Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
  • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
  • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
  • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
  • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/005—Processes
  • H01L33/0093—Wafer bonding; Removal of the growth substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67011—Apparatus for manufacture or treatment
  • H01L21/67144—Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/673—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere using specially adapted carriers or holders; Fixing the workpieces on such carriers or holders
  • H01L21/67333—Trays for chips

Definitions

• the present invention relates to the field of technologies for optoelectronics. It finds a particularly advantageous application in the manufacture of optoelectronic systems by mass transfer of unitary optoelectronic devices, for example light-emitting diodes based on GaN. STATE OF THE ART
• a self-emissive display screen is an example of a known optoelectronic system.
• Such a screen comprises a plurality of pixels emitting their own light.
• Each pixel is thus typically formed by one or more LEDs, more particularly mini-LEDs or micro-LEDs.
• Each LED is a unitary optoelectronic device.
• mass transfer technologies for LEDs have been developed. Some transfer technologies are based on a principle known as “pick and place” according to the usual Anglo-Saxon terminology (meaning “pick and place”).
• unitary devices are individualized on a donor substrate.
• a manipulation substrate is then attached to a free face of the unitary devices.
• the donor substrate can then be eliminated, for example by trimming.
• the unitary devices are then detached from the handling substrate and transferred to a receiving substrate.
• a solution disclosed by document US 9379092 B2 consists in forming a sacrificial structure partially enveloping each device, during the manufacture of the devices.
• the donor substrate is removed by trimming.
• the sacrificial structures and the holding studs make it possible to maintain and stabilize the devices during trimming.
• the etching of the sacrificial structures then makes it possible to partially release the devices.
• the devices are no longer retained except by the small-sized holding studs.
• the devices are then assembled on a receiving substrate and detached from the handling substrate. Detachment is facilitated by the use of holding studs.
• a disadvantage of this solution is that the manufacture of the device must be adapted to provide and form in particular the sacrificial structure. This makes the process complex and restrictive. This limits the versatility of the transfer process. Furthermore, sufficient space must be provided between the unitary devices to allow the etching of the sacrificial structures. This limits the possibilities of densification of unitary devices and therefore of cost reduction. Retention pads may leave residue on devices upon detachment. It is then more difficult to obtain good electrical contact on the devices.
• the present invention aims to at least partially overcome the drawbacks mentioned above.
• an object of the present invention is to propose a transfer structure making it possible to transfer an optoelectronic device in an optimized manner.
• Another object of the present invention is to provide a method for transferring optoelectronic devices.
• one aspect relates to a transfer structure comprising a support and an optoelectronic device attached to the support, the support comprising a base part having a support face, and at least one element projecting from the support, the optoelectronic device having a first face comprising a central zone and a peripheral zone surrounding the central zone.
• the at least one projecting element of the support is attached to the peripheral zone of the first face of the optoelectronic device, so that the support face, the at least one projecting element and the first face of the device form a cavity under the central zone.
• the at least one projecting element is located under the optoelectronic device and at the edge thereof.
• the at least one projecting element is similar to one or more vertical cantilevers supporting the peripheral zone of the optoelectronic device.
• the lateral bulk of the transfer structure is reduced. This makes it possible to increase the density of optoelectronic devices on the support.
• a cavity delimited by the vertical cantilevers is thus formed under the central zone of the device. This makes it easy to detach the device optoelectronics of its support, for example by exerting a vertical force on the optoelectronic device.
• the central zone of the device is also preserved. It can be functionalized, for example by carrying metal contacts of the optoelectronic device.
• Another aspect relates to a transfer system comprising a plurality of adjacent transfer structures.
• at least one projecting element of two adjacent transfer structures is common to the peripheral zones of said adjacent transfer structures. This makes it possible to increase the density of transfer structures within said transfer system.
