An active pixel sensor and a processing method

Abstract

An embodiment of the present disclosure discloses an active pixel sensor and a processing method. The active pixel sensor includes: a pixel device layer having a plurality of pixel regions; a collimation frame having support columns and a collimation portion, wherein a plurality of the support columns are discretely distributed, and the collimation frame is disposed on the pixel device layer through the support columns; the collimation portion has a boundary wall and an inner wall, the boundary wall encloses a plurality of collimation channels, each of the collimation channels corresponds to a position of each of the pixel regions one by one, the inner wall is disposed in the collimation channels surrounded by the boundary wall, and a radial dimension of the collimation channels matches a dimension of the pixel regions; the collimation portion is configured to guide electrons to fall on corresponding pixel regions.

Description

Technical Field

[0001] The present invention relates to the field of optical devices, and more particularly, to an active pixel sensor and a processing method thereof. Background Art

[0002] An electron bombardment type active pixel sensor is a high-performance low-light imaging device, which adopts a light-photoelectron-electron multiplication mode. When the substrate of the active pixel sensor is thinned and the photoelectrons emitted by the photocathode bombard the back surface of the substrate under the action of an accelerating electric field, the incident photoelectron energy dissipates to generate electron-hole pairs, obtaining electron bombardment semiconductor gain.

[0003] The electrons emitted by the photocathode have a transverse initial velocity and do not vertically aim at the predetermined pixel area for emission. Therefore, it is possible to bombard other non-predetermined pixel positions, causing crosstalk; in addition, the emitted electrons are accelerated by the electric field to become high-energy electrons, which are used to impact, for example, the anode of an image sensor, generating backscattered electrons or secondary electrons. These electrons may jump into adjacent non-predetermined pixel positions, causing secondary bombardment of the anode of other non-predetermined pixel positions, thereby forming a crosstalk problem.

[0004] Therefore, a new technical solution is needed to solve the above technical problems. Summary of the Invention

[0005] An object of the present invention is to provide a new technical solution for an active pixel sensor.

[0006] According to a first aspect of the present invention, an active pixel sensor is provided. The active pixel sensor includes: a pixel device layer having a plurality of pixel regions; a collimation frame having support columns and a collimation portion, wherein a plurality of the support columns are discretely distributed, and the collimation frame is disposed on the pixel device layer through the support columns; the collimation portion has a boundary wall and an inner wall, the boundary wall encloses a plurality of collimation channels, each of the collimation channels corresponds to a position of each of the pixel regions one by one, the inner wall is disposed in the collimation channels surrounded by the boundary wall, and a radial dimension of the collimation channels matches a dimension of the pixel regions; the collimation portion is configured to guide electrons to fall on corresponding pixel regions.

[0007] Optionally, the pixel device layer includes a base frame disposed on the pixel regions, the base frame having a base wall, and the base wall encloses a plurality of base channels, each of the base channels corresponds to a position of each of the pixel regions one by one.

[0008] Optionally, one end of the support column is fixedly connected to the base frame, the other end of the support column is fixedly connected to the collimation part, and the end face of the other end of the support column is flush with the end face of the collimation part away from the base frame.

[0009] Optionally, the inner wall includes a first inner wall and a second inner wall, the first inner wall and the second inner wall are arranged at intervals, and the first inner wall is closer to the boundary wall than the second inner wall.

[0010] Optionally, the distance between the first inner wall and the boundary wall is less than the distance between the first inner wall and the second inner wall.

[0011] Optionally, the first inner wall and the second inner wall are annularly distributed around the center of the collimation channel, and the first inner wall surrounds the second inner wall;

[0012] The radial dimension of the second inner wall is greater than the distance between the first inner wall and the second inner wall;

[0013] The distance between the first inner wall and the second inner wall is greater than the distance between the first inner wall and the boundary wall.

[0014] Optionally, the collimation part further has a connecting wall, and the connecting wall is configured to connect and fix the inner wall to the boundary wall.

[0015] Optionally, in the collimation channel, the connecting wall and the inner wall and / or the boundary wall jointly enclose a plurality of sub-channels.

[0016] Optionally, the connecting wall and the boundary wall and the first inner wall enclose a plurality of first sub-channels;

[0017] The connecting wall and the first inner wall and the second inner wall enclose a plurality of second sub-channels;

[0018] The radial dimension of the second sub-channel is greater than the radial dimension of the first sub-channel.

[0019] Optionally, the second inner wall itself is annularly distributed, surrounding and forming a third sub-channel, and the radial dimension of the third sub-channel is greater than the radial dimension of the second sub-channel.

