TWI842206B - Imaging systems with image sensors for side radiation incidence during imaging and method of using the same - Google Patents

Abstract

Disclosed herein is a system comprising an image sensor which comprises: M metal layers (metal layers (i), i=1, ..., M) and M radiation detectors (radiation detectors (i), i=1, ..., M). For each value of i, the radiation detector (i) comprises (A) a radiation absorption layer (i) which comprises multiple sensing elements, and (B) Ni integrated circuit chips configured to process electrical signals generated in the radiation absorption layer (i). M is an integer greater than 1. Ni, i=1, ..., M are positive integers. The M metal layers and the radiation absorption layers (i), i=1, ..., M together form a stack of layers.

Description

Imaging system having an image sensor for side radiation incidence during imaging and method of using the same

The present invention relates to an imaging system, and in particular to an imaging system having an image sensor for side radiation incidence during imaging.

A radiation detector is a device that measures a property of radiation. Examples of the property may include the spatial distribution of intensity, phase, and polarization of the radiation. The radiation measured by the radiation detector may be radiation that has passed through an 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. The radiation may be of other types, such as alpha rays and beta rays. An imaging system may include one or more image sensors, each of which may have one or more radiation detectors.

This article discloses a system, which includes an image sensor, which includes M metal layers (metal layer (i), i=1, ..., M) and M radiation detectors (radiation detector (i), i=1, ..., M). For each value of i, the radiation detector (i) includes (A) a radiation absorption layer (i) including multiple sensing elements, and (B) Ni integrated circuit chips configured to process electrical signals generated in the radiation absorption layer (i). M is an integer greater than 1. Ni, i=1, ..., M are positive integers. The M metal layers and the radiation absorption layer (i), i=1, ..., M together form a stack of layers.

In one aspect, the stack comprises 2×M layers.

In one aspect, the M metal layers comprise a metal having an atomic number of at least 26.

In one aspect, the metal is tungsten, platinum or gold.

In one aspect, the M metal layers and the radiation absorbing layers (i), i=1, ..., M are arranged in the stack in an alternating manner.

On the one hand, the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and a plane perpendicular to the best fitting plane intersects all of the M metal layers and does not intersect any radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M.

In one aspect, the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and the thickness of each of the M metal layers measured in a direction perpendicular to the best fitting plane is in the range of 50 microns to 100 microns.

In one aspect, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) comprises an application specific integrated circuit (ASIC).

In one aspect, the M metal layers are configured to block and absorb X-rays.

In one aspect, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) is sandwiched between the metal layer (i) and the radiation absorbing layer (i).

In one aspect, for each value of i, the metal layer (i) includes Pi gaps, Pi is a positive integer not greater than Ni, and for each value of i, the Ni integrated circuit chips of the radiation detector (i) are located within the Pi gaps of the metal layer (i).

On the one hand, for every value of i, Ni>Pi.

In one aspect, for each value of i, Ni=Pi, and for each value of i, the Ni integrated circuit chips of the radiation detector (i) are respectively located in the Pi gaps of the metal layer (i).

In one aspect, the best fitting plane passes through all sensing elements of the radiation absorbing layer (i), i=1, ..., M, and for each value of i, for each of the Pi gaps in the metal layer (i), each straight line intersecting each gap and perpendicular to the best fitting plane intersects the radiation absorbing layer (i).

In one aspect, the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and for each value of i, the thickness of each of the Ni integrated circuit chips of the radiation detector (i) measured in a direction perpendicular to the best fitting plane is less than the thickness of the metal layer (i) measured in a direction perpendicular to the best fitting plane.

In one aspect, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) is not in direct physical contact with the radiation absorbing layer of another radiation detector of the M radiation detectors.

On the one hand, each straight line segment having two end points on two adjacent radiation absorbing layers in the radiation absorbing layer (i), i=1, ..., M intersects with (A) at least one metal layer in the M metal layers or (B) at least one gap in one metal layer in the M metal layers.

On the one hand, each straight line segment on two adjacent radiation absorbing layers in the radiation absorbing layer (i), i=1, ..., M, respectively, intersects with a metal layer in the M metal layers.

In one aspect, the system further includes a radiation source; a best fit plane passes through all sensing elements of a radiation absorbing layer in (i), i=1, ..., M; and a straight line parallel to the best fit plane intersects both the radiation source and the image sensor. A method for using the system is also disclosed herein. The method includes transmitting radiation from the radiation source to the image sensor and to an object between the radiation source and the image sensor; and using the image sensor to capture an image of the object by using a portion of the radiation from the radiation source that has passed through the object.

