Method for transferring chips onto a substrate

Abstract

Title: Method for transferring chips onto a substrate. The invention relates to a method for transferring a set of chips (21, 22, … 29) onto a substrate. The method comprises providing a support (10) including a base (11) and a rim (12) including a first face (121) and a second face (122). The method includes arranging a first chip (21) and a second chip (22) in the support (10) by placing them on the base (11) of the support (10) and then applying a force to the chips so as to slide them against the first and second faces. The method further includes immobilizing the first and second chips and transferring each arranged chip onto the substrate. Figure for the abstract: Fig. 2B

Description

Title of the invention: Method for transferring chips onto a substrate technical field

[0001] The present invention relates to the field of electronics. It concerns in particular a method for transferring chips onto a substrate. The invention finds particularly advantageous applications in fields as varied as sensors and imagers. STATE OF THE ART

[0002] Electronic chips are used in a wide variety of fields, including microelectronics and optoelectronics. In all these fields, the chips are generally mounted on substrates that allow for various functionalities, including electrical interconnections and mechanical, optical, and / or thermal interfaces. The substrates can be printed circuit boards (PCBs), metal packages, or ceramic packages. The characteristics of the substrate on which the chips are mounted depend on the specific features of each chip.

[0003] To perform the transfer, the chips may, in particular, have beads on their rear face and be flipped over and transferred onto the substrate (flip chip). These chips can be very large (for example, 12 mm x 2 mm). These chips can be made of silicon or any other material depending on their function.

[0004] To create high-resolution devices (for example, sensors or imagers), one solution is to fabricate a single, large monolithic chip. However, the manufacturing of these large monolithic chips has a low yield. This technique is therefore not optimal.

[0005] An alternative is to fabricate several smaller chips, which have a better manufacturing yield, and join them together. The main challenge with this technique is to join the chips as close together as possible, or in contact with each other, in order to limit dead zones between the chips. Currently, to perform chip joining, the chips are picked up by the arm of a piece of equipment and positioned one by one on the substrate. However, this method has many drawbacks. First, this hybridization method is limited by the positioning accuracy of the equipment, which is currently around + / -0.5 µm. Furthermore, this hybridization method is time-consuming when many chips need to be joined: for example, a 5x5 chip array can take many hours to be placed on the substrate.Finally, this method of hybridization is risky because if one of the hybridizations goes wrong, it leads to the sacrifice of all of them. chips that are already hybridized, given that it is particularly difficult to cleanly remove a chip in order to hybridize a new one.

[0006] Another solution is to employ a mass reflow process, where the components are left free and self-align on their mounting pads when the interconnect material liquefies during heating. However, the positioning accuracy of the mounting pads does not allow this self-alignment phenomenon to be used on all substrates, particularly large ceramic substrates.

[0007] An objective of the present invention is therefore to provide a method for transferring chips onto a substrate that resolves at least some of the problems described above. Preferably, the method can be used on a wide range of substrates, preferably all substrates commonly used in microelectronics and optoelectronics. Preferably, the method will have a better yield than state-of-the-art methods. Advantageously, the method will provide accuracy at least equal to, and preferably greater than, the accuracy of currently employed methods. The method will advantageously reduce dead zones between chips. The method will advantageously reduce process risk and assembly time. SUMMARY

[0008] To achieve this objective, according to one embodiment, a method for transferring a set of chips onto a substrate is provided, the method being characterized in that it comprises: a. a supply of a support comprising a base extending parallel to a principal plane and a rim projecting from the base, the rim comprising at least a first face forming a first wedge and a second face forming a second wedge, the first face and the second face extending principally, in projection onto the principal plane, respectively in a first direction and in a second direction distinct from the first direction, b. an arrangement in the support of a first chip of the chip set, with: i. placing the first chip on the bottom of the support, ii. applying a force to the first chip so as to make it slide against the first and second sides of the rim, c. an arrangement in the support of a second chip in the chip assembly, with: i. a placement of the second chip on the bottom of the support, ii. applying a force to the second chip so as to make it slide against the first face of the rim and against an edge, called the secondary edge, of the first chip, d. immobilization of the first chip and the second chip in the principal plane, e. a transfer of each chip arranged on the substrate.

