Radiation sensor element and method

Abstract

The present disclosure relates to a radiation sensor element (100) comprising a semiconductor substrate (101) having a bulk refractive index, a front surface (102), a back surface (103) extending essentially along a reference plane (104), and a plurality of pixel portions (110). Each pixel portion (111, 112) comprises a collection area (120) on the back surface (103) and a textured area (130) on the front surface (102). The textured area (130) comprises high-aspect-ratio nanostructures (135) extending essentially along a thickness direction perpendicular to the reference plane (104) and forming a light conversion layer (136) having an effective refractive index gradually varying towards the bulk refractive index to reduce reflection of light incident from a front side of the semiconductor substrate (101) onto said pixel portion.

Description

Technical Field

[0001] This disclosure relates to radiation detectors. More specifically, this disclosure relates to semiconductor pixel detectors. Background Technology

[0002] Semiconductor pixel detectors are widely used in consumer electronics (e.g., cameras) and in various industrial and scientific environments (e.g., photodetectors, X-ray detectors, and particle detectors).

[0003] In conventional detectors, crosstalk between pixels (e.g., optical crosstalk) can pose a significant challenge. Optical crosstalk has typically been reduced by depositing dielectric antireflective coatings. However, dielectric antireflective coatings can exhibit reduced antireflective performance at high incident angles. Furthermore, in conventional semiconductor detectors that include scintillators for converting ionizing radiation into non-ionizing electromagnetic radiation, mounting the scintillator to the substrate can be challenging.

[0004] Therefore, it may be desirable to develop new solutions related to semiconductor pixel detectors. Summary of the Invention

[0005] This summary is provided to introduce a selection of concepts in a simplified form, which are further described in the following detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0006] According to a first aspect, a radiation sensor element is provided. The radiation sensor element includes: a semiconductor substrate having: a majority charge carrier of a first polarity, a majority refractive index, a front surface defining a front side of the semiconductor substrate, and a rear surface disposed opposite to the front surface and extending substantially along a reference plane.

[0007] The radiation sensor element includes a plurality of pixel portions, each of the plurality of pixel portions including a collection region on the rear surface for collecting free charge carriers of a second polarity opposite to the first polarity sign.

[0008] Each of the plurality of pixel portions includes a textured region on the front surface, the textured region including a high aspect ratio nanostructure that extends substantially along a thickness direction perpendicular to the reference plane and forms a light conversion layer having an effective refractive index that gradually changes toward the body refractive index to reduce reflection of light emitted by a scintillator and incident on the pixel portion from the front side of the semiconductor substrate.

[0009] The radiation sensor element includes an intermediate portion between two pixel portions of the plurality of pixel portions. The intermediate portion includes a central region on the front surface, the central region having a root mean square (RMS) roughness lower than the RMS roughness of a textured region of either of the two pixel portions. The radiation sensor element includes a scintillator coupled to the central region.

[0010] According to a second aspect, a method for fabricating a radiation sensor element comprising a plurality of pixel portions is provided. The method includes: providing a semiconductor substrate having: a first polarity of majority charge carriers, a first polarity of refractive index, a front surface defining a front side of the semiconductor substrate, and a rear surface disposed opposite to the front surface and extending substantially along a reference plane; for each of the plurality of pixel portions, forming a collection region on the rear surface for collecting free charge carriers of a second polarity opposite to the first polarity; and for each of the plurality of pixel portions, forming a textured region on the front surface, the textured region comprising a high aspect ratio nanostructure, the high aspect ratio nanostructure... The pixel structure extends substantially along a thickness direction perpendicular to the reference plane and forms a light conversion layer having an effective refractive index that gradually changes towards the body refractive index to reduce the reflection of light emitted by the scintillator and incident on the pixel portion from the front side of the semiconductor substrate; an intermediate portion is formed between two pixel portions of the plurality of pixel portions, the intermediate portion including an intermediate region on the front surface, the root mean square (RMS) roughness of the intermediate region being lower than the RMS roughness of the textured region of either of the two pixel portions; and the scintillator is attached to the intermediate region. Attached Figure Description

[0011] This disclosure will be better understood from the following detailed description, which is taken in conjunction with the accompanying drawings, in which:

[0012] Figure 1 An isometric view of a radiation sensor element is shown.

[0013] Figure 2 Described along Figure 1 A partial cross-sectional view of the radiation sensor element in cross-sectional plane II, and

[0014] Figure 3 The illustration shows a method for manufacturing a radiation sensor element comprising multiple pixel portions.

[0015] Unless otherwise indicated, any of the foregoing figures may be drawn out of scale, such that any element in the figures may be drawn in an inaccurate scale relative to other elements in the figures, in order to highlight particular structural aspects of the embodiments of the figures.

[0016] Furthermore, corresponding elements in the embodiments of any two of the foregoing figures may be disproportionate to each other in the two figures in order to highlight specific structural aspects of the embodiments of the two figures. Detailed Implementation

[0017] Figure 1 and Figure 2 A radiation sensor element 100 according to one embodiment is described. Specifically, Figure 2 Described along Figure 1 A partial cross-sectional view of the radiation sensor element 100 in cross-sectional plane II. Because... Figure 2 The cross-section of the radiation sensor element 100 is described. Figure 2 No restrictions Figure 1 and Figure 2 The shape of the embodiment is not limited. Figure 1 and Figure 2 The embodiments in relation to Figure 1 The cross-sectional plane II forms the shape of any portion in any direction of the angle. In other embodiments, the radiation sensor element can be coupled with... Figure 1 and Figure 2 The radiation sensor element 100 in the embodiments may be the same as, similar to or different from that in the embodiments.

[0018] In this example, "radiation" should be understood broadly to encompass, for example, electromagnetic radiation and particle radiation. Radiation can generally be classified as either ionizing or non-ionizing radiation.

