Radioactivity detector 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] The present invention relates to a radiation detector for spatially 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 sensor material of the sensor tiles. More specifically, the top side of the sensor tile comprises a continuous electrode, while the bottom side of the sensor tile comprises separate electrodes in the form of metallizations and / or conductive layers in contact with the sensor material and spaced apart from each other. Such metallizations contribute to sensor pixels. The sensor pixels are connected to assigned readout circuits of the readout chip. Each metallization is connected to a contact of the assigned readout circuit by a bump bond manufactured by an under bump metallization (UBM) process. Such contacts can also be referred to as electrodes of the readout chip.

[0003] The ionizing radiation that it is desired to detect and measure interacts with the sensor material and deposits energy in the sensor material. The deposited energy is converted into electron-hole pairs in the sensor material. In the sensor material, an electric field is created by applying a voltage on the upper electrode of the sensor and setting a virtual ground at the input of the first amplification stage of the assigned readout circuit. The charge collected in one of the sensor pixels is thus processed in the assigned readout circuit.

[0004] Prior art hybrid pixel detectors have sensor pixels that are usually square shaped. This design is suitable for many applications, such as computed tomography, X-ray diffraction applications, scanning transmission electron microscopes, scanning electron microscopes, or electron microscopes. 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 it is desired to achieve different resolutions, in most scenarios it becomes impossible to use the same readout chip, or even if it can be used, it suffers from a combination of the following drawbacks: a) In cases where the overall sensor surface that can be accommodated is smaller and the size of the sensor tile is reduced in view of the smallness of the sensor pixels, such a redesigned sensor tile, if the same readout chip as before works on it, will greatly exceed the size of the readout chip, resulting in wasted space. b) In the case where the readout chip is redesigned to fit the smaller dimensions of the redesigned sensor tile, it is necessary to realize a redesign of the chip, which is labor-intensive and uneconomical in terms of both costs and resources. c) In the case where a previous sensor tile must or should remain at its original size and is filled with additional sensor pixels and the previous readout chip must continue to serve this sensor tile, an additional readout chip is needed to serve the increased number of sensor pixels on the sensor tile. Such an additional readout chip consumes a lot of space in both x and y directions. Summary of the Invention

[0006] Therefore, the general object of the present invention is to provide a radiation detector which allows for flexibility in variable resolution within a set of sensor pixels while at the same time allowing 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 a radiation detector according to claim 1. The radiation detector allows for a position-resolved detection of radiation, provided that it comprises a sensor tile of a sensor material sensitive to radiation 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), cadmium zinc telluride (CdZnTe) or germanium (Ge). The sensor material is preferably selected according to the type of radiation to be detected.

[0008] To read out the individual sensor pixels of the 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 tiles, the readout chip comprising a set of readout circuits, each of which is preferably responsible for reading out an assigned sensor pixel.

[0009] In order to clarify the geometrical relationship of the components of the radiation detector relative to each other, the sensor tile is determined to extend in a horizontal plane spanned by a first axis and a second axis orthogonal to the first axis. Typically, the width of the sensor tile along the first axis and the height along the second axis each exceed, preferably by at least a factor of 10, the thickness of the sensor tile along a third axis orthogonal to the first and second axes. A set of sensor pixels is arranged in the horizontal plane and thus covers a part of, for example, the bottom surface of the sensor tile. The sensor pixels comprise a conductive material, for example in the form of a metallization or implant, which is also referred to as a bottom electrode. This term comes from its function of acting as an electrode in combination with a top electrode, preferably a continuous top electrode on the opposite surface, i.e. the top surface, of the sensor tile. The sensor pixels are electrically separated from each other, preferably by insulating gaps between the metallizations or implants.

[0010] The radiation is expected to strike the top surface of the sensor tile, which includes a top electrode. Preferably, the top electrode is transparent for the radiation to be detected. Energy deposited by the radiation incident on the internal sensor material is converted into electrode-hole pairs. The resulting charges are transported along the field lines of an electric field applied between the set of top and bottom electrodes. Thus, each sensor pixel collects radiation-induced charges from an assigned volume within the sensor material. The arrangement of the sensor pixels along the first and second axes thus allows for position-resolved detection of the incident radiation.

[0011] The signal processing in each readout circuit may include one or more, preferably all, of amplifying, shaping, filtering, differentiating, integrating, storing, and / or counting 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-delay integration (TDI) of the pixel signal depending on the signal in the neighboring pixel. In each readout circuit, the processed signal may achieve a final state, which may then be stored for a certain time, e.g., 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 store the previous final state, if desired, such as in a storage cell, e.g., in an analog or digital first-in-first-out circuit (FIFC).

[0012] Given that it is desired that the radiation detector not waste space outside the area required by the sensor tile, the sensor tile is preferably placed on top of the readout chip with the bottom electrodes facing the top surface of the readout chip, which preferably comprises electrical contacts for each readout circuit.

[0013] At least two adjacent inner sensor pixels of a set exhibit an extension along a second axis, e.g. the y axis, that exceeds their extension along a first axis, e.g. the x axis. At the same time, for the preferably inner readout circuits serving these two adjacent inner sensor pixels, the dimensioning is set as follows: the extension of each of these readout circuits along the first axis differs from the extension of the assigned sensor pixel along the first axis and / or the extension of each of these assigned readout circuits along the second axis differs from the extension of the assigned sensor pixel along the second axis.