[0009] Thus, the first and second faces act as shims when arranging the chips. Existing techniques allow these shims to be manufactured and oriented relative to each other with high precision. These shims thus enable precise positioning of the individual chips.

[0010] The ability to press the chips against the surfaces also significantly reduces dead zones between the chips. The positioning of a chip relative to the adjacent chip is no longer dependent on the accuracy of the equipment. The chips are pressed against each other by applying a force towards the edge of the support. By applying sufficient force, the chips come into contact with each other. Thus, thanks to the method according to the invention, dead zones are almost non-existent or even completely eliminated.

[0011] According to one embodiment, the chips are immobilized using a liquid spread on the base of the support, exploiting the suction effect between the base of the support and the chips. The use of the liquid limits chip damage caused by scratching against the base during their arrangement. Furthermore, the suction effect between the base of the support and the chips ensures very good retention of the chips in their desired position.

[0012] The chip arrangement steps within the support can also be performed manually. Sliding the chips against the edges does not require as much precision from the operator or the equipment as in the prior art. The positioning accuracy comes from the precision of the support's edge geometry. Therefore, it is not necessary to use a robotic arm to position the chips. This reduces the cost of the process and also significantly reduces the time required to transfer the chips onto the substrate. For example, hybridizing the chips of a 5x5 array one by one onto a substrate using a robotic arm can take several days. Arranging the chips in the support and then transferring the arranged chips onto the substrate, according to the method of the invention, takes only about an hour.

[0013] Furthermore, the method according to the invention makes it possible to substantially align all the upper faces of the chips in a single plane. This plane typically corresponds to the gripping face of the tool used for transfer (whether it be a transfer arm or directly the transfer substrate). The method according to The invention thus allows, in addition to an arrangement of the chips in the longitudinal plane, their precise positioning along the vertical and thus makes it possible to obtain excellent flatness of all the upper faces of the chips.

[0014] Furthermore, the process according to the invention can be implemented on any type of substrate, without constraint in terms of materials or surface area.

[0015] The transfer method according to the invention is therefore easier to implement, more economical, and much less time-consuming than the methods used until now. It also significantly reduces dead zones between chips. Overall, the method according to the invention offers a much higher yield than existing methods. BRIEF DESCRIPTION OF THE FIGURES

[0016] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0017] [Fig.1A] Fig.1A is a top view of the support used in the process according to the invention.

[0018] [Fig.1B] Fig.1B is a perspective view of the support used in the process according to the invention.

[0019] [Fig.2A] [Fig.2B] [Fig.2C] [Fig.2D] Figures 2A to 2D illustrate the successive arrangement of chips in the support by the method according to the present invention.

[0020] [Fig.3A][Fig.3B] Figures 3A and 3B represent a set of chips arranged in the support.

[0021] [Fig.4] Fig.4 illustrates an example of an arm that can be used for transferring onto a substrate for the chips arranged in the support.

[0022] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the dimensions are not representative of reality. DETAILED DESCRIPTION

[0023] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0024] According to a preferred example, the first and second sides of the rim do not touch.

[0025] According to a preferred example, the rim has a so-called distant edge connecting the first edge and the second edge, and whose shape, when projected onto the principal plane, deviates of a form consisting of the extension of the first section and the second section up to their intersection, the portion thus forming a clearance.

[0026] According to a preferred example, the distant panel has, in projection into the principal plane, a shape of a circular arc whose extrados is turned towards the outside of the support.

[0027] According to a preferred example, the arrangement of the first chip is such that when two adjacent edges of the first chip, called principal edges, forming a corner of the first chip, are in contact with the first face and the second face, said corner of the first chip is not in contact with the rim.

[0028] According to one example, the rim forms a closed contour in projection into the principal plane.

[0029] According to one embodiment, immobilizing the first chip and the second chip in the principal plane comprises: a. Before the arrangement of the first and second chips in the support, a liquid is placed on the bottom of the support, b. When arranging the first chip in the holder, place the first chip on the bottom of the holder so that some of the liquid extends between the bottom and the first chip, c. When arranging the second chip in the holder, place the second chip on the bottom of the holder so that some of the liquid extends between the bottom and the second chip. d. after arranging the first chip and the second chip in the support, applying to each of the first and second chips a force directed towards the bottom of the support so as to expel at least part of the liquid present between said chip and the bottom of the support.