• Another aspect relates to a method for transferring a plurality of optoelectronic devices from a first substrate to a second substrate, said method comprising at least the following steps:
• the optoelectronic devices each having a first face on a side opposite the first substrate, said first face comprising a central zone and a peripheral zone surrounding the central zone,
• a support for the optoelectronic devices comprising a base part having a support face, and at least one element projecting from the support face, each peripheral zone being attached to said at least one projecting element, so that the support face, the at least one protruding element and the first face of the device form a cavity under the central zone,
• the method advantageously makes it possible to transfer a plurality of optoelectronic devices via the support.
• the optoelectronic devices can comprise at least one light-emitting diode, typically formed on the first substrate, and preferably a part of electrical interconnections hybridized on the diode.
• This part of electrical interconnections can be formed separately on a support layer, then added by hybridization on the diode, before forming the support.
• the electrical interconnection part may also include an electronic control circuit dedicated to driving the diode, to form “smart” LEDs, according to the usual English terminology (meaning “smart” LED).
• the support can be made independently of the devices. This reduces the constraints on the design of the devices.
• the at least one projecting element of the support can be formed from the device, for example by taking advantage of the support layer of the electrical interconnection part.
• This method can advantageously be applied during the transfer of LEDs or smart LEDs from a donor substrate, for example a growth substrate, to a receiver substrate, for example a CMOS substrate comprising LED control electronics.
• FIGURES 1A to 1M illustrate steps of an LED transfer method according to a first embodiment of the present invention.
• FIGURES 2A to 2M illustrate steps of an LED transfer method according to a second embodiment of the present invention.
• FIGURES 3A to 3I illustrate steps of an LED transfer method according to a third embodiment of the present invention.
• the transfer structure comprises at least two projecting elements, and preferably at least four projecting elements, regularly arranged on either side of the central zone. This makes it possible to balance the mechanical forces applied to the support or the structure.
• the protruding elements are preferably arranged according to a central symmetry with respect to the center or the barycenter of the central zone, in projection on a base plane parallel to the face of the support.
• the central zone of the first face comprises at least one metallic contact.
• this metallic contact is not covered or is not partially covered by a projecting element. It is thus directly functional, without a prior stage of cleaning or removal of the element(s) covering it.
• the at least one projecting element has a first dimension along a first direction x, a second dimension along a second direction y, and a third dimension along a third direction z, the first and second directions x, y forming a base plane parallel to the support face, and the third direction z being perpendicular to this base plane.
• Said first, second and third dimensions are such that at least one of the first and second dimensions is less than the third dimension.
• the at least one projecting element extends mainly vertically, for example along z or in a zx plane or in a zy plane. Its horizontal extension, in an xy plane, thus remains limited.
• the optoelectronic device comprises at least one light-emitting diode in line with the central zone, and has a second face opposite the first face, said second face forming a light-emitting face.
• the at least one light-emitting diode is preferably circumscribed by the peripheral zone, in projection on a base plane parallel to the face of the support.
• the at least one light-emitting diode in this case occupies only the central zone. It does not extend to the peripheral zone.
• the optoelectronic device further comprises a part of electrical interconnections forming the first face. This part of electrical interconnections can comprise vias and/or one or more electronic control microcircuits, also called pICs.
• the optoelectronic device comprising at least one light-emitting diode and an electronic control microcircuit associated with said at least one diode typically forms a “smart LED”.
• the adjacent optoelectronic devices are separated from each other by trenches formed directly above the at least one projecting element.
• the optoelectronic devices are thus “individualized”.
• the trenches can totally or partially separate the optoelectronic devices from one another.
• the trenches can extend, in a direction perpendicular to the face of the support, under a reference plane comprising the first faces of the devices.
• the bottom of the trenches can be located above said reference plane.
• the at least one protruding element has a first dimension along a first direction x and a second dimension along a second direction y, the first and second directions x, y forming a base plane parallel to the support face , and the trenches have at least one dimension along at least one of the first and second directions x, y smaller than the first and second dimensions of the at least one projecting element.
