Method and structure for transferring a semiconductor device

Abstract

The invention relates to a method for transferring a semiconductor device (100) by IR laser ablation. An active layer is transferred from a donor substrate to a silicon transfer substrate (3), by performing bonding by a splitting layer (20) between the active layer and the transfer substrate (3). The semiconductor device (100) is then formed from the active layer, on the transfer substrate (3). The semiconductor device (100) is next assembled with a receiver substrate (2) and then released under infrared radiation through the transfer substrate (3). The splitting layer (20) advantageously comprises a metal release layer (21) and a mineral absorption layer (22). The invention also relates to a transfer structure allowing the implementation of the transfer method.

Description

[0001] "Process and structure for transferring a semiconductor device"

[0002] TECHNICAL FIELD

[0003] The present invention relates to the field of microelectronics and optoelectronics technologies. It finds particularly advantageous application in the mass transfer of semiconductor devices, for example GaN-based light-emitting diodes on silicon.

[0004] STATE OF THE ART

[0005] A semiconductor device typically comprises at least one so-called "active" semiconductor layer having a role in the operation of said device. A semiconductor device refers, for example, in a non-exhaustive manner, to a CMOS circuit, i.e. based on complementary metal-oxide-semiconductor transistors (CMOS being the acronym for "Complementary Metal Oxide Semiconductor"), or to a MEMS micro-electromechanical system (acronym for "MicroElectroMechanical Systems"), or to an optoelectronic device of the LED type (acronym for "Light Emitting Diode"). In the following, one or more LEDs or micro-LEDs are chosen as examples to illustrate the transfer method and structure, without this being limiting.

[0006] Typically, to form a self-emissive display screen comprising a plurality of RGB (Red Green Blue) pixels emitting their own light, different LEDs are assembled on a screen support, which comprises, for example, control electronics.

[0007] LEDs are typically formed on a donor substrate or growth substrate, then individualized—that is, separated from each other—before being transferred to the display medium or a receiving substrate. Not all LEDs from the donor substrate are necessarily transferred to the receiving substrate.

[0008] The LED growth substrate is preferably silicon-based, in order to benefit from the production capacities of microelectronics industry equipment. To collectively transfer a large number of LEDs from a silicon-based growth substrate, one solution is to use a glass transfer substrate on which the LEDs are bonded by an organic adhesive. The growth substrate is removed and then the LEDs are individualized and brought into contact with the receiving substrate. UV laser radiation then degrades the organic adhesive through the glass transfer substrate, to release the LEDs and assemble them to the receiving substrate. This UV laser ablation method requires a glass transfer substrate that is not very compatible with the production equipment of the microelectronics industry (substrate detection, mechanical deformation). Furthermore, organic adhesives are sensitive to temperature.They can cause significant deformation of the plates. They also degrade under the influence of temperature. Therefore, carrying out intermediate technological steps on LEDs, after removal of the growth substrate, becomes more complicated.

[0009] To overcome these drawbacks, document WO2022111141 A1 discloses a solution consisting of using mineral bonding, for example “oxide-oxide”, between the transfer substrate and the devices of the donor substrate. In this solution, a silicon transfer substrate provided with an inorganic scission layer, typically based on aluminum, is used. IR laser radiation then degrades the scission layer through the silicon transfer substrate, to release the devices assembled to the recipient substrate. In practice, this solution requires a very energetic IR laser, and can partially degrade the devices to be transferred.

[0010] US2022406621A1 describes another laser ablation method using an inorganic scission layer. This solution also requires a high-energy IR laser.

[0011] The present invention aims to at least partially overcome the drawbacks of the solutions mentioned above.

[0012] In particular, an object of the present invention is to provide an optimized method for transferring a semiconductor device. Another object of the present invention is to provide a transfer structure for a semiconductor device, making it possible to implement the transfer method.

[0013] Other objects, features, and advantages of the present invention will become apparent upon examination of the following description and the accompanying drawings. It is understood that other advantages may be incorporated. In particular, certain features and advantages of the transfer method may apply mutatis mutandis to the transfer structure, and vice versa. SUMMARY

[0014] To achieve the above-mentioned objectives, one aspect relates to a method of transferring at least one semiconductor device, from a first substrate called donor to a second substrate called receiver, using a silicon-based transfer substrate.