[0030] Pressing the chip against the bottom of the support increases the suction effect between the base of the support, the liquid, and the chip. The chip is thus firmly pressed against the base of the support and held securely in the desired position.

[0031] Advantageously, the step of applying the liquid to the bottom of the support is repeated several times during the arrangement of the chips in the support. Adding liquid during the process compensates for evaporation, particularly of the liquid not covered by the chips. All the chips thus benefit from the presence of the liquid, which allows them to adhere to the bottom of the support by suction.

[0032] According to one example, the liquid is chosen from the following: ethanol, isopropyl alcohol, water, acetone, a deoxidizing flux. The liquid can be chosen for various properties, particularly its deoxidizing properties, especially when the chips have certain solder materials. This is particularly advantageous when beads, for example indium beads, are present at the fleas. Isopropyl alcohol in particular has deoxidizing properties that can be exploited.

[0033] According to one embodiment, the step of immobilizing the first chip and the second chip in the main plane comprises: a. When arranging the first chip in the holder, apply an adhesive agent between the base and the first chip. b. When arranging the first chip in the holder, place an adhesive agent between the base and the second chip.

[0034] According to a preferred example, the step of transferring each arranged chip onto the substrate includes heating the support.

[0035] According to one embodiment, the step of immobilizing the first chip and the second chip in the main plane includes pressing the first chip and the second chip against the bottom of the support by suction.

[0036] According to one example, the method further comprises an arrangement in the support of a third chip from the chip assembly, with: a. the placement of the third chip on the bottom of the support, b. applying a force to the third chip so as to make it slide against its stop: i. against the first face and against an edge called the secondary edge of the first chip, or ii. against the second face and against an edge of the second chip, c. an immobilization of the third chip in the principal plane.

[0037] According to one embodiment, along a third direction perpendicular to the principal plane: a. The chips to be transferred have a thickness e20, the thickness e20 being measured when the chips are placed on the bottom of the support, b. The rim has a height h[2,

[0038] with hi2 <e20.

[0039] According to one embodiment, the step of transferring the set of chips arranged on the substrate comprises the following step: a. While the arranged chip assembly is in the support, bring the substrate onto the arranged chip assembly.

[0040] According to one embodiment, the step of transferring the assembly of chips arranged on the substrate comprises the following steps: a. Remove the assembled chips from the holder using an arm, b. place the set of arranged chips on the substrate, the arm being configured to allow the relative positioning of the chips of the set of arranged chips to be maintained during the execution of these steps.

[0041] According to one example, the arm is configured to suction each of the arranged chips.

[0042] Preferably, the first direction and the second direction are perpendicular. This is advantageous in the typical case of rectangular or square chips.

[0043] It is specified that, within the framework of the present invention, the terms "on", "overcomes", "covers", "underlying", "opposite" and their equivalents do not necessarily mean "in contact with". Thus, for example, the depositing, transferring, gluing, assembling or applying a first element onto a second element does not necessarily mean that the two elements are directly in contact with each other, but means that the first element at least partially covers the second element by being either directly in contact with it or by being separated from it by at least one other element.

[0044] A coordinate system, preferably orthonormal, comprising the X, Y, and Z axes is shown in Figures IA, IB, and 2A. This coordinate system is applicable by extension to the other figures. In this patent application, the terms thickness for a layer or plate and height for a structure or device will be preferred. The height is measured perpendicular to the principal XY plane. The thickness is measured in a direction normal to the principal plane of extension of the layer or plate. Thus, a layer / plate typically has a thickness in the third direction Z when it extends mainly along the principal XY plane, and a protruding element, for example, a trench or a tab, has a height in the third direction Z. Unless otherwise stated, the relative terms "on," "under," "below," "above," and "below" refer to positions measured in the Z direction.

[0045] The terms "approximately", "about", "in the order of" mean "to within 10%, preferably to within 5%".

[0046] The method according to the invention employs a support 10 illustrated in Figures IA and IB. The support 10 has a base 11 and a rim 12 projecting from the base 11. The base 11 extends parallel to a principal plane XY. The rim 12 is typically substantially perpendicular to the base 11. The rim 12 of the support 10 has a height hi2 measured along the third direction Z perpendicular to the principal plane XY.