[0014] In other words, the extension of the associated sensor pixels is non-square, in particular rectangular, and the extension of the associated readout circuits differs in at least one direction, preferably in both directions, so that 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 to be reused, at least two adjacent, preferably all, inner sensor pixels of the 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 pixel may be rectangular. Thus, the inner sensor pixel and the assigned readout circuit do not have to be of the same shape as in conventional radiation detectors.

[0016] In particular, the extension of the allocated readout circuit in a first dimension, for example along the x-axis, is less than the extension of the sensor pixels in the same direction, while at the same time the extension of the readout circuit along a second dimension, for example along the y-axis, is greater than the extension of the sensor pixels in the same direction. Of course, the x and y axes can be interchanged in the above teachings.

[0017] In particular, when using an existing readout chip, different resolutions required for the application are achieved by adapting the sensor pixel layout to shapes that provide different resolutions in the x and y directions. Thus, rectangular or hexagonal inner sensor pixels are possible, even if the readout circuit has a square shape as is common for prior art applications. This allows the same readout chip to be used for several different sensor pixel designs according to the application. This is advantageous, since the development of a readout chip is a non-trivial endeavor. On the other hand, sensor tiles can be redesigned much easier and with shorter design-to-production cycles than new readout chip designs.

[0018] In particular, the pixel dimensions can be reduced in the direction where high resolution is required, while increasing in the other direction where low resolution is sufficient. This design of at least two adjacent inner sensor pixels allows these two different direction-dependent resolutions. At the same time, a readout chip that was originally designed to be used with a conventional sensor pixel of square shape can be used in combination with such a sensor pixel. Thus, the same readout chip can be used for different resolution requirements, especially by sacrificing the resolution in one direction to enhance the resolution in the other direction.

[0019] Regarding the definition of the terms "extension", "shape", "inner sensor pixel", etc., see below.

[0020] The set of sensor pixels may comprise all pixels on a sensor tile, or, for example, a group of sensor pixels that are spaced apart from another group. The set of sensor pixels typically comprises a subset of inner sensor pixels, which have adjacent sensor pixels in each of the first and second axis directions. Thus, there may be another subset of sensor pixels that includes outer sensor pixels that do not meet the requirements of an inner sensor pixel.

[0021] The extension of each of the two adjacent inner sensor pixels along the first axis is determined by the extension of the conductive material of the sensor pixel along the first axis plus the distance of the gap between the conductive material of the adjacent inner sensor pixels in the direction of the first axis. In the same way, the extension of each of the two adjacent inner sensor pixels along the second axis is determined by the extension of the conductive material of the sensor pixel along the second axis plus the distance of the gap between the conductive material of the adjacent inner sensor pixels in the direction of the second axis.

[0022] The set of readout circuits may comprise all readout circuits of a readout chip or a group of readout circuits, at least these readout circuits being members of the set electrically connected to at least two inner sensor pixels of the subset. Typically, the set of readout circuits comprises all readout circuits of a readout chip. The subset comprises the inner readout circuits of the set. The inner readout circuits refer to the readout circuits in each direction of the first axis and the second axis.

[0023] Each readout circuit is preferably provided with contacts on the top surface of the readout chip facing the sensor tile. After assembly of the readout chip with the sensor tile, the readout circuit is electrically connected via its respective contact to the assigned sensor pixel / bottom electrode for receiving an electrical signal therefrom.

[0024] The extension of each inner readout circuit along the first axis is N i is defined by the distance between the contacts of the two outermost inner readout circuits on the first axis divided by N i represents the number of inner readout circuits along the first axis. The extension of each inner readout circuit along the second axis is M i is defined by the distance between the contacts of the two outermost inner readout circuits on the second axis divided by M irepresents the number of inner readout circuits along the second axis. Therefore, all inner readout circuits are assumed to have the same extension along the first axis and the same extension along the second axis.

[0025] Usually, the extension, especially the scale x introduced later, d and y d etc., equivalence between the extensions shall be assumed in cases where the extensions compared to one another are within 10%. In particular, a rectangle having a side length ratio less than 1.1:1 and greater than 0.9:1 shall be considered a square.

[0026] The radiation detected is ionizing radiation and may typically include, for example, one of electrons with energies from a few keV to a few hundreds of keV in the case where the HPD is an electron detector, x-rays with energies from a few hundreds of eV to a few hundreds of kdV in the case where the HPD is an x-ray detector, or other types of ionizing radiation. Thus, the radiation detector of the present invention may be used for imaging applications, but also 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 can tolerate any resolution in the other direction, such as one of electron energy loss spectroscopy (EELS), small angle x-ray scattering (SAXS), wavelength dispersive spectroscopy, etc., where it is advantageous to have higher resolution in one direction (e.g., the x direction) than in the other (e.g., the y direction).