[0015] The method comprises at least the following steps:

[0016] - provide the donor substrate comprising at least one active layer intended to be integrated into the semiconductor device, at a first face,

[0017] - provide the silicon-based transfer substrate, having a second face,

[0018] - forming a split layer on at least one of the first face and the second face, the split layer being inorganic,

[0019] - assembling the donor substrate with the transfer substrate, via the splitting layer,

[0020] - removing the donor substrate, while retaining the at least one active layer on the transfer substrate, and forming the at least one semiconductor device from the at least one active layer,

[0021] - provide the receiving substrate,

[0022] - assembling the at least one semiconductor device with the receiving substrate,

[0023] - illuminating, by infrared radiation, the scission layer through the transfer substrate, so as to at least partially eliminate the scission layer, to detach the at least one semiconductor device from the transfer substrate.

[0024] Advantageously, the formation of the splitting layer comprises a formation of a metal release layer on the side of the semiconductor layer, and a formation of a mineral absorption layer on the side of the transfer substrate, such that the splitting layer comprises the metal release layer and the mineral absorption layer, the mineral absorption layer being configured to absorb at least 20% of the infrared radiation upon illumination.

[0025] Thus, the splitting layer is in the form of a bilayer, advantageously allowing the separation of the functions of each of the metal release and mineral absorption layers.

[0026] The metal release layer is intended to melt or vaporize under the effect of heat imparted by the absorption layer which absorbs the IR radiation. The metal release layer further shields the at least one semiconductor device from infrared radiation, by reflecting the IR radiation back to the absorption layer.

[0027] The mineral absorption layer effectively absorbs infrared radiation, producing enough heat to partially or completely melt or vaporize the metal release layer. This can reduce the energy of the IR radiation.

[0028] In the context of the development of the present invention, it was observed that the use of a simple layer of aluminum as a scission layer, although theoretically conceivable, in practice requires a very high laser power due to the reflectivity of aluminum. A "picosecond" (ps) pulsed IR laser cannot be used in practice. The addition of a mineral absorption layer, for example based on a refractory transition nitride, makes it possible to sufficiently reduce the energy required for the melting / vaporization of the metallic release layer, to allow the use of a pulsed IR laser delivering an energy less than or equal to 10 microJoules (pJ).

[0029] WO2022111141 A1 provides alternatively for the splitting layer either an aluminum layer or a light / heat conversion layer. In the first case, as indicated, the energy required is very high due to the reflectivity of the aluminum. In the second case, the reflectivity of the layer decreases and the devices are no longer protected from IR radiation.

[0030] Practical developments carried out in the context of the development of the present invention have led to the consideration of a combination of absorption and release / reflection layers which is not envisaged in the alternatives proposed by document WO2022111141 A1.

[0031] This combination advantageously makes it possible to reduce the required energy delivered by the pulsed IR laser while protecting the devices to be transferred.

[0032] Preferably, the metal release layer is directly in contact with the mineral absorption layer. There is no interlayer between the metal release layer and the mineral absorption layer. This allows the melting / vaporization of the metal release layer with locally reduced energy because all the energy absorbed by the mineral absorption layer is directly transmitted to the metal release layer. It is thus possible to use a reduced energy density to release a semiconductor device from the transfer substrate via the melting / vaporization of this metal release layer. A power density less than or equal to 10 E 11 watts / cm 2 is typically sufficient, unlike the laser ablation method disclosed in document US2022406621A1 requiring intercalating a silicon-based layer between the metallic release layer and the mineral absorption layer.

[0033] Another aspect relates to a transfer structure comprising in stack, in the following order:

[0034] - a first substrate called donor,

[0035] - at least one active layer intended to be integrated into at least one semiconductor device,

[0036] - a split layer,

[0037] - a silicon-based transfer substrate,

[0038] The stack is configured such that, under illumination by infrared (IR) radiation through the transfer substrate, the split layer is at least partially removed, so as to detach the transfer substrate from the stack.

[0039] Advantageously, the split layer comprises:

[0040] - a metal release layer on the active layer side,

[0041] - a mineral absorption layer on the transfer substrate side, the mineral absorption layer being configured to absorb at least 20% of the infrared radiation upon illumination. Such a transfer structure advantageously makes it possible to implement the transfer method described above.

[0042] The stack of layers does not include organic layers. This stack can thus be advantageously processed by conventional microelectronics process steps, for example to form a semiconductor device from the active layer, after removal of the donor substrate and before detachment from the transfer substrate.

