Imager and method of manufacturing an imager

Abstract

The present invention relates to an imager and a method of manufacturing an imager. The method includes the following steps: attaching (100) an imaging sensor to a first substrate; cutting (101) the first substrate at a predetermined distance around the attached imaging sensor; attaching (102) a drive circuit board for driving the imaging sensor to the cut first substrate in a manner close to the attached imaging sensor; connecting (103) the drive circuit board for driving the imaging sensor to the attached imaging sensor to obtain a first block; repeating the attaching step, the cutting step, the attaching step, and the connecting step to obtain a second block; placing the cut first substrates in a side-by-side contact manner and docking (104) the obtained first and second blocks together; attaching (105) the docked blocks to a main substrate; connecting (106) the drive circuit boards of the imaging sensors of the docked first and second blocks to a main board of the imager.

Description

Technical Field

[0001] The technical field of the present invention is the technical field of manufacturing imagers composed of CCD or CMOS imaging sensors butted together. More specifically, the present invention relates to butting together photosensitive plates for digital sensors, for example, for X-ray medical imaging using CMOS (Complementary Metal Oxide Semiconductor) technology. Background Art

[0002] Photosensitive sensors are typically made of solid-state photosensitive elements arranged in a matrix array. The photosensitive elements are made of semiconductor materials, which are usually single-crystalline silicon, polycrystalline silicon, or amorphous silicon for CCD or CMOS sensors. The photosensitive elements include at least one photodiode, phototransistor, or photoresistor. These elements are arranged on or integrated into a substrate, which is usually a carrier (also called a plate) made of glass, plastic (polymer), metal, or another synthetic material (carbon, alloy, ceramic, etc.) or silicon. Then a photosensitive plate is obtained.

[0003] In the context of manufacturing an imager for X-ray medical imaging, the operation of butting together photosensitive plates (i.e., end-to-end connecting photosensitive plates using CCD or CMOS technology) involves observing strict tolerances. Specifically, it is important to limit the loss of pixel areas on the butting line and ensure the alignment of pixels from various butted-together sensors. Additionally, due to the risk of cracking, fragmentation, and / or electrostatic discharge, it is necessary to avoid any contact between the plates during the operation of butting together the photosensitive plates.

[0004] So far, this operation of butting together photosensitive plates has been carried out using complex, expensive, and time-consuming industrial means to ensure alignment tolerances and eliminate the risk of inter-plate collisions.

[0005] In addition, the complex industrial means of the prior art have limitations specific to the size of a single plate. They are based on devices for clamping plates of a predetermined size and achieve alignment with the aid of cameras for alignment according to the spacing associated with the size of a single plate.

[0006] Another problem with the current solutions relates to testing the qualification of the obtained product. Specifically, such testing of the qualification of the product obtained after such a long and complex operation can only be carried out after the butting and wire bonding operations are completed. In other words, in the prior art methods, if non-conformity is detected, the finished product can only be as it is. The product is discarded. This results in the loss of materials used and the loss of time.

[0007] In other words, the known prior art solutions for butting together photosensitive plates do not provide a fast, cheap, flexible, and easy-to-test solution during the butting process. Summary of the Invention

[0008] The present invention aims to overcome all or some of the above problems by providing a method for docking photosensitive plates together, which allows the manufacture of connecting sub-elements that can be tested individually, thus significantly reducing the risk of detecting non-conformities on the finished product. Additionally, the method which is the subject of the present invention facilitates the alignment of the sub-elements. The method also provides great flexibility in terms of the size of the obtained sensor without the need for substantial investment or long-term complex development. Other advantages of the method according to the present invention are described in detail below.

[0009] To this end, a subject of the present invention is a method for manufacturing an imager, the method comprising the following steps:

[0010] - A first step of attaching an imaging sensor to a first substrate;

[0011] - A second step of cutting out the first substrate at a predetermined distance around the attached imaging sensor;

[0012] - A third step of attaching a drive circuit board for driving the imaging sensor to the cut-out first substrate in a manner close to the attached imaging sensor;

[0013] - A fourth step of connecting the drive circuit board for driving the imaging sensor to the attached imaging sensor to obtain a first tile;

[0014] - Repeating the first step, the second step, the third step and the fourth step to obtain a second tile;

[0015] - A fifth step of placing the cut-out first substrates in an edge-to-edge contact manner and docking the obtained first and second tiles together;

[0016] - A sixth step of attaching the docked tiles to a main substrate;

[0017] - A seventh step of connecting the drive circuit boards of the imaging sensors of the docked first and second tiles to the main board of the imager.