[0019] In this specification, "ionizing" radiation can refer to radiation with sufficient particle or photon energy to induce ionization in a medium. For example, ionizing radiation can include radiation with particle or photon energy of at least 3.89 electron volts (eV), at least 10 eV, or at least 33 eV. On the other hand, "non-ionizing" radiation in this example can refer to radiation with insufficient particle or photon energy to induce substantial ionization in a medium. For example, non-ionizing radiation can include radiation with particle or photon energy less than 33 eV, less than 10 eV, or less than 3.89 eV.

[0020] In this specification, "radiation detector" can refer to a complete, operational radiation detector. A radiation detector typically includes at least one radiation sensor. A radiation detector may also include other components, units, and / or structures.

[0021] In this disclosure, "radiation sensor" can refer to an operable unit, module, or device configured to detect and / or measure radiation and to register, indicate, and / or respond to said radiation.

[0022] Furthermore, "radiation sensor element" can refer to an element that can be formed into a radiation sensor as described above. Optionally, the radiation sensor element can be used as an element of a radiation sensor that also includes other elements and / or structures. The radiation sensor element may include an active material, in which the physical properties of the active material are utilized to record, indicate, and / or respond to radiation incident on the active material. The radiation sensor element may correspond to an indirect conversion radiation sensor element or a direct conversion radiation sensor element.

[0023] In this disclosure, "indirect conversion radiation sensor element" can refer to a radiation sensor element comprising a scintillator for converting ionizing radiation into non-ionizing electromagnetic radiation and an active material for detecting electromagnetic radiation emitted by the scintillator.

[0024] In contrast, a "direct conversion radiation sensor element" can refer to a radiation sensor element that does not require the use of a scintillator to convert ionizing radiation into non-ionizing electromagnetic radiation in order to detect the ionizing radiation.

[0025] In this specification, "scintillator" can refer to an element comprising a material that emits light when excited by ionizing radiation, such as particle radiation. Typically, the luminescence of a scintillator can result in light emission with a large solid angle. Therefore, light from a scintillator is typically able to reach textured regions at a high angle of incidence.

[0026] exist Figure 1 and Figure 2 In one embodiment, the radiation sensor element 100 includes a semiconductor substrate 101.

[0027] In this example, "semiconductor" can refer to materials such as silicon (Si) or germanium (Ge), which have an electrical conductivity between that of conductive materials (such as metals) and that of insulating materials (such as many plastics and glass). Semiconductor materials can typically have doped energy levels, which can be tuned to achieve controlled performance tuning of the semiconductor material.

[0028] In this specification, "substrate" can mean a layer or other element or structure adapted or configured to provide a surface on which other layers or other elements or structures can be joined, bonded, mounted, arranged, deposited, laminated, and / or fabricated. Therefore, "semiconductor substrate" can mean a substrate comprising semiconductor materials (such as semiconductor wafers or dies), and / or a substrate formed of semiconductor materials.

[0029] Figure 1 and Figure 2 The semiconductor substrate 101 of the embodiment has a first polarity of majority charge carriers. Figure 1 and Figure 2 In this embodiment, the first polarity is negative. In other embodiments, the semiconductor substrate may have a majority charge carrier of the first polarity, which may be negative or positive.

[0030] Throughout this disclosure, "charge carrier" can refer to a freely moving particle or quasi-particle carrying charge within an element or a portion of an element. Typically, such an element or a portion of an element may include one or more types of charge carriers. For example, a semiconductor may include electrons and holes as charge carriers. Thus, "majority charge carrier" can refer to a type of charge carrier that is more common or more abundant in an element or a portion of an element. For example, in an n-type semiconductor, electrons may act as the majority charge carrier. Furthermore, "bulk" can refer to a larger and / or more significant portion of an element. Additionally or alternatively, bulk can refer to the interior and / or central portion of an element. Thus, "bulk majority charge carrier" can refer to the majority charge carriers in the bulk portion of an element.

[0031] Figure 1 and Figure 2 In this embodiment, the semiconductor substrate 101 may be formed of Si. In other embodiments, the semiconductor substrate may comprise any suitable one or more materials, such as Si and / or Ge.

[0032] Figure 1 and Figure 2 The semiconductor substrate 101 of the embodiment can have a bulk resistivity of at least 100 ohm-meters (Ωm) under normal temperature and pressure (NTP) conditions, which corresponds to a bulk resistivity of less than or equal to approximately 4 × 10⁻⁶. 11 per cubic centimeter (cm) -3 The majority charge carrier concentration is [missing information]. In other embodiments, the semiconductor substrate, which may or may not be formed of Si, can have any suitable majority charge carrier concentration, for example, a majority charge carrier concentration less than or equal to about 1 × 10⁻⁶. 20 cm -3 or 1×10 16 cm -3 or 1×10 12 cm -3 .

[0033] Figure 1 and Figure 2 The semiconductor substrate 101 of the embodiment has a bulk refractive index.

[0034] In this specification, the "refractive index" of a medium may refer to the ratio between the speed of light in a vacuum and the phase velocity of light in the medium. Generally, the term "refractive index" may or may not refer to the complex refractive index. Furthermore, the "body refractive index" of an element may refer to the refractive index of the body portion of the element.

[0035] In this example, "light" can refer to electromagnetic radiation of any wavelength within the relevant wavelength range. This range of relevant wavelengths may or may not overlap with or coincide with the ultraviolet portion (wavelengths from approximately 10 nanometers (nm) to approximately 400 nm), the visible portion (wavelengths from approximately 400 nm to approximately 700 nm), and / or the infrared portion (wavelengths from approximately 700 nm to approximately 1 millimeter (mm)) of the electromagnetic spectrum.

[0036] Figure 1 and Figure 2 The semiconductor substrate 101 of the embodiment has a front surface 102. The front surface 102 of the semiconductor substrate 101 defines the front side of the semiconductor substrate 101.