[0043] BRIEF DESCRIPTION OF THE FIGURES

[0044] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of embodiments thereof which are illustrated by the following accompanying drawings in which:

[0045] Figures 1A to 6 schematically illustrate steps of a transfer method according to an embodiment of the present invention.

[0046] Figures 7 to 14 schematically illustrate steps of a transfer method according to another embodiment of the present invention.

[0047] The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications. In particular, the dimensions of the different layers and parts of the transfer structures and the LEDs are not necessarily representative of reality.

[0048] DETAILED DESCRIPTION

[0049] Before beginning a detailed review of embodiments of the invention, it is recalled that the invention according to its first aspect notably comprises the following optional characteristics which can be used in combination or alternatively:

[0050] According to one example, the at least one semiconductor device comprises a plurality of semiconductor devices each having a characteristic dimension less than or equal to 100 pm, preferably less than or equal to 10 pm, and preferably less than or equal to 5 pm.

[0051] In one example, the illumination is configured to decouple only certain semiconductor devices from the plurality of semiconductor devices. The method thus enables localized transfer of micro-components.

[0052] In one example, the semiconductor devices of the plurality of semiconductor devices are separated from each other prior to illumination, the semiconductor devices remaining held by the splitting layer on the transfer substrate. The semiconductor devices are typically individualized prior to decoupling by laser illumination.

[0053] In one example, the illumination is performed by a pulsed IR laser producing IR radiation of energy between 0.1 pJ and 10 pJ, preferably between 1 pJ and 10 pJ, for a duration between 100 femtoseconds (fs) and 10 picoseconds (ps). Such a laser advantageously emits “low” energy radiation that can be shaped to target individual semiconductor devices.

[0054] In one example, the IR radiation has a wavelength of 2.5 pm or less. In one example, the illumination is performed by a pulsed IR laser producing IR radiation in the form of pulses, and the energy of a pulse is between 0.1 pJ and 10 pJ. In one example, the duration of a pulse is between 100 femtoseconds (fs) and 10 picoseconds (ps).

[0055] According to one example, the separation of the semiconductor devices from each other is carried out by anisotropic etching in a direction normal to the second face. According to one example, the anisotropic etching extends to the metal release layer, preferably to the mineral absorption layer, preferably to the second face. The ablation of the scission layer can advantageously make the detachment more clean or precise. The semiconductor devices are detached locally from the transfer substrate. The semiconductor devices can be removed individually or in small groups. The transfer of the semiconductor devices is not collective. The plurality of semiconductor devices is not transferred to the receiving substrate.

[0056] In one example, the mineral absorption layer has a resistivity of between 50 p. ohm. cm (micro-ohm-centimeter) and 1 m. ohm. cm (milli-ohm-centimeter). Such an absorption layer conducts the charge carriers produced upon absorption of IR radiation. These charge carriers are advantageously conducted to the metal release layer to increase the heat transmitted to the metal release layer.

[0057] In one example, the mineral absorption layer is chosen from a refractory material having a melting temperature greater than or equal to 1500°C. This allows the implementation of most or all of the thermal processes in the microelectronics industry, without the mineral absorption layer being degraded. Thermal degradation under IR illumination is thus restricted to the metal release layer.

[0058] According to one example, the mineral absorption layer is chosen from a refractory material based on a transition metal, preferably based on Ti, V, Zr, Ta, Hf, Nb, W.

[0059] According to one example, the mineral absorption layer is selected from transition metals such as Ti, V, Zr, Ta, Hf, Nb, W.

[0060] According to one example, the mineral absorption layer is selected from transition metal-based refractory nitrides such as TiN, VN, ZrN, TaN, HfN, NbN, or their alloys. According to another example, the mineral absorption layer is selected from transition metal-based refractory carbides. According to another example, the mineral absorption layer is selected from transition metal-based refractory borides.

[0061] According to one example, the mineral absorption layer has a thickness between 10 nm and 100 nm.

[0062] According to one example, the mineral absorption layer has an extinction coefficient k > 1 for an illumination wavelength less than or equal to 2.5 pm.

[0063] In one example, the metal release layer has an infrared reflectivity of 97% or greater. This protects the semiconductor device from IR radiation during illumination. In one example, the metal release layer has a resistivity of between 2.5 p. ohm. cm (micro-ohm-centimeter) and 50 p. ohm. cm (micro-ohm-centimeter).

[0064] In one example, the metal release layer has a thickness between 30 nm and 200 nm.