[0047] The rim 12 comprises at least a first face 121 and a second face 122. These two faces 121, 122 form wedges which will be used, during the implementation of the method, to correctly position the chips.

[0048] When projected onto the principal plane XY, the first panel 121 extends substantially along a first direction X and the second panel 122 along a second direction Y. By "the panel extends substantially along a direction," it is meant that the general shape of the panel is elongated along this direction. Typically, the panel is parallel to this direction. However, it is not excluded that the panel may exhibit deviations by in relation to this general direction. For example, the panel may have recesses in the direction perpendicular to its main direction of extension, such as in the form of crenellations. It is also possible to dimension the panel so that contact between the adjacent chip and the panel occurs at two bearing points. This can limit the contact area between the chips and the edge, thus reducing chip degradation. A panel may also be discontinuous and have through-holes in the direction perpendicular to its main direction of extension. Such openings also limit the contact area between the chips and the edge. Furthermore, the openings in the panels facilitate the drainage of excess liquid used to hold the chips in their respective arranged positions (see below).

[0049] Preferably, the first face 121 and the second face 122 are perpendicular to each other. This is advantageous for positioning rectangular or square chips.

[0050] The rim 12 optionally includes a third face 123 and a fourth face 124. Advantageously, the faces 121, 122, 123, 124 of the rim 12 are perpendicular to each other. The rim 12 thus has, in projection onto the principal plane XY, a general rectangular or square shape.

[0051] The rim 12 preferably further comprises a distant face 125 connecting the first face and the second face 122. The distant face 125 forms a recess 13 relative to the general shape of the rim 12. The distant face 125 forms an open contour connected on one side to the first face 121 and on the other side to the second face 122. This open contour encompasses the corner that would have been formed if the first face 121 and the second face 122 had been extended to their intersection. The rim 12 thus defines a larger periphery of the support 10 than if the first and second faces 121, 122 had simply been extended to their intersection. The distant face 125 typically has an arc-shaped form. The intrados of the distant face 125 is then opposite the rest of the support 10. Its extrados is turned outwards from the support 10.

[0052] As will become apparent during the description of the method according to the invention, the clearance 13 formed by the distant pan 125 makes it possible to limit the damage to the corner of the first chip 21 arranged in the support 10.

[0053] According to another embodiment not shown, the rim 12 does not include a distant face 125 and the rim 12 forms an open contour between the first face 121 and the second face 122. The absence of a corner formed by the first face 121 and the second face 122 also helps to limit damage to the corner of the first chip 21 when it is placed in the support 10. The absence of a corner formed by the first and second faces 121, 122 also makes it easier to remove excess material. liquid used to maintain the chips in their respective arranged positions (see below).

[0054] Advantageously, the panels, and in particular the first and second panels 121, 122, admit an opening or form a recess with respect to their principal direction of extension at the corners of the chips when the latter are in their respective arranged positions. This makes it possible to limit the degradation of the chips at their corners.

[0055] In the two examples described above, it is understood that the spacing between the first panel 121 and the second panel 122 is dimensioned so as to allow these two panels 121, 122 to act simultaneously as a stop for the first chip 21 placed in the support 10, as will be described later.

[0056] It is understood that the shape of the rim 12 described above is given by way of example and that it is possible to use a support 10 whose rim 12 has a different geometry. The geometry illustrated in Figures IA and IB is, however, the preferred geometry for implementing the method according to the invention.

[0057] The support 10 can be made of silicon or stainless steel. The base 11 can, for example, be a silicon wafer. The various facets 121, 122, 123, 124 of the rim 12 can be silicon shims. These shims may have been bonded to the silicon substrate forming the base 11. They may also have been manufactured directly on the wafer by an etching process. It is also possible that the shims forming the facets were simply deposited on the base 11. The support 10 can also be obtained by mechanical machining, for example, using silicon carbide (SiC) tooling.

[0058] Different embodiments of the process according to the invention will now be described in detail with reference to figures 2A to 2D.

[0059] A first step of the process is the provision of a support 10 as described above.

[0060] According to a first principal embodiment, liquid is then deposited in the support 10, on the base 11. This liquid can be chosen from: ethanol, isopropyl alcohol, water, acetone. This liquid can also be a flux for deoxidizing the metal pads of the chips.