[0020] Optionally, the ratio of the height of the collimation frame to the radial dimension of the pixel region ranges from 1.5 to 3.5.

[0021] Optionally, the ratio of the height of the collimation frame to the radial dimension of the pixel region is 2.

[0022] Optionally, the ratio of the height of the base frame to the radial dimension of the pixel region ranges from 0.2 to 1.0.

[0023] Optionally, the ratio of the height of the base frame to the radial dimension of the pixel region is 0.5.

[0024] According to another aspect of the present invention, there is provided a method for manufacturing an active pixel sensor. The method includes: providing a pixel device layer having a plurality of pixel regions; depositing a substrate layer on the pixel device layer, etching the substrate layer to form a base frame on the pixel device layer; depositing a sacrificial layer around the base frame, performing a first etching from the top surface of the sacrificial layer, the depth of the hole formed by the first etching being the depth from the top surface of the sacrificial layer to the pixel device layer, depositing a collimation layer material in the hole to form a support pillar; performing a second etching from the top surface of the sacrificial layer, the depth of the hole formed by the second etching being less than the depth from the top surface of the sacrificial layer to the pixel device layer, depositing a collimation layer material in the hole to form a collimation portion; and releasing the sacrificial layer.

[0025] Optionally, when etching the substrate layer, a strip-shaped mask is provided at the edge corresponding to the pixel region, and the substrate layer is etched to form the base frame;

[0026] When performing the first etching on the sacrificial layer, a strip-shaped mask is provided at the position corresponding to the support pillar, and the thickness of the strip-shaped mask is the same as the thickness of the support pillar;

[0027] When performing the second etching on the sacrificial layer, at the position corresponding to the inside of the pixel region, a cross-distributed strip-shaped mask is provided on the sacrificial layer, and the cross-distributed collimation portion is etched and formed.

[0028] In the embodiments of the present disclosure, the collimation frame is disposed on the pixel device layer through the support pillar. On the premise of effectively collimating the electrons emitted by the photocathode, the double walls avoid excessive contact between the walls and the pixel device layer, reduce signal loss, and ultimately achieve the purpose of improving image quality.

[0029] Other features and advantages of the present invention will become clear from the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0030] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0031] Figure 1 is a cross-sectional view of an active pixel sensor according to an embodiment of the present disclosure.

[0032] Figure 2 is a top view of a collimation frame according to an embodiment of the present disclosure.

[0033] Figure 3It is a schematic diagram of the primary bombardment of electrons emitted by a photocathode according to an embodiment of the present disclosure.

[0034] Figure 4 It is a schematic diagram of the secondary bombardment of electron reflection according to an embodiment of the present disclosure.

[0035] Figures 5 - 11 It is a schematic diagram of a processing method of an active pixel sensor according to an embodiment of the present disclosure.

[0036] Description of reference numerals:

[0037] 1. Pixel device layer; 11. Pixel area; 21. Support pillar; 22. Collimating part; 221. Boundary wall; 2211. Collimating channel; 222. Inner wall; 2221. First inner wall; 2222. Second inner wall; 223. Connecting wall; 2231. First sub-channel; 2232. Second sub-channel; 2233. Third sub-channel; 3. Photocathode; 301. First emitted electron; 302. Second emitted electron; 303. First scattered electron; 304. Second scattered electron; 4. Substrate frame; 41. Substrate wall; 411. Substrate channel; 5. Sacrificial layer; 6. Substrate layer. Detailed implementation manners

[0038] Now, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that: Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0039] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present invention, its application, or its use.

[0040] Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be regarded as part of the specification.

[0041] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0042] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0043] According to an embodiment of the present disclosure, an active pixel sensor is provided. As Figure 1 shown, the active pixel sensor includes: a pixel device layer 1 and a collimating frame.

[0044] The pixel device layer 1 has a plurality of pixel regions 11. The collimation frame has support columns 21 and a collimation portion 22. A plurality of support columns 21 are discretely distributed. The collimation frame is disposed on the pixel device layer 1 through the support columns 21.

[0045] The collimation portion 22 has a boundary wall 221 and an inner wall 222. The boundary wall 221 encloses a plurality of collimation channels 2211. Each collimation channel 2211 corresponds to the position of each pixel region 11 one by one. The inner wall 222 is disposed within the collimation channels 2211 surrounded by the boundary wall 221. The radial dimension of the collimation channels 2211 matches the dimension of the pixel regions 11.