[0037] Throughout this disclosure, "surface" can refer to a finite portion of a plane in a general sense, which may have non-zero curvature that is potentially position-dependent, and which may be connected or disconnected, path-connected or path-disconnected, simply connected or not simply connected. Additionally or alternatively, a surface can refer to a portion of the outer boundary of a body or element. Specifically, a surface can refer to a portion of the outer boundary of a body or element that is visible from a particular viewing direction or a portion thereof.

[0038] Figure 1 and Figure 2 The semiconductor substrate 101 of the embodiment has a rear surface 103. The rear surface 103 of the semiconductor substrate 101 is arranged opposite to the front surface 102, and the rear surface extends substantially along an imaginary reference plane 104.

[0039] In this example, "reference plane" can refer to an imaginary, generalized plane that may or may not have non-zero, potentially position-dependent curvature. Therefore, a reference plane may or may not be a plane.

[0040] Figure 1 and Figure 2 The reference plane 104 in this embodiment is planar. In other embodiments, the semiconductor substrate may be flat or curved, having a front surface that extends substantially along a planar reference plane, or respectively, substantially along a curved reference plane.

[0041] exist Figure 1 and Figure 2In this embodiment, the thickness direction is defined as perpendicular to the reference plane 104. Figure 1 and Figure 2 In this configuration, the thickness direction extends vertically. In some embodiments, the reference plane is curved, and the thickness direction may be position-dependent. In other such embodiments, a single, position-independent thickness direction may be defined.

[0042] exist Figure 1 and Figure 2 In one embodiment, the radiation sensor element 100 includes a plurality of pixel portions 110.

[0043] Throughout this disclosure, "a plurality of" elements or features may refer to a group of two or more of the aforementioned elements or features, or a group of three or more of the aforementioned elements or features. Furthermore, a "portion" of a radiation sensor element may refer to a portion of the radiation sensor element that extends from a region on the front surface of the semiconductor substrate to a region on the rear surface of the semiconductor substrate. In this example, "region" may refer to a portion of the surface. Therefore, a "pixel portion" may refer to a portion of the radiation sensor element that can be used in the radiation sensor element to record, indicate, and / or respond to radiation specifically incident on the pixel portion. The individual pixel portions of a plurality of pixel portions may be adjacent to each other or may not be adjacent to each other; that is, they may or may not share a common boundary. Such a common boundary may, for example, extend within the semiconductor substrate.

[0044] exist Figure 1 and Figure 2 In this embodiment, each pixel portion of the plurality of pixel portions 110 may have the same or similar features. Therefore, Figure 1 and Figure 2 In one embodiment, each pixel portion may belong to the plurality of pixel portions 110, and the radiation sensor element 100 may include only a single plurality of pixel portions 110. In other embodiments, the radiation sensor element may include at least one (i.e., one or more, two or more, etc.) plurality of pixel portions.

[0045] Figure 1 and Figure 2 In one embodiment, multiple pixel portions 110 form a regular, rectangular two-dimensional array of pixel portions. In other embodiments, the multiple pixel portions may or may not form an array of pixel portions (e.g., a one-dimensional or two-dimensional array of pixel portions), the array of pixel portions may or may not be regular, and the pixel portions may have any suitable symmetry.

[0046] Figure 1 and Figure 2In one embodiment, each of the plurality of pixel portions 110 may have a lateral dimension of 1 mm × 1 mm parallel to the reference plane 104. In other embodiments, each of the plurality of pixel portions may have any suitable lateral shape and size; for example, in the case of substantially cubic pixel portions, the lateral dimension may range from 5 μm × 5 μm to 10 mm × 10 mm, or from 10 μm × 10 μm to 1 mm × 1 mm, or from 50 μm × 50 μm to 0.5 mm × 0.5 mm.

[0047] exist Figure 1 and Figure 2 In one embodiment, each of the plurality of pixel portions 110 includes a collection region 120 on the rear surface 103 of the semiconductor substrate 101.

[0048] In this example, a "collection region" can refer to a region that can be disposed on the rear surface of a semiconductor substrate having a first polarity of majority charge carriers, the collection region being adapted or configured to collect free charge carriers of a second polarity opposite to the first polarity. Such free charge carriers can be collected, for example, in integrated or external electronic readout circuitry. Specifically, the collection region of a pixel portion can be adapted or configured to collect free charge carriers from said pixel portion.

[0049] like Figure 2 The diagram schematically depicts two exemplary pixel portions 111 and 112, with a collection region 120 defined by a collection doped well 121. The collection region defined by the collection doped well can facilitate the separation of free charge carriers, which can improve the quantum efficiency of the radiation sensor element. In other embodiments, the collection region can be defined in any suitable manner, for example, by a collection doped well, or by an interface between the semiconductor substrate and the conductor pattern (such as a metallized pad or solder bump), or by a via in a dielectric layer on the rear surface of the semiconductor substrate.

[0050] In this disclosure, "layer" can refer to a typically sheet-like element disposed on a surface or body. Alternatively or additionally, a layer can refer to one of a series of typically sheet-like elements that are superimposed, covered, or stacked. A layer can typically include multiple sublayers of different materials or different material compositions. Some layers may be path-connected, while others may be locally path-connected and disconnected.

[0051] In this disclosure, "dielectric" material can refer to a material capable of exhibiting low electrical conductivity. Additionally or alternatively, the dielectric material can be polarized. Typically, the dielectric material can have any suitable relative permittivity, for example, a relative permittivity of at least 2, at least 3, at least 5, or at least 20. Therefore, a dielectric layer can refer to a layer comprising a dielectric material or formed of a dielectric material.

[0052] In this example, the presence of a "via" in a layer can refer to the shape of the layer such that the layer includes discontinuity. Alternatively, a via can refer to a hole in a topological (isomorphic) sense.

[0053] Figure 1 and Figure 2 In this embodiment, a doped collection well 121 is formed in a semiconductor substrate 101. Such a doped collection well can typically be formed at least in part by a dopant implantation step and / or a dopant diffusion step.