[0061] The liquid can be deposited in the form of drop(s) on the bottom 11 of the support 10. It is also possible to implement a flow of the liquid. The liquid then forms a flow on the bottom 11 of the support 10.

[0062] Next, a first chip 21 is arranged in the support 10, as illustrated in [Fig.2A]. This arrangement is carried out in the following manner.

[0063] The first chip 21 is placed on the base 11 of the support 10. Preferably, the first chip 21 is placed on the base 11 of the support 10 so that the liquid extends between the base 11 and the chip 21. The first chip 21 can be deposited using forceps such as tweezers or a suction pen, which allows very good preservation of the chips during the operation.

[0064] The first chip 21 is then moved to its arranged position. To do this, a force is applied to the first chip 21 to move it until it is against both the first face 121 and the second face 122 of the rim 12. The arrows shown in [Fig. 1A] illustrate that in the illustrated case, this force has a component along the first direction X and a component along the second direction Y.

[0065] During its movement to its arranged position, the first chip 21 slides on the base 11 thanks to the applied lateral force. The liquid helps to limit damage to the chip from friction with the base 11 of the support 10.

[0066] Applying force to the first chip 21 can be done manually by a user. The movement of the first chip 21 can optionally be carried out in two steps: a first step to bring the first chip 21 against the first face 121, and a second step to bring it against the second face 122 by sliding it against the first face 121. However, it is then preferable to apply force again to the first chip 21 to ensure that it is firmly pressed against both faces 121 and 122. It is also possible to apply force successively several times along the first X direction and along the second Y direction.

[0067] This gives us the configuration illustrated in [Fig.2A]: the first chip 21 is in contact with both the first face 121 and the second face 122. More precisely, a first edge 21a of the first chip 21 is in contact with the first face 121 and a second edge 21b of the first chip 21 is in contact with the second face 122 of the rim 12. It is then held in place by suction effect.

[0068] As illustrated in [Fig. 2A], thanks to the clearance 13, the corner 21* of the first chip 21, formed by its first edge 21a and its second edge 21b, is free. In other words, it is not in contact with the rim 12. Indeed, if the first face 121 and the second face 122 were extended to form an angle (typically a right angle), the corner 21* would be complementary to this angle. However, if the force applied to the first chip 21 were misdirected and / or applied with too much force, or due to manufacturing tolerances of the chips and the substrate, the corner 21*, which is a point of weakness of the first chip 21, could be damaged. The clearance 13 therefore limits the degradation of the first chip 21 at this corner 21*. It is also noted that the first chip 21 also experiences forces directed against the first pan 121 and the second pan 121 when the other chips are arranged.Indeed, as will become apparent later, the first chip 21 subsequently serves itself. acting as a stop for other chips and / or serving as a support point for other chips which will themselves act as stops. The clearance thus protects corner 21* throughout the process.

[0069] The method further includes a step of arranging a second chip 22 ([Fig. 2B]). The arrangement of the second chip 22 is carried out according to the same principle as that of the first chip 21, except that the second chip 22 does not come into direct contact with the two faces 121, 122, but comes abutting on the one hand against one of the first face 121 and the second face 122, and on the other hand against an edge of the first chip 21. In the example illustrated in [Fig. 2B], the second chip 22 comes abutting against the first face 121 and against the referenced edge 21d of the first chip 21.

[0070] Thus, during this step, the first chip 21 acts as a stop for the second chip 22.

[0071] The movement of the second chip 22 is carried out in a similar manner to that of the first chip 21: the second chip 22 is placed on the liquid disposed on the bottom 11 of the support 10, then is slid into its arranged position.

[0072] This gives us the configuration illustrated in [Fig.2B].

[0073] The successive arrangement of the first chip 21 and the second chip 22 can be carried out sequentially: first the complete arrangement of the first chip 21, then the complete arrangement of the second chip 22. This is the preferred embodiment and the one illustrated in Figures 2A and 2B. It is understood, however, that it is possible for the arrangement of the first chip 21 and that of the second chip 22 to be carried out in parallel. For example, it is possible to place the first chip 21 against the first face 121, place the second chip 22 against the second face 121, and then place the assembly formed by the first chip 21 and the second chip 22 against the second face 122.

[0074] The method may include the arrangement of other chips. Figures 2C and 2D illustrate the arrangement of a third chip 23 and a fourth chip 24.