• the trenches are thus narrower than the at least one projecting element.
• the width of the trenches is less than the width of the at least one projecting element, said widths being taken in the same direction of the base plane.
• the trenches extend in the at least one projecting element in a third direction z perpendicular to the first and second directions x, y.
• the bottom of the trenches is then located under the reference plane comprising the first faces of the devices.
• the method further comprises, after removal of the first substrate and before separation of the optoelectronic devices, a formation of trenches separating the optoelectronic devices from each other, so that these are individualized and supported only by the at least one protruding element.
• the trenches are formed by etching directly above the at least one projecting element, from a second face of the optoelectronic devices opposite the first face.
• the etching is configured so that the trenches partly continue in the at least one protruding element.
• the optoelectronic devices each comprise at least one light-emitting diode and a part of electrical interconnections, the at least one light-emitting diode being produced on the first substrate and said part of interconnections electrical connections being made separately on a support layer, said portion of electrical interconnections then being transferred by hybridization onto the at least one light-emitting diode, before forming the support.
• the at least one projecting element is formed before being attached to the peripheral zones of the first faces of the optoelectronic devices.
• the at least one protruding element is formed by etching a silicon substrate. The solid part of the silicon substrate then forms the base part of the support. The support is thus formed separately from the optoelectronic device.
• the at least one protruding element is formed by etching the support layer, then is attached to a flat substrate so as to form the support, before removing the first substrate.
• the at least one protruding element is thus formed from the microelectronic device.
• the support is thus formed after the at least one protruding element is attached to the peripheral zones of the first faces of the optoelectronic devices.
• the method further comprises, before separating the optoelectronic devices, fixing only part of said optoelectronic devices to the support face, said fixing being carried out by depositing an adhesive material in the cavity, between the area central and the support face. This makes it possible to retain certain devices on the support, during the transfer of the other devices to the second substrate, called the receiver substrate.
• the method further comprises, before fixing, an electrical test configured to detect faulty optoelectronic devices, said fixing being carried out for said faulty optoelectronic devices only. This makes it possible to retain the faulty devices on the support, during the transfer of the other devices to the receiving substrate.
• the method is in particular dedicated to the transfer of light-emitting diodes (LEDs), and in particular of smart LEDs.
• LEDs light-emitting diodes
• the invention can be implemented more widely for various optoelectronic devices, or even for MEMS electromechanical devices or microsystems.
• the invention can therefore be implemented in the context of laser or photovoltaic devices.
• the transfer structure and the transfer method are dedicated to the transfer of “elementary” devices whose dimensions do not exceed a few tens or hundreds of microns.
• These elementary devices or components are generally manufactured by microelectronic technologies, then cut out and/or assembled.
• the latter can be encapsulated in a protective casing, for example based on epoxy resin.
• a protective casing typically contains a plurality of elementary components and cannot be likened to an elementary or unitary device within the meaning of the present invention.
• the transfer structure and the transfer method according to the present invention are not applicable to the transfer of such boxes, the dimensions of which are generally greater than several millimeters and have no common measure with the optoelectronic devices covered by the present invention.
• the casing and handling of the casings belong to the field of “packaging”, whereas the present invention is typically implemented before considering any packaging step.
• a person skilled in the art of packaging is not the person skilled in the art to which the present invention is directed.
• the fields of packaging and of the present invention are perfectly distinct and do not implement the same technologies.
• the relative arrangement of a third layer interposed between a first layer and a second layer does not necessarily mean that the layers are directly in contact with each other. , but means that the third layer is either directly in contact with the first and second layers, or separated from them by at least one other layer or at least one other element.
• the terms and phrases "to support” and “to cover” or “to cover” do not necessarily mean "in contact with”.
• LED light-emitting diode
• LED simply “diode”
• a “LED” can also be understood as a “mini-LED” or “micro-LED” or a smart LED, as the case may be.