[0054] exist Figure 1 and Figure 2 In one embodiment, the radiation sensor element 100 includes a main contact region 122 on the rear surface 103 of the semiconductor substrate 101, such as... Figure 2 As shown. Typically, when electrical connections for individual pixels are not required on one or more sides of the radiation sensor element, such a body contact region on the rear surface of the semiconductor substrate can facilitate the bonding of the scintillator to the semiconductor substrate and / or enable the arrangement of multiple radiation sensor elements close together. In other embodiments, the radiation sensor element may include one or more body contact regions, which may or may not be arranged on the rear surface of the semiconductor substrate.

[0055] Throughout this specification, "body contact region" may refer to a region on the surface (e.g., the back surface) of a semiconductor substrate having a first polarity of body majority charge carriers, which body contact region is adapted or configured to collect free charge carriers of the first polarity and / or collect free charge carriers from the body portion of the semiconductor substrate.

[0056] like Figure 2 As schematically depicted, the body contact region 122 is defined by a body contact doped well 123. The body contact region defined by the collecting contact doped well can facilitate the separation of free charge carriers, which can improve the quantum efficiency of the radiation sensor element. In other embodiments, the body contact region can be defined by any suitable means, for example, by a body contact doped well, or by an interface between the semiconductor substrate and the conductor pattern (such as a metallized pad or solder bump), or by a via in a dielectric layer on the semiconductor substrate.

[0057] Although Figure 1 and Figure 2 Neither of these are specifically described, but radiation sensor elements, such as... Figure 1 and Figure 2 The radiation sensor element 100 of the embodiment may typically include one or more conductor patterns electrically connected to the collection area and / or the body contact area.

[0058] like Figure 2 The diagram illustrates two exemplary pixel portions 111 and 112, each of the plurality of pixel portions 110 including a textured region 130 on the front surface 102.

[0059] In this example, "textured region" can refer to a non-smooth, patterned, and / or nanostructured region that can be arranged on the front surface of a semiconductor substrate.

[0060] Figure 1 and Figure 2 The textured region 130 of the embodiment includes a high aspect ratio nanostructure 135.

[0061] In this disclosure, "high aspect ratio nanostructure" can refer to a nanostructure in which the height in the thickness direction is many times its lateral dimension. Such nanostructures can include, for example, cylindrical pillars, conical pillars, or narrow cones.

[0062] Figure 1 and Figure 2 The high aspect ratio nanostructure 135 in one embodiment extends substantially along the thickness direction. In other embodiments, where the reference plane is curved, the high aspect ratio nanostructure may extend substantially along a position-dependent thickness direction or along a single position-independent thickness direction.

[0063] like Figure 2 The diagram illustrates two exemplary pixel portions 111 and 112. Figure 1 and Figure 2 In this embodiment, a high aspect ratio nanostructure 135 forms a light conversion layer 136. The light conversion layer 136 has a refractive index n that is oriented towards the host. B Gradually changing effective refractive index This reduces the reflection of light incident from the front side of the semiconductor substrate 101 onto the individual pixel portions 110. Typically, this high aspect ratio nanostructure can reduce optical crosstalk between individual pixels of a radiation sensor element, particularly when a scintillator is arranged on the front side of at least one pixel portion of the radiation sensor element. This reduction in optical crosstalk can be caused by a reduction in reflection within the radiation sensor element (e.g., between the scintillator and the semiconductor substrate).

[0064] Throughout this specification, "light conversion layer" may refer to a layer that is not definitively defined based on a continuous material interface (such as a transverse interface), having a refractive index n from the ambient environment. i refractive index n of the main body B Gradually changing effective refractive index n eff This is to reduce the reflection of light incident on the radiation sensor element from the front side. For example, in a radiation sensor element designed for use exposed to ambient air with a refractive index of approximately 1, the effective refractive index can be reduced from the approximately 1 refractive index to the main refractive index n. B Gradually changing.

[0065] In this example, "effective refractive index" is a supplementary definition regarding the interaction of light with the nanostructured layer. Subwavelength characteristics, or characteristics substantially within the relevant wavelength range, can cause light to behave differently in such a nanostructured layer than it would in a corresponding layer of the same material without such characteristics. This different behavior can be described by the supplementary term "effective refractive index"; light behaves in and interacts with this nanostructured layer as if the layer were made of a gradually varying host material whose refractive index at each stage of the transition layer is equal to the effective refractive index n at that stage. eff .

[0066] Figure 1 and Figure 2 In one embodiment, the high aspect ratio nanostructure 135 is irregularly arranged. This irregular arrangement of the high aspect ratio nanostructure can reduce the reflectivity of the textured regions. In other embodiments, the high aspect ratio nanostructure can be arranged in any suitable manner, for example, irregularly or regularly.

[0067] exist Figure 2 The text describes two effective refractive indices used for the two optical conversion layers 136. This indicates They can be independent of each other. Therefore, at any given level of the optical conversion layer 136, They can have the same, similar, or different values. In other embodiments, any two effective refractive indices of any two light conversion layers can be independent of each other or not independent of each other.

[0068] Figure 1 and Figure 2 In this embodiment, the high aspect ratio nanostructure 135 is continuous and integral with the semiconductor substrate 101. Furthermore, the high aspect ratio nanostructure 135 is formed of the same material as the semiconductor substrate 101. Figure 1 and Figure 2In some embodiments, this common material may be Si. Generally, high aspect ratio nanostructures formed from a material common to the semiconductor substrate and / or continuously formed with and / or integrally formed with the semiconductor substrate typically exhibit lower recombination losses. In other embodiments, the high aspect ratio nanostructure may or may not be formed from a material common to the semiconductor substrate and / or continuously formed with and / or integrally formed with the semiconductor substrate. In these other embodiments, this common material may be any suitable material, such as Si or Ge.

[0069] Figure 1 and Figure 2 The high aspect ratio nanostructure 135 in one embodiment may be a black silicon (b-Si) spike. In other embodiments, the high aspect ratio nanostructure may be a b-Si spike or any other nanostructure suitable for forming a light conversion layer having an effective refractive index that gradually changes towards the host refractive index.