[0028] The following embodiments relate to the extension and shape of the sensor pixels. - preferably, two adjacent inner sensor pixels exhibit the same extension along the first axis and the same extension along the second axis, and are therefore of the same shape, which, when applied to all inner sensor pixels of the subset, allows the same resolution along each of the x and y axes; - preferably, two adjacent inner sensor pixels are of the same rectangular shape, i.e. the area of ​​the conductive material is essentially of rectangular shape. The rectangular shape maximizes the area covered by the sensor pixels with different extensions in the x and y directions. - preferably, two adjacent inner sensor pixels each exhibit an extension along the second axis that is at least four times larger than the extension along the first axis, so that the difference in resolution is not negligible. This embodiment allows a significant increase in the resolution along one axis at the expense of the resolution along the other axis. Preferably, all inner sensor pixels of a subset are of the same rectangular shape, the advantages of which have already been mentioned above. - Preferably, all sensor pixels of a set are of the same rectangular shape, thereby applying a constant resolution per axis across the entire sensor tile. - preferably at least four, and preferably all, inner sensor pixels of the subset are of the same rectangular shape and are arranged in a two-dimensional array along the first and second axis. In this context, an array is understood as a regular arrangement of sensor pixels, in which the rectangular sensor pixels of a column all extend between the same x-coordinate in width and the rectangular sensor pixels of a row all extend between the same y-coordinate in height. Thus, there is no shift or offset between sensor pixels of the same column and the same row. This allows a constant resolution in both directions. In a different embodiment than the one previously described, at least four, and preferably all, inner sensor pixels of the subset are of the same rectangular shape and are arranged with one of a row offset relative to each other and a column offset relative to each other. Preferably, the offset is at most half the extension of the inner sensor pixel along the offset axis. Preferably, the offset is half 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 sensor pixel extension 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 an axis orthogonal to the offset axis. - preferably, each of the two adjacent inner sensor pixels is of the same rectangular shape and comprises a local asymmetry in the area where electrical contact means, such as bump bonds, engage the sensor pixel to connect it to an assigned readout circuit, allowing a straight vertical connection of the underlying square readout circuit with the centrally placed contact. Preferably, the local asymmetries are represented by ridges on the boundaries of the sensor pixels, which minimizes irregular shape variations between inner sensor pixel areas. - preferably, each of the two adjacent inner sensor pixels comprises another local asymmetry in the form of a recess complementary to the raised portion of the adjacent sensor pixel, thereby allowing the raised portion in the adjacent sensor pixel;

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

[0030] The following embodiments more explicitly relate to the extension of the sensor pixel in relation to the extension of the readout circuitry, and therefore address the resolution achieved while at the same time maintaining the footprint required by the sensor tile-readout circuitry arrangement. - preferably, the extension of each of the two readout circuits along the first axis exceeds the extension of the assigned sensor pixel along the first axis, this geometry paving the way for one readout circuit to overlap 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 geometry paves the way for one readout circuit to overlap two assigned sensor pixels and also for a second readout circuit to overlap two assigned sensor pixels. - preferably, the extension of each of the two inner readout circuits along the first axis is at least twice the extension of the assigned sensor pixel along the first axis. This geometry paves the way for the readout circuits to require no more area than the sensor pixel. Preferably, the extension along the second axis of each of the two inner readout circuits is less than or equal to half the extension along the second axis of its assigned sensor pixel. - preferably, the extension along the first axis of each of the two inner readout circuits is twice the extension of the assigned sensor pixel along the first axis and the extension along the second axis of each of the two inner readout circuits is half the extension of the assigned sensor pixel along the second axis, this geometry implementing a resolution ratio of 2:1 while the two readout circuits and the two assigned sensor pixels require the same area. - preferably, the extension along the first axis of each of the two inner readout circuits is 3 / 2 times the extension of the assigned sensor pixel along the first axis, and wherein the extension along the second axis of each of the two inner readout circuits is 2 / 3 times the extension of the assigned sensor pixel along the second axis. This geometry implements a resolution ratio of 3:2, even though six readout circuits and six assigned sensor pixels may require the same area.

[0031] The following embodiments relate to the geometrical configuration of the sensor pixels and readout circuitry relative to each other. - preferably, two adjacent inner sensor pixels are arranged next to each other along a first axis, combining to form a rectangle, and the two assigned inner readout circuits are arranged next to each other along a second axis, thereby spanning a rectangle that coincides with the rectangle spanned by the two adjacent inner sensor pixels. Thus, all pairs of inner sensor pixels and readout circuits are of the same size, and may preferably completely overlap, as will be introduced in the following embodiments. Preferably, the rectangle spanned by two adjacent inner sensors has the same position along the first and second axes as the rectangle spanned by the two assigned inner read-out circuits. - preferably, the rectangle spanned by two adjacent inner sensors does not overlap with the rectangle spanned by two assigned inner readout circuits. Preferably, a redistribution layer is applied in the context of this embodiment, as will be explained hereafter. Preferably, at least one of the two inner readout circuits of the subset is out of overlap with the assigned sensor pixel. - preferably, each of the inner sensor pixels of the subset requires an area that exceeds an area of ​​the allocated inner readout circuitry, the area of ​​the allocated inner readout circuitry being determined by multiplying its extension along the first axis by its extension along the second axis. - preferably, all inner sensor pixels of the subset exceed the combined area of ​​all inner readout circuits of the subset, this combined area being determined by the extension of the inner readout circuits along the first axis multiplied by the extension of the readout circuits along the second axis multiplied by the number of inner readout circuits.