[0046] The collimation portion 22 is configured to direct electrons to fall on the corresponding pixel regions.

[0047] The pixel device layer 1 may have a plurality of pixel regions 11. Each pixel region 11 is used to receive corresponding electrons emitted from the photocathode 3. A collimation frame is disposed on the pixel device layer 1. The collimation frame is used to collimate the electrons emitted from the photocathode 3, intercept electrons with too large a lateral velocity or a deviated movement trajectory, so that the emitted electrons accurately bombard the predetermined pixel regions 11, and prevent the emitted electrons from entering other pixel regions 11 to cause crosstalk phenomena and affect the image quality.

[0048] For example, as Figures 3 - 4 shown, the working principle of the collimation frame of this embodiment is described in detail:

[0049] As Figure 3 shown, due to the action of the accelerating electric field, the first emitted electrons 301 and the second emitted electrons 302 emitted from the photocathode 3 generally move vertically downward in an accelerated manner. However, due to the initial lateral velocity at the time of emission, the positions where they reach the corresponding pixel regions 11 on the pixel device layer 1 have a certain lateral offset relative to the positions where the photocathode 3 emits. Therefore, the first emitted electrons 301 and the second emitted electrons 302 may fall into other pixel regions 11, causing crosstalk phenomena.

[0050] In the embodiment of the present disclosure, a collimation frame is disposed above the pixel device layer 1, and the collimation frame has an inner wall 222. The first emitted electrons 301 and the second emitted electrons 302 with a relatively large initial lateral velocity during emission will hit the inner wall 222 or the boundary wall 221, which can prevent the electrons emitted from the photocathode 3 from entering other pixel regions 11, and thus also avoid the generation of crosstalk problems.

[0051] As Figure 4As shown, after the first emitted electron 301 and the second emitted electron 302 bombard the predetermined pixel area 11, there may be some backscattered electrons or secondary electrons generated due to reflection or other situations, such as the first scattered electron 303 and the second scattered electron 304. After the first scattered electron 303 and the second scattered electron 304 move a certain distance towards the photocathode 3, they are secondarily bombarded on the pixel device layer 1 under the action of the electric field. The first scattered electron 303 and the second scattered electron 304 in the predetermined pixel area 11 may also jump into other pixel areas 11 during the secondary bombardment process.

[0052] In the embodiment of the present disclosure, a collimation frame is provided above the pixel device layer 1, and the collimation frame can prevent the first scattered electron 303 and the second scattered electron 304 from bouncing into other pixel areas 11, thereby also avoiding the generation of crosstalk problems.

[0053] As Figure 1 shown, the collimation frame has support columns 21 and a collimation part 22. A plurality of support columns 21 are discretely distributed. The collimation frame is disposed on the pixel device layer 1 through the support columns 21.

[0054] Preferably, there are four support columns 21, which are evenly distributed at the edge positions of the pixel device layer 1. The support column 1 can support a suspended area formed between the collimation frame 1 and the pixel device layer 1. As Figure 1 shown, there is a distance between the collimation part 22 and the pixel device layer 1. The collimation part 22 is relatively far from the pixel device layer 1, that is, relatively closer to the photocathode 3. In this way, electrons emitted from the photocathode 3 with a relatively large initial lateral velocity are more likely to hit the inner wall 222 or the boundary wall 221, and thus are less likely to jump into other pixel areas 11.

[0055] By disposing the collimation frame on the pixel device layer 1 through the support columns 21, the double walls of the inner wall 222 and the outer wall 221 can effectively collimate the electrons emitted by the photocathode 3 while avoiding excessive contact between the walls and the pixel device layer, reducing signal loss, and ultimately achieving the purpose of improving image quality.

[0056] If the collimation part 22 is relatively close to the pixel device layer 1, then even if the electrons have a relatively small initial lateral velocity during emission, they may hit the inner wall 222 at a position close to the pixel device layer 1 and thus be intercepted. This implementation method causes electrons that could originally bombard the pixel device layer 1 normally to be absorbed by the collimation frame before reaching the corresponding pixel area 11, which will result in more electrons being intercepted and this design method will cause some signal loss. In the technical solution, the distance between the collimation part 222 and the pixel device layer 1 can be changed.

[0057] The collimation part 22 has a boundary wall 221 and an inner wall 222. The boundary wall 221 encloses to form a plurality of collimation channels 2211. Each collimation channel 2211 corresponds to the position of each pixel region 11 one by one. The radial dimension of the collimation channel 2211 matches the dimension of the pixel region 11. The plurality of collimation channels 2211 formed by enclosing the boundary wall 221 correspond to the positions of each pixel region 11. The boundary wall 221 can collimate the electrons incident on each pixel region 11, avoiding the electrons emitted from the photocathode 3 from falling into other pixel regions 11 and generating crosstalk.