[0070] In this example, "black silicon" can refer to a type of nanoscale surface formation on silicon, which produces a light conversion layer with a gradually varying effective refractive index. The b-Si surface can include multiple needle-like and / or spike-like surface formations. Each of these multiple surface formations can have different sizes and / or be arranged irregularly.

[0071] Figure 1 and Figure 2 The high aspect ratio nanostructure 135 of the embodiment can have an average height in the thickness direction ranging from 500 nm to 1500 nm. In other embodiments, the high aspect ratio nanostructure can have any suitable average height in the thickness direction, for example, an average thickness in the range of 500 nm to 1500 nm, or in the range of about 600 nm to 1200 nm, or in the range of 800 nm to 1000 nm.

[0072] Figure 1 and Figure 2 The high aspect ratio nanostructure 135 of the embodiment has an average width in the lateral direction parallel to the reference plane 104 that can be in the range of 50 nm to 500 nm. In other embodiments, the high aspect ratio nanostructure can have any suitable average width in the thickness direction, for example, an average width in the range of 50 nm to 500 nm, or in the range of about 100 nm to 400 nm, or in the range of 200 nm to 300 nm.

[0073] like Figure 2 The diagram illustrates two exemplary pixel portions 111 and 112. Figure 1 and Figure 2The radiation sensor element 100 of one embodiment includes a dielectric material 150 conformally coated with a high aspect ratio nanostructure 135. This dielectric material typically reduces recombination losses in the radiation sensor element. In other embodiments, the radiation sensor element may or may not include this dielectric material.

[0074] In this example, "conformally coated" high aspect ratio nanostructures can refer to the material forming a shape with a substantially uniform coating thickness along the high aspect ratio nanostructure. In this example, "substantially uniform coating thickness" can refer to a relative standard deviation of the coating thickness of less than 50%, or less than 25%, or less than 15%, and / or a standard deviation of the thickness of less than 20 nm, or less than 10 nm, or less than 5 nm. Typically, the coating thickness of the material conformally coated with the high aspect ratio nanostructure can be measured along the surface normal of the high aspect ratio nanostructure. This coating thickness can, for example, be in the range of about 1 nm to 100 nm, or about 2 nm to 50 nm, or about 3 nm to 30 nm, or about 5 nm to about 20 nm.

[0075] Figure 1 and Figure 2 The dielectric material 150 of the embodiment is formed from Figure 2 The first pixel portion 111 described extends continuously to Figure 2 The second pixel portion 112 described is a layer. In other embodiments, the dielectric material may be formed as one or more sheets (e.g., layers).

[0076] The dielectric material 150 in this embodiment can have a net charge of a second polarity. Figure 1 and Figure 2 In one embodiment, the second polarity is positive. This net charge of the second polarity typically repels free charge carriers of the second polarity to a collection region on the back surface of the semiconductor substrate. This can reduce recombination losses in the radiation sensor element. In other embodiments, the radiation sensor element may include a dielectric material on a high aspect ratio nanostructure, which may or may not have a net charge, which may or may not be a second polarity. In other embodiments, the radiation sensor element includes a dielectric material with a second polarity net charge on a high aspect ratio nanostructure, and each of the plurality of pixel portions may or may not include a front substrate layer extending along the front surface of the semiconductor substrate and having a majority charge carrier of the first polarity. Typically, a front substrate layer with a majority charge carrier of the first polarity can exhibit reduced Auger recombination, which can increase the sensitivity of the radiation sensor element, particularly at shorter wavelengths.

[0077] Figure 1 and Figure 2 The dielectric material 150 of the embodiments may include, for example, one or more positively charged silicon oxides (such as non-stoichiometric silicon oxide (SiO2)). x In other embodiments, any suitable one or more dielectric materials, such as SiO2, can be used. x Or one or more negatively charged aluminum oxides (e.g., non-stoichiometric aluminum oxide (AlO)). x )).

[0078] exist Figure 1 and Figure 2 In some embodiments, the radiation sensor element 100 may include a scintillator 170. For example... Figure 1 As shown by dashed lines, this scintillator 170 can be disposed on, for example, the front side of a semiconductor substrate 101. Typically, a scintillator converts ionizing radiation into non-ionizing electromagnetic radiation that can be detected using a radiation sensor element having a semiconductor substrate that interacts weakly with high-energy radiation. In other embodiments, the radiation sensor element may or may not include such a scintillator. In one embodiment, the radiation sensor element includes a scintillator on the front side of the semiconductor substrate, which may be directly or indirectly, or indirectly or not directly or indirectly, coupled to the semiconductor substrate.

[0079] exist Figure 1 and Figure 2 In one embodiment, the radiation sensor element 100 includes a plurality of intermediate portions 140 between the respective pixel portions of a plurality of pixel portions 110. Figure 1 In the image, a middle section 140 is highlighted using a dashed line. Figure 2 The text describes a distinct intermediate portion 140 disposed between two exemplary pixel portions 111, 112. In other embodiments, the radiation sensor element may or may not include at least one intermediate portion disposed between the respective pixel portions of the plurality of pixel portions. In one embodiment, the respective pixel portions of the plurality of pixel portions are adjacent to each other such that the textured regions of the respective pixel portions form a continuous region on the front surface of the semiconductor substrate.

[0080] Throughout this disclosure, "intermediate portion" can refer to a part of a radiation sensor element, which may be disposed between a first pixel portion and a second pixel portion of a plurality of pixel portions. The intermediate portion may extend from the front surface of the semiconductor substrate to the rear surface of the semiconductor substrate, or it may not extend from the front surface of the semiconductor substrate to the rear surface of the semiconductor substrate.

[0081] Although Figure 1The highlighted middle portion 140 is arranged between the pixel portions of a row or column of pixel portions, but the middle portion can generally exist between any two pixel portions of multiple pixel portions, such as between two pixel portions of a row or column of pixel portions and / or between two pixel portions arranged diagonally opposite each other.

