Radioactivity detectors for location-resolved detection of radiation

Abstract

A radiation detector for the spatially resolved detection of radiation comprises at least one sensor tile (1) having a radiation-sensitive sensor material (11). The sensor tile (1) defines a horizontal plane spanned by a first axis (x) and a second axis (y) orthogonal to the first axis (x). A set of sensor pixels (12) of conductive material are arranged in the horizontal plane and in contact with the sensor material (11). The set includes inner sensor pixels (12). i ) and a subset of the inner sensor pixels (12 iJ ) has adjacent sensor pixels (12) in the direction of each of a first axis (x) and a second axis (y). At least two adjacent inner sensor pixels (121) of the subset exhibit an extension along a second axis (y) that exceeds their extension along the first axis (x). The radiation detector further comprises at least one readout chip (2) assigned to at least one sensor tile (1) and extending along the first axis (x) and the second axis (y). The readout chip (2) comprises a set of integrated readout circuits (21), each readout circuit (21) of the set being electrically connected to one of the sensor pixels (12) of the set for reading out a charge input from the assigned sensor pixel (12). The set of readout circuits (21) comprises an inner readout circuit (21). p ), and an inner read circuit (21 i ) has a readout circuit (21) in each direction of a first axis (x) and a second axis (y). Each of the two inner readout circuits (211) assigned to and connected to two adjacent inner sensor pixels (121) exhibits an extension along the first axis (x) that is different from the extension (xd) of the assigned sensor pixel (121) along the first axis (x) and / or an extension along the second axis (y) that is different from the extension (yd) of the assigned sensor pixel (12d) along the second axis (y).

Description

[Technical Field]

[0001] This invention relates to a radiation detector for position-resolved detection of radiation. [Background technology]

[0002] Prior art hybrid pixel detectors (HPDs) comprise pixelated sensor tiles connected pixel by pixel to a readout chip. In prior art HPDs, semiconductors are typically used as the sensor material for the sensor tiles. More specifically, the upper side of the sensor tile comprises continuous electrodes, while the lower side comprises separated electrodes in the form of metallization and / or conductive layers that are in contact with the sensor material and separated from each other. Such metallizations contribute to the sensor pixels. The sensor pixels are connected to assigned readout circuits on the readout chip. Each metallization is connected to the contacts of the assigned readout circuit by bump bonds manufactured by an underbump metallization (UBM) process. Such contacts can also be referred to as electrodes on the readout chip.

[0003] The ionizing radiation to be detected and measured interacts with the sensor material, depositing energy within it. This deposited energy is converted into electron-hole pairs within the sensor material. Within the sensor material, an electric field is formed by applying a voltage to the upper electrode of the sensor and establishing a virtual ground at the input of the first amplification stage of the assigned readout circuit. Thus, the charge collected within one of the sensor pixels is processed within the assigned readout circuit.

[0004] Prior art hybrid pixel detectors have sensor pixels that are typically square in shape. This design is suitable for many applications, such as computed tomography, X-ray diffraction, scanning transmission electron microscopy, scanning electron microscopy, or electron microscopy. What these applications have in common is that, given the square shape of the sensor pixels, the same resolution is achieved in both the x and y directions.

[0005] However, when different resolutions are desired, in most scenarios it becomes impossible to use the same readout chip, or if it is possible, the following drawbacks come into play. a) In cases where the overall acceptable sensor surface area is smaller and the size of the sensor tile is reduced in light of the small size of the sensor pixels, such redesigned sensor tiles would result in the read chip being significantly larger than the original read chip, resulting in wasted space. b) In cases where the readout chip is redesigned to fit the smaller dimensions of the redesigned sensor tile, it is necessary to redesign the chip, which is economically uneconomical in terms of both cost and resources, and requires considerable effort. c) In cases where the existing sensor tile must remain the same size, or is required to remain the same size, and is filled with additional sensor pixels, and the previous readout chip must continue to work with this sensor tile, an additional readout chip is required to work with the increased number of sensor pixels on the sensor tile. Such an additional readout chip consumes a lot of space in both the x and y directions. [Overview of the project]

[0006] Therefore, the overall objective of the present invention is to provide a radiation detector that allows for flexibility in variable resolution within a set of sensor pixels, while simultaneously enabling the continued use of existing readout chips of a given size and / or a given number of readout circuits.

[0007] This problem is solved by the radiation detector according to claim 1. The radiation detector enables position-resolved detection of radiation, provided that it comprises a sensor tile of a radiation-sensitive sensor material and a set of sensor pixels comprising a conductive material in contact with the sensor material. The sensor material can be, for example, one of silicon (Si), gallium arsenide (GaAs), cadmium telluride (CdTe), zinc cadmium telluride (CdZnTe), or germanium (Ge). The sensor material is preferably selected according to the type of radiation to be detected.

[0008] To read out individual sensor pixels of a set, a readout chip is provided, preferably in the form of an ASIC (Application-Specific Integrated Circuit), extending in a horizontal plane parallel to the sensor tile. The readout chip comprises a set of readout circuits, each of which is preferably responsible for reading out an assigned sensor pixel.

[0009] To clarify the geometric relationships between the components of the radiation detector, the sensor tile is determined to extend across a horizontal plane with a first axis and a second axis perpendicular to the first axis. Typically, the width of the sensor tile along the first axis and the height along the second axis are greater than, preferably at least 10 times, the thickness of the sensor tile along the third axis perpendicular to the first and second axes. A set of sensor pixels is arranged within the horizontal plane and thus covers, for example, a portion of the bottom surface of the sensor tile. The sensor pixels comprise, for example, conductive material in the form of metallizations or implants, which are also referred to as bottom electrodes. This term comes from their function as electrodes in combination with top electrodes, preferably on the opposite surface of the sensor tile, i.e., the top surface. The sensor pixels are electrically isolated from each other, preferably by insulating the gaps between the metallizations or implants.