• “surround” does not necessarily mean “surround by a closed contour”.
• the at least one protruding element can form a discontinuous contour around the central zone, projecting into a base plane parallel to the face of the support.
• the attachment points of the at least one projecting element on the peripheral zone can form a discontinuous outline.
• the parts of the optoelectronic device cooperating with the at least one projecting element are not necessarily continuous.
• the cavity can thus be partially open.
• regularly arranged or "a regular arrangement” means a periodic arrangement of the projecting elements, for example so that adjacent projecting elements are spaced from each other by a substantially constant distance.
• a substrate, a layer, a device, "based" on a material M is understood to mean a substrate, a layer, a device comprising this material M only or this material M and possibly other materials, for example elements alloy, impurities or doping elements.
• a GaN-based diode typically comprises GaN and AlGaN or InGaN alloys.
• a reference frame preferably orthonormal, comprising the axes x, y, z is shown in the appended figures.
• a layer typically has a thickness along z, when it extends mainly along an xy plane, and a protruding element has a height along z.
• the relative terms “over”, “under”, “underlying” preferably refer to positions taken in the direction z.
• the projecting elements can be in the form of pillars extending along z, or low walls extending along an xz or yz plane.
• the projecting elements When the projecting elements are similar to low walls extending along xz, they typically have a width dimension along y. When the projecting elements are similar to low walls extending along yz, they typically have a width dimension along x.
• the width dimension of the protrusions may vary along the height of the protrusions. In this case, the width can correspond to an average width value over the entire height.
• the trenches typically extend along xz or yz planes and typically have a width dimension along y or along x, respectively. Also in the case of trenches, the width can correspond to an average width value over the entire height.
• the dimensional values are understood to within manufacturing and measurement tolerances.
• a direction substantially normal to a plane means a direction having an angle of 90 ⁇ 10° relative to the plane.
• FIGS. 1 A to 1 M A first embodiment of the method according to the invention is illustrated in FIGS. 1 A to 1 M.
• This first embodiment aims to transfer smart LEDs from a growth substrate 1 onto a receiver substrate 2.
• the smart LEDs typically comprise a emissive part 10 based on LEDs or pLEDs and an electrical interconnection part 20.
• This electrical interconnection part 20 may in particular comprise control electronics based on integrated microcircuits pIC.
• a first step of this method consists in providing a growth substrate 1 carrying LEDs 10i, IO2, IO3.
• These LEDs 10i, IO2, IO3 can typically comprise so-called RGB LEDs (acronym for Red Green Blue), for example a red LED
• the growth substrate 1 carries only monochrome LEDs.
• the growth substrate 1 may typically be based on III-V materials.
• a substrate 1 can comprise a silicon or sapphire base on which buffer and/or nucleation layers based on III-V materials are epitaxially grown (not shown). 10i LEDs,
• the LEDs 10i, IO2, IO3 can be encapsulated in an encapsulation material 11.
• Metal contacts 1 C are typically formed on each of the LEDs 101, 102, 103.
• the electrical interconnection part 20 is control electronics.
• the control electronics 20 are typically formed in a semiconductor layer 22 comprising 2O2 integrated circuits.
• Contact pads 20i are typically arranged on each of the integrated microcircuits 2O2.
• Contact pads 20i and the metal contacts 1 ⁇ 4 are aligned opposite each other, then assembled with each other.
• the growth substrate 1 carrying the LEDs can be assembled to the support layer 21 carrying the pIC 2O2, by hybridization between the metal contacts 10 4 and the contact pads 20i.
• a plurality of smart LEDs 30i are formed. These smart LEDs 30i are inserted between growth substrate 1 and support layer 21 .
• the support layer 21 is first removed, for example by trimming or by thinning, so as to expose a first face 301 of the smart LEDs 30i.
• Metallic contact pads 2O3 can be formed on this face 301 at the level of the pIC 2O2.