[0082] The following provides a detailed description of two exemplary pixel portions 111 and 112. While the discussion below primarily concerns the two exemplary pixel portions 111 and 112 and the intermediate portion 140 between them, any features disclosed below may or may not be applicable. Figure 1 and Figure 2 Any two pixel portions and / or the intermediate portion 140 between the multiple pixel portions 110 in the embodiment.

[0083] Figure 2 The intermediate portion 140 described herein includes an intermediate region 141 on the front surface 102 of the semiconductor substrate 101. In other embodiments, the intermediate portion between any two pixel portions of a plurality of pixel portions may or may not include such an intermediate region. In one embodiment, the radiation sensor element includes a scintillator disposed on the front side of the radiation sensor element, the scintillator being coupled to the intermediate region of the intermediate portion. In the embodiment described herein, the coupling may be direct or indirect. Therefore, the coupling may be implemented by any suitable means, for example, at least in part by a bonding process, which may or may not include an underfill step.

[0084] In this example, the "intermediate region" may refer to a region on the front surface of the semiconductor substrate. Alternatively, the intermediate region may be arranged laterally between two pixel portions of a plurality of pixel portions.

[0085] Figure 2The intermediate region 141 described herein has a root mean square (RMS) roughness lower than the RMS roughness of the textured region 130 of the two exemplary pixel portions 111, 112. This lower RMS roughness may result in higher reflectivity of light incident on the intermediate portion from the front side of the radiation sensor element over a wide spectral range. This can reduce the generation of free charge carriers in and / or near the intermediate portion. The reduction in generated free charge carriers can reduce crosstalk between individual pixels of the radiation sensor element, especially in the absence of a scintillator. In other embodiments, the radiation sensor element may include or may not include at least one intermediate portion between any two of the plurality of pixel portions, the intermediate portion comprising an intermediate region on the front surface having an RMS roughness lower than the RMS roughness of the textured region of either of the two pixel portions.

[0086] In this disclosure, "roughness" can refer to surface roughness with a high spatial frequency. Specifically, "root mean square roughness" can refer to mean square roughness, which can be measured on the surface and / or the cross-sectional profile of the surface. Such a measurement can be performed according to at least one of the standards ISO 4287:1997 and ISO 25178. In such a measurement, any suitable method or method can be used, such as atomic force microscopy (AFM), scanning electron microscopy (SEM), scanning tunneling microscopy (STM), and / or profilometry. In the case of textured regions, such a measurement can be performed on the macroscopic portion of said textured region.

[0087] In this specification, "macro portion" may refer to at least a portion of a region that is large enough to be visible to the naked eye. Alternatively or additionally, the macro portion of a textured region may include or extend across at least 100 textured units, or at least 400 textured units, or at least 900 textured units, such as a high aspect ratio nanostructure.

[0088] Figure 2The RMS roughness of the intermediate region 141 described herein can be less than or equal to 0.2 times the RMS roughness of the textured region of either of the two pixel portions 111, 112. Therefore, the RMS roughness of the intermediate region 141 can be higher than or equal to five times the RMS roughness of the textured region 130 of the first pixel portion 111, and higher than or equal to five times the RMS roughness of the textured region 130 of the second pixel portion 112. Typically, a higher difference in RMS roughness can result in lower crosstalk between the individual pixels of the radiation sensor element. In other embodiments, any suitable ratio can be used between the RMS roughness of the two textured regions and the RMS roughness of the intermediate region disposed between the two textured regions. For example, the RMS roughness of the intermediate region between the two pixel portions can be less than or equal to 0.2 times, 0.1 times, 0.05 times, or 0.01 times the RMS roughness of the textured region of either of the two pixel portions.

[0089] Figure 2 The intermediate region 141 described herein extends substantially parallel to the reference plane 104. An intermediate region extending substantially parallel to the reference plane can typically facilitate the bonding of a scintillator to a semiconductor substrate. In other embodiments, the intermediate region may extend substantially parallel to the reference plane or may not extend substantially parallel to the reference plane.

[0090] Figure 2 The textured regions 130 of the two pixel portions 111 and 112 described herein have a maximum distance to the reference plane 104. In addition, Figure 2 The intermediate region 141 described herein has a minimum distance to the reference plane 104. minimum distance Greater than Such This can typically facilitate further bonding of the scintillator to the semiconductor substrate. This is likely due to the reduced risk of breakage of the high aspect ratio nanostructure during the bonding process, as direct contact between the high aspect ratio nanostructure and the scintillator can be avoided. In other embodiments, for any intermediate portion between any two pixel portions of a plurality of pixel portions, It can be greater than or not greater than

[0091] Reference Figure 2The radiation sensor element 100 includes a metal coating 160. The metal coating 160 is disposed on the front side of the semiconductor substrate 101 such that its projection onto a reference plane 104 intersects with the projection of the intermediate region 141 onto the reference plane 104. This metal coating can increase the reflectivity of the radiation sensor element for light incident on the intermediate portion over a broad spectral range, which can reduce the generation of free charge carriers in and / or near the intermediate portion. This reduction in generated free charge carriers can reduce crosstalk between individual pixels of the radiation sensor element, particularly in the absence of a scintillator. In other embodiments, the radiation sensor element may or may not include this metal coating.

[0092] In this example, "coating" can refer to an element extending on a surface or a portion of a surface, such as a layer. Specifically, a coating on the "front side" of a region may be directly or indirectly attached to said region, or may not be directly or indirectly attached to said region. Furthermore, "metallic coating" can refer to a coating comprising or formed of a metallic material.

[0093] It should be understood that any of the foregoing embodiments of the first aspect can be used in combination with each other. In other words, multiple embodiments can be combined to form another embodiment of the first aspect.

[0094] The above discussion primarily focused on the structure and materials of radiation sensor elements. The following section will emphasize aspects related to the methods used to manufacture radiation sensor elements comprising multiple pixel portions. The implementations, definitions, details, and advantages related to structure and materials described above are adapted, with appropriate modifications, to the methods discussed below, and vice versa.