[0010] The radiation is expected to strike the upper surface of the sensor tile, including the upper electrode. Preferably, the upper electrode is transparent with respect to the radiation being detected. The energy deposited by the radiation incident on the internal sensor material is converted into electrode hole pairs. The resulting charge is transported along the electric field lines of the electric field applied between the upper and lower electrode sets. Thus, each sensor pixel collects radiation-induced charge from an allocated volume within the sensor material. Therefore, the arrangement of sensor pixels along the first and second axes enables position-resolved detection of incident radiation.

[0011] Signal processing within each readout circuit may include one or more, preferably all, amplification, shaping, filtering, differentiation, integration, storage, and / or counting of the charge in the electrical signal provided by the assigned sensor pixel. The readout circuit may also provide inter-pixel communication, which may suggest rejection, summing, filtering, or time-delayed integration (TDI) of the pixel signal in response to the signal in the adjacent pixel. In each readout circuit, the processed signal may achieve a final state, in which case it may be stored for a certain period of time, for example, until it can be read out. The final state may be represented by one or more counter values ​​per readout circuit, by one or more analog signals per sensor pixel, or by a combination thereof. The readout circuit may also, if desired, store the previous final state in, for example, an analog or digital first-in, first-out circuit (FIFC), such as in a storage cell.

[0012] Assuming that it is desirable that the radiation detector does not waste space outside the area required by the sensor tile, the sensor tile is preferably positioned on top of the readout chip, with its bottom electrode facing the top surface of the readout chip. The top surface of the readout chip is preferably provided with electrical contacts for each readout circuit.

[0013] At least two adjacent inner sensor pixels in a set have extensions along a second axis, e.g., the y-axis, that extend beyond an extension along a first axis, e.g., the x-axis. Simultaneously, for the preferred inner readout circuits that operate on these two adjacent inner sensor pixels, the dimensioning is set as follows: each extension of these readout circuits along the first axis is different from the extension of the assigned sensor pixel along the first axis, and / or each extension of these assigned readout circuits along the second axis is different from the extension of the assigned sensor pixel along the second axis.

[0014] In other words, the extension of the associated sensor pixel is non-square, particularly rectangular, and the extension of the associated readout circuit differs in at least one direction, preferably both directions. Thus, the associated adjacent inner sensor pixels provide different resolutions in the x and y directions, and the assigned readout circuits have different shapes.

[0015] In particular, in the case where the readout chip is an existing readout chip that is reused, at least two adjacent, preferably all, inner sensor pixels of a subset are designed such that, on the one hand, different resolutions are achieved in different directions, and on the other hand, the geometric shape of these sensor pixels is different from the geometric shape of the assigned readout circuit. In particular, the shape of the readout circuit may be, for example, a square, while the shape of the assigned sensor pixels may be a rectangle. Thus, the inner sensor pixels and the assigned readout circuit do not need to be the same shape as in conventional radiation detectors.

[0016] In particular, the extension of the assigned readout circuit along the first dimension, for example, the x-axis, is less than the extension of the sensor pixel in the same direction, while at the same time, the extension of the readout circuit along the second dimension, for example, the y-axis, exceeds the extension of the sensor pixel in the same direction. Naturally, the x and y axes can be swapped in the above teaching.

[0017] In particular, when using existing readout chips, different resolutions required for an application are achieved by adapting the sensor pixel layout to a shape that provides different resolutions in the x and y directions. Therefore, even if the readout circuit has a square shape common to prior art applications, rectangular or hexagonal inner sensor pixels are possible. This makes it possible to use the same readout chip even with multiple different sensor pixel designs according to the application. This is advantageous because developing the readout chip is a significant undertaking. On the other hand, sensor tiles can be redesigned much more easily than designing a new readout chip, and with a shorter design-to-production cycle.

[0018] In detail, pixel dimensions can be reduced in directions where high resolution is required, while pixel dimensions can be increased in other directions where lower resolution is sufficient. This design of at least two adjacent inner sensor pixels enables these two different direction-dependent resolutions. At the same time, readout chips originally designed for use with conventional square-shaped sensor pixels can be used in combination with such sensor pixels. Thus, the same readout chip can be used for different resolution requirements, particularly by enhancing the resolution in one direction at the expense of the resolution in another.

[0019] For definitions regarding terms such as "extension," "shape," and "internal sensor pixel," please refer to the following.

[0020] A set of sensor pixels may comprise all pixels on a sensor tile, or, for example, a group of sensor pixels located separately from another group. Typically, a set of sensor pixels comprises a subset of inner sensor pixels, where each inner sensor pixel has adjacent sensor pixels in the directions of the first and second axes. Therefore, another subset of sensor pixels may exist, including outer sensor pixels that do not satisfy the requirements of inner sensor pixels.

[0021] The extension of each of two adjacent inner sensor pixels along the first axis is determined by adding the distance of the gap between the conductive materials of adjacent inner sensor pixels in the direction of the first axis to the extension of the conductive material of the sensor pixel along the first axis. Similarly, the extension of each of two adjacent inner sensor pixels along the second axis is determined by adding the distance of the gap between the conductive materials of adjacent inner sensor pixels in the direction of the second axis to the extension of the conductive material of the sensor pixel along the second axis.

[0022] A set of read circuits may comprise all or a group of read circuits of a read chip. At least these read circuits are components of the set that are electrically connected to at least two inner sensor pixels of a subset. Typically, a set of read circuits comprises all read circuits of a read chip. A subset comprises the inner read circuits of that set. The inner read circuits represent read circuits in the directions of the first axis and the second axis.

[0023] Each readout circuit is thought to have contacts on the top surface of the readout chip, preferably facing the sensor tile. After the readout chip is assembled with the sensor tile, the readout circuit is electrically connected via its respective contacts to the assigned sensor pixel / bottom electrode to receive an electrical signal from there.

[0024] Each extension of the inner readout circuit along the first axis is N i Defined by the distance between the contacts of the two outermost inner readout circuits on the first axis, divided by -1, at which point N i This represents the number of internal readout circuits along the first axis. The extension of each internal readout circuit along the second axis is M i It is defined by the distance between the contacts of the two outermost inner readout circuits on the second axis, divided by -1, at which point M iThis represents the number of internal readout circuits along the second axis. Therefore, it is assumed that all internal readout circuits have the same extension along the first axis and the same extension along the second axis.