[0032] In another preferred embodiment, a rerouting or redistribution layer is disposed 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 the metallized bottom electrode on the sensor surface. Preferably, the rerouting layer comprises an insulating material and a conductive trace disposed between the sensor tile and the readout chip.

[0033] Each conductive material of the sensor pixel may be included in a stack of layers to form an individual electrode on the bottom side of the sensor tile. Such a stack may include, for example, n++ or p++ implant(s), different metals, insulating layer(s), e.g., SiO, SiN, under-bump metallization, etc. The different layers in this stack may not have to have the same size. The top layer of the stack may define the area towards which the electric field inside the sensor tile bends. Charges of one polarity (electrons or holes depending on the polarity of the applied voltage) created in response to the energy impact of ionizing radiation drift along the electric field lines towards 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 location where the top layer of the stack is present to a different xy location where the bottom layer of the stack is present. This may further be used to cross the xy area covered by the top layers of the pixel stacks of different sensors.

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

[0035] Embodiments in the above categories may be applied alone 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 multiple embodiments in a different category.

[0036] The invention will be better understood and objects other than those set forth above will become more apparent when considered in relation to the following detailed description. [Brief description of the drawings]

[0037] [Figure 1] 1 is a cutaway view of a radiation detector according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cutaway view of the sensor tile 1 of FIG. [Diagram 3] FIG. 2 is a top view of a readout chip of a radiation detector according to an embodiment of the present invention. [Figure 4] FIG. 2 is a bottom view of a sensor tile of a radiation detector according to an embodiment of the present invention. [Diagram 5] 2 is a schematic transparent top view of a cutaway of a radiation detector according to an embodiment of the present invention; [Figure 6] 4 is a cutaway view of a radiation detector according to another embodiment of the present invention. [Figure 7] 2 is a schematic transparent top view of a cutaway of a radiation detector according to an embodiment of the present invention; [Figure 8] 4 is another schematic transparent top view of a cutaway of a radiation detector in accordance with an embodiment of the present invention. FIG. [Figure 9] 4 is another schematic transparent top view of a cutaway of a radiation detector in accordance with an embodiment of the present invention. FIG. [Figure 10] 2 is a schematic bottom view of a cutout of a sensor tile of a radiation detector according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Figure 1 shows a cutaway view of a radiation detector according to an embodiment of the 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 top electrode 13 and a number of isolated bottom electrodes 12, the sensor material being represented by a conductive material, e.g. in the form of metallization, that contributes 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 the top, as indicated by the arrows.

[0039] The sensor tile 1 is disposed in a 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, which in combination define the horizontal plane. The sensor tile is characterized by its planar extension in the horizontal plane, provided that its extension in each of the first and second axes exceeds its thickness in the z direction, i.e. the third axis.

[0040] The readout chip 2 also has its main extension along the first and second axes x, y and is arranged parallel to the sensor tile 1, in particular below the sensor tile 1. The readout chip 2 comprises a readout circuit 21 and electrical input contacts 22 on its top 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 to bump bonds 4. The inner sensor pixels are 12 i The outer sensor pixels are called o The inner read circuit is called 21 i The outer read circuit is called 21 o It is called.

[0041] 1 is mounted on a high density interconnect (HDI) printed circuit board 3 which has additional readout electronics. Electrical connections between I / O pads 23 of the readout chip 2 and I / O pads 31 of the HDI PCB 3 are established by, for example, wire bonds 5.

[0042] Incident radiation that it is desired to detect and measure 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] FIG. 2 shows a cutaway view of the sensor tile 1 of FIG. 1. A positive or negative voltage is applied to the continuous top electrode 13. The top electrode 13 may consist of a stack built up of sensor implants, for example one or more of p++, n++, metals, for example Al, Au, Ag, Cu, other conductive and / or insulating layers. The bottom electrode 12 may also be represented by a layer of the stack. Electric field lines lead from the top electrode 13 to the bottom electrode 12. The charges created in the sensor material 11 drift along the electric field lines. In FIG. 2, all layers in the stack 12 of the bottom electrode have the same size, in particular the same extension along the first axis x. The boundaries of the volume 14 assigned to each sensor pixel 12 are indicated by dotted lines.

[0044] Thus, each sensor pixel 12 collects radiation induced charge from an assigned volume 14 within the sensor material 11, which is shown for all sensor pixels 12 in FIG. 2 and for only one sensor pixel 12 in FIG.

[0045] Returning to Fig. 1, the charge collected from the assigned volume 14 reaches the readout circuit 21 where it is processed, via the assigned metallization 21, the assigned bump bond 4 and the respective contacts 22. The readout circuits 21 are preferably represented by electronic devices integrated in the semiconductor material of the readout chip 2. Preferably, each readout circuit 21 serves a dedicated sensor pixel 12 and is therefore separate from the other readout circuits 21 and their contacts 22, unless the results of the processing in the individual readout circuits 21 are combined and transferred, multiplexed etc. to be sent to the PCB 3. The readout circuits 21 are therefore represented by dotted rectangles separately from the adjacent readout circuits 21 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 cutaway view of FIG. 1, all of the 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 of all the inner sensor pixels 12 is greater than the extension along the first axis x. i The extensions along the second axis y of the inner sensor pixel 12 are the same, so that here, i are of the same rectangular shape.