[0095] Specifically, it should be understood that the method according to the second aspect can be used to provide a radiation sensor element according to any embodiment described in relation to the first aspect. Accordingly, the method according to the second aspect can be used to manufacture any radiation sensor element according to any embodiment of the first aspect.

[0096] Figure 3 A method 300 for manufacturing a radiation sensor element comprising multiple pixel portions is illustrated. In other embodiments, this method may include, respectively, [the following steps are not specified in the original text]. Figure 3 The processes and / or steps of the embodiments are similar to or substantially different from those of the embodiments.

[0097] In this specification, "process" can refer to a series of one or more steps that lead to a final result. Alternatively, "step" can refer to a measure taken to achieve one or more predefined final results. Typically, a process can be a single-step process or a multi-step process. Furthermore, a process can be divided into multiple subprocesses, wherein the subprocesses may or may not share common steps.

[0098] exist Figure 3 In one embodiment, method 300 includes: in process 301, providing a semiconductor substrate. The semiconductor substrate has a first polarity of majority charge carriers, which may be negative or positive. The semiconductor substrate also has a main refractive index and a front surface that defines a front side of the semiconductor substrate. The semiconductor substrate also has a rear surface that is arranged opposite to the front surface and extends substantially along a reference plane.

[0099] Figure 3 Method 300 of an embodiment includes, in process 302, forming a collection region on a rear surface for each of a plurality of pixel portions. These collection regions are adapted to collect free charge carriers of a second polarity opposite to a first polarity. In some embodiments, the process of forming the collection regions may include, for example, an ion implantation step.

[0100] exist Figure 3 In one embodiment, method 300 includes, in process 303, forming a textured region on the front surface for each of a plurality of pixel portions. Each textured region includes a high aspect ratio nanostructure extending substantially along a thickness direction perpendicular to a reference plane and forming a light conversion layer having an effective refractive index that gradually changes towards the bulk refractive index of the semiconductor substrate. This reduces the reflection of light incident from the front side of the semiconductor substrate onto the pixel portion.

[0101] exist Figure 3In some embodiments, the process 303 for forming the textured region may include, for example, a metal-assisted chemical etching (MACE) step; an atmospheric dry etching (ADE) step; and / or a reactive ion etching (RIE) step, such as a deep reactive ion etching (DRIE) step. Typically, such etching steps can help form textured regions with low defect density and well-defined nanoscale features. In other embodiments, the process for forming the textured region may include any suitable one or more steps, such as a MACE step, an ADE step, and / or a RIE step (such as a DRIE step).

[0102] exist Figure 3 In one embodiment, method 300 includes, in an optional process 304, forming an intermediate portion between two pixel portions of a plurality of pixel portions. The intermediate portion includes an intermediate region on the front surface of a semiconductor substrate, the intermediate region having an RMS roughness lower than the RMS roughness of a textured region of either of the two pixel portions. In other embodiments, methods for manufacturing a radiation sensor element comprising a plurality of pixel portions may or may not include this process of forming an intermediate portion.

[0103] As shown in the order of the boxes representing processes 302, 303, and 304, the steps implementing processes 302, 303, and 304 can generally be performed in a variety of alternative orders. Furthermore, a step can typically function in multiple processes within processes 302, 303, and 304. For example, an etching step, such as a MACE step, an ADE step, and / or a RIE step (such as a DIRE step), can function in the process of forming the textured region as well as in the process of forming the intermediate portion. This can occur, for example, if a semiconductor substrate with a pre-polished surface is provided, and the etching of the semiconductor substrate in the etching step is performed locally, for example, using an etching mask.

[0104] exist Figure 3 In one embodiment, method 300 includes, in an optional process 305, attaching a scintillator to an intermediate region. This process typically includes, for example, an adhesive bonding step. In other embodiments, methods for manufacturing a radiation sensor element comprising multiple pixel portions may or may not include the process of attaching the scintillator.

[0105] In one embodiment, a method for manufacturing a radiation sensor element comprising multiple pixel portions includes, with Figure 3The processes corresponding to processes 301, 302, and 303 of method 300 in the embodiments. In other embodiments, the method for manufacturing a radiation sensor element comprising a plurality of pixel portions may include processes corresponding to... Figure 3 The process corresponding to processes 301, 302 and 303 of the method 300 of the embodiment, and the process corresponding to at least one of processes 304 and 305.

[0106] Typically, the steps of a method for manufacturing a radiation sensor element comprising multiple pixel portions can be performed in a plurality of alternative sequences, wherein these steps implement the... Figure 3 The process corresponds to any one of processes 301, 302, 303, 304, and 305 in the method 300 of the embodiment. Additionally, the method for manufacturing a radiation sensor element comprising multiple pixel portions can typically include any number of additional processes or steps, which are related to... Figure 3 Additional processes or steps related to the method 300 of the embodiment are not disclosed in this example.

[0107] For example, in one embodiment, a method for fabricating a radiation sensor element comprising a plurality of pixel portions includes: depositing a dielectric material onto a high aspect ratio nanostructure, the dielectric material being conformally coated onto the high aspect ratio nanostructure.

[0108] In another embodiment, which may be based on the foregoing embodiments, a method for manufacturing a radiation sensor element comprising a plurality of pixel portions includes forming a metal coating on the front side of a central region. In this embodiment, the process of forming the metal coating may include, for example, an evaporation step or a sputtering step.

[0109] It will be apparent to those skilled in the art that the basic idea of ​​this invention can be implemented in various ways as technology advances. Therefore, this invention and its embodiments are not limited to the examples described above; rather, they can be varied within the scope of the claims.

[0110] It will be understood that any of the benefits and advantages described above may be associated with one embodiment or with multiple embodiments. The embodiments are not limited to any or all of those embodiments that solve the described problems or that have any or all of the described benefits and advantages.