[0075] The third chip 23 can be positioned in two distinct locations: either against the second face 122 and against a secondary edge 21c of the first chip 21 (example illustrated in [Fig.2C]), or against the first face 121 and against an edge 22d of the second chip 22. In both cases, the arrangement of the third chip 23 is carried out as for the previous chips 21, 22: the third chip 23 is placed on the liquid and is slid on the bottom 11 of the support 10 until it reaches its arranged position.

[0076] During this step, the first chip 21 or the second chip 22 acts as a stop for the third chip 23.

[0077] Several positions are also possible for the fourth chip 24 (in contact with the first face 121, in contact with the second face 122, or only in contact with previously arranged chips). [Fig. 2D] illustrates the example in which the second and third chips 22, 23 have each been placed against a separate face 121, 122, and in which the fourth chip 24 is placed against each of these two chips 22, 23. The fourth chip 24 is thus in contact with the reference edge 22c of the second chip 22 and with the reference edge 23d of the third chip 23.

[0078] In this example, both the second chip 22 and the third chip 23 act as a stop for the fourth chip 24.

[0079] The process can continue in this way for any number of chips, for example a 3x3 matrix, i.e., a matrix of nine chips. Figures 3A (perspective view) and 3B (top view) illustrate such a matrix of nine chips 21, 22, 23, 24, 25, 26, 27, 28, 29 arranged in the support 10.

[0080] Preferably, the support 10, and in particular the rim 12, will have been dimensioned larger than the size of the final chip array. In particular, as illustrated in Figures 3A and 3B, preferably, there is a gap between the chips 25, 26, 27, 28, 29 on the one hand and the second and third sides 123, 124 on the other. This gap facilitates the handling of the chips.

[0081] In general, the arrangement of the set of chips to be transferred can be achieved by arranging each chip 21, 22, ... 29 in the holder 10 with: a. a placement of the chip 21, 22, ... 29 on the base 11 of the support 10 in such a way that part of the liquid extends between the base 11 and the chip 21, 22, ... 29, b. applying a force to the chip 21, 22, ... 29 so as to make it slide until it is stopped by the first face 121 and by the second face 122 of the rim 12, possibly by means of one or more chips 21, 22, ... 29 previously arranged in the support 10.

[0082] Advantageously, when a chip is positioned correctly, a force directed towards the bottom 11 of the support 10 is applied to the chip. This creates a suction effect between the bottom 11, the liquid, and the chip. This suction effect holds the chip in place.

[0083] Moreover, preferably, liquid is added repeatedly to the bottom 11 of the support 10 in order to have liquid available for the arrangement of all the chips.

[0084] As explained previously for the arrangement of the first two chips 21, 22, it is possible to carry out in parallel the arrangement of several chips of the set of chips 21, 22... 29.

[0085] The third panel 123 and / or the fourth panel 124 can also be used to push the set of chips against the first panel 121 and the second panel 122. In this example, the third and fourth sides 123, 124 are removable relative to the base 11. The operator or equipment can use these sides to simultaneously push several chips placed on the base 11 of the holder 10 and ensure that they are correctly arranged. This step is typically performed once all the chips are arranged on the base 11 of the holder 10.

[0086] The chips have a thickness e20 measured along the third direction Z. The thickness e20 can be greater than the height h[2 of the rim 12, as illustrated in [Fig. 3A]. For example: e20 = 250 pm and h[2 = 180 pm. e20 can also be less than h[2. This is a perfectly feasible scenario in the case of very thin chips, for example; in this case, the rim must then be removable in order to be able to remove the chips.

[0087] The method further comprises a step of transferring all the arranged chips onto a substrate. Advantageously, all the arranged chips are transferred simultaneously onto the substrate.

[0088] This reporting step can be carried out in different ways.

[0089] According to a first example, during this step, the arranged chips are held in the support 10 and the substrate is inverted and brought against the chips to perform the transfer. In this example, it is preferable that e20 > hi2 so that the chips are more easily accessible.