[0025] Typically, extensions, especially the scale x introduced later, are used. d and y d When comparing extensions in the x and y directions, equivalence between extensions is assumed if the compared extensions are within a 10% range. In particular, rectangles with a side length ratio less than 1.1:1 and greater than 0.9:1 are considered to be squares.

[0026] The detected radiation is ionizing radiation, and typically includes, for example, electrons with energies from a few keV to several hundred keV in the case where the HPD is an electron detector, or X-rays with energies from several hundred eV to several hundred kdV in the case where the HPD is an X-ray detector, or other types of ionizing radiation. Therefore, the radiation detector of the present invention can be used for imaging applications, but can also be used for imaging diffraction patterns formed by X-rays or electrons.

[0027] On the other hand, there are applications that require high resolution in one direction, but where the resolution in the other direction can be anything. Such applications include, for example, electron energy loss spectroscopy (EELS), small-angle X-ray scattering (SAXS), and wavelength-dispersive spectroscopy, in which case it is advantageous if the resolution in one direction (e.g., the x-direction) is higher than that in the other direction (e.g., the y-direction).

[0028] The following embodiments relate to the extension and shape of the sensor pixel. - Preferably, two adjacent inner sensor pixels exhibit the same extension along the first axis and the same extension along the second axis. Thus, they are of the same shape. This allows for the same resolution along both the x and y axes when applied to all inner sensor pixels in a subset. - Preferably, two adjacent inner sensor pixels are of the same rectangular shape, i.e., the area of ​​the conductive material is essentially rectangular. The rectangular shape maximizes the area covered by sensor pixels having different extensions in the x and y directions. Preferably, each of the two adjacent inner sensor pixels has an extension along a second axis that is at least four times larger than the extension along the first axis. Therefore, the difference in resolution is not negligible. This embodiment allows for a significant increase in resolution along one axis at the expense of resolution along the other axis. - Preferably, all inner sensor pixels in the subset are of the same rectangular shape. The advantages of this embodiment have already been stated above. - Preferably, all sensor pixels in the set are of the same rectangular shape, thereby applying a constant resolution on each axis across the entire sensor tile. - Preferably, at least four, preferably all, inner sensor pixels of a subset are of the same rectangular shape and are arranged in a two-dimensional array along the first and second axes. In this context, the array is understood as a regular arrangement of sensor pixels, where the rectangular sensor pixels in a column all extend between the same x-coordinates in width, and the rectangular sensor pixels in a row all extend between the same y-coordinates in height. Thus, there is no shift or offset between sensor pixels in the same column and the same row. This allows for constant resolution in both directions. - In different embodiments other than those described above, at least four, preferably all, of the subset of inner sensor pixels are of the same rectangular shape and are arranged with a row offset and a column offset relative to each other. - Preferably, the offset is located at the maximum half of the extension of the inner sensor pixel along the offset axis. - Preferably, the offset is half of the extension of the inner sensor pixel along the offset axis. - Preferably, the offset is one-third of the extension of the inner sensor pixel along the offset axis. - Preferably, the offset is the extension of the sensor pixels in the offset axis divided by an integer, where the maximum integer of the division operation is less than the number of readout circuits along the axis perpendicular to the offset axis. Preferably, each of the two adjacent inner sensor pixels is of the same rectangular shape and has a locally asymmetrical portion within the area where an electrical contact means, such as a bump bond, engages with the sensor pixel to connect the sensor pixel to the assigned readout circuit. This allows for a straight vertical connection between the underlying square readout circuit and the centrally located contact. - Preferably, local asymmetries are represented by ridges on the boundaries of sensor pixels. This minimizes irregular shape variations between the inner sensor pixel areas. - Preferably, each of the two adjacent inner sensor pixels has another local asymmetry portion in the form of a recess that complements the raised portion of the adjacent sensor pixel. This enables the raised portion within the adjacent sensor pixel.

[0029] The following embodiments relate to the extension and shape of the readout circuit. - Preferably, each of the two inner read circuits exhibits the same extension along the first and second axes. This results in a square inner read circuit, which is the shape of read circuits in many conventional read chips. - Preferably, all internal readout circuits in the subset are of the same square shape. - Preferably, all readout circuits in the set are of the same square shape. - Preferably, at least four, preferably all, of the subset of inner read circuits are of the same square shape and are arranged in a two-dimensional array along the first and second axes. Here again, the array is understood as a regular arrangement in which the square read circuits of the columns all extend between the same x coordinates in width and the rectangular read circuits of the rows all extend between the same y coordinates in height. Thus, there are no shifts or offsets between read circuits of the same column and the same row. This allows for a packed arrangement of the read circuits.

[0030] The following embodiments relate more explicitly to extensions of sensor pixels related to extensions of readout circuits. Thus, these embodiments address resolutions achieved while simultaneously maintaining the footprint required by sensor tile-readout circuit configurations. - Preferably, the extensions of each of the two readout circuits along the first axis extend beyond the extension of the assigned sensor pixel along the first axis. This geometric shape opens up a path for one readout circuit to overlap with two sensor pixels. Preferably, the extension of each of the two inner readouts along the second axis is less than the extension of the assigned sensor pixel along the second axis. This geometric shape opens up a way that allows one readout circuit to overlap with two assigned sensor pixels, and a second readout circuit to overlap with two assigned sensor pixels. Preferably, each extension of the two inner readout circuits along the first axis is at least twice the length of the extension of the assigned sensor pixel along the first axis. This geometric shape ensures that the readout circuits do not require an area greater than that of the sensor pixel. - Preferably, the extensions of each of the two internal readout circuits along the second axis are no more than half the length of the extension of the assigned sensor pixels along the second axis. Preferably, the extension of each of the two inner readout circuits along the first axis is twice the length of the extension of the assigned sensor pixel along the first axis, and the extension of each of the two inner readout circuits along the second axis is half the length of the extension of the assigned sensor pixel along the second axis. This geometric shape allows for a 2:1 resolution ratio while the two readout circuits and the two assigned sensor pixels require the same area. Preferably, the extension of each of the two inner readout circuits along the first axis is 3 / 2 times the extension of the assigned sensor pixels along the first axis, where the extension of each of the two inner readout circuits along the second axis is 2 / 3 times the extension of the assigned sensor pixels along the second axis. This geometric shape allows a 3:2 resolution ratio to be implemented, while the six readout circuits and six assigned sensor pixels may require the same area.