• the number and position of the 2O3 contact pads may vary depending on the architecture of the 2O2 pICs.
• a central zone 301 c and a peripheral zone 301 p of the first face 301 can be defined.
• the central zone 301 c is preferably situated substantially plumb, along z, with the pIC and/or the LEDs 10i, I O2, IO3.
• the contact pads 2O3 are preferably located within the central zone 301c.
• the peripheral zone 301 p is preferably situated substantially plumb, along z, with the encapsulation material surrounding the LEDs 10i, IO2, IO3.
• the peripheral zone 301p surrounds the central zone 301c.
• a support 40i comprising a base portion 42 and protrusions 41 is provided.
• This support 40i can be formed from a solid substrate, for example a silicon substrate.
• the projecting elements 41 are preferably formed by etching the solid substrate.
• These protruding elements 41 can thus have different shapes or patterns. They can, for example, be like pillars or low walls separated from each other.
• the projecting elements 41 can form a continuous network, for example a grid with square or rectangular meshes, in top view along z.
• the projecting elements 41 have a width U1 or L41 and a height fl. The width U1 is typically less than the height fl.
• the projecting elements 41 may have a trapezoidal or frustoconical shape, as illustrated in FIG. 1D.
• the top 411 of the projecting elements 41 may be slightly less wide than the base 412 of the projecting elements 41. This may be due to the burn settings to achieve 40i media.
• the width U1 can be between 500 nm and 100 microns.
• the height fl can be between 500 nm and 1 mm.
• the support 40i is assembled with the smart LEDs 30i carried by the growth substrate 1.
• the protruding elements 41 are aligned with the peripheral zones 301p of each of the smart LEDs 30i.
• at least two protruding elements 41 are assembled on two opposite sides of a peripheral zone 301 p.
• at least four protruding elements 41 are assembled on four opposite sides of a peripheral zone 301 p.
• the protruding elements 41 can thus be distributed in a regular manner along a peripheral zone 301 p considered, in projection along z. This improves the mechanical stability of the assembly.
• Transfer structures 50i are thus formed. These transfer structures 50i each comprise an electronic device, in this case a smart LED 30i, and at least partially the support 40i.
• a cavity 43 is thus formed in each transfer structure 50i. This cavity 43 is bordered by projecting elements 41 , support face 400 and first face 301 .
• the cavity 43 typically makes it possible to house metal contacts 203. The latter are thus protected without being covered by a protective layer or another element. This avoids a subsequent step of cleaning these 2O3 metal contacts.
• the transfer structures 50i have sufficient mechanical strength to remove the growth substrate 1. As illustrated in FIG. 1F, the growth substrate 1 is then removed, for example by trimming. A face 302 of the smart LEDs is thus exposed. This face 302 typically makes it possible to emit light.
• Trenches 60 are formed between each of the smart LEDs, so as to individualize the smart LEDs between them. These trenches 60 can be formed by etching from the face 302.
• the trenches 60 are made substantially in line with the peripheral zones of each transfer structure 50i, in particular in line with the projecting elements 41 . They typically pass through the encapsulation material delimiting each group of LEDs 10i, 10 2 , 103 of the smart LEDs 30i.
• the trenches 60 illustrated in FIG. 1F extend mainly along a plane yz. They are deep enough to isolate the parts based on LEDs 10i, 10 2 , 103 of the smart LEDs from each other.
• the bottom 61 of the trenches 60 can be located in the semiconductor layer 22, above a reference plane R comprising the first face 301, as illustrated in FIG. 1F.
• the bottom 61 of the trenches 60 can be located under the reference plane R.
• the width leo of the trenches 60 is less than the width U1 of the projecting elements 41.
• the trenches 60 thus extend along z in the projecting elements 41 .
• FIG. 1H shows a plurality of smart LEDs separated from each other, in top view.
• the semiconductor layer 22 can form a perimeter for the LEDs 10i, 10 2 , 103, in projection in the xy plane.