[0058] For the technical feature that the radial dimension of the above-mentioned collimation channel 2211 matches the dimension of the pixel region 11, there are various implementation manners in practical applications. For example, when the pixel region 11 is in a rectangular or square area, the boundary wall 221 can enclose to form a square or rectangular collimation channel 2211. The radial side length of the square collimation channel 2211 is the same as or substantially consistent with the side length of the pixel region 11 below it. In another implementation manner, for example, when the pixel region 11 is in a circular area, the boundary wall 221 can enclose to form a barrel-shaped collimation channel 2211. The diameter of the barrel-shaped collimation channel 2211 is the same as or substantially consistent with the diameter of the pixel region 11. In other embodiments, the radial cross-section of the collimation channel 2211 is the same as the shape and dimension of the pixel region 11.

[0059] The inner wall 222 is disposed inside the collimation channel 2211 surrounded by the boundary wall 221.

[0060] It should be noted that the greater the wall density of the boundary wall 221 of the collimation part 22 and the more the area in contact with the pixel device layer 1, the better the effect of the collimation frame in preventing crosstalk. However, an overly dense boundary wall 221 will cause the electrons that can normally bombard the corresponding pixel region 11 to be absorbed by the boundary wall 221 before reaching the pixel device layer 1, thereby causing a large amount of signal loss in the active pixel sensor and ultimately reducing the image quality.

[0061] In the embodiment of the present disclosure, by arranging the collimation frame on the pixel device layer 1 through the support posts 21, it is possible to reduce the absorption loss of the boundary wall 221 to the electrons that normally bombard the corresponding pixel region 11 on the premise of effective collimation, thereby reducing the signal loss and improving the image quality. Further, this design can exchange for a reduction in the density of the boundary wall 221. Finally, a balance point is found between the problem of reducing the density of the boundary wall 211 and improving the collimation effect, that is, under the condition of reducing the density of the boundary wall 221, reducing the signal loss, and increasing the setting of the support posts 21 can still enable the collimation frame to maintain a good collimation effect. The technical solution of the present disclosure can ensure good filtering performance and ensure the signal accuracy of image sensing.

[0062] In one example, the pixel device layer 1 includes a base frame 4. The base frame 4 is disposed on the pixel region 11. The base frame 4 has a base wall 41. The base wall 41 encloses to form a plurality of base channels 411. Each base channel 411 corresponds to the position of each pixel region 11 one by one.

[0063] In the embodiment of the present disclosure, the pixel device layer 11 includes a base frame 4. On the basis of the collimation of the collimation frame, the base frame 4 can further collimate the electrons emitted by the photocathode 3, avoiding the phenomenon that electrons jump into other pixel regions 11 and generating crosstalk.

[0064] The base frame 4 is disposed on the pixel region 11. The base frame 4 has a base wall 41. The base wall 41 encloses to form a plurality of base channels 411. Each base channel 411 corresponds to the position of each pixel region 11 one by one. This enables each base channel 11 to correspond to each collimation channel 2211, and can further perform a good collimation operation on the electrons. The double collimation operation avoids the crosstalk phenomenon caused by electrons jumping into other pixel regions 11, thereby effectively improving the image quality.

[0065] In one example, one end of the support column 21 is fixedly connected to the base frame 4. The other end of the support column is fixedly connected to the collimation portion 22, and the end surface of the other end of the support column 21 is flush with the end surface of the collimation portion 22 away from the base frame 4.

[0066] This enables the collimation portion 22 to be disposed on the base frame 4 through the support column 21, avoiding a large amount of contact between the boundary wall 221 in the collimation portion 22 and the pixel device layer 1, that is, reducing the effective height of the wall body of the boundary wall 221. Furthermore, a large number of electrons can bombard the pixel device layer 1 more under the premise of effective collimation, rather than being absorbed by the boundary wall 221 before effectively bombarding the pixel device layer 1 during the bombardment process. Finally, the purpose of reducing signal loss and improving image quality is achieved.

[0067] In one example, the inner wall 222 includes a first inner wall 2221 and a second inner wall 2222. The first inner wall 2221 and the second inner wall 2222 are arranged at intervals. The first inner wall 2221 is closer to the boundary wall 221 than the second inner wall 2222.