2-2, 8-8: Line

100: Radiation Detector

105, 105.1, 105.2, 105.3: Radiation detectors

110: Radiation absorption layer

111: First mixed area

112: Intrinsic area

113: Second mixed area

114: Dispersed Area

115, 115.1, 115.2, 115.3: Radiation absorption layer

119A, 119B: electrical contacts

120: Electronic device layer

121: Electronic systems

125a, 125a.1, 125a.2, 125b, 125b.1, 125b.2, 125c, 125c.1, 125d, 125d.1: integrated circuit chips

127, 640: thickness

130: Filling material

131:Through hole

150: Element

600: Image sensor

610.1, 610.2, 610.3: Metal layer

612a.1, 612b.1, 612c.1, 612d.1: gaps

620: Best fitting plane

630: Plane

650: Viewpoint

900: Imaging system

910: Radiation source

912: Fallout

920: Object

1000:Flowchart

1010, 1020: Steps

FIG1 schematically shows a radiation detector according to an embodiment.

FIG2 schematically shows a simplified cross-sectional view of a radiation detector according to an embodiment.

FIG3 schematically shows a detailed cross-sectional view of a radiation detector according to an embodiment.

FIG4 schematically shows a detailed cross-sectional view of a radiation detector according to an alternative embodiment.

FIG5 schematically shows a perspective view of another radiation detector according to an embodiment.

FIG6 schematically shows a side view of an image sensor according to an embodiment.

FIG7 schematically shows a side view of an image sensor according to an alternative embodiment.

FIG8 schematically shows a cross-sectional view of the image sensor of FIG7 according to an embodiment.

FIG9 schematically shows an imaging system according to an embodiment.

FIG10 shows a flow chart outlining the operation of the imaging system according to an embodiment.

Radiation detector

FIG1 schematically shows a radiation detector 100 as an example. The radiation detector 100 may include an array of picture elements 150 (also referred to as sensing elements 150). The array may be a rectangular array (as shown in FIG1 ), a honeycomb array, a hexagonal array, or any other suitable array. The array of picture elements 150 in the example of FIG1 has 4 columns and 7 rows; however, in general, the array of picture elements 150 may 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 characteristics of the radiation (e.g., energy, wavelength, and frequency of the particles). Radiation may include particles such as photons and subatomic particles. Each pixel 150 may be configured to count the number of radiation particles incident thereon whose energy falls into multiple energy intervals over a period of time. All pixels 150 may be configured to count the number of radiation particles incident thereon in multiple energy intervals over the same period of time. When the incident radiation particles have similar energies, the pixel 150 may be configured to count only the number of radiation particles incident thereon over a period of time without measuring the energy of a single radiation particle.

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 to digitize an analog signal representing the total energy of multiple incident radiation particles into a digital signal. The 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 arrival of a radiation particle. The pixels 150 may not necessarily be individually addressable.

The radiation detector 100 described herein may have applications such as X-ray telescopes, X-ray mammography, industrial X-ray defect detection, X-ray microscopes or microradiography, X-ray casting inspection, X-ray nondestructive inspection, X-ray 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.

FIG. 2 schematically illustrates a simplified cross-sectional view of the radiation detector 100 of FIG. 1 along line 2-2 according to an embodiment. Specifically, the radiation detector 100 may include a radiation absorbing layer 110 and an electronic device 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. The semiconductor material may have a high quality attenuation coefficient 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 (e.g., p-i-n or p-n) formed by one or more discrete regions 114 of the first doped region 111, 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 (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 FIG3 , each discrete region 114 of the second doped region 113 forms a diode having the first doped region 111 and the optional intrinsic region 112. That is, in the example of FIG3 , the radiation absorbing layer 110 has a plurality of diodes (more specifically, 7 diodes correspond to 7 picture elements 150 of one column in the array of FIG1 , and for simplicity, only 2 picture elements 150 are marked in FIG3 ). Multiple diodes may have an electrical contact 119A as a common electrode. The first doped region 111 may also have a discrete portion.

