Imager manufacturing method

Abstract

To provide a method for producing an imager.SOLUTION: A method for producing an imager includes: a step (100) of attaching an imaging sensor to a first substrate; a step (101) of cutting out the first substrate at a predetermined distance around the imaging sensor; a step (102) of attaching a driver circuit board for driving the imaging sensor, close to the imaging sensor; a step (103) of connecting the driver circuit board to the attached imaging sensor to obtain a first tile; a step of repeating the attaching, cutting-out, attaching, and connecting steps to obtain a second tile; a step (104) of butting together the obtained first tile and second tile by placing the cut-out first substrates in edge-to-edge contact; a step (105) of attaching the butted-together tiles to a main substrate; and a step (106) of connecting the driver circuit boards to a motherboard of the imager.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technical field of the invention is that of manufacturing imagers consisting of butt-bonded CCD or CMOS imaging sensors, and more particularly, the invention relates to butt-bonding of photosensitive plates for digital sensors, e.g., for X-ray medical imaging using CMOS (Complementary Metal Oxide Semiconductor) technology. [Background technology]

[0002] Photosensitive sensors are generally made from solid-state photosensitive elements arranged in a matrix array. The photosensitive elements are made from semiconductor materials, usually monocrystalline 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 generally a carrier (also called a plate) made of glass, plastic (polymer), or metal, or other synthetic material (carbon, alloy, ceramic, etc.) or silicon. A photosensitive plate is then obtained.

[0003] In manufacturing imagers for X-ray medical imaging, butt-joining the plates, i.e., connecting the plates end-to-end using CCD or CMOS technology, involves maintaining tight tolerances. Specifically, it is important to both limit the loss of pixel area on the butt line and ensure alignment of pixels from the various butt-joined sensors. Additionally, any contact between plates during butt-joining must be avoided due to the risk of breakage, chipping, and / or electrostatic discharge.

[0004] To date, this process of butt-joining photosensitive plates is performed using industrial procedures that are complex, expensive, and subject to strict alignment tolerances and long cycle times to eliminate the risk of inter-plate collisions.

[0005] Additionally, the complex industrial means of the prior art are limited to one board size only: they are based on a means for gripping a board of a given dimension, and alignment is achieved by an alignment camera according to a spacing associated with one board size.

[0006] Another problem with current solutions relates to testing the conformance of the resulting product. Specifically, testing the conformance of the product obtained after this long and complicated operation can only be done after the butt joint and wire bonding operation is completed. In other words, if an incompatibility is detected in the prior art method, it can only occur on the finished product. The product is discarded. This results in a loss of material used and a loss of time.

[0007] In other words, known existing solutions for butt-joining photosensitive plates do not provide a solution that is fast, inexpensive, flexible, and easily testable during the butt-joining process. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to overcome all or some of the above-mentioned problems by providing a method for butt-joining photosensitive plates that allows the production of individually testable connected subelements, thereby substantially reducing the risk of incompatibilities being detected on the finished product. In addition, the method that is the subject of the present invention allows for easy alignment of the subelements. It also provides a high degree of flexibility regarding the dimensions of the sensors obtained, without substantial investments or lengthy and complex developments. Other advantages of the method according to the invention are explained in more detail below. [Means for solving the problem]

[0009] To that end, one subject of the present invention is a first step of attaching an imaging sensor to a first substrate; a second step of dividing the first substrate at a predetermined distance around the attached imaging sensor; a third step of attaching a driver circuit board for driving the imaging sensor to the divided first substrate near the attached imaging sensor; a fourth step of connecting a driver circuit board to the attached imaging sensor to drive the imaging sensor to acquire the first tile; - repeating the first, second, third and fourth steps to obtain a second tile; a fifth step of butt-joining the resulting first and second tiles by placing the divided first substrates in edge-to-edge contact; a sixth step of attaching the butt-jointed tiles to a main substrate; a seventh step of connecting the driver circuit boards of the imaging sensors of the butt-jointed first and second tiles to the imager motherboard; A method for manufacturing an imager comprising:

[0010] Advantageously, the method of manufacturing an imager according to the invention includes a step of testing the compatibility of the tiles after the fourth step of connecting a driver circuit board for driving the imaging sensor to the coupled imaging sensor.