[0068] For example, the number of the inner walls 222 is also balanced between improving the collimation effect and reducing the signal loss to degrade the image quality. If there are too many inner walls 222, that is, the density of the inner walls 222 is too high, the electrons emitted from the photocathode 3 will be absorbed by the inner walls 222 before reaching the pixel device layer 1, ultimately resulting in excessive signal loss and degraded image quality. In this embodiment, the inner wall 222 includes a first inner wall 2221 and a second inner wall 2222. The appropriate density of the inner walls 222 enables ensuring good collimation effect while still not losing a large amount of signals, thereby ensuring good image quality.

[0069] In one example, the distance between the first inner wall 2221 and the boundary wall 221 is less than the distance between the first inner wall 2221 and the second inner wall 2222.

[0070] For example, as Figure 2 shown, the distance between the first inner wall 2221 and the boundary wall 221 is less than the distance between the first inner wall 2221 and the second inner wall 2222. This can make the tolerance of the lateral deviation of electrons between the first inner wall 2221 and the second inner wall 2222 greater than that between the first inner wall 2221 and the boundary wall 221, preventing many normal (smaller lateral deviation) electrons from being blocked by the inner wall 222 before approaching the bombardment of the pixel device layer 1, thereby reducing the image quality.

[0071] In one example, the first inner wall 2221 and the second inner wall 2222 are annularly distributed around the center of the collimation channel 2211. The first inner wall 2221 surrounds the second inner wall 2222. As Figure 2 shown, the first inner wall 2221 is located near the boundary wall 221 and forms a larger rectangular structure by surrounding. The second inner wall 2222 is located inside the first inner wall 2221.

[0072] The radial dimension of the second inner wall 2222 is greater than the distance between the first inner wall 2221 and the second inner wall 2222.

[0073] The distance between the first inner wall 2221 and the second inner wall 2222 is greater than the distance between the first inner wall 2221 and the boundary wall 221.

[0074] It should be noted that the larger the distance, the higher the tolerance of the lateral deviation of electrons; the smaller the distance, the lower the tolerance of the lateral deviation of electrons. Generally, the aperture of the inner wall 222 of the collimation part 22 corresponding to the center of the pixel device layer 1 is larger, and the tolerance of the lateral deviation of electrons is higher, which can prevent many normal (smaller lateral deviation) electrons from being blocked by the inner wall 222 before approaching the bombardment of the pixel device layer 1, thereby unnecessarily losing more signals.

[0075] The inner wall 222 of the collimating portion 22 at the boundary of the corresponding pixel device layer 1 has a smaller aperture, so it has a lower tolerance for the lateral offset of electrons, which can effectively prevent electrons from jumping into other pixel regions and thus prevent the occurrence of crosstalk phenomena.

[0076] In an embodiment of the present disclosure, for example, as Figure 2 shown, the radial dimension of the second inner wall 2222 is greater than the spacing between the first inner wall 2221 and the second inner wall 2222. The spacing between the first inner wall 2221 and the second inner wall 2222 is greater than the spacing between the first inner wall 2221 and the boundary wall 221. In this way, in the collimating frame corresponding to a single pixel region 11, the spacing between the boundary wall 221, the first inner wall 2221, and the second inner wall 2222 increases step by step, which can effectively collimate electrons with a large offset amount and also avoid many electrons with a small lateral offset being blocked by the inner wall 222 before moving close to bombarding the pixel device layer 1, ultimately achieving the purpose of obtaining more signals and improving the image quality.

[0077] In one example, the collimating portion 22 further has a connecting wall 223. The connecting wall 223 is configured to connect and fix the inner wall 222 to the boundary wall 221. For the fixation and support of the inner wall structure itself, a connecting wall can be used to connect the inner wall to the boundary wall, thereby realizing the fixation of the inner wall itself.

[0078] For example, the connecting wall 223 can connect the inner wall 222 and the boundary wall 221, so that the inner wall 222 can be stably connected to the boundary wall 221. As Figure 2 shown, a connecting wall can be provided between the first inner wall 2221 and the boundary wall 221. Further, a connecting wall is also provided between the first inner wall and the second inner wall, so that the second inner wall is connected to the boundary wall through the connecting wall and the first inner wall. This design ensures a good collimation effect and avoids the problem of collimation failure caused by the shaking or falling off of the inner wall 222.

[0079] In one example, in the collimating channel 2211, the connecting wall 223 and the inner wall 222 and / or the boundary wall 221 together enclose a plurality of sub-channels.