[0090] According to a second example, an arm is used to extract the arranged chips from the support 10 and transfer them to the substrate. The arm is then configured to maintain the relative position of the arranged chips during the transfer. A schematic cross-sectional view of an example of an arm that can be used in this step is shown in [Fig. 4]. The arm may include a suction system configured to suction and hold each chip against a tool 30 typically located at the end of the arm. The tool 30 may thus have openings 35, 36 through which the chips are suctioned. Typically, the tool 30 has a main opening 36 intended to be positioned opposite a chip and connected via narrow openings to a plurality of secondary openings 35, each intended to be positioned opposite a separate chip. References 21', 22', 23', 24', 25', 26', 27', 28' and 29' of the [Fig.4] illustrate the location against tool 30 intended for each of the chips 21, 21, 23, 24, 25, 26, 27, 28 and 29. .

[0091] In this second example, the chips can either extend beyond the rim 12 along the third direction Z (e20>hi2) or be set back from the rim 12 (e2o <hi2) ou être au même niveau (e20="hi2)." cela dépendra des dimensions de l’outil contre lequel les puces sont aspirées.

[0092] According to another embodiment, the support 10 is mounted on. The transfer onto the substrate is then done directly by moving the arm in relation to the substrate and deactivating the suction.

[0093] Preferably, during the transfer step, the support 10 is heated. This reduces or even eliminates the suction effect of the chips arranged against the base 11 of the support 10 and facilitates their transfer onto the substrate.

[0094] To facilitate the removal of the chips from the support 10, it is also possible to provide that the base 11 of the support 10 has a certain roughness. The roughness of the support 10 will thus limit the suction effect.

[0095] The method has been described so far for a first main embodiment, in which the immobilization of the chips in their respective arranged positions is done by means of a liquid spread on the bottom 11 of the support 10. Other embodiments are however conceivable for immobilizing the chips while they are being transferred onto the substrate.

[0096] According to a second main embodiment, an adhesive agent is placed between the chips 21, 22... 29 and the base 11 of the support 10. The adhesive agent can be applied to the chips, to the base 11 or to both before the chips are placed in the support 10.

[0097] The adhesive agent may include, in particular, a glue, an adhesive gel, an adhesive tape.

[0098] Preferably, the properties of the adhesive agent (in particular its viscosity) allow the chips to be moved into their arranged position. Thus, the chips 21, 22... 29 can be placed on the base 11 of the support 10 and slid onto this base 11 by means of the adhesive agent.

[0099] As in the first main embodiment, preferably, to facilitate the detachment of the chips from the support 10 and their transfer onto the substrate, the support 10 is heated. Preferably, the support 10 is heated to a temperature at least equal to the melting point of the adhesive agent.

[0100] According to a third main embodiment, the chips are pressed against the bottom 11 of the support 10 by suction. This suction is typically carried out under vacuum. In this embodiment, the suction is maintained throughout the transfer of the chips onto the substrate. In this embodiment, it is preferable to transfer the chips onto the substrate by bringing the substrate onto the chips.

[0101] It is understood that all the features described in the first main embodiment apply to the second and third main embodiments.

[0102] In view of the different embodiments described above, it appears that the present invention offers an effective solution for transferring chips onto a substrate.

[0103] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

Demands

1. A method for transferring a set of chips (21, 22, ... 29) onto a substrate, the method being characterized in that it comprises: • a supply of a support (10) comprising a base (11) extending parallel to a principal plane (XY) and a rim (12) projecting from the base (11), the rim (12) comprising at least a first face (121) forming a first wedge and a second face (122) forming a second wedge, the first face (121) and the second face (122) extending principally, in projection onto the principal plane (XY), respectively along a first direction (X) and along a second direction (Y) distinct from the first direction (X), • an arrangement in the support (10) of a first chip (21) of the set of chips (21, 22, ... 29), with: i. a placement of the first chip (21) on the bottom (11) of the support (10), ii. applying a force to the first chip (21) so as to make it slide against the first face (121) and against the second face (122) of the rim (12), • an arrangement in the support (10) of a second chip (22) of the chip assembly (21, 22, ... 29), with: i. a placement of the second chip (22) on the bottom (11) of the support (10), ii. applying a force to the second chip (22) so as to make it slide against the first face (121) of the rim (12) and against an edge (21d), called the secondary edge (21d), of the first chip (21), • immobilization of the first chip (21) and the second chip (22) in the principal plane (XY), • a report of each chip (21, 22) arranged on the substrate.