[0065] According to one example, the metal release layer is based on a simple metal such as aluminum, tin, zinc or based on a metal alloy having a melting temperature less than or equal to 700°C.

[0066] In one example, the metal release layer has a melting temperature of less than or equal to 700°C.

[0067] According to one example, the mineral absorption layer is made of a refractory material having a melting temperature greater than or equal to 2500°C.

[0068] According to one example, the mineral absorption layer is based on a refractory transition nitride selected from TiN, VN, ZrN, TaN, HfN, NbN, or an alloy of said refractory transition nitrides. Unless incompatibility exists, technical characteristics described in detail for a given embodiment may be combined with the technical characteristics described in the context of other embodiments described by way of example and not limitation, so as to form another embodiment which is not necessarily illustrated or described. Such an embodiment is obviously not excluded from the invention.

[0069] In the present invention, the method is particularly dedicated to the transfer of semiconductor devices, in particular devices of micrometric dimensions such as light-emitting diodes (LEDs). The individual LEDs or semiconductor devices typically have dimensions, in projection in an xy base plane, of between 2.5 pm X 2.5 pm and 100 pm X 100 pm.

[0070] The invention can be implemented more broadly for various microelectronic or optoelectronic devices, or even for MEMS electromechanical devices or microsystems. The invention can, for example, be implemented in the context of laser or photovoltaic devices.

[0071] Unless explicitly stated, it is specified that, in the context of the present invention, the relative arrangement of a third layer interposed between a first layer and a second layer does not necessarily mean that the layers are in direct 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. Thus, the terms and phrases “to rest” and “to cover” or “to cover” do not necessarily mean “in contact with”.

[0072] The steps of the method as claimed are understood in the broad sense and may optionally be carried out in several sub-steps.

[0073] In this patent application, the terms "light-emitting diode", "LED" or simply "diode" are used synonymously. An "LED" can also be understood to mean a "micro-LED" or even a smart LED, as the case may be. A portion or element described as "sacrificial" means that this element is intended to be "sacrificed", i.e. removed during a subsequent process step.

[0074] A substrate, a layer, a device, "based" on a material M, means a substrate, a layer, a device comprising this material M only or this material M and possibly other materials, for example alloying elements, impurities or doping elements. Thus, a GaN-based diode typically comprises GaN and alloys of AIGaN or InGaN.

[0075] A reference frame, preferably orthonormal, comprising the x, y, z axes is shown in certain attached figures. This reference frame is applicable by extension to the other figures in the same sheet of figures.

[0076] In this patent application, we will preferably speak of thickness for a layer and height for a structure or device. The thickness is taken along a direction normal to the main extension plane of the layer, and the height is taken perpendicular to the base plane xy. Thus, a layer typically has a thickness along z, when it extends mainly along an xy plane, and a projecting element, for example a device, has a height along z. The relative terms "on", "under", "underlying" preferably refer to positions taken along the z direction.

[0077] Dimensional values ​​are understood to be within manufacturing and measurement tolerances.

[0078] The terms "substantially", "approximately", "of the order of" mean, when they refer to a value, "within 10%" of that value or, when they refer to an angular orientation, "within 10°" of that orientation. Thus, a direction substantially normal to a plane means a direction presenting an angle of 90±10° with respect to the plane.

[0079] In the present patent application, the optical absorption coefficient, denoted a or a, is defined by the ratio between the absorbance and the length of the optical path traveled by electromagnetic radiation in a given medium (expressed in m -1 or in cm' 1 ).

[0080] The extinction coefficient (also called attenuation coefficient) of the medium, denoted k, measures the energy loss of electromagnetic radiation passing through this medium. Similar to the absorption coefficient, it also takes into account, in addition to absorbance, the effects due to scattering as well as luminescence. It depends on the material and the wavelength. It is the imaginary part of the complex refractive index: n = n'+ in" with k = n". Transparent materials have a low extinction coefficient while opaque materials have a high extinction coefficient.

[0081] In the context of the present invention, the illumination is carried out in the infrared wavelength range, preferably in the near infrared range, for wavelengths between 1 pm and 2.5 pm.

[0082] An object of the invention is to transfer, via a transfer structure and an IR laser ablation method, a semiconductor or optoelectronic device onto a receiving substrate, for example a screen support. One principle of the invention consists in carrying out the transfers and bondings via a split layer comprising a metal release layer and a mineral absorption layer, preferably in direct contact with each other. The metal release layer is a sacrificial layer in the transfer method. In particular, the absorption layer absorbs IR light and transforms it into heat. This heat diffuses in particular towards the metal release layer. This typically induces, at the interface between the two layers, a partial melting or a partial vaporization of the metal release layer. The interface between the two layers is then degraded and the two layers can separate.Some of the release layer that has not melted may remain on the side of the device that is being transferred.