[0080] For example, the plurality of sub-channels can collimate electrons in multiple directions, avoiding the occurrence of crosstalk phenomena caused by electrons jumping into other pixel regions 11.

[0081] In one example, the connecting wall 223 and the boundary wall 221 and the first inner wall 2221 enclose a plurality of first sub-channels 2231.

[0082] The connecting wall 223 and the first inner wall 2221 and the second inner wall 2222 enclose a plurality of second sub-channels 2232.

[0083] The radial dimension of the second sub-channel 2232 is larger than that of the first sub-channel 2231.

[0084] The radial dimension of the second sub-channel 2232 is larger than that of the first sub-channel 2231. This enables the second sub-channel 2232 to have a greater tolerance for the lateral offset of electrons than the first sub-channel 2231, preventing many normal (less laterally offset) electrons from being blocked by the inner wall 222 before reaching near the bombarding pixel device layer 1, thereby reducing the image quality. In contrast, the first sub-channel is located at the edge of the entire collimation channel. When electrons corresponding to other pixel regions deviate to the position corresponding to the current pixel region, they are more likely to appear at the edge of the collimation channel. Therefore, the smaller radial dimension of the first sub-channel is more conducive to intercepting the electrons that deviate from other regions into this region, and also helps to intercept the electrons located at the boundary position in this region and having a tendency to deviate outwards.

[0085] In one example, the second inner wall 2222 itself is annularly distributed, surrounding to form a third sub-channel 2233. The radial dimension of the third sub-channel 2233 is larger than that of the second sub-channel 2232.

[0086] It should be noted that the larger the radial dimension of the sub-channel, the higher the tolerance for the lateral offset of electrons; the smaller the radial dimension of the sub-channel, the lower the tolerance for the lateral offset of electrons. Generally, when electrons are emitted from the center of the pixel region 11 corresponding to the photocathode 3, even if they have a certain initial lateral velocity, they are likely to fall into the predetermined pixel region 11. When electrons are emitted from the edge of the pixel region 11 corresponding to the photocathode 3, if they have a certain initial lateral velocity, the probability of falling into a non-predetermined pixel region 11 is relatively large. Therefore, setting the radial dimensions of the first sub-channel 2231, the second sub-channel 2232, and the third sub-channel 2233 to increase gradually provides a higher tolerance for the lateral offset of the first emitted electrons 301 at the center of the pixel region 11 corresponding to the photocathode 3, and a lower tolerance for the lateral offset of the second emitted electrons 302 at the edge of the pixel region 11 corresponding to the photocathode 3.

[0087] In the embodiments of the present disclosure, the structure formed by surrounding the second inner wall 2222 is located inside the structure surrounded by the first inner wall 2221, and it is used to enclose a rectangular structure of the third sub-channel 2233 in the central region corresponding to the pixel region 1. The radial dimension of the third sub-channel 2233 is larger than the radial dimension of the second sub-channel 2232 jointly surrounded by the first inner wall, the second inner wall, and the connecting wall. In this way, in the collimation frame corresponding to a single pixel region 11, the radial dimensions of the first sub-channel 2231, the second sub-channel 2232, and the third sub-channel 2233 increase step by step, which can avoid many electrons with relatively small lateral offsets being blocked by the inner wall 222 before moving close to bombarding the pixel device layer 1 on the premise of effectively collimating electrons with relatively large offsets, and ultimately achieve the purpose of obtaining more signals and improving the image quality.

[0088] In one example, the ratio of the height of the collimation frame to the radial dimension of the pixel region 11 ranges from 1.5 to 3.5.

[0089] For example, the height of the collimation frame is the height of the support column 21. The ratio of the height of the collimation frame to the radial dimension of the pixel region 11 ranges from 1.5 to 3. This size ratio range can enable the collimation frame to still achieve a good collimation effect without a large loss of signals, and ultimately improve the image quality.

[0090] Preferably, the ratio of the height of the collimation frame to the radial dimension of the pixel region 11 is 2. Under this ratio characteristic, the collimation frame provided by this solution reaches the optimal effect. Compared with the embodiments shown in Figure 1 and Figure 2 , the collimation frame can achieve a good collimation effect and effectively reduce the overall thickness of the image sensor.

[0091] In one example, the ratio of the height of the base frame to the radial dimension of the pixel region 11 ranges from 0.2 to 1.0.

[0092] For example, the ratio of the height of the base frame to the radial dimension of the pixel region 11 ranges from 0.2 to 1.0. This size ratio range can enable the base frame to still achieve a good collimation effect without a large loss of signals, and ultimately improve the image quality.