[0011] Advantageously, the method of manufacturing an imager according to the invention includes a step of storing the tiles after the fourth step of connecting a driver circuit board for driving the imaging sensors to the coupled imaging sensors.

[0012] Advantageously, in the method for manufacturing an imager according to the invention, the second step of dividing the first substrate is a step of dividing by a laser beam or by a Bessel beam.

[0013] Advantageously, the method for manufacturing an imager according to the invention comprises, after the first mounting step, a step of marking the first substrate.

[0014] In a method of manufacturing an imager according to the present invention, the first tile has dimensions different from the dimensions of the second tile.

[0015] The present invention also relates to an imager including a first tile and a second tile, each of the tiles comprising: a first substrate; an imaging sensor mounted on a first substrate, the first substrate being split at a predetermined distance around the periphery of the coupled imaging sensor; a drive circuit board for driving the imaging sensor, the drive circuit board being attached to the first substrate near the imaging sensor and connected to the imaging sensor; Including, the first tile and the second tile are butt-joined by placing the first substrates in edge-to-edge contact; The imager includes a main board on which the butt-jointed tiles are mounted, and a motherboard connected to a driver circuit board for driving the imaging sensors of the butt-jointed first and second tiles.

[0016] The first tile may have dimensions that are different from the dimensions of the second tile.

[0017] The invention will be better understood and other advantages will become apparent on reading the detailed description of one embodiment thereof, given by way of example, and which is illustrated by the accompanying drawings, in which: [Brief explanation of the drawings]

[0018] [Figure 1] 2 shows a diagram of the steps of a method for manufacturing an imager according to the present invention; [Figure 2] 1 shows a schematic representation of the main steps of a method for manufacturing an imager according to the present invention; [Figure 3] 1 illustrates schematically one embodiment of an imager according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] For clarity, the drawings are not all to scale. Furthermore, like elements are designated by like reference numerals throughout the various drawings.

[0020] 1 shows a diagram of the steps of a method for manufacturing an imager according to the present invention. The method for manufacturing an imager comprises steps 100 to 106, which are described in detail below. Optionally, it may also include steps 107, 108, and 109, employed individually or in combination.

[0021] FIG. 2 shows a schematic representation of the main steps of the method for manufacturing an imager according to the invention.

[0022] The method for manufacturing the imager 10 includes a first step 100 of attaching the imaging sensor 11 to a first substrate 12. The method according to the present invention may be applied to an imaging sensor 11 using CMOS or CCD technology. The imaging sensor 11 is shown here as having a rectangular shape, but may have other polygonal shapes. The imaging sensor 11 includes an imaging area 31 and a drive and connection area 32 for connecting the imaging sensor 11 to a driver circuit board and providing drive for the imaging sensor 11. The first substrate 12 may be made of a glass, ceramic, or crystalline material suitable for supporting the imaging sensor 11. The step 100 of attaching the imaging sensor 11 to the first substrate 12 is typically performed by bonding. Such bonding is advantageously achieved by attaching a double-sided adhesive film to the first substrate 12. Alternatively, an adhesive may be applied to the substrate 12. While bonding by an adhesive film remains the preferred attachment method, other methods of attaching the imaging sensor 11 to the first substrate 12 may also be implemented.

[0023] Bonding of the individual imaging sensors 11 to the first substrate 12 is therefore done without stringent alignment constraints: alignment is within a few millimeters rather than within a few micrometers as required by prior art methods.