[0111] The term "comprising" is used in this specification to mean including one or more features or actions that follow it, without excluding the presence of one or more additional features or actions. It will also be understood that "a" refers to one or more of these items.

[0112] Figure Labels

[0113] 100 Radiation Sensor Element

[0114] 101 Semiconductor Substrate

[0115] 102 Front Surface

[0116] 103 rear surface

[0117] 104 reference surface

[0118] More than 110 pixels

[0119] 111 pixel portion

[0120] 112 pixel portion

[0121] 120 Collection Area

[0122] 121 Collecting Doped Wells

[0123] 122 Main contact area

[0124] 123 Body Contact Doped Well

[0125] 130 textured regions

[0126] 135 high aspect ratio nanostructure

[0127] 136 Light Conversion Layer

[0128] 140 Middle section

[0129] 141 Middle Area

[0130] 150 Dielectric Material

[0131] 160 Metallic Coating

[0132] 170 Scintillator

[0133] 300 methods

[0134] 301 provides semiconductor substrates

[0135] 302 Formation of collection area

[0136] 303 forms textured regions

[0137] 304 forms the middle part

[0138] 305 Connection blinking

Claims

1. A radiation sensor element (100), the radiation sensor element comprising: A semiconductor substrate (101) having: a majority of charge carriers of a first polarity, a bulk refractive index, a front surface (102) defining a front side of the semiconductor substrate (101), and a back surface (103) arranged opposite the front surface (102) and extending along a reference plane (104); The radiation sensor element (100) comprises: a plurality of pixel portions (110), each pixel portion (111, 112) of the plurality of pixel portions (110) comprising a collection area (120) on the back surface (103) for collecting free charge carriers of a second polarity opposite the sign of the first polarity; wherein each pixel portion (111, 112) of the plurality of pixel portions (110) comprises a textured area (130) on the front surface (102), the textured area (130) comprising high-aspect-ratio nanostructures (135) extending along a thickness direction perpendicular to the reference plane (104) and forming a light conversion layer (136) having an effective refractive index gradually varying towards the bulk refractive index to reduce reflection of light emitted by a scintillator (170) and incident on the pixel portion from the front side of the semiconductor substrate (101); The radiation sensor element (100) comprises: an intermediate portion (140) between two pixel portions (111, 112) of the plurality of pixel portions (110), the intermediate portion (140) comprising an intermediate area (141) on the front surface (102), the intermediate area having a root mean square roughness lower than a root mean square roughness of the textured area (130) of any of the two pixel portions (111, 112); and The radiation sensor element (100) comprises: the scintillator (170) coupled to the intermediate area (141).

2. The radiation sensor element (100) according to claim 1, wherein The root mean square roughness of the intermediate area (141) is less than or equal to 0.2 times, or 0.1 times, or 0.05 times, or 0.01 times the root mean square roughness of the textured area (130) of any of the two pixel portions (111, 112).

3. The radiation sensor element (100) according to claim 1, wherein The intermediate area (141) extends parallel to the reference plane (104).

4. The radiation sensor element (100) according to claim 1, wherein The textured area (130) of the two pixel portions (111, 112) has a maximum distance to the reference plane (104) and the intermediate area (141) has a minimum distance to the reference plane (104) , the minimum distance is greater than the maximum distance .

5. The radiation sensor element (100) according to claim 1, wherein The radiation sensor element (100) comprises: a metal coating (160) on the front side of the semiconductor substrate (101), a projection of the metal coating (160) on the reference plane (104) intersecting a projection of the intermediate area (141) on the reference plane (104).

6. The radiation sensor element (100) according to claim 1, wherein The semiconductor substrate (101) and the high-aspect-ratio nanostructures (135) are formed of silicon.

7. The radiation sensor element (100) according to claim 1, wherein The radiation sensor element (100) comprises: a dielectric material (150) conformally coating the high-aspect-ratio nanostructures (135).

8. The radiation sensor element (100) according to claim 7, wherein The dielectric material (150) has a net charge of the second polarity.

9. The radiation sensor element (100) according to any one of claims 1 to 8, wherein The collection region (120) is defined by a collection doped well (121) of majority charge carriers of a second polarity.

10. The radiation sensor element (100) according to any one of claims 1 to 8, wherein The radiation sensor element (100) comprises: the scintillator (170) arranged on a front side of the semiconductor substrate (101).

11. A method (300) for manufacturing a radiation sensor element comprising a plurality of pixel portions, the method (300) comprising: - providing a semiconductor substrate (301) having: majority body charge carriers of a first polarity, a body refractive index, a front surface defining a front side of the semiconductor substrate, and a back surface arranged opposite to the front surface and extending along a reference plane; - for each pixel portion of the plurality of pixel portions, forming a collection region (302) on the back surface for collecting free charge carriers of a second polarity opposite to the first polarity sign; - for each pixel portion of the plurality of pixel portions, forming a textured region (303) on the front surface, the textured region comprising high aspect ratio nanostructures extending along a thickness direction perpendicular to the reference plane and forming a light conversion layer having an effective refractive index gradually varying towards the body refractive index to reduce reflection of light emitted by a scintillator and incident on the pixel portion from the front side of the semiconductor substrate; - forming an intermediate portion (304) between two pixel portions of the plurality of pixel portions, the intermediate portion comprising an intermediate region on the front surface, the intermediate region having a root mean square roughness lower than a root mean square roughness of the textured region of any of the two pixel portions; and - coupling the scintillator (305) onto the intermediate region.

12. The method (300) of claim 11, wherein, The process of forming the textured region (303) comprises: a metal-assisted chemical etching step; an atmospheric dry etching step; and / or a reactive ion etching step.

13. The method (300) of claim 11, wherein, The radiation sensor element is the radiation sensor element (100) according to any one of claims 1 to 10.

14. The method (300) of claim 12, wherein, The radiation sensor element is the radiation sensor element (100) according to any one of claims 1 to 10.

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