[0047] As can already be derived from FIG. 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, and preferably all inner readout circuits 21 i The same is true for the inner readout circuit 21 along the second axis y, which is not shown in FIG. i The extension of the inner sensor pixel 12 along the second axis y i Preferably, the length of each inner readout circuit 21 along the second axis y is less than the extension of the i The extension of the inner readout circuit 21 is the same as that along the first axis x. i are of the same square shape.

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

[0049] In the cutaway view of FIG. 1, several inner sensor pixels 12 i The assigned inner read circuit 21 i The reason is that such inner sensor pixel 12 is not shown electrically connected to the iare electrically connected to the assigned read-out circuitry by bump bonds, which cannot be imagined from Fig. 1 since they are located in the plane x, z with y>0, which will be better understood in connection with the subsequent figures.

[0050] The radiation detector of FIG. 1 provides a lower resolution along a second axis y than along a first axis x. i corresponds to sensor pixel 12 i The shape is different from the sensor pixel 12 i This requires the same area of ​​the readout chip 2 underneath.

[0051] 3 shows a top view of a cutaway of a readout chip 2 as 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 an array of rows and columns. The set includes an outer readout circuit 21 o and an inner read circuit 21 i In particular, the four outermost inner readout circuits in each direction x, y are oi In addition, the input contacts 22 are indicated by dots for at least some of the readout circuits 21. In this example, the input contacts 22 are located in the lower left quarter of each readout circuit 21. However, the input contacts 22 may alternatively be located in the center of each readout circuit 21, at different locations, or even at variable locations across the readout circuits 21. In this embodiment, the readout circuits 21 have an essentially square shape.

[0052] In order to compare the size and / or shape of the readout circuit 21 with that of the assigned sensor pixels, the following assumptions are made, as illustrated in relation to FIG.

[0053] Each inner readout circuit 21 along the first axis x i / twenty one oi With respect to the extension dx of x However, the inner readout circuit 21 is the outermost one along the first axis x. oiThis distance D is measured between the contacts 22 of x is N i Divided by -1, then N i is the inner readout circuit 21 along the first axis x i / twenty one oi The result represents the number of times each of the inner read circuits 21 i / twenty one oi is determined to have an extension d along the first axis x x It is.

[0054] In the same way, distance D y However, the inner readout circuit 21 is the outermost one along the second axis x. oi This distance D is measured between the contacts 22 of y is M i Divided by -1, then M i is the inner readout circuit 21 along the second axis y i / twenty one oi The result represents the number of times each of the inner read circuits 21 i / twenty one oi is determined to have an extension d along the second axis y y It is.

[0055] 4 shows a bottom view of a cutaway of a sensor tile 1 as used in a radiation detector according to an embodiment of the present invention. In this embodiment, the inner sensor pixel 12 i The subsets are arranged in an array of rows and columns. Each inner sensor pixel 12 of the subset i is the extension of the metallization x s and y s 1. The inner sensor pixels 12 adjacent along the first axis x are i The gap between the metallizations of size g x The inner sensor pixel 12 i The metallizations of are indicated by straight rectangles. The gaps between adjacent metallizations along the second axis y are of size g yIn order to compare the size and / or shape of the readout circuitry with that of the assigned sensor pixel 12, the following assumptions are made: i Extension of x d x s +g x and the inner sensor pixel 12 along the second axis y is set to i Extension y d is y s +g y is set to.

[0056] 5 shows a schematic transparent top view of a cutaway of a radiation detector according to an embodiment of the present invention, which in this particular embodiment shows the geometric layout of the sensor pixels 12 relative to the readout circuitry 21. i has a rectangular shape defined by its corresponding sensor pixel boundaries, shown by solid lines. i has a square shape defined by the corresponding readout circuit boundaries shown by dot / slash lines. For illustration purposes, gaps have been omitted.

[0057] Sensor pixel rectangular aspect ratio x d :y d is 1:4. Sensor pixel 12 i The extension along the x-axis (width) of the readout circuit 21 i The x-axis (width) of the sensor pixel 12 is half of its extension. i The extension along the y-axis (height) of the readout circuit 21 i The extension along the y-axis (height) of each of the two horizontally (x-direction) adjacent sensor pixels 12 is twice that of the i are two vertically (y-direction) adjacent readout circuits 21 i It covers roughly the same area.

[0058] Two adjacent sensor pixels12 i and the assigned read circuit 21 i The connection between the left sensor and pixel 12i The upper readout circuit 21 i Connect to the right sensor Pixel 12 i may be implemented to connect to the bottom readout circuit. The relationship is shown diagrammatically by the arrows. In this embodiment, the sensor pixel 12 i However, the read circuit 21 i Note that the vector is shifted in both the x and y directions relative to

[0059] Sensor Pixel 12 i Read circuit 21 assigned from i The electrical connection to the readout circuit 21 may be performed in several steps. In a preferred embodiment, the sensor pixel metallization and the readout circuit contacts, e.g., their under bump metallization (UBM), are in the same xy coordinates but on different parallel planes (vertically shifted). i Top sensor pixel 12 i If the overhang does not overlap the UBM, a rerouting layer may be required.