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

When radiation from a radiation source (not shown) strikes the radiation absorbing layer 110 including the diode, the radiation particles can be absorbed and one or more electric carriers (e.g., electrons, holes) can be generated by a variety of mechanisms. The electric carriers can drift to the electrode of one of the diodes under an electric field. The electric field can be an external electric field. The electrical contact 119B can include discrete portions, each of which is in electrical contact with the discrete region 114. The term "electrical contact" can be used interchangeably with the term "electrode". In an embodiment, the charge carriers can drift in various directions so that the charge carriers generated by a single radiation particle are substantially not shared by two different discrete regions 114 (here “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 region 114 compared to the rest of the charge carriers). The charge carriers generated by the radiation particles incident on the surrounding area of the coverage of one of these discrete regions 114 are substantially not shared with another of these discrete regions 114. The image element 150 associated with the discrete region 114 can 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 charge carriers generated by radiation particles incident therein flow toward the discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of these charge carriers flow through the image element 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 does not include diodes. The semiconductor material may have a high quality attenuation coefficient for the radiation of interest. In one embodiment, the electronic device layer 120 of FIG. 4 is similar in structure and function to the electronic device 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. The radiation particles can generate 10 to 100,000 charge carriers. The charge carriers can drift to the electrical contacts 119A and 119B under an electric field. The electric field can be an external electric field. The electrical contact 119B can include a discrete portion. In an embodiment, the charge carriers can drift in various directions so that the charge carriers generated by a single radiation particle are substantially not shared by two different discrete portions of the electrical contact 119B (here "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 portion compared to the rest of the charge carriers). The charge carriers generated by the radiation particles incident on the surrounding area of the coverage of one of these discrete portions of the electrical contact 119B are substantially not shared with another of these discrete portions of the electrical contact 119B. The picture element 150 associated with the discrete portion of the electrical contact 119B can 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 charge carriers generated by the radiation particles incident therein flow toward the discrete portion of the electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow through the picture element associated with a discrete portion of the electrical contact 119B.

Radiation detector with integrated circuit chip

FIG5 schematically shows a perspective view of a radiation detector 105 according to an embodiment. In an embodiment, the radiation detector 105 may include a radiation absorbing layer 115 and one or more integrated circuit chips 125 (e.g., four integrated circuit chips 125a, 125b, 125c, and 125d as shown).

In an embodiment, the radiation detector 105 may be similar to the radiation detector 100 of FIGS. 1 to 4 because (A) the radiation absorption layer 115 of the radiation detector 105 is similar in structure and function to the radiation absorption layer 110 of the radiation detector 100, and (B) the integrated circuit chip 125 of the radiation detector 105 is similar in function to the electronic device layer 120 of the radiation detector 100.

Specifically, in an embodiment, the integrated circuit chip 125 may be configured to process the electrical signal generated in the radiation absorption layer 115. In an embodiment, each integrated circuit chip 125 may include an ASIC (application specific integrated circuit).

Image sensor

FIG6 schematically shows a side view of an image sensor 600 according to an embodiment. In an embodiment, the image sensor 600 may include a plurality of radiation detectors 105 (e.g., three radiation detectors 105.1, 105.2, and 105.3 as shown). The radiation detectors 105.1, 105.2, and 105.3 may include radiation absorbing layers 115.1, 115.2, and 115.3, respectively.

In an embodiment, the image sensor 600 may also include a plurality of metal layers 610 (e.g., three metal layers 610.1, 610.2, and 610.3 as shown in the figure). In an embodiment, the three metal layers 610.1, 610.2, and 610.3 and the three radiation absorbing layers 115.1, 115.2, and 115.3 together form a six-layer stack as shown in the figure.

In an embodiment, three metal layers 610.1, 610.2 and 610.3 and three radiation absorbing layers 115.1, 115.2 and 115.3 can be arranged in an alternating manner in a stack as shown in the figure. "Alternating manner" means that the layers in the stack are arranged in the order of metal layer 610, then radiation absorbing layer 115, then metal layer 610, and then radiation absorbing layer 115.

In an embodiment, the metal layer 610 of the image sensor 600 may include a metal having an atomic number of at least 26 (e.g., tungsten, platinum, and gold). In an embodiment, the metal layer 610 may block and absorb X-rays.