[0031] The following embodiments relate to the geometric shapes of sensor pixels and readout circuits relative to each other. - Preferably, two adjacent inner sensor pixels are positioned next to each other along a first axis to combine to form a rectangle, and two assigned inner readout circuits are positioned next to each other along a second axis, thereby extending into a rectangle that coincides with the rectangle formed by the two adjacent inner sensor pixels. Thus, all pairs of inner sensor pixels and readout circuits are the same size and may preferably overlap completely, as introduced in the following embodiments. Preferably, the rectangle in which two adjacent inner sensors are located has the same position along the first and second axes as the rectangle in which two assigned inner readout circuits are located. - Preferably, the rectangles extending from two adjacent inner sensors do not overlap with the rectangles extending from two assigned inner readout circuits. Preferably, a redistribution layer is applied in connection with this embodiment, as will be described later. - Preferably, at least one of the two inner readout circuits of the subset is excluded from overlap with the assigned sensor pixels. Preferably, each of the subset of inner sensor pixels requests an area greater than the area of ​​the allocated inner readout circuit, the area of ​​the allocated inner readout circuit is determined by multiplying its extension along the first axis by its extension along the second axis. - Preferably, all internal sensor pixels in the subset exceed the combined area of ​​all internal readout circuits in the subset, which is determined by multiplying the extension of the internal readout circuits along the first axis by the extension of the readout circuits along the second axis, and then multiplying this by the number of internal readout circuits.

[0032] In another preferred embodiment, a rerouting or redistribution layer is placed between the sensor tile and the readout chip. The rerouting layer preferably serves to electrically connect the sensor pixels to the UBM contacts of the assigned readout circuit. The rerouting layer can be deposited on a metallized bottom electrode on the sensor surface. Preferably, the rerouting layer comprises an insulating material and conductive traces placed between the sensor tile and the readout chip.

[0033] Each conductive material of a sensor pixel may be incorporated into a stack of layers to form individual electrodes on the bottom side of the sensor tile. Such a stack may include, for example, n++ or p++ implants, different metals, insulating layers, such as SiO, SiN, or underbump metallization. The different layers in this stack do not need to be the same size. The top layer of the stack may define the area in which the electric field inside the sensor tile bends. A charge of one polarity (electrons or holes, depending on the polarity of the applied voltage) generated in response to the energy shock of ionization radiation drifts along the electric field lines toward the top layer of the stack. For example, by combining this stack with insulating layers and through vias penetrating the insulating layers, this structure may be used to route signals from an xy position where the top layer of the stack is located to a different xy position where the bottom layer of the stack is located. This may further be used to traverse xy regions covered by the top layers of pixel stacks of different sensors.

[0034] A typical readout circuit extension is between 10 μm x 10 μm and 2 mm x 2 mm if it is square, and between 10 μm and 2 mm in width and height if it is rectangular. A typical sensor pixel extension may be between 10 μm and 10 mm in width and height.

[0035] The embodiments in the above categories can be applied individually or in combination with one or more other embodiments in the same category, or with one or more embodiments in a different category, or with one of several embodiments in a different category.

[0036] The present invention will be better understood and purposes other than those described above will become clearer when considered in light of the following detailed description. [Brief explanation of the drawing]

[0037] [Figure 1] This is a cross-sectional view of a radiation detector according to an embodiment of the present invention. [Figure 2] Figure 1 is a cross-section of sensor tile 1. [Figure 3] This is a top view of a readout chip for a radiation detector according to an embodiment of the present invention. [Figure 4] This is a bottom view of a sensor tile of a radiation detector according to an embodiment of the present invention. [Figure 5] This is a schematic transparent top view of the cut-out portion of a radiation detector according to an embodiment of the present invention. [Figure 6] This is a cross-sectional view of a radiation detector according to another embodiment of the present invention. [Figure 7] This is a schematic transparent top view of the cut-out portion of a radiation detector according to an embodiment of the present invention. [Figure 8] This is another schematic transparent top view of the cut-out portion of a radiation detector according to an embodiment of the present invention. [Figure 9] This is another schematic transparent top view of the cut-out portion of a radiation detector according to an embodiment of the present invention. [Figure 10] This is a schematic bottom view of the cut-out portion of the sensor tile of a radiation detector according to an embodiment of the present invention. [Modes for carrying out the invention]

[0038] Figure 1 shows a cross-section of a radiation detector according to an embodiment of the present invention. A sensor tile 1 is electrically connected to a readout chip 2, which is further electrically connected to a circuit board 3. The sensor tile 1 comprises a sensor material 11 sandwiched between a continuous upper electrode 13 and a plurality of separate bottom electrodes 12, the sensor material being represented, for example, by a conductive material in the form of metallization contributing to the sensor pixels. The sensor material is sensitive to the radiation to be detected. The radiation is assumed to strike the sensor tile 1 from above, as indicated by the arrows.

[0039] The sensor tile 1 is arranged in the horizontal plane x, y, where in this example, the x-axis is referred to as the first axis and the y-axis is referred to as the second axis orthogonal to the first axis, and these axes together define the horizontal plane. The sensor tile is characterized by a planar extension in the horizontal plane, on the premise that its extensions in the first and second axes respectively exceed its thickness in the z-direction, i.e., the third axis.

[0040] The readout chip 2 also has its main extensions along the first and second axes x, y, is arranged parallel to the sensor tile 1, and in particular, is arranged under the sensor tile 1. The readout chip 2 comprises a readout circuit 21 and electrical input contacts 22 on its upper surface. Preferably, each readout circuit 21 has an assigned input contact 22 from which it receives an input signal. Preferably, the sensor pixels 12 of the sensor tile 1 and the input contacts 22 of the readout chip 2 are electrically connected to each other in a one-to-one relationship, which means that the number of input contacts 22 / readout circuits 21 is equal to the number of sensor pixels 12. In this example, the corresponding sensor pixels 12 and input contacts 22 are located above / below each other along the third axis and are here electrically connected by bump bonds 4. The inner sensor pixels are referred to as 12 i and the outer sensor pixels are referred to as 12 o The inner readout circuits are referred to as 21 i and the outer readout circuits are referred to as 21 o and are so called.