[0060] Figure 6 shows another embodiment of a radiation detector according to the invention, including a rerouting between the sensor pixels 12 and the readout circuit 21. In addition to the radiation detector of figure 1, a redistribution layer 6 is provided, which establishes an electrical one-to-one connection between the sensor pixels 12 and the corresponding input contacts 22 of the readout circuit 21 via conductor tracks 61 in a dielectric material 62. Contacts 63 of / on the redistribution layer 6 connect to the bump bonds 4 and thus to the contacts 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- or y-axis from the assigned sensor pixel 12, the redistribution layer 6 is preferably applied.

[0061] 7 shows a schematic transparent top view of a cutaway of a radiation detector according to an embodiment of the present invention. In this embodiment, the inner right sensor pixel 12 ir , i.e., two adjacent inner sensor pixels 12 along the first axis xi Each inner right sensor pixel 12 of the pair ir Each of the inner lower readout circuits 21 il A bump 121 is shown to cover the centrally placed bump bond 4 in the inner lower readout circuit 21. il The bump bond 4, which also represents the contact location x, y of the inner right sensor pixel 12, can be connected to the inner right sensor pixel 12 without the need for lateral rerouting. ir From 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 of the inner right sensor pixels 12 ir 1. In this embodiment, the contacts 22 and bump bonds 4 can all remain centered over the readout circuit 21.

[0062] It should be noted that if the sensor pixel 12 deviates only slightly from a rectangular shape, the deviation being 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, it is also considered rectangular.

[0063] 8 shows a schematic transparent top view of a cutaway of a radiation detector according to another embodiment of the present invention. In this embodiment, the inner sensor pixel 12 i In this embodiment, an insulating layer, for example SiO2, SiN, or any other dielectric layer used in semiconductor processing, covers the inner sensor pixel 12. i and the inner readout circuit 21 i6. A via 64, as shown by 64 in FIG. 6, is made (e.g., etched) through the insulating layer. The hole 64 is metallized with an electrical conductor, resulting in a part of the conductor path 61, see FIG. 6. The bump bond 4 is then connected to the metallized hole 64 by a conductive trace, also 61 in FIG. 6, which is also made from, for example, copper, silver, aluminum. In this embodiment, the inner sensor pixel 12 i The original rectangular shape of is maintained.

[0064] 9 shows a schematic transparent top view of a cutaway of a radiation detector according to another embodiment of the present invention. i The shape of the sensor pixel corresponds to 12 i In this embodiment, an insulating layer made of, for example, SiO2, SiN, or any other insulating layer used in semiconductor processing, is provided between the sensor pixel 21 and the semiconductor device 20. i and the inner readout circuit 21 i A hole 64 is, for example, etched through the insulating layer, and the hole 64 is filled with a conductive material. The bump bond 4 locations are then connected to the conductive material in the hole 64 by a conductive trace 61 made, for example, from copper, silver, aluminum. This embodiment is suitable for example for the x-direction sensor pixel 12 i The resolution of the read circuit 21 i This is advantageous in cases where one wishes to select a non-integer divisor or multiplier of the resolution of the different readout circuits 21. i The xy area between the inner sensor pixels is 12 i A sensor pixel 12 having a shape similar to or the same as i to produce uniform resolution in the x or y direction across the entire sensor tile. In cases where the routing needs to cover a larger distance across a large portion of the different sensor pixels, it is advantageous to leave a cavity in the sensor pixel metallization where the trace 61 crosses the pixel.

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

[0066] It should be noted that routing can be used such that the total area covered by the sensor pixels can be different from the total area covered by the readout circuitry. In particular, the area covered by the sensor pixels can be larger than the area covered by the readout circuitry.

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

[0068] 10 shows a schematic top view of a cut-out of a sensor tile of a radiation detector according to an embodiment of the present invention. In this embodiment, the inner sensor pixel 12 i are rectangular in shape and are arranged in rows offset relative to each other. In this example, the inner sensor pixels 12 of adjacent rows i is the width of the inner sensor pixel, i.e., half the offset of its extension along the x-axis, O ff This allows for even higher resolution in the x direction. Of course, the pattern in Fig. 10 may be repeated in both +y / -y directions and continued in +x / -x.