[0024] The method according to the present invention then includes a second step 101 of dividing the first substrate 12 at a predetermined distance 14 around the periphery of the bonded imaging sensor 11. This divides the first substrate 12 around the entire periphery of the imaging sensor, leaving a small gap along the imaging area 31 of the imaging sensor 11 and a larger gap along one edge of the drive and connection area 32. This second gap is intended to accommodate a driver circuit board for driving the imaging sensor 11. Because the imaging sensor 11 is bonded to the first substrate 12, it is the first substrate 12 that is divided. This division must be precise (on the order of 5 μm) and can be performed using conventional equipment, such as by dividing a laser beam or a Bessel beam. A Bessel beam is a form of laser beam that is constructed by interference over long distances, allowing for intense concentration of energy that may extend long distances inside transparent materials without diffraction. Bessel beams, generated using ultrafast lasers, allow for deep drilling of exposed materials, and are particularly suitable for cutting nanochannels with high aspect ratios. Thus, it is possible to cut grooves with very small diameters (less than 2 μm) into glass layers several millimeters thick. After cutting the nanochannel into the first substrate, it may be split along the line defined by the nanochannel. This approach allows for good control of the split to provide the high-quality, precise machining required for accurately machining glass on an industrial scale.

[0025] The splitting step may be performed from either the front or back side of the first substrate 12. Splitting from the back side is still the preferred solution to avoid contamination on the imaging sensor 11. It is also possible to perform the splitting step with a blade, but it is still important to ensure precision of the split and to ensure that no contaminants get into the imaging sensor so as not to damage it.

[0026] The splitting step provides other advantages in terms of mechanical and electrical (ESD) protection for the subassembly of imaging sensors 11 that are attached to the first substrate 12. Specifically, the first substrate 12 is split to a size larger than the dimensions of the imaging sensors 11, eliminating the risk of lateral contact between the imaging sensors 11 during subsequent handling.

[0027] FIG. 2 shows an enlarged view of the first substrate 12 at a distance 14 from the imaging sensor 11 after a dividing step 101 that leaves a small base all around the imaging area 31 of the imaging sensor 11 .

[0028] The method according to the present invention further comprises a third step 102 of attaching a driver circuit board 13 for driving the imaging sensor 11 to the divided first substrate 12 in the vicinity of the attached imaging sensor 11. More specifically, the driver circuit board 13 is attached to the first substrate 12 so as to be juxtaposed with the drive and connection region 32 of the imaging sensor 11. In particular, the driver circuit board 13 may be attached by an adhesive film or by bonding using an adhesive.

[0029] The method according to the present invention then includes a fourth step 103 in which a driver circuit board 13 for driving the imaging sensor 11 is connected to the mounted imaging sensor 11 to obtain a first tile 21. The driver circuit board 13 is connected to the drive and connection area 32 of the imaging sensor 11. The connection step 103 may be performed by wire bonding. Wire bonding is one of the techniques used to make the electrical connection between the imaging sensor 11 and the driver circuit board 13. The wiring is realized using wires soldered between two connection pads provided for this purpose on each of the elements to be connected. Soldering is generally performed ultrasonically. The material of the wires is aluminum, gold, or copper. The diameter of the wires is on the order of 20 μm. Steps 100 to 103 are performed consecutively for one tile. Several steps 100 to 103 may be performed in parallel, i.e., simultaneously, to obtain several tiles.

[0030] The first, second, third, and fourth steps are repeated to obtain a second tile 22. This results in two tiles 21, 22, each on its own first substrate 12. In other words, there are the same number of first substrates 12 and tiles. Although the method is described here using two tiles, the principles apply equally to any number of tiles. While six tiles are visible in the imager of Figure 2, the method is particularly advantageously applicable to much larger imagers that implement many more tiles.

[0031] The method according to the invention includes a fifth step 104 of butt-joining the obtained first tile 21 and second tile 22 by placing the two divided first substrates 12 in edge-to-edge contact. Butt-joining refers to an end-to-end joining operation. Tile 21 is juxtaposed with tile 22. In other words, after the dividing step 101, the first substrate 11 presents sides that are substantially perpendicular to the plane of the imaging sensor 11. Each tile therefore has three free sides around the imaging area 31. The two tiles are butt-joined by placing one free side of one tile in contact with one side of the other tile. By butt-joining tiles two by two, it is possible to obtain imaging sensors 11 with very large areas.

[0032] Once the tiles are butt-joined, their positions are fixed. The method then includes a sixth step 105 of attaching the butt-joined tiles 21, 22 to a main substrate 23. The main substrate 23 is attached to the backside of the tiles, which helps stiffen the imager.