[0041] The radiation detector of FIG. 1 is mounted on a high-density interconnect (HDI) printed circuit board 3 having additional readout electronics. The electrical connection between the I / O pads 23 of the readout chip 2 and the I / O pads 31 of the HDI PCB 3 is established, for example, by wire bonds 5.

[0042] The incident radiation for which detection and measurement are desired interacts with the sensor material 11 contained within the sensor tile 1 and deposits energy within the sensor material 11. The deposited energy is converted into electron-hole pairs within the sensor material 11.

[0043] Figure 2 shows a cross-section of sensor tile 1 of Figure 1. A positive or negative voltage is applied to the continuous upper electrode 13. The upper electrode 13 may consist of a stack constructed from a sensor implant, e.g., p++, n++, one or more metals, e.g., Al, Au, Ag, Cu, and other conductive and / or insulating layers. The bottom electrode 12 may also be represented by layers of a stack. An electric field line is steered from the upper electrode 13 to the bottom electrode 12. The charge created within the sensor material 11 drifts along the electric field line. In Figure 2, all layers within the stack 12 of the bottom electrode are of the same size, and in particular, have the same extension along the first axis x. The boundaries of the volume 14 assigned to each sensor pixel 12 are shown by dotted lines.

[0044] Therefore, each sensor pixel 12 collects radiation-induced charge from an assigned volume 14 within the sensor material 11, as shown for all sensor pixels 12 in Figure 2 and for only one sensor pixel 12 in Figure 1.

[0045] Returning to Figure 1, the charge collected from the assigned volume 14 reaches the readout circuit 21 through the assigned metallization 21, the assigned bump coupling 4, and their respective contacts 22, where it is processed. The readout circuit 21 is preferably represented by an electronic device integrated within the semiconductor material of the readout chip 2. Preferably, each readout circuit 21 works for a dedicated sensor pixel 12 and is therefore isolated from other readout circuits 21 and their contacts 22 unless the results of processing within an individual readout circuit 21 are combined and transferred, multiplexed, etc., to be sent to the PCB 3. Thus, the readout circuits 21 are represented separately from adjacent readout circuits 21 by dotted rectangles in relation to their assigned contacts and because each readout circuit consumes an area of ​​the readout chip 2 in the horizontal plane x, y.

[0046] In the cross-section of Figure 1, all sensor pixels 12 have the same extension along the first axis x. Each inner sensor pixel 12 along the second axis y i The extension extends beyond its extension along the first axis x. Preferably, all inner sensor pixels 12 i The extension along the second axis y is the same, and thereafter, the inner sensor pixel 12 i These are all of the same rectangular shape.

[0047] As can already be derived from Figure 1, the extension of each inner readout circuit 21i along the first axis x exceeds the extension of each inner sensor pixel 12i along the first axis x, preferably all inner readout circuits 21 i The same applies to this. Preferably, although not shown in Figure 1, an inner readout circuit 21 along the second axis y. i The extension is along the second axis y, the inner sensor pixel 12 i It is less than the extension of the second axis y. Preferably, each inner readout circuit 21 along the second axis y i The extension is the same as the one along the first axis x, thereby the inner readout circuit 21 i These are all of the same square shape.

[0048] Preferably, although not apparent from Figure 1, each inner readout circuit 21 along the second axis y i The extension is assigned to the inner sensor pixel 12 i It is half of the extension, and each extension of the inner readout circuit along the first axis x is assigned to the inner sensor pixel 12 along the first axis x. i It is twice the length of the extension.

[0049] In the cross-section of Figure 1, several inner sensor pixels 12 i The assigned internal readout circuit 21 i It is not indicated that it is electrically connected to such an inner sensor pixel 12. iIt is electrically connected to the assigned readout circuit by bump coupling, but this is not apparent from Figure 1 because it is located in the plane x, z where y>0. This will be better understood in relation to the subsequent figures.

[0050] The radiation detector in Figure 1 provides a lower resolution along the second axis y than along the first axis x. Corresponding internal readout circuit 21 i This corresponds to sensor pixel 12 i It has a different shape, and the sensor pixel 12 i The same area of ​​the read chip 2 below is required.

[0051] Figure 3 shows a top view of a cutout of a readout chip 2 used in a radiation detector according to an embodiment of the present invention. In this embodiment, a set of readout circuits 21 are arranged in a row and column array. The set is an outer readout circuit 21 o A subset of and the internal readout circuit 21 i This includes a subset of the above. In particular, the four outermost inner readout circuits in each direction x, y are 21 oi As shown by [this]. In addition, the input contacts 22 are indicated by [this] for at least some of the readout circuits 21. In this example, the input contacts 22 are located within the lower left quarter of each readout circuit 21. However, the input contacts 22 may also be located within the center of each readout circuit 21, at different locations, or at variable locations across the readout circuits 21. In this embodiment, the readout circuit 21 has an essentially square shape.

[0052] To compare the size and / or shape of the readout circuit 21 with that of the assigned sensor pixels, the following assumptions can be made, as shown in relation to Figure 3.

[0053] Each inner readout circuit 21 along the first axis x i / twenty one oi Regarding the extension dx, the distance D x However, along the first axis x, the outermost inner readout circuit 21 oiThis distance D is measured between the contact points 22. x is, N i Divided by -1, at this point N i This is the inner readout circuit 21 along the first axis x. i / twenty one oi This represents the number of each internal readout circuit 21. i / twenty one oi An extension d is determined to be present along the first axis x. x That is the case.

[0054] Similarly, distance D y However, along the second axis x, the outermost inner readout circuit 21 oi This distance D is measured between the contact points 22. y M i It is divided by -1, and at this point M i This is the inner readout circuit 21 along the second axis y. i / twenty one oi This represents the number of each internal readout circuit 21. i / twenty one oi An extension d is determined to be located along the second axis y. y That is the case.