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

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

Claims

1. 1. A radiation detector for location resolved detection of radiation, comprising: at least one sensor tile (1) having a sensor material (11) sensitive to said radiation, the at least one sensor tile (1) defining a horizontal plane spanned by a first axis (x) and a second axis (y) perpendicular to said first axis (x); a set of sensor pixels (12) arranged in said horizontal plane, each sensor pixel (12) comprising a conductive material in contact with said sensor material (11); The set of sensor pixels (12) includes inner sensor pixels (12 ｉ ) 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 of said subset (12 ｉ ) is an extension (X ) along the first axis (x) ｄ ) along the second axis (y) ｄ ) and The inner sensor pixels (12) along the first axis (x). ｉ ) of the extension portion (X ｄ ) is the extension (x) of the conductive material along the first axis (x). ｓ ), the inner sensor pixel (12 ｉ ) and an inner sensor pixel (12) arranged adjacent to the first axis (x) direction. ｉ ) the gap distance (g ｘ ) is determined by adding The inner sensor pixel (12) along the second axis (y) ｉ The extension (y ｄ ) is the extension (y) of the conductive material along the second axis (y). ｓ ), the inner sensor pixel (12 ｉ ) and an inner sensor pixel (12) arranged adjacent to the second axis (y) direction. ｉ ) the gap distance (g ｙ a set of sensor pixels (12) determined by adding at least one readout chip (2) assigned to said at least one sensor tile (1) and extending along said first axis (x) and said second axis (y); a set of readout circuits (21) integrated in the readout chip (2), each readout circuit (21) of the set comprising contacts (22), each readout circuit (21) being electrically connected via the contacts (22) 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) includes an inner readout circuit (21 ｉ ), and an inner read circuit (21 ｉ ) has a readout circuit (21) in each direction of the first axis (x) and the second axis (y), Each inner readout circuit (21) along the first axis (x) ｉ ) extension (d ｘ ) is N ｉ The two outermost inner readout circuits (21) on the first axis (x) divided by −1. ｏｉ The distance (D) between the contacts (22) ｘ ), where N ｉ The inner readout circuit (21) along the first axis (x) ｉ ) Each inner readout circuit (21) along the second axis (y) ｉ ) extension (d ｙ ) is M ｉ The two outermost inner readout circuits (21) on the second axis (y) divided by −1. ｏｉ The distance (D) between the contacts (22) ｙ ), where M ｉ The inner readout circuit (21) along the second axis (y) ｉ ) The two adjacent inner sensor pixels (12 ｉ The two inner read circuits (21) are assigned to and connected to the ｉ ) are The assigned inner sensor pixels (12) along the first axis (x). ｉ an extension (d) along the first axis (x) different from the extension (xd) along the first axis (x) ｘ ), and / or The assigned inner sensor pixel (12) along the second axis (y). ｉ The extension (y ｄ ) along the second axis (y), which is different from the extension (d ｙ and a set of readout circuits (21) for indicating the

2. The two adjacent inner sensor pixels (12 ｉ ) have the same extension (x) along the first axis (x) ｄ ) and the same extension (y ｄ ) and Preferably, the two adjacent inner sensor pixels (12 ｉ ) are of the same rectangular shape, Preferably, the two adjacent inner sensor pixels (12 ｉ ) each having an extension (x) along the first axis (x) ｄ an extension (y) along said second axis (y) that is at least four times greater than said first axis (y); ｄ ) and Preferably, all inner sensor pixels of said subset (12 ｉ ) are of the same rectangular shape, Preferably, all sensor pixels of the set (12 ｉ 2. The radiation detector of claim 1, wherein all of the first and second electrodes are of the same rectangular shape.

3. At least four, preferably all, of the inner sensor pixels of the subset (12 ｉ 2. The radiation detector of claim 1, wherein said first and second axes (x, y) are of the same rectangular shape and are arranged in a two-dimensional array along said first and second axes (x, y).

4. At least four, preferably all, of the inner sensor pixels of the subset (12 ｉ ) are of the same rectangular shape and are arranged in one of the rows and columns offset with respect to each other; Preferably, the offset (o ｆｆ ) along the offset axis (x, y) of the inner sensor pixel (12 ｉ ) of the extension (x ｄ , y ｄ ) at up to half Preferably, the offset (o ｆｆ ) along the offset axis (x, y) of the inner sensor pixel (12 ｉ ) of the extension (x ｄ , y ｄ ) and Preferably, the offset (O ｆｆ ) along the offset axis (x, y) of the inner sensor pixel (12 ｉ ) of the extension (x ｄ , y ｄ ) is one third of Preferably, the offset (o ｆｆ ) is the sensor pixel extension (x,y) in the offset axis (x,y) divided by an integer ｄ , y ｄ ), the largest integer being the readout circuit (21) along the axis perpendicular to the offset axis (x, y). ｉ 2. The radiation detector of claim 1, wherein the number of adjacent pixels is less than the number of adjacent pixels.

5. The two adjacent inner sensor pixels (12) are of the same rectangular shape. ｉ Each of the inner sensor pixels (12) comprises a local asymmetric portion, in which electrical contact means are provided between the inner sensor pixels (12) and the local asymmetric portion. ｉ ) to the assigned inner read circuit (21 ｉ ) to connect to the inner sensor pixel (12 ｉ ) and Preferably, the local asymmetry is a function of the inner sensor pixel (12 ｉ ) represented by a ridge (121) in said shape, Preferably, the two adjacent inner sensor pixels (12 ｉ ) each of the adjacent sensor pixels (12 ｉ 2. The radiation detector according to claim 1, further comprising a local asymmetry in the form of a recess (122) complementary to said raised portion (121) of said first surface.