[0093] Preferably, the ratio of the height of the base frame to the radial dimension of the pixel region 11 is 0.5. Under this ratio characteristic, the base frame provided by this solution reaches the optimal effect. Compared with the embodiments shown in Figure 1 and Figure 2 , the collimation frame can achieve a good collimation effect and effectively reduce the overall thickness of the image sensor.

[0094] According to another embodiment of the present disclosure, a processing method for an active pixel sensor is provided. The processing method includes:

[0095] Providing a pixel device layer 1 having a plurality of pixel regions 11.

[0096] Depositing a substrate layer 6 on the pixel device layer 1. Etching the substrate layer 6 to form a substrate frame 4 on the pixel device layer 1.

[0097] Depositing a sacrificial layer 5 around the substrate frame 4. Performing a first etching from the top surface of the sacrificial layer 5. The depth of the hole formed by the first etching is the depth from the top surface of the sacrificial layer 5 to the pixel device layer 1. Depositing a collimation layer material in the hole to form a support pillar 21.

[0098] Performing a second etching from the top surface of the sacrificial layer 5. The depth of the hole formed by the second etching is less than the depth from the top surface of the sacrificial layer 5 to the pixel device layer 1. Depositing a collimation layer material in the hole to form a collimation portion 22.

[0099] Releasing the sacrificial layer 5.

[0100] For example, as Figures 5 - 11 shown, depositing a substrate layer 6 on the pixel device layer 1, etching the substrate layer 6 to form a substrate frame 4 on the pixel device layer 1.

[0101] Depositing a sacrificial layer 5 around the substrate frame 4. The material of the sacrificial layer 5 includes but is not limited to polyimide (PI) and phosphosilicate glass (PSG). The height of the sacrificial layer 6 is the same as the height of the collimation frame, and is used for etching the support pillar 21 and the collimation portion 22.

[0102] Performing a first etching from the top surface of the sacrificial layer 5. The depth of the hole formed by the first etching is the depth from the top surface of the sacrificial layer 5 to the pixel device layer 1. Depositing a collimation layer material in the hole formed by the first etching to ensure that the etched hole is filled with the collimation material to form a support pillar 21. The height of the support pillar 21 is the distance from the top surface of the sacrificial layer 5 to the pixel device layer 1.

[0103] Performing a second etching from the top surface of the sacrificial layer 5. The depth of the hole formed by the second etching is less than the depth from the top surface of the sacrificial layer 5 to the pixel device layer 1. Depositing a collimation layer material in the hole to form a collimation portion 22. So that a suspended area is formed between the collimation portion 22 and the pixel device layer 1, avoiding a large amount of contact between the boundary wall 221 in the collimation portion 22 and the pixel device layer 1, that is, reducing the effective height of the boundary wall 221 of the wall body, and further enabling a large number of electrons to bombard the pixel device layer 1 more under the premise of effective collimation, rather than being absorbed by the boundary wall 221 before effectively bombarding the pixel device layer 1 during the bombardment process, ultimately achieving the purpose of reducing signal loss and improving image quality.

[0104] The collimation materials include but are not limited to Si3N4, SiO2, and SiON.

[0105] Release the sacrificial layer 5. Finally, a complete collimation frame is formed on the pixel device layer 1.

[0106] In one example, when etching the substrate layer, a strip mask is set at the edge corresponding to the pixel region, and the substrate layer is etched to form the base frame.

[0107] When performing the first etching on the sacrificial layer, a strip mask is set at the position corresponding to the support pillar, and the thickness of the strip mask is the same as the thickness of the support pillar.

[0108] When performing the second etching on the sacrificial layer, at the position corresponding to the pixel region, strip masks distributed crosswise are set on the sacrificial layer, and crosswise distributed collimation parts are etched.

[0109] In the embodiment of the present disclosure, in the embodiment of the present disclosure, the collimation frame is arranged on the pixel device layer 1 through the support pillar 21. On the premise of effectively collimating the electrons emitted by the photocathode, the double walls avoid excessive contact between the walls and the pixel device layer 1, reduce signal loss, and finally achieve the purpose of improving image quality.

[0110] In the above embodiments, the differences between the embodiments are mainly described. As long as the different optimization features between the embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, it will not be elaborated here.