[0018] Advantageously, after the fourth step of connecting the drive circuit board for driving the imaging sensor to the engaged imaging sensor, the method for manufacturing an imager according to the present invention includes a step of testing the qualification of the tile.

[0019] Advantageously, after the fourth step of connecting the drive circuit board for driving the imaging sensor to the engaged imaging sensor, the method for manufacturing an imager according to the present invention includes a step of storing the tile.

[0020] Advantageously, in the method of manufacturing an imager according to the present invention, the second step of excising the first substrate is a step of cutting by means of a laser beam or a Bessel beam.

[0021] Advantageously, after the first attachment step, the method of manufacturing an imager according to the present invention includes a step of marking the first substrate.

[0022] In the method of manufacturing an imager according to the present invention, the size of the first block is different from the size of the second block.

[0023] The present invention also relates to an imager, the imager including a first block and a second block, each of the blocks including:

[0024] - a first substrate;

[0025] - an imaging sensor, the imaging sensor being attached to the first substrate, the first substrate being excised at a predetermined distance around the attached

[0026] imaging sensor;

[0027] - a drive circuit board for driving the imaging sensor, the drive circuit board being attached to the first substrate in a manner close to the imaging sensor and connected to the imaging sensor,

[0028] the first block and the second block being butted together by placing the first substrate in an edge-to-edge contact manner;

[0029] and the imager including: a main substrate, the butted-together blocks being attached to the main substrate; and a main board, the main board being connected to the drive circuit board for driving the imaging sensors of the butted-together first block and second block.

[0030] The size of the first block may be different from the size of the second block. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be better understood by reading the detailed description of one embodiment provided by way of example, and further advantages will become apparent, the description being illustrated by the accompanying drawings, in which:

[0032] Figure 1 a step diagram of the method of manufacturing an imager according to the present invention is shown;

[0033] Figure 2 the main steps of the method of manufacturing an imager according to the present invention are schematically shown;

[0034] Figure 3An embodiment of an imager according to the present invention is schematically shown.

[0035] For clarity, these figures are not all drawn to the same scale. In addition, the same elements will have the same reference numerals in different figures. Detailed Description

[0036] Figure 1 A step diagram of a method of manufacturing an imager according to the present invention is shown. The method of manufacturing an imager includes steps 100 to 106 which will be described in detail below. Optionally, the method may include steps 107, 108, 109 which may be employed individually or in combination.

[0037] Figure 2 The main steps of a method of manufacturing an imager according to the present invention are schematically shown.

[0038] The method of manufacturing imager 10 includes a first step 100 of attaching imaging sensor 11 to a first substrate 12. The method according to the present invention can be applied to imaging sensors 11 using CMOS or CCD technology. Imaging sensor 11 is shown herein as having a rectangular shape, but it may take other polygonal shapes. Imaging sensor 11 includes an imaging area 31 and a drive and connection area 32 which is intended to connect imaging sensor 11 to a drive circuit board and provide drive to imaging sensor 11. First substrate 12 may be made of glass, ceramic or crystal material suitable for supporting imaging sensor 11. The step 100 of attaching imaging sensor 11 to first substrate 12 is generally performed by bonding. This bonding is advantageously achieved by applying a double-sided adhesive film to first substrate 12. Alternatively, the adhesive may be deposited on substrate 12. Although bonding by means of an adhesive film remains the preferred attachment method, other methods of attaching imaging sensor 11 to first substrate 12 may be achieved.

[0039] Thus, the bonding of the individual imaging sensor 11 to the first substrate 12 is performed without strict alignment constraints. The alignment is within a few millimeters, rather than within a few micrometers as required by prior art methods.