6. The two inner readout circuits (21 ｉ ) each having the same extension (d) along the first axis (x) and the second axis (y) ｘ , d ｙ ) and Preferably, the two inner readout circuits (21 ｉ ) are of the same square shape, Preferably, all the inner readout circuits (21) of said subset ｉ ) are of the same square shape, Preferably, all the readout circuits (21) of the set ｉ 2. The radiation detector of claim 1, wherein all of the first and second electrodes have the same square shape.

7. At least four, preferably all, of the inner readout circuits (21 ｉ 2. The radiation detector of claim 1, wherein said first and second axes (x, y) are of the same square shape and are arranged in a two-dimensional array along said first and second axes (x, y).

8. The two inner readout circuits (21) along the first axis (x). ｉ Each of the extensions (d ｘ ) along the first axis (x) of the assigned inner sensor pixel (12 ｉ ) of the extension (x ｄ 13. The radiation detector of claim 1, wherein the radiation detector has a capacitance greater than 1.

9. The two inner readout circuits (21) along the second axis (y) ｉ Each of the extensions (d ｙ ) along the second axis (y) of the assigned inner sensor pixel (12 ｉ The extension (y ｄ 9. The radiation detector of claim 8, wherein the n-th order is less than 1.

10. The two inner readout circuits (21) along the first axis (x). ｉ Each of the extensions (d ｘ ) along the first axis (x) of the assigned sensor pixel (12 ｉ ) of the extension (x ｄ 9. The radiation detector of claim 8, wherein the .lambda.-dimension is at least twice as large as the .lambda.-dimension.

11. The two inner readout circuits (21 ｉ The extension (d) along the second axis (y) of each of the ｙ ) along the second axis (y) of the assigned sensor pixel (12 ｉ The extension (y ｄ 11. The radiation detector of claim 10, wherein the luminance is equal to or less than half of the luminance of the radiation detector.

12. The two inner readout circuits (21 ｉ The extension (d) along the first axis (x) of each of the ｘ ) along the first axis (x) of the assigned sensor pixel (12 ｉ ) of the extension (x ｄ ) is twice as large as The two inner readout circuits (21 ｉ The extension (d) along the second axis (y) of each of the ｙ ) along the second axis (y) of the assigned sensor pixel (12 ｉ The extension (y ｄ 12. The radiation detector of claim 11, wherein the axial length of the radiation detector is half of the axial length of the radiation detector.

13. The two inner readout circuits (21 ｉ The extension (d) along the first axis (x) of each of the ｘ ) along the first axis (x) of the assigned sensor pixel (12 ｉ ) of the extension (x ｄ ) times 3 / 2, The two inner readout circuits (21 ｉ The extension (d) along the second axis (y) of each of the ｙ ) along the second axis (y) of the assigned sensor pixel (12 ｉ The extension (y ｄ 12. The radiation detector of claim 11, wherein the luminance is 2 / 3 times the luminance of the radiation detector.

14. The two adjacent inner sensor pixels (12 ｉ ) are arranged next to each other along the first axis (x) and combine to span a rectangle; The two assigned inner read circuits (21 ｉ ) are arranged next to each other along the second axis (y), whereby the two adjacent inner sensor pixels (12 ｉ 2. The radiation detector of claim 1, wherein the first and second electrodes extend into a rectangle that coincides with the rectangle in which the second and third electrodes extend.

15. The two adjacent inner sensor pixels (12 ｉ The rectangle in which the two inner readout circuits (21) extend is ｉ 15. The radiation detector of claim 14, wherein the first and second axes (x, y) are the same as the rectangle that the first and second axes (x, y) span.

16. The two adjacent inner sensor pixels (12 ｉ The rectangle in which the two inner readout circuits (21) extend is ｉ 15. The radiation detector of claim 14, wherein each of the plurality of pixels does not overlap the rectangle.

17. The two inner readout circuits (21) of the subset ｉ At least one of the assigned sensor pixels (12) ｉ 2. The radiation detector of claim 1, wherein the radiation detector is out of overlap with the first and second radiation detectors.

18. The inner sensor pixels of the subset (12 ｉ ) each of the assigned inner read circuits (21 ｉ ) requires an area greater than that required by the allocated inner read circuit (21) ｉ ) is determined by dividing the area of ​​the first axis (x) by the area of ​​its extension (d ｘ ) along the second axis (y) and its extension (d ｙ 2. The radiation detector of claim 1, wherein the signal is determined by multiplying the signal by a factor of 1.

19. All inner sensor pixels of the subset (12 ｉ ) all the inner readout circuits (21) of said subset ｉ ) along the first axis (x), the combined area of ​​the inner readout circuit (21 ｉ ) of the extension (d ｘ ) along the second axis (y) and its extension (d ｙ ) is multiplied by the inner read circuit (21 ｉ 2. The radiation detector of claim 1, wherein the detection signal is determined by multiplying the number of detection signals by a number of times.

20. a rerouting layer (6) between the sensor tile (1) and the readout chip (2) for electrically connecting the sensor pixels (12) to the contacts (22) of the assigned readout circuit (21); 2. The radiation detector of claim 1, wherein the rerouting layer (6) preferably comprises an insulating material (62) including conductive traces (61) arranged between the sensor tile (1) and the readout chip (2).

Images