshold voltage. The final voltage of the measured element is summed, and Wherein, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element column. The imaging system of claim 8, Wherein, the first sensing element whose final voltage in each sensing element column exceeds the final voltage of the second sensing element in each sensing element column by at least a predetermined voltage tolerance value does not perform the above-mentioned step. The summation of the final voltage, wherein the first sensing element is adjacent to the second sensing element, and Wherein, the second sensing element is located between the first sensing element and the M collimator regions. The imaging system of claim 8, Wherein, for the first sensing element whose final voltage in each sensing element column exceeds the final voltage of the second sensing element of the adjacent sensing element column by at least a predetermined voltage tolerance value, the final voltage measurement is not performed. the addition, and Wherein, a straight line perpendicular to the reference straight line intersects both the first sensing element and the second sensing element. The imaging system of claim 1, Wherein, each radiation absorbing layer in the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, Wherein, the sensing element columns of the image sensor are arranged in a plurality of sensing element column groups of adjacent sensing element columns, Wherein, for each sensing element column group of the image sensor, the imaging system is configured to calculate the final voltage of the sensing element whose voltage in each sensing element column group exceeds a predetermined threshold voltage add up, Wherein, each sensing element column group includes N sensing element columns, N is an integer greater than 1, and Wherein, for each sensing element row in each sensing element row group, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element row. A method comprising: The incident radiation is received with an image sensor of the imaging system, the image sensor comprising: A stack of M radiation detectors, each of said radiation detectors comprising (A) a radiation absorbing layer and (B) an electronics layer configured to process electrical signals generated in said radiation absorbing layer, M being greater than 1 an integer of ; and M collimator regions for the M electronics layers of the M radiation detectors, respectively, Wherein, there is a reference straight line for the image sensor, so that for each electronic device layer in the M electronic device layers, the Each line intersects the corresponding collimator region, and Wherein, for each radiation-absorbing layer in the M radiation-absorbing layers, each straight line that intersects each radiation-absorbing layer and is parallel to the reference straight line does not collide with any of the M collimator regions. Collimator regions intersect. The method according to claim 12, wherein the M collimator regions are respectively located on the M electronic device layers and are in direct physical contact with the M electronic device layers. The method of claim 12, wherein each of the M collimator regions completely shields the corresponding electronics layer from the same radiation source. The method of claim 12, wherein each of the M collimator regions has the shape of a plate having the same thickness as the corresponding electronics layer. The method of claim 12, wherein the M radiation absorbing layers and the M electronic device layers are arranged in an alternating manner. The method of claim 12, wherein the M collimator regions comprise tungsten. The method of claim 12, wherein, for each of the M radiation detectors, the radiation absorbing layer of each radiation detector is configured to generate an electrical signal in response to incident X-ray photons, and Wherein, the electronics layer of each radiation detector is configured to process generated electrical signals. The method of claim 12, Wherein, each radiation absorbing layer in the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, Wherein, the method further includes: for each sensing element column of each radiation absorbing layer in the M radiation absorbing layers, using the imaging system to increase the voltage in each sensing element column beyond a predetermined threshold voltage is summed to the final voltage of the sense element, and Wherein, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element column. The method of claim 19, Wherein, the first sensing element whose final voltage in each sensing element column exceeds the final voltage of the second sensing element in each sensing element column by at least a predetermined voltage tolerance value does not perform the above-mentioned step. The summation of the final voltage, wherein the first sensing element is adjacent to the second sensing element, and Wherein, the second sensing element is located between the first sensing element and the M collimator regions. The method of claim 19, Wherein, for the first sensing element whose final voltage in each sensing element column exceeds the final voltage of the second sensing element of the adjacent sensing element column by at least a predetermined voltage tolerance value, the final voltage measurement is not performed. the addition, and Wherein, a straight line perpendicular to the reference straight line intersects both the first sensing element and the second sensing element. The method of claim 12, Wherein, each radiation absorbing layer in the M radiation absorbing layers includes a plurality of sensing elements arranged in a plurality of sensing element columns, Wherein, the sensing element columns of the image sensor are arranged in a plurality of sensing element column groups of adjacent sensing element columns, Wherein, the method further includes: for each sensing element column group of the image sensor, using the imaging system to detect the voltage in each sensing element column group exceeding a predetermined threshold voltage The final voltage of the elements is summed, Wherein, each sensing element column group includes N sensing element columns, N is an integer greater than 1, and Wherein, for each sensing element row in each sensing element row group, a straight line parallel to the reference straight line intersects all sensing elements in each sensing element row.

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