[0040] The method according to the invention then comprises a second step 101 of cutting out the first substrate 12 at a predetermined distance 14 around the bonded imaging sensor 11. The first substrate 12 is cut out all the way around the imaging sensor, while leaving a small sill along the imaging area 31 and a greater space along the edges of the drive and connection area 32 of the imaging sensor 11. This second space is intended to accommodate the drive circuit board for driving the imaging sensor 11. Since the imaging sensor 11 is bonded to the first substrate 12, it is the first substrate 12 that is cut out. This cutting must be precise (about 5 μm) and can be carried out using conventional equipment, for example by cutting with a laser beam or a Bessel beam. A Bessel beam is a form of laser beam constructed by interference over a long distance, allowing a highly concentrated energy that can be extended without diffraction occurring inside the transparent material. The Bessel beam generated using an ultrafast laser allows for deep ablation of the exposed material, which is particularly suitable for cutting out nanochannels with a high aspect ratio. Thus, channels with a very small diameter (less than 2 μm) can be cut out in a glass layer several millimeters thick. After cutting out the nanochannels in the first substrate, the first substrate can be cut along the lines defined by the nanochannels. This technique allows for good control of the cutting to provide the processing quality and precision required for precise machining of glass on an industrial scale.

[0041] The cutting-out step can be carried out from the front or from the back of the first substrate 12. Cutting from the back remains the preferred solution to avoid possible splashing on the imaging sensor 11. The cutting-out step can also be carried out using a blade, but it is still important to ensure the cutting precision and to ensure that no contaminants are allowed to enter the imaging sensor so as not to damage the imaging sensor.

[0042] In terms of mechanical and electrical (ESD) protection of the subassembly of the imaging sensor 11 attached to the first substrate 12, the cutting-out step provides another advantage. Specifically, the first substrate 12 is cut out beyond the dimensions of the imaging sensor 11, thus eliminating the risk of lateral contact between the imaging sensors 11 during subsequent processing.

[0043] Figure 2 An enlarged view of the first substrate 12 after the cutting-out step 101 is shown, with the first substrate 12 leaving a small sill all around the imaging area 31 of the imaging sensor 11 at a distance 14 from the imaging sensor 11.

[0044] The method according to the invention further comprises a third step 102 which attaches the drive circuit board 13 for driving the imaging sensor 11 to the excised first substrate 12 in a manner close to the attached imaging sensor 11. More specifically, the drive circuit board 13 is attached to the first substrate 12 to be juxtaposed with the drive and connection area 32 of the imaging sensor 11. Specifically, the drive circuit board 13 can be attached by bonding, by means of an adhesive film or using an adhesive.

[0045] Next, the method according to the invention comprises a fourth step 103 which connects the drive circuit board 13 for driving the imaging sensor 11 to the attached imaging sensor 11 to obtain a first block 21. The drive circuit board 13 is connected to the drive and connection area 32 of the imaging sensor 11. The connection step 103 can be carried out by wire bonding. Wire bonding is one of the techniques for making electrical connections between the imaging sensor 11 and the drive circuit board 13. The wiring is achieved using wires between two connection pads provided for this purpose and soldered to the respective elements to be connected. The soldering is usually carried out by ultrasonic waves. The material of the wires is aluminum, gold or copper. The diameter of the wires is about 20 μm. Steps 100 to 103 are carried out sequentially for a block. Multiple steps 100 to 103 can be carried out in parallel (i.e., simultaneously) to obtain multiple blocks.

[0046] To obtain a second block 22, the first step, the second step, the third step and the fourth step are repeated. Then two blocks 21, 22 are obtained, each on its first substrate 12. In other words, the number of first substrates 12 and blocks is the same. Here two blocks are used to explain the method, but the principle equally applies to any number of blocks. Six blocks can be seen on an Figure 2 imager, and the method is particularly advantageously applicable to implementing imagers of very large size with a large number of blocks.

[0047] The method according to the invention comprises a fifth step 104 which docks together the first block 21 and the second block 22 obtained by placing two of the excised first substrates 12 in side-to-side contact. Docking together means the action of end-to-end connection. Block 21 is juxtaposed with block 22. In other words, after the excision step 101, the first substrate 11 shows a side substantially perpendicular to the plane of the imaging sensor 11. Thus, each block has three free sides around the imaging area 31. The two blocks are docked together by placing the free side of one block in contact with the side of the other block. By docking the blocks together in pairs, an imaging sensor 11 of very large area can be obtained.