[0055] Figure 4 shows a bottom view of the cut portion of the sensor tile 1 used in a radiation detector according to an embodiment of the present invention. In this embodiment, the inner sensor pixel 12 i A subset of these is arranged in a row and column array. Each of the subset's inner sensor pixels 12 i This is the extension of that metallization x s and y s This shows the adjacent inner sensor pixels 12 along the first axis x. i The gap between the metallizations is size g x It is the inner sensor pixel 12 i The metallization is indicated by a straight rectangle. The gap between adjacent metallizations along the second axis y is size g. yThe following assumptions are made to compare the size and / or shape of the readout circuit with that of the assigned sensor pixels 12: the inner sensor pixels 12 along the first axis x i extension x d is, x s +g x The inner sensor pixel 12 is set to the second axis y. i extension y d is, y s +g y It will be set to this.

[0056] Figure 5 shows a schematic transparent top view of the cut section of a radiation detector according to an embodiment of the present invention. This transparent top view shows the geometric layout of the sensor pixels 12 relative to the readout circuit 21 in this particular embodiment. Sensor pixels 12 i It has a rectangular shape defined by its corresponding sensor pixel boundary, shown by a solid line. Readout circuit 21 i It has a square shape defined by the corresponding readout circuit boundary, indicated by dots / slashes. For illustrative purposes, the gap is omitted.

[0057] Aspect ratio x of the sensor pixel rectangle d :y d The aspect ratio is 1:4. Sensor pixel 12 i The extension along the x-axis (width) is the readout circuit 21 i This is half of the extension along the x-axis (width). Sensor pixel 12 i The extension along the y-axis (height) is the readout circuit 21 i It is twice the length of the extension along the y-axis (height). Each of the two horizontally (x-direction) adjacent sensor pixels 12 i This refers to two vertically (y-direction) adjacent readout circuits 21 i It covers almost the same area.

[0058] Two adjacent sensor pixels 12 i and assigned readout circuit 21 i The connection between them is to the left sensor pixel 12i is connected to the upper readout circuit 21 i and the right sensor pixel 12 i may be implemented to be connected to the bottom readout circuit. The relationship is schematically shown by arrows. In this embodiment, note that the sensor pixel 12 i is shifted in both the x-direction and the y-direction with respect to the readout circuit 21 i

[0059] The sensor pixel 12 i to the assigned readout circuit 21 i The electrical connection up to may be performed in several steps. In a preferred embodiment, the sensor pixel metallization and the readout circuit contacts, such as its under bump metallization (UBM), are in the same x-y coordinates but on different parallel planes (shifted vertically). If the protrusion of the sensor pixel 12 i on the readout circuit 21 i does not overlap with the UBM, a rerouting layer may be required.

[0060] FIG. 6 shows another embodiment of a radiation detector according to the present invention, including rerouting between the sensor pixel 12 and the readout circuit 21. In addition to the radiation detector of FIG. 1, a redistribution layer 6 is provided, and this redistribution layer establishes an electrical one-to-one connection between the sensor pixel 12 and the corresponding input contact 22 of the readout circuit 21 via a conductor track 61 in a dielectric material 62. The contact 63 on / above the redistribution layer 6 is connected to the bump bond 4 and thus to the contact 22 of the readout circuit 21. Typically, the redistribution layer 6 is monolithically integrated on the sensor tile 1. In the case where the readout circuit 62 is laterally offset in the x-axis or y-axis from the assigned sensor pixel 12, the redistribution layer 6 is preferably applied.

[0061] FIG. 7 shows a schematic transparent top view of a cutout of a radiation detector according to an embodiment of the present invention. In this embodiment, the inner right sensor pixel 12 ir , that is, two adjacent inner sensor pixels 12 along the first axis x​i each inner right sensor pixel 12 of the pair ir each has an assigned inner lower readout circuit 21 il to cover the bump bond 4 placed at the center within it, a raised portion 121 is shown. Thus, the assigned inner lower readout circuit 21 il the bump bond 4 which also represents the contact locations x, y of it can be vertically connected from the inner right sensor pixel 12 ir without requiring lateral rerouting. The inner left sensor pixel 12 il i.e., two adjacent inner sensor pixels 12 along the first axis x i each inner left sensor pixel 12 of the pair il each shows a recess 122 that complements the raised portion of the inner right sensor pixel 12 so as not to short-circuit its raised portion. In this embodiment, the contacts 22 and the bump bond 4 can all remain placed at the center on the readout circuit 21. ir It should be noted that in the case where the sensor pixel 12 deviates slightly from the rectangular shape and the deviation is less than a quarter of the readout circuit extension along the first axis x and less than a quarter of the readout circuit extension along the second axis y, this can also be considered as a rectangle.

[0062] Figure 8 shows a schematic transparent top view of a cutout portion of a radiation detector according to another embodiment of the present invention. In this embodiment, the rectangular shape of the inner sensor pixel 12

[0063] is completely maintained. In this embodiment, an insulating layer, for example, of SiO2, SiN, or any other dielectric layer used in semiconductor processing, is between the inner sensor pixel 12 i and the inner readout circuit 21 i i ​It is applied between the two. A via 64, as shown by 64 in Figure 6, is created through the insulating layer (e.g., by etching). The hole 64 is metallized by an electrical conductor, resulting in a portion of the conductor path 61. See Figure 6. The bump bond 4 is then connected to the metallized hole 64 by a conductive trace, also made from, for example, copper, silver, or aluminum, which is also 61 in Figure 6. In this embodiment, the inner sensor pixel 12 i The original rectangular shape is maintained.