• four projecting elements 41 are shown for each of the smart LEDs. These projecting elements 41 are distributed symmetrically on each of the four sides of a smart LED.
• a given projecting element 41 is preferably shared by two adjacent smart LEDs. According to a possibility not illustrated, the projecting elements 41 can be located at the level of the corners of the smart LEDs. In this case a projecting element 41 is shared by four adjacent smart LEDs.
• FIG. 11 is a sectional view along plane B-B shown in FIG. 1H. Trenches 60 extending mainly along an xz plane are also formed to separate the smart LEDs from one another.
• a transfer device 70 for example an elastomer buffer, is brought into contact with the faces 302 of the smart LEDs.
• This transfer device 70 typically rests vertically on the faces 302.
• the transfer device 70 is then removed while maintaining the smart LEDs 30i.
• the force exerted by the transfer device 70 makes it possible to separate the support 40i from the smart LEDs 30i.
• the small bearing surface between the projecting elements 41 and the smart LEDs 30i facilitates the separation of the support 40i.
• the bonding strength between the transfer device 70 and the face 302 of a smart LED is preferably greater than the retaining force between the projecting elements 41 and said smart LED 30i.
• the transfer device 70 can also exert a mechanical force directed towards the support and/or parallel to the support so as to break by pressure and/or shear the projecting elements 41 .
• the smart LEDs 30i are then brought by the transfer device 70 facing the receiver substrate 2.
• the smart LEDs 30i are then assembled to the receiver substrate 2, then the transfer device 70 is removed .
• This first embodiment of the invention makes it possible to efficiently transfer 30i smart LEDs from a growth substrate 1 to a receiver substrate 2.
• the smart LEDs 30i are taken one by one by the transfer device 70.
• the transfer device 70 makes it possible to modify a spacing or a separation distance between the smart LEDs 30i during the transfer, after separation of the support 40i and before transfer onto the receiver substrate 2.
• the surface density of the smart LEDs 30i can thus vary between the support 40i and the receiver substrate 2.
• the receiver substrate 2 can comprise reception structures 200 for the smart LEDs 30i, such as contact pads.
• the receiver substrate 2 can be a screen substrate comprising electrical tracks and associated contact pads.
• FIGS. 2A to 2M illustrate a second embodiment making it possible to transfer optoelectronic devices from a growth substrate to a receiver substrate.
• a growth substrate 1 carrying LEDs 10i, I O2, I O3 and contacts 1C is provided as before.
• the electrical interconnection part 20 comprises vias 20 4 . These vias are more commonly referred to as TSVs (acronym for “Through Silicon Vias”). Vias or TSVs are typically electrically conductive. These vias 20 4 pass through the semiconductor layer 22. The vias 20 4 are typically associated with the contact pads 20i.
• the electrical interconnection part 20 may optionally include other elements such as the pICs seen previously.
• the part 20 of electrical interconnections is carried by the support layer 21, as before.
• the LEDs 10i, I O2, I O3 are assembled with the electrical interconnections, by hybridization between the respective contact pads 10 4 , 20i.
• Each device 30 2 comprises a group of LEDs 10i, I O2, I O3 and a part of electrical interconnections.
• the protrusions 41 are formed from the support layer 21 .
• an etching of the support layer 21 configured to stop on the semiconductor layer 22 typically makes it possible to form the projecting elements 41 at the level of the peripheral zones 301 p.
• Projecting elements 41 can therefore have a trapezoidal or frustoconical shape, as illustrated in FIG. 2C.
• the top 411 of the projecting elements 41 is here wider than the base 412 of the projecting elements 41 .
• contact pads 203 can be formed on the first faces 301 of the devices at the level of the vias 20 4 , between the projecting elements 41 .
• a flat substrate 44 is then assembled to the projecting elements 41 so as to form the base part 42 of the support 40 2 .
• the base part 42 and the projecting elements 41 are therefore formed separately and then assembled.