[0033] Finally, the method according to the present invention includes a seventh step 106 of connecting the driver circuit boards 13 of the imaging sensors 11 of the butt-jointed first tile 21 and second tile 22 to the motherboard 24 of the imager 10. Steps 104-106 are performed sequentially. They may also be performed in parallel, i.e., simultaneously, for multiple groups of tiles.

[0034] In one embodiment of the present invention, the method of manufacturing an imager may include a step 107 of testing the compatibility of the tiles after a fourth step 103 of connecting a driver circuit board 13 for driving the imaging sensor 11 to the mounted imaging sensor 11.

[0035] The division of the imaging sensors 11 individually onto the first substrate 12 and their connection to the driver circuit board 13 allows each tile to be isolated. Each tile can therefore be individually tested and characterized before storing, pairing, and butt-joining the tiles to produce the final imager.

[0036] By testing the compatibility of each individual tile, the risk of discarding high value added subassemblies is avoided because the compatibility testing occurs very early in the imager manufacturing process, eliminating potentially defective tiles.

[0037] In one embodiment of the present invention, the method for manufacturing an imager may include a step 108 of storing the tiles after a fourth step 103 of connecting a driver circuit board 13 for driving the imaging sensor 11 to the combined sensor 11.

[0038] In particular, manufacturing individual tiles addresses the need for secure storage. Because each imaging sensor 11 is bonded to its first substrate 12, there is little or no risk of breakage. Also, due to the UV treatment, it is possible to provide traceability when receiving the imaging sensor at the time of film cutting, prior to the end date. Specifically, the method according to the present invention may manufacture the imager in two stages: steps 100-103 are performed to obtain individual tiles, which are then stored. In a second stage, several stored, recently manufactured tiles may be butt-joined.

[0039] In one embodiment of the present invention, the method of manufacturing the imager may include a step 109 of marking the first substrate 12 after the first attachment step 100. The marking may be done by tagging, attaching a barcode, or etching a number or code, thereby allowing tracking of the imaging sensor 11. Once bonded to the first substrate 12, the first substrate 12 may be easily etched to associate chip manufacturing data (batch number, image characteristics, etc.).

[0040] Finally, it may be noted that the first tile 21 may have dimensions that are different from the dimensions of the second tile 22. This ability to butt-join tiles of different sizes provides great flexibility in the types of imagers that can be manufactured using the method of the present invention.

[0041] The present invention provides a solution that allows large imagers to be manufactured using standard equipment and methods in a new and innovative way. It avoids the risk of wasting high value-added material due to misalignment during traditional butt bonding (bonding all chips onto one substrate), breaking the imaging sensors during the butt bonding operation of the imaging sensors onto one substrate, or damaging the imaging sensors through static shock that can only be detected during testing after all the imaging sensors are assembled.

[0042] The present invention provides a solution that allows for fast separation of the "imaging sensor bonded to a first substrate" subassembly on the order of 200-300 mm / s, which means short cycle times. By manufacturing individual tiles, the present invention allows for safe storage of tested, working tiles.

[0043] Because each imaging sensor is bonded to a portion of the first substrate, the present invention allows for high traceability of the imaging sensors on the first substrate of a tile.

[0044] FIG. 3 schematically illustrates one embodiment of an imager according to the present invention. The imager 20 includes a first tile 21 and a second tile 22, each of which includes a first substrate 12, an imaging sensor 11 mounted on the first substrate 12, the imaging sensor 11 being separated by a predetermined distance 14 around the periphery of the combined imaging sensor 11, and a driver circuit board 13 adjacent to and connected to the imaging sensor 11 for driving the imaging sensor 11 mounted on the first substrate 12. According to the present invention, the first tile 21 and the second tile 22 are butt-joined by placing the two first substrates 12 in edge-to-edge contact. The imager 20 further includes a main board 23 on which the butt-joined tiles are mounted, and a motherboard 24 connected to the driver circuit boards 13 that drive the imaging sensors 11 of the butt-joined first tile 21 and second tile 22, for driving the multiple driver circuit boards 13 of the imaging sensors 11. The imager 20 therefore includes a plurality of tiles and a plurality of first substrates 12 (each tile having its own first substrate). The tiles are butt-joined by placing the individual first substrates of the tiles in edge-to-edge contact. The tiles so butt-joined are then attached to a main substrate 23 that is different from the first substrates.