2. Method according to the preceding claim in which the first face (121) and the second face (122) of the rim (12) do not touch.

3. A method according to any one of the preceding claims in which the rim (12) has a so-called distant face (125) connecting the first face (121) and the second face (122) and whose shape, in projection in the principal plane (XY), deviates from a shape consisting of the extension of the first face (121) and the second face (122) up to their intersection, the portion (125) thus forming a clearance (13).

4. Method according to the preceding claim in which the distant panel (125) has, in projection in the principal plane (XY), a shape of arc of a circle whose extrados is turned towards the outside of the support (10).

5. A method according to any one of the preceding claims wherein the arrangement of the first chip (21) is such that when two adjacent edges (21a, 21b) of the first chip (21), called principal edges (21a, 21b), forming a corner (21*) of the first chip (21), are in contact with the first face (121) and the second face (122), said corner (21*) of the first chip (21) is not in contact with the rim (12).

6. A method according to any one of the preceding claims, wherein the immobilization of the first chip (21) and the second chip (22) in the principal (XY) plane comprises: • before arranging the first chip (21) and the second chip (22) in the holder (10), arranging a liquid on the bottom (11) of the holder (10), • during the arranging of the first chip (21) in the holder (10), placing the first chip (21) on the bottom (11) of the holder (10) such that a portion of the liquid extends between the bottom (11) and the first chip (21), • during the arranging of the second chip (22) in the holder (10), placing the second chip (22) on the bottom (11) of the holder (10) such that a portion of the liquid extends between the bottom (11) and the second chip (22), • after the arrangement in the support (10) of the first chip (21) and the second chip (22),an application to each of the first chip (21) and the second chip (22) of a force directed towards the bottom (11) of the support (10), so as to expel at least part of the liquid present between said chip (21, 22) and the bottom (11) of the support (10).

7. A method according to the preceding claim in which the step of disposing of the liquid on the bottom (11) of the support (10) is repeated several times during the arrangement of the chips (21, 22, ... 29) in the support (10).

8. A method according to any one of the two preceding claims wherein the liquid is selected from the following liquids: ethanol, isopropyl alcohol, water, acetone, a deoxidizing flux.

9. A method according to any one of claims 1 to 5 wherein the step of immobilizing the first chip (21) and the second chip (22) in the principal plane (XY) comprises: • when arranging the first chip (21) in the support (10), disposing of an adhesive agent between the base (11) and the first chip (21), • when arranging the first chip (21) in the support (10), disposing of an adhesive agent between the base (11) and the second chip (22).

10. A method according to any one of the preceding claims wherein the step of transferring each chip (21, 22) arranged on the substrate includes heating the support (10).

11. A method according to any one of claims 1 to 5 wherein the immobilization step of the first chip (21) and the second chip (22) in the principal plane (XY) comprises pressing the first chip (21) and the second chip (22) against the bottom (11) of the support (10) by suction.

12. A method according to any one of the preceding claims further comprising an arrangement in the support (10) of a third chip (23) of the set of chips (21, 22, ... 29), with: • a placement of the third chip (23) on the bottom (11) of the support (10), • an application of a force to the third chip (23) so as to make it slide against: i. the first face (121) and against an edge called the secondary edge (21c) of the first chip (21), or ii. against the second face (122) and against an edge (22d) of the second chip (22), • an immobilization of the third chip (23) in the principal plane (XY).

13. A method according to any one of the preceding claims, wherein, along a third direction (Z) perpendicular to the principal plane (XY): • the chips to be transferred have a thickness e20, the thickness e20 being measured when the chips are placed on the bottom (11) of the support (10), • the rim (12) has a height h12, with h12 <e20.

14. A method according to any one of the preceding claims wherein the step of transferring the arranged chip assembly onto the substrate comprises the following step: • while the arranged chip assembly is in the support (10), bring the substrate onto the arranged chip assembly.

15. A method according to any one of claims 1 to 13 wherein the step of transferring the arranged chip assembly onto the substrate comprises the following steps: • removing the arranged chip assembly from the support (10) using an arm, • placing the arranged chip assembly onto the substrate, the arm being configured to allow the relative positioning of the chips in the arranged chip assembly to be maintained during the execution of these steps.

16. A method according to the preceding claim in which the arm is configured to suck up each of the arranged chips.

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