[0048] Once the blocks are butted together, the positions of the individual blocks are fixed. The method then includes a sixth step 105 of attaching the butted-together blocks 21, 22 to a main substrate 23. The main substrate 23 is on the back side of the blocks, which helps to strengthen the imager.

[0049] Finally, the method according to the invention includes a seventh step 106 which connects the drive circuit board 13 of the imaging sensor 11 of the first block 21 and the second block 22 butted together to the main board 24 of the imager 10. Steps 104 to 106 are executed in sequence. The steps can be executed in parallel (i.e., simultaneously) for multiple sets of blocks.

[0050] In one embodiment of the invention, after the fourth step 103 of connecting the drive circuit board 13 for driving the imaging sensor 11 to the attached imaging sensor 11, the method of manufacturing the imager may include a step 107 of testing the eligibility of the blocks.

[0051] The excision of the imaging sensors 11 performed separately on the first substrate 12 and their connection to their drive circuit boards 13 allow the individual blocks to be separated. Thus, the individual blocks can be tested and characterized separately before storing, pairing and butting them together to manufacture the final imager.

[0052] Since the eligibility test is carried out early in the method of manufacturing the imager and the eligibility test allows defective blocks to be removed, testing the eligibility of the individual blocks avoids the risk of discarding high-value-added sub-components.

[0053] In one embodiment of the invention, after the fourth step 103 of connecting the drive circuit board 13 for driving the imaging sensor 11 to the joined imaging sensor 11, the method of manufacturing the imager may include a step 108 of storing the blocks.

[0054] In addition, manufacturing individual blocks addresses the need for safe storage. Since each imaging sensor 11 is joined to its first substrate 12, there is little or no risk of breakage. Tracking of the imaging sensors accommodated on the cutting film can also be achieved before the end time of the UV treatment. Specifically, with the method according to the invention, the imager can be manufactured in two stages: execute steps 100 to 103 to obtain individual blocks and then store the blocks. In the second stage, multiple stored and recently manufactured blocks can be butted together.

[0055] In one embodiment of the present invention, after the first attachment step 100, the method of manufacturing an imager may include a step 109 of marking the first substrate 12. The marking may be performed by tagging, pasting a barcode, or by etching a number or code that allows tracing of the image sensor 11. Once bonded to the first substrate 12, the first substrate 12 can be easily etched to link to chip manufacturing data (batch number, image characteristics, etc.).

[0056] Finally, it can be noted that the size of the first block 21 may be different from the size of the second block 22. This possibility of docking blocks of different sizes provides great flexibility for this type of imager that can be manufactured using the method according to the present invention.

[0057] The present invention provides a solution that uses standard equipment and methods in a novel and creative way, enabling the manufacture of large-sized imagers. The present invention avoids the risk of discarding high added value due to misalignment during conventional docking (bonding all chips to a single substrate), breakage of the image sensors during the operation of docking a set of image sensors together on a single substrate, or damage to the image sensors by electrostatic shock (which can only be detected during testing after all the image sensors are assembled).

[0058] The present invention provides a solution that allows rapid excision of the "image sensor bonded to the first substrate" sub-assembly at a magnitude of 200 mm / s to 300 mm / s (which means short cycle times). By manufacturing individual blocks, the present invention allows safe storage of the tested and functional blocks.

[0059] Since each image sensor is bonded to a part of the first substrate, the present invention allows good tracing of the image sensors on the first substrate of the block.