[0111] Although some specific embodiments of the present invention have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. An active pixel sensor, characterized in that , including: A pixel device layer having a plurality of pixel regions; A collimation frame having support columns and a collimation portion, with a plurality of the support columns discretely distributed, and the collimation frame is disposed on the pixel device layer through the support columns; The collimation portion has a boundary wall and an inner wall. The boundary wall encloses a plurality of collimation channels, and each collimation channel corresponds to the position of each pixel region one by one. The inner wall is disposed within the collimation channels surrounded by the boundary wall, and the radial dimension of the collimation channels matches the dimension of the pixel regions; The collimation portion is configured to guide electrons to fall on corresponding pixel regions.

2. The active pixel sensor according to claim 1, wherein The pixel device layer includes a base frame disposed on the pixel regions, and the base frame has a base wall that encloses a plurality of base channels, and each base channel corresponds to the position of each pixel region one by one.

3. The active pixel sensor according to claim 2, characterized in that, One end of the support column is fixedly connected to the base frame, and the other end of the support column is fixedly connected to the collimation portion, and the end surface of the other end of the support column is flush with the end surface of the collimation portion away from the base frame.

4. The active pixel sensor according to claim 1, characterized in that, The inner wall includes a first inner wall and a second inner wall, the first inner wall and the second inner wall are spaced apart, and the first inner wall is closer to the boundary wall than the second inner wall.

5. The active pixel sensor according to claim 4, characterized in that, The distance between the first inner wall and the boundary wall is less than the distance between the first inner wall and the second inner wall.

6. The active pixel sensor according to claim 4, characterized in that, The first inner wall and the second inner wall are annularly distributed around the center of the collimation channel, and the first inner wall surrounds the second inner wall; The radial dimension of the second inner wall is greater than the distance between the first inner wall and the second inner wall; The spacing distance between the first inner wall and the second inner wall is greater than the distance between the first inner wall and the boundary wall.

7. The active pixel sensor according to claim 4, characterized in that, The collimation portion further has a connecting wall configured to connect and fix the inner wall to the boundary wall.

8. The active pixel sensor according to claim 7, wherein In the collimation channel, the connecting wall and the inner wall and / or the boundary wall jointly enclose a plurality of sub-channels.

9. The active pixel sensor according to claim 7, characterized in that, The connecting wall and the boundary wall and the first inner wall enclose a plurality of first sub-channels; The connecting wall and the first inner wall and the second inner wall enclose a plurality of second sub-channels; The radial dimension of the second sub-channel is greater than the radial dimension of the first sub-channel.

10. The active pixel sensor according to claim 9, wherein The second inner wall is annularly distributed by itself, surrounding to form a third sub-channel, and the radial dimension of the third sub-channel is greater than the radial dimension of the second sub-channel.

11. The active pixel sensor according to claim 1, wherein The ratio of the height of the collimation frame to the radial dimension of the pixel region ranges from 1.5 to 3.

5.

12. The active pixel sensor according to claim 1, wherein, The ratio of the height of the collimation frame to the radial dimension of the pixel region is 2.

13. The active pixel sensor according to claim 2, wherein The ratio of the height of the base frame to the radial dimension of the pixel region ranges from 0.2 to 1.

0.

14. The active pixel sensor according to claim 2, characterized in that, The ratio of the height of the base frame to the radial dimension of the pixel region is 0.

5.

15. A method for manufacturing an active pixel sensor according to any one of claims 1 to 14, characterized in that, including: Providing a pixel device layer having a plurality of pixel regions; Depositing a substrate layer on the pixel device layer, etching the substrate layer, and forming a base frame on the pixel device layer; Deposit a sacrificial layer around the base frame, perform a first etching from the top surface of the sacrificial layer, and the depth of the holes formed by the first etching is the depth from the top surface of the sacrificial layer to the pixel device layer. Deposit a collimation layer material in the holes to form support pillars; Perform a second etching from the top surface of the sacrificial layer, and the depth of the holes formed by the second etching is less than the depth from the top surface of the sacrificial layer to the pixel device layer. Deposit a collimation layer material in the holes to form collimation parts; Release the sacrificial layer.

16. The processing method according to claim 15, wherein, When etching the substrate layer, set a strip-shaped mask at the edge corresponding to the pixel area to etch the substrate layer to form the base frame; When performing the first etching on the sacrificial layer, set a strip-shaped mask at the position corresponding to the support pillar, and the thickness of the strip-shaped mask is the same as the thickness of the support pillar; When performing the second etching on the sacrificial layer, at the position corresponding to the pixel area, set strip-shaped masks with cross distribution on the sacrificial layer, and etch to form collimation parts with cross distribution.

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