In an embodiment, referring to FIG. 6 , each integrated circuit chip 125 of the image sensor 600 may be sandwiched between the corresponding metal layer 610 and the corresponding radiation absorption layer 115. For example, the integrated circuit chip 125a.1 of the radiation detector 105.1 is sandwiched between the corresponding metal layer 610.1 and the corresponding radiation absorption layer 115.1. For another example, the integrated circuit chip 125b.1 of the radiation detector 105.1 is sandwiched between the corresponding metal layer 610.1 and the corresponding radiation absorption layer 115.1.

In an embodiment, referring to FIG. 6 , the best fit plane 620 passes through all sensing elements 150 of one of the three radiation absorbing layers 115.1, 115.2, and 115.3 (e.g., the radiation absorbing layer 115.1 as shown). Note that the best fit plane 620 is perpendicular to the page; therefore, the best fit plane 620 is represented by a straight line. In an embodiment, the structure of the image sensor 600 may be such that there is at least one plane (e.g., plane 630) that (A) is perpendicular to the best fit plane 620, (B) intersects all metal layers 610, and (C) does not intersect any radiation absorbing layer 115. In other words, structurally, all metal layers 610 protrude from the image sensor 600 in the same direction (e.g., upward as shown). Note that plane 630 is chosen to be perpendicular to the page; therefore, plane 630 is represented by a straight line.

In an embodiment, referring to FIG. 6 , the thickness of each metal layer 610 measured in a direction perpendicular to the best fitting plane 620 may be in the range of 50 microns to 100 microns. For example, the thickness 640 of the metal layer 610.1 measured in a direction perpendicular to the best fitting plane 620 is in the range of 50 microns to 100 microns.

In an embodiment, referring to FIG. 6 , the structure of the image sensor 600 can make each straight line segment of the two end points on the two adjacent radiation absorption layers 115 intersect with the metal layer 610. For example, each straight line segment of the two end points on the two adjacent radiation absorption layers 115.1 and 115.2 intersects with the metal layer 610.2.

In an embodiment, the IC chips 125 of different radiation detectors 105 may be arranged in a staggered manner. For example, a line perpendicular to the stack and passing through one IC chip may not pass through another IC chip.

Alternative embodiments of image sensors

FIG. 7 schematically illustrates the image sensor 600 of FIG. 6 as viewed from viewpoint 650 according to an alternative embodiment. FIG. 8 schematically illustrates a cross-sectional view of the image sensor 600 of FIG. 7 along line 8-8 according to an embodiment.

In an embodiment, referring to FIGS. 7 and 8 , each metal layer 610 may include one or more gaps 612 (e.g., four gaps 612a.1, 612b.1, 612c.1, and 612d.1 of metal layer 610.1 as shown in the figure). In an embodiment, for each radiation detector 105, the integrated circuit chip 125 of each radiation detector 105 may be located in the gap 612 of the corresponding metal layer 610, respectively. For example, for the radiation detector 105.1, the four integrated circuit chips 125a.1, 125b.1, 125c.1 and 125d.1 of the radiation detector 105.1 are respectively located in the four gaps 612a.1, 612b.1, 612c.1 and 612d.1 of the corresponding metal layer 610.1.

Generally speaking, the number of gaps 612 of each metal layer 610 may be equal to or less than the number of integrated circuit chips 125 of the corresponding radiation detector 105. The case where the number of gaps 612 of the metal layer 610 is equal to the number of integrated circuit chips 125 of the corresponding radiation detector 105 is described above.

In the case where the number of voids 612 of the metal layer 610 is less than the number of integrated circuit chips 125 of the corresponding radiation detector 105, at least one of the voids 612 accommodates multiple integrated circuit chips 125. For example, referring to Figures 7 and 8, if the voids 612a.1 and 612b.1 are replaced by a larger void (not shown), the larger void can accommodate two integrated circuit chips 125a.1 and 125b.1. In other words, the two integrated circuit chips 125a.1 and 125b.1 are in the larger void. Note that in this case, the metal layer 610.1 has three voids: void 612c.1, void 612d.1, and the larger void described above.

In an embodiment, referring to FIG. 8 , the structure of the image sensor 600 can be such that for each gap 612 of each metal layer 610, each straight line intersecting each gap 612 and perpendicular to the best fitting plane 620 intersects with the corresponding radiation absorption layer 115. For example, for the gap 612a.1 of the metal layer 610.1, each straight line intersecting the gap 612a.1 and perpendicular to the best fitting plane 620 intersects with the corresponding radiation absorption layer 115.1. For another example, for the gap 612b.1 of the metal layer 610.1, each straight line intersecting the gap 612b.1 and perpendicular to the best fitting plane 620 intersects with the corresponding radiation absorption layer 115.1.