• a transfer structure 50 2 is thus obtained.
• the growth substrate 1 is then removed and trenches 60 are formed so as to separate the devices 30 2 from one another.
• the bottom 61 of the trenches 60 can be located above the reference plane R (FIG. 2F), or below the reference plane R (FIG. 2G).
• Figure 2H shows the devices seen from above, each being supported by four projecting elements 41 .
• Figure 2I shows the devices according to section plane BB shown in Figure 2H.
• a transfer device 70 is assembled to the faces 302 of the devices (FIG. 2J).
• the transfer device 70 then exerts a vertical traction along z so as to separate the devices 30 2 from the support 40 ⁇ (FIG. 2 K).
• the devices 30 2 are then brought by the transfer device 70 facing a receiver substrate 2 (FIG. 2L).
• the devices 30 2 are assembled to the receiver substrate 2 then the transfer device 70 is removed (FIG. 2M).
• FIG. 3A to 3I A third embodiment of the invention is illustrated in Figures 3A to 3I.
• the devices 303 are RGB pixels comprising three LEDs 10i, 102, 103.
• the LEDs 10i, 102, I O3 carried by the growth substrate 1 are directly assembled to the support 403, without an intermediate hybridization step (FIG. 3A).
• a transfer structure 503 comprising the pixel 303 and at least partially the support 403 is thus formed (FIG. 3B).
• the growth substrate 1 is then removed and trenches 60 are formed so as to individualize the pixels 303 between them.
• Figure 3D shows the pixels seen from above, each being supported by four projecting elements 41 .
• Figure 3E shows the pixels along section plane B-B shown in Figure 3D. Only the sub-pixels formed by the green LEDs IO2 are visible here.
• a transfer device 70 is assembled to the faces 302 of the pixels (FIG. 3F).
• the transfer device 70 then removes the pixels 303 from the support 403 (FIG. 3G).
• the pixels 303 are then brought by the transfer device 70 facing a receiver substrate 2 (FIG. 3H).
• the pixels 303 are assembled to the receiver substrate 2 then the transfer device 70 is removed (FIG. 3I).
• an electrical test of all the LEDs is carried out so as to detect the faulty LEDs.
• an adhesive material for example an epoxy glue
• the adhesive material typically extends from the central area of the failed LED to the support face 400.
• the bond strength of the adhesive material is typically greater than the bond strength of the transfer device to face 302 of the LED. .
• the faulty LED advantageously remains attached to the support. It is not transferred onto the receiver substrate 2. This facilitates repair at the level of the receiver substrate, for example if this receiver substrate is directly a screen substrate intended to be integrated into the final product.
• the transfer structure can thus be advantageously modified locally to fix a faulty LED to the support, before transferring the other LEDs.
• the cavity present under each of the LEDs can advantageously be used to achieve this attachment, typically by filling said cavity with an adhesive material.
• the fixing of one or more LEDs can be carried out without said LEDs failing, for example so as to form a particular arrangement of the LEDs transferred onto the receiving substrate.
• the distribution of the LEDs on the receiver substrate is then different from the initial distribution of the LEDs on the support or the donor substrate.
• the transfer structures and the transfer methods according to the invention therefore advantageously make it possible to transfer optoelectronic devices from a donor substrate to a receiver substrate.
• the invention is however not limited to the embodiments previously described.
• the number, shape and arrangement of the protruding elements can be adapted according to the optoelectronic devices to be transferred.

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• Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)
• Electroluminescent Light Sources (AREA)

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• 2021
  • 2021-06-30 FR FR2107034A patent/FR3124889A1/fr active Pending
• 2022
  • 2022-06-23 EP EP22738581.2A patent/EP4364200A1/de active Pending
  • 2022-06-23 US US18/575,609 patent/US20240313152A1/en active Pending
  • 2022-06-23 WO PCT/EP2022/067146 patent/WO2023274828A1/fr active Application Filing

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