[0064] Figure 9 shows a schematic transparent top view of the cut section of a radiation detector according to another embodiment of the present invention. Figure 9 shows the readout circuit 21 i The shape corresponds to sensor pixel 12 i This describes non-overlapping embodiments of the present invention. In this embodiment, for example, an insulating layer made of SiO2, SiN, or any other insulating layer used in semiconductor processing is provided for the sensor pixel 21. i and internal readout circuit 21 i It is applied between the two. The hole 64 is etched, for example, through the insulating layer, and the hole 64 is filled with a conductive material. The location of the bump bond 4 is then connected to the conductive material in the hole 64 by a conductive trace 61 made of, for example, copper, silver, or aluminum. This embodiment is applied to, for example, the sensor pixel 12 in the x direction. i The resolution of the readout circuit 21 i This is advantageous in cases where you want to select it as a non-integer divisor or multiplier of the resolution. Different readout circuit 21 i The xy area between them is the inner sensor pixel 12 i Sensor pixels 12 that are similar to or have the same shape as the above. i This can result in uniform resolution in the x or y direction across all sensor tiles. In cases where routing needs to cover a larger distance that crosses a significant portion of different sensor pixels, it is advantageous for trace 61 to leave a cavity of sensor pixel metallization across the pixels.

[0065] In different embodiments, routing is performed in a similar manner within the upper layer of the read chip. In different embodiments, an interposer (e.g., glass, or Si, ceramic) is used, and routing is performed on different layers within the interposer.

[0066] Note that routing can be used so that the total area covered by sensor pixels differs from the total area covered by the readout circuit. In particular, the area covered by sensor pixels may be larger than the area covered by the readout circuit.

[0067] The embodiment described in Figure 9 can be easily extended to sensor pixels with different aspect ratios. In the case of a 1:9 aspect ratio x:y, three inner sensor pixels (left, center horizontal, right) are each connected to one of three readout circuits (top, center vertical, bottom).

[0068] Figure 10 shows a schematic top view of the cut portion of the sensor tile of a radiation detector according to an embodiment of the present invention. In this embodiment, the inner sensor pixel 12 i These are rectangular in shape and are arranged in rows offset from each other. In this example, the inner sensor pixels 12 of adjacent rows i This is the width of the inner sensor pixel, i.e., the offset of half the extension along the x-axis O ff The image is shifted by . This makes it possible to achieve even higher resolution in the x-direction. Naturally, the pattern in Figure 10 may be repeated in both the +y / -y directions, or it may continue in the +x / -x directions.

[0069] For example, further offsets are possible, such as an offset of 1 / 3 of the pixel width, 1 / 4 of the pixel width, or 1 / n of the pixel width, where n is n i、行 -1 or less, n i、行 The inner sensor pixel 12 i This is the total number of rows. Offset per row + O ffInstead of shifting the sensor pixels, the "alternating" pattern is used, alternating +O per row. ff and -O ff This may be achieved by shifting the sensor pixels.

[0070] In this case, each row of inner sensor pixels is sampled at different intervals of the radiation distribution in the x-direction. In cases where the radiation distribution in the y-direction is insufficient, i.e., where the radiation has at least approximately the same distribution across the y-extension of the n-offset row, this oversampling method allows for the reconstruction of the 1D distribution. By combining the signals obtained from the shifted rows, it becomes possible to obtain a signal with oversampling along the x-direction (i.e., increased sampling resolution).

Claims

1. A radiation detector for location-resolved detection of radiation, At least one sensor tile (1) having a continuous upper electrode (13), a plurality of separate bottom electrodes (12), and a radiation-sensitive sensor material (11), defining a horizontal plane extending a first axis (x) and a second axis (y) perpendicular to the first axis (x), and the sensor material (11) being sandwiched between the upper electrode (13) and the bottom electrode (12) in the direction of a third axis (z) perpendicular to the first axis (x) and the second axis (y), A set of sensor pixels (12) arranged in the horizontal plane, each sensor pixel (12) comprising an upper electrode (13) portion that contacts the sensor material (11) and a bottom electrode (12), The set of sensor pixels (12) includes the inner sensor pixels (12 ｉ ) has a subset of inner sensor pixels (12 ｉ ) has adjacent sensor pixels (12) in each direction of the first axis (x) and the second axis (y), At least two adjacent inner sensor pixels (12) of the subset ｉ ) is the length along the first axis (x) (x ｄ The length (y) along the second axis (y) that exceeds ) ｄ ) indicates, The length (x) of the inner sensor pixel (12) along the first axis (x) ｉ is determined by adding to the length (x) of its bottom electrode (12) along the first axis (x) ｄ the distance (g) of the gap between the inner sensor pixel (12) ｓ and the inner sensor pixel (12) arranged adjacent in the direction of the first axis (x) ｉ to the inner sensor pixel (12) ｉ arranged adjacent in the direction of the first axis (x). ｘ ​ The inner sensor pixel (12) along the second axis (y) ｉ The length (y ｄ ) is the length (y) of the bottom electrode (12) along the second axis (y). ｓ ) the inner sensor pixel (12 ｉ ) and the inner sensor pixels (12) arranged adjacent to each other in the direction of the second axis (y) ｉ The distance of the gap between (g) ｙ The set of sensor pixels (12) is determined by adding ) At least one readout chip (2) is assigned to the at least one sensor tile (1) and extends along the first axis (x) and the second axis (y), A set of read circuits (21) integrated within the read chip (2), wherein each read circuit (21) in the set is provided with a contact (22), and each read circuit (21) is electrically connected to one of the sensor pixels (12) in the set via the contact (22) to read a charge input from an assigned sensor pixel (12). The set of read circuits (21) is an internal read circuit (21 ｉ ) comprises a subset of internal readout circuits (21 ｉ ) has adjacent readout circuits (21) in the direction of the first axis (x) and the second axis (y), Each inner readout circuit (21) along the first axis (x) ｉ ) length (d ｘ ) is N ｉ The two outermost inner readout circuits on the first axis (x) divided by -1 (21 ｏｉ The distance between the contacts (22) (D ｘ Defined by ), at this time N ｉ This is the inner readout circuit (21) along the first axis (x). ｉ It represents the number of ), Each inner readout circuit (21) along the second axis (y) ｉ ) length (d ｙ ) is M ｉ The two outermost inner readout circuits on the second axis (y) divided by -1 (21 ｏｉ The distance between the contacts (22) (D ｙ Defined by, at this time M ｉ This is the inner readout circuit (21) along the second axis (y). ｉ It represents the number of ), The two adjacent inner sensor pixels (12 ｉ Two of the internal readout circuits (21) are assigned to and connected to the above. ｉ Each of the following is: The assigned inner sensor pixels (12) along the first axis (x) ｉ A length (d) along the first axis (x) that is different from the aforementioned length (xd) of ). ｘ ), and / or The assigned inner sensor pixels (12) along the second axis (y) ｉ The length (y ｄ ) is different from the length (d) along the second axis (y). ｙ A radiation detector comprising a set of readout circuits (21) that show ).