In an embodiment, referring to FIG. 8 , the thickness of each integrated circuit chip 125 measured in a direction perpendicular to the best fitting plane 620 may be less than the thickness of the corresponding metal layer 610 measured in a direction perpendicular to the best fitting plane 620. For example, the thickness 127 of the integrated circuit chip 125a.1 measured in a direction perpendicular to the best fitting plane 620 is less than the thickness 640 of the corresponding metal layer 610.1 measured in a direction perpendicular to the best fitting plane 620.

In an embodiment, referring to FIG. 8 , each integrated circuit chip 125 of the radiation detector 105 is not in direct physical contact with the radiation absorption layer 115 of another radiation detector 105. For example, the integrated circuit chip 125a.2 of the radiation detector 105.2 is not in direct physical contact with any radiation absorption layer 115 of other radiation detectors 105.1 and 105.3. For another example, the integrated circuit chip 125b.2 of the radiation detector 105.2 is not in direct physical contact with any radiation absorption layer 115 of other radiation detectors 105.1 and 105.3.

In an embodiment, referring to FIG. 8 , the structure of the image sensor 600 can make each straight line segment with two end points on two adjacent radiation absorption layers 115 intersect with (A) at least one metal layer 610 or (B) at least one gap 612. For example, each straight line segment with two end points on two adjacent radiation absorption layers 115.1 and 115.2 intersects with (A) at least one metal layer 610.2 or (B) at least one gap 612 of the metal layer 610.2.

Imaging system

FIG. 9 schematically illustrates an imaging system 900 according to an embodiment. In an embodiment, the imaging system 900 may include a radiation source 910 and the image sensor 600 of FIG. 8 (or the image sensor 600 of FIG. 6 ).

In an embodiment, referring to FIG. 9 , the radiation source 910 and the image sensor 600 may be arranged so that a straight line (not shown) parallel to the best fitting plane 620 intersects both the radiation source 910 and the image sensor 600. This arrangement allows side radiation incidence during imaging using the image sensor 600.

In an embodiment, a radiation source 910 may transmit radiation 912 to an image sensor 600 and to an object 920 located between the radiation source 910 and the image sensor 600. In an embodiment, the image sensor 600 may capture an image of the object 920 by using a portion of the radiation 912 from the radiation source 910 that has passed through the object 920. The term "image" in this application is not limited to the spatial distribution of properties of radiation (e.g., intensity). For example, the term "image" may also include the spatial distribution of the density of a substance or element.

Flowchart outlining the operation of the imaging system

FIG. 10 shows a flow chart 1000 summarizing the operation of the imaging system 900 of FIG. 9. In step 1010, radiation is transmitted from a radiation source to an image sensor and to an object located between the radiation source and the image sensor. For example, in the above-described embodiment, referring to FIG. 9, radiation 912 is transmitted from a radiation source 910 to an image sensor 600 and to an object 920 located between the radiation source 910 and the image sensor 600.

In step 1020, the image sensor captures an image of the object by using a portion of the radiation from the radiation source that has passed through the object. For example, in the above embodiment, referring to FIG. 9 , the image sensor 600 captures an image of the object 920 by using a portion of the radiation 912 from the radiation source 910 that has passed through the object 920.

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 illustrative purposes and are not intended to be limiting, and the true scope and spirit are indicated by the attached patent application scope.

105.1, 105.2, 105.3: Radiation detectors

115.1, 115.2, 115.3: Radiation absorption layer

125a.1, 125b.1: Integrated circuit chip

600: Image sensor

610.1, 610.2, 610.3: Metal layer

620: Best fitting plane

630: Plane

640:Thickness

650: Viewpoint

Claims (20)