[0045] In the imager 20 shown in Figure 3, the first tile 21 has dimensions that are different from the dimensions of the second tile 22. However, the present invention also relates to imagers 10 in which all of the tiles have the same dimensions.

[0046] The present invention applies to any image sensor fabricated by butt-joining photosensitive plates based on CMOS or other technologies. [Explanation of symbols]

[0047] 10 Imager 11 Imaging Sensor 12 First substrate 13 Driver circuit board 14 distance 20 Imager 21 First Tile 22 Second Tile 23 Main board 24 Motherboard 31 Imaging Area 32 Drive and connection area

Claims

1. A method of manufacturing an imager (10, 20), comprising the steps of: a. a first step (100) of attaching an imaging sensor (11) to a first substrate (12); b. A second step (101) of dividing the first substrate (12) at a predetermined distance around the attached imaging sensor (11); c) a third step (102) of mounting a driver circuit board (13) for driving the imaging sensor (11) on the divided first substrate (12) so as to be juxtaposed with the drive and connection area (32) of the mounted imaging sensor (11); d. A fourth step (103) of connecting the driver circuit board (13) for driving the imaging sensor (11) to the attached imaging sensor (11) to acquire a first tile (21); e. Repeating the first, second, third and fourth steps to obtain a second tile (22) on the first substrate (12); f. A fifth step (104) of butt-joining the resulting first tile (21) and second tile (22) by placing the two divided first substrates (12) in edge-to-edge contact; g. A sixth step (105) of attaching the butt-joined first tile (21) and second tile (22) to a main substrate (23); h. A seventh step (106) of connecting the driver circuit boards (13) of the imaging sensors (11) of the butt-jointed first and second tiles (21 and 22) to a motherboard (24) of the imager (10, 20); A manufacturing method comprising:

2. 2. The method for manufacturing an imager (10, 20) according to claim 1, further comprising a step (107) of testing compatibility of the first tile (21) and the second tile (22) after the fourth step (103) of connecting the driver circuit board (13) for driving the imaging sensor (11) to the coupled imaging sensor (11).

3. 3. A method for manufacturing an imager (10, 20) according to claim 1 or 2, further comprising a step (108) of storing the first tile (21) and the second tile (22) after the fourth step (103) of connecting the driver circuit board (13) for driving the imaging sensor (11) to the coupled imaging sensor (11).

4. 4. The method for manufacturing an imager (10, 20) according to claim 1, wherein the second step (101) of dividing the first substrate (12) is a step of dividing by a laser beam or by a Bessel beam.

5. A method for manufacturing an imager (10, 20) according to any one of claims 1 to 4, comprising, after said first step (100), a step (109) of marking said first substrate (12).

6. A method for manufacturing an imager (20) according to any one of claims 1 to 5, wherein the first tile (21) has dimensions different from the dimensions of the second tile (22).

7. An imager (10, 20), The invention includes a first tile (21) and a second tile (22), each of which comprises: a. a first substrate (12); b. an imaging sensor (11) attached to the first substrate (12), the first substrate (12) being divided at a predetermined distance (14) around the periphery of the imaging sensor (11) to which it is coupled; c. a driver circuit board (13) attached to the first substrate (12) to be connected to the imaging sensor (11) and to drive the imaging sensor (11); Including, The first tile (21) and the second tile (22) are butt-joined by placing two of the first substrates (12) in edge-to-edge contact; It includes a main board (23) on which the butt-jointed first tile and the butt-jointed second tile are mounted, and a motherboard (24) connected to the driver circuit board (13) for driving the imaging sensors (11) of the butt-jointed first tile (21) and second tile (22). An imager (10, 20) characterized by:

8. 8. The imager (20) of claim 7, wherein the first tile (21) has dimensions different from dimensions of the second tile (22).

Images