[0060] Figure 3An embodiment of an imager according to the present invention is schematically shown. The imager 20 includes a first block 21 and a second block 22. Each of the blocks 21, 22 includes: a first substrate 12; an imaging sensor 11 attached to the first substrate 12, the first substrate 12 being cut away at a predetermined distance 14 around the joined imaging sensor 11; a drive circuit board 13 for driving the imaging sensor 11, the drive circuit board 13 being attached to the first substrate 12 in a manner close to the imaging sensor 11 and connected to the imaging sensor 11. According to the present invention, the first block 21 and the second block 22 are butted together by placing two first substrates 12 in an edge-to-edge contact manner. The imager 20 further includes: a main substrate 23 to which the butted blocks are attached; and a main board 24 that is connected to the drive circuit boards 13 for driving the imaging sensors 11 of the butted first block 21 and second block 22 to drive the plurality of drive circuit boards 13 of the imaging sensors 11. Thus, the imager 20 includes a plurality of blocks and a plurality of first substrates 12 (each block having its own first substrate). The blocks are butted together by placing the separate first substrates of the blocks in an edge-to-edge contact manner. The blocks butted together in this way are attached to a main substrate 23 different from the first substrate.

[0061] In Figure 3 In the imager 20 shown, the size of the first block 21 is different from the size of the second block 22. However, the present invention also relates to an imager 10 in which all blocks have the same size.

[0062] The present invention is applicable to any image sensor manufactured by butting together photosensitive plates based on CMOS or another technology.

Claims

1. A method of manufacturing an imager (10, 20), wherein, the method comprises the following steps: a. A first step (100) of attaching an imaging sensor (11) to a first substrate (12); b. A second step (101) of cutting the first substrate (12) at a predetermined distance around the attached imaging sensor (11); c. A third step (102) of attaching a drive circuit board (13) for driving the imaging sensor (11) to the cut first substrate (12) in a manner close to the attached imaging sensor (11); d. A fourth step (103) of connecting the drive circuit board (13) for driving the imaging sensor (11) to the attached imaging sensor (11) to obtain a first block (21); e. Repeating the first step, the second step, the third step and the fourth step to obtain a second block (22) located on the first substrate (12); f. A fifth step (104) of placing two cut first substrates (12) in an edge-to-edge contact manner and docking the obtained first block (21) and second block (22) together; g. A sixth step (105) of attaching the docked blocks (21, 22) to a main substrate (23); h. A seventh step (106) of connecting the drive circuit board (13) of the imaging sensor (11) of the docked first block (21) and second block (22) to the main board (24) of the imager (10, 20).

2. The method of manufacturing an imager (10, 20) according to claim 1, wherein, after the fourth step (103) of connecting the drive circuit board (13) for driving the imaging sensor (11) to the engaged imaging sensor (11), the method comprises a step (107) of testing the qualification of the blocks (21, 22).

3. The method of manufacturing an imager (10, 20) according to claim 1 or 2, wherein, after the fourth step (103) of connecting the drive circuit board (13) for driving the imaging sensor (11) to the engaged imaging sensor (11), the method comprises a step (108) of storing the blocks (21, 22).

4. The method of manufacturing an imager (10, 20) according to any one of claims 1 to 3, wherein, the second step (101) of cutting the first substrate (12) is a step of cutting by means of a laser beam or a Bessel beam.

5. The method of manufacturing an imager (10, 20) according to any one of claims 1 to 4, wherein, after the first step (100), the method comprises a step (109) of marking the first substrate (12).

6. The method of manufacturing an imager (20) according to any one of claims 1 to 5, wherein, the size of the first block (21) is different from the size of the second block (22).

7. An imager (10, 20), wherein, The imager (10, 20) includes a first block (21) and a second block (22), and each of the first block (21) and the second block (22) includes: a. A first substrate (12); b. An imaging sensor (11) attached to the first substrate (12), and the first substrate (12) is cut away at a predetermined distance (14) around the joined imaging sensor (11); c. A drive circuit board (13) for driving the imaging sensor (11), and the drive circuit board (13) is attached to the first substrate (12) in a manner close to the imaging sensor (11) and connected to the imaging sensor (11), The first block (21) and the second block (22) are docked together by placing two first substrates (12) in edge-to-edge contact; and The imager (10, 20) includes: a main substrate (23) to which the docked blocks are attached; and a main board (24) that is connected to the drive circuit board (13) for driving the imaging sensors (11) of the first block (21) and the second block (22) docked together.

8. The imager (10, 20) according to claim 7, wherein, the size of the first block (21) is different from the size of the second block (22).

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