An imaging system having an image sensor for side radiation incidence during imaging, the imaging system comprising an image sensor, the image sensor comprising: M metal layers (metal layer (i), i=1, ..., M); and M radiation detectors (radiation detector (i), i=1, ..., M), wherein, for each value of i, the radiation detector (i) comprises (A) a radiation absorption layer (i) comprising a plurality of sensing elements, and (B) Ni integrated circuit chips configured to process electrical signals generated in the radiation absorption layer (i), wherein M is an integer greater than 1, wherein Ni, i=1, ..., M are positive integers, and wherein the M metal layers and the radiation absorption layer (i), i=1, ..., M together form a stack of layers. An imaging system as described in claim 1 having an image sensor for side radiation incidence during imaging, wherein the stack comprises 2×M layers. An imaging system as described in claim 1 having an image sensor for side radiation incidence during imaging, wherein the M metal layers comprise a metal having an atomic number of at least 26. An imaging system as described in claim 3 having an image sensor for side radiation incidence during imaging, wherein the metal is tungsten, platinum or gold. An imaging system having an image sensor with side radiation incident during imaging as described in claim 1, wherein the M metal layers and the radiation absorbing layers (i), i=1, ..., M are arranged in the stack in an alternating manner. An imaging system having an image sensor with side radiation incident during imaging as described in claim 1, wherein the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and wherein a plane perpendicular to the best fitting plane intersects all of the M metal layers and does not intersect any radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M. An imaging system having an image sensor with side radiation incident during imaging as described in claim 1, wherein the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and wherein the thickness of each of the M metal layers measured in a direction perpendicular to the best fitting plane is in the range of 50 microns to 100 microns. An imaging system as described in claim 1 having an image sensor for side radiation incidence during imaging, wherein, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) includes a dedicated integrated circuit. An imaging system as described in claim 1 having an image sensor for side radiation incidence during imaging, wherein the M metal layers are configured to block and absorb X-rays. An imaging system as described in claim 1 having an image sensor for side radiation incidence during imaging, wherein, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) is sandwiched between the metal layer (i) and the radiation absorbing layer (i). An imaging system as claimed in claim 1 having an image sensor for side radiation incidence during imaging, wherein, for each value of i, the metal layer (i) includes Pi gaps, Pi is a positive integer not greater than Ni, and wherein, for each value of i, the Ni integrated circuit chips of the radiation detector (i) are within the Pi gaps of the metal layer (i). An imaging system as described in claim 11 having an image sensor with side radiation incident during imaging, wherein, for each value of i, Ni>Pi. An imaging system having an image sensor with side radiation incident during imaging as described in claim 11, wherein, for each value of i, Ni=Pi, and wherein, for each value of i, the Ni integrated circuit chips of the radiation detector (i) are respectively located in the Pi gaps of the metal layer (i). An imaging system having an image sensor with side radiation incident during imaging as described in claim 13, wherein the best fitting plane passes through all sensing elements of the radiation absorbing layer (i), i=1, ..., M, and wherein, for each value of i, for each of the Pi gaps in the metal layer (i), each straight line intersecting each gap and perpendicular to the best fitting plane intersects the radiation absorbing layer (i). An imaging system having an image sensor with side radiation incident during imaging as described in claim 13, wherein the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and wherein, for each value of i, the thickness of each of the Ni integrated circuit chips of the radiation detector (i) measured in a direction perpendicular to the best fitting plane is less than the thickness of the metal layer (i) measured in a direction perpendicular to the best fitting plane. An imaging system as described in claim 13 having an image sensor for side radiation incidence during imaging, wherein, for each value of i, each of the Ni integrated circuit chips of the radiation detector (i) is not in direct physical contact with the radiation absorbing layer of another radiation detector of the M radiation detectors. An imaging system having an image sensor for side radiation incident during imaging as described in claim 13, wherein two end points are respectively on the radiation absorbing layers (i), i=1, ..., M, and each straight line segment on two adjacent radiation absorbing layers intersects with (A) at least one metal layer among the M metal layers or (B) at least one gap in a metal layer among the M metal layers. An imaging system having an image sensor with side radiation incident during imaging as described in claim 1, wherein two end points are respectively on the radiation absorbing layer (i), i=1, ..., M, and each straight line segment on two adjacent radiation absorbing layers intersects with a metal layer among the M metal layers. An imaging system as claimed in claim 1 having an image sensor with side radiation incident during imaging, further comprising a radiation source, wherein the best fitting plane passes through all sensing elements of a radiation absorbing layer in the radiation absorbing layer (i), i=1, ..., M, and wherein a straight line parallel to the best fitting plane intersects both the radiation source and the image sensor. A method of using an imaging system as claimed in claim 19 having an image sensor with side radiation incident during imaging, comprising: transmitting radiation from the radiation source to the image sensor and to an object located between the radiation source and the image sensor; and using the image sensor to capture an image of the object by using a portion of the radiation from the radiation source that has passed through the object.