2. The two adjacent inner sensor pixels (12 ｉ ) along the first axis (x) of the same length (x ｄ ) and the same length along the second axis (y) ｄ A radiation detector according to claim 1, which shows ).

3. At least four of the subset's inner sensor pixels (12 ｉ The radiation detector according to claim 1, wherein the elements are of the same rectangular shape and are arranged in a two-dimensional array along the first and second axes (x, y).

4. At least four of the subset's inner sensor pixels (12 ｉ ) are of the same rectangular shape and are located in one of the rows and columns that are offset from each other by less than half the length (x d, y d) of the inner sensor pixels (12 i) along the offset axis (x, y), The radiation detector according to claim 1.

5. The two adjacent inner sensor pixels (12) are of the same rectangular shape. ｉ Each of the ) has a local asymmetric portion, and in the local asymmetric portion, an electrical contact means is provided for the inner sensor pixel (12 ｉ ) is assigned to the internal readout circuit (21 ｉ ) to connect to the inner sensor pixel (12 ｉ A radiation detector according to claim 1, which engages with ).

6. The two internal read circuits (21 ｉ Each of the ) has the same length (d) along the first axis (x) and the second axis (y). ｘ d ｙ A radiation detector according to claim 1, which shows ).

7. At least four internal readout circuits of the subset (21 ｉ The radiation detector according to claim 1, wherein the elements are of the same square shape and are arranged in a two-dimensional array along the first and second axes (x, y).

8. The two inner readout circuits (21) along the first axis (x) ｉ The length of each of the aforementioned (d ｘ ) along the first axis (x) the assigned inner sensor pixel (12 ｉ The length (x ｄ A radiation detector according to claim 1, which exceeds the limits of ).

9. The two inner readout circuits (21) along the second axis (y) ｉ The length of each of the aforementioned (d ｙ ) along the second axis (y) the assigned inner sensor pixel (12 ｉ The length (y ｄ The radiation detector according to claim 8, wherein the radiation level is less than ).

10. The two inner readout circuits (21) along the first axis (x) ｉ The length of each of the aforementioned (d ｘ ) along the first axis (x) the assigned inner sensor pixel (12 ｉ The length (x ｄ The radiation detector according to claim 8, which is at least twice the size of the following:

11. The two internal read circuits (21 ｉ The length (d) along each of the second axes (y) of the respective second axes (y) ｙ ) along the second axis (y) the assigned inner sensor pixel (12 ｉ The length (y ｄ The radiation detector according to claim 10, wherein the value is less than half of the value of the radiation detector.

12. The two internal read circuits (21 ｉ The length (d) along each of the first axes (x) of the first axis (x) ｘ ) along the first axis (x) the assigned inner sensor pixel (12 ｉ The length (x ｄ ) is twice as much as, The two internal read circuits (21 ｉ The length (d) along each of the second axes (y) of the respective second axes (y) ｙ ) along the second axis (y) the assigned inner sensor pixel (12 ｉ The length (y ｄ The radiation detector according to claim 11, which is half of ).

13. The two internal read circuits (21 ｉ The length (d) along each of the first axes (x) of the first axis (x) ｘ ) along the first axis (x) the assigned inner sensor pixel (12 ｉ The length (x ｄ ) is 3 / 2 times, The two internal read circuits (21 ｉ The length (d) along each of the second axes (y) of the respective second axes (y) ｙ ) along the second axis (y) the assigned inner sensor pixel (12 ｉ The length (y ｄ The radiation detector according to claim 11, which is 2 / 3 times the value of the above.

14. The two adjacent inner sensor pixels (12 ｉ These elements are arranged adjacent to each other along the first axis (x) and combine to form a rectangle. The two internal readout circuits (21) that have been assigned ｉ ) are arranged adjacent to each other along the second axis (y), thereby the two adjacent inner sensor pixels (12 ｉ The radiation detector according to claim 1, wherein the radiation extends in a rectangle that coincides with the rectangle that extends.

15. The rectangle in which the two adjacent inner sensor pixels (12 ｉ ) extend is the same as the rectangle in which the two assigned inner readout circuits (21 ｉ ) extend and has positions along the first and second axes (x, y). The radiation detector according to claim 14.

16. The two adjacent inner sensor pixels (12 ｉ The rectangle that extends from the two assigned inner readout circuits (21 ｉ The radiation detector according to claim 14, wherein the rectangle extending from the detector does not overlap with the rectangle.

17. The two inner readout circuits of the subset (21 ｉ At least one of the assigned inner sensor pixels (12 ｉ A radiation detector according to claim 1, which avoids overlap with ).

18. each of the inner sensor pixels (12 of the subset ｉ ), has an area exceeding the area of the assigned inner readout circuit (21 ｉ ), and the area of the assigned inner readout circuit (21 ｉ ), is determined by multiplying its length (d ｘ ) along the first axis (x) by its length (d ｙ ) along the second axis (y), the radiation detector according to claim 1.

19. All of the inner sensor pixels (12) of the subset ｉ The combined area of ​​the subset of internal readout circuits (21 ｉ The combined area of ​​the internal readout circuits (21i) of the subset exceeds the combined area of ​​the internal readout circuits (21i) along the first axis (x). ｉ The length (d) of the aforementioned length (d ｘ ) along the length (d) of the second axis (y) ｙ The result of multiplying this by the internal readout circuit (21 ｉ The radiation detector according to claim 1, which is determined by multiplying by the number of ).

20. The radiation detector according to claim 1, further comprising a rerouting layer (6) between the sensor tile (1) and the readout chip (2) for electrically connecting the sensor pixel (12) to the contact (22) of the assigned readout circuit (21).

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