[0083] Figures 1A and 1B illustrate two variants in which the split layer 20 is respectively formed directly on the transfer substrate 3 (Figure 1A) or directly on the donor substrate 1 (Figure 1B).

[0084] According to a first example illustrated in Figure 1A, a donor substrate 1 typically comprising an active layer 10 topped by a mineral bonding layer 11 is provided. The donor substrate 1 is preferably silicon-based.

[0085] The active layer O may for example be based on GaN (p-GaN and / or n-GaN), and / or AIGaN, and / or InGaN epitaxially grown on the donor substrate 1. It typically constitutes an active layer, comprising for example a PN junction or quantum wells, configured to form a semiconductor device, for example one or more LEDs. The active layer 10 may also comprise three-dimensional structures arranged next to each other, for example based on InGaN, such as nanowires or nano-pyramids. The active layer 10 may also comprise sub-layers which may be structured and intended to form for example electrical contacts, for example on p-GaN and on n-GaN, for example based on transparent conductive oxide (TCO).

[0086] The mineral bonding layer 11 is typically based on silicon oxide SiO2. In particular, it makes it possible to planarize the active layer 10 so as to obtain a flat face 201 suitable for mineral bonding, and allowing direct bonding of SiO2 to SiO2.

[0087] The transfer substrate 3 is silicon-based. In this example, the splitting layer 20 is formed on a face 202 of the transfer substrate 3. The exposed face 203 of the splitting layer

[0088] 20 is typically flat and suitable for mineral bonding. The mineral bonding can for example be a molecular bond. The mineral bonding between the transfer substrate 3 and the donor substrate 1 is done here between the faces 201, 203.

[0089] The splitting layer 20 comprises at least one mineral absorption layer 22, and at least one metal release layer 21. The mineral absorption layer 22 is formed on the side of the transfer substrate 3, for example directly on the face 202. The metal release layer 21 is formed on the mineral absorption layer 22, so that the mineral absorption layer 22 is interposed between the transfer substrate 3 and the release layer

[0090] 21 metallic. The exposed face 203 of the splitting layer 20 corresponds here to a face of the metallic release layer 21. According to a possibility not illustrated, a silicon oxide layer is formed on the face 203 of the splitting layer 20. The bonding is then carried out by a molecular bonding of the SiO2-SiO2 type. The mineral absorption layer 22 is typically at least partially electrically conductive and preferably has a resistivity of between 50 p. ohm. cm and 1 m. ohm. cm. This makes it possible to optimize the electronic transfer of heat transfer between the mineral absorption layer 22 and the metallic release layer 21. The mineral absorption layer 22 has a thickness along z preferably of between 10 nm and 100 nm. It typically has an optical extinction coefficient k > 1 in the near infrared range, for wavelengths less than or equal to 2.5 pm.This makes it possible to absorb at least 20%, or even at least 30% or at least 40%, of infrared radiation in the near infrared range. The mineral absorption layer 22 may be based on a transition metal, for example Ti, Ta, W, Zr, Nb, Hf. It may alternatively be based on a nitride of these transition metals, called a refractory transition nitride, for example TiN, TaN, VN, ZrN, HfN, NbN. It may alternatively be based on a carbide of these transition metals, called a refractory transition carbide, for example TiC, TaC, VC. It may alternatively be based on a boride of these transition metals, called a refractory transition boride, for example TiB2, TaB, TaB2, VB2, HfB2. The mineral absorption layer 22 may be based on a combination or alloy of these materials, for example C5HfTa4. The mineral absorption layer 22 preferably has a melting temperature greater than or equal to 1500°C.This prevents the mineral absorption layer 22 from thermally degrading during illumination. Thus, after illumination, the integrity of the mineral absorption layer 22 is preserved.

[0091] The metallic release layer 21 is typically electrically conductive and preferably has a resistivity of between 2.5 p. ohm. cm and 50 p. ohm. cm. The metallic release layer 21 has a thickness along z preferably of between 30 nm and 200 nm. It typically has an optical reflectivity greater than or equal to 97% in the near infrared range, for wavelengths less than or equal to 2.5 pm. During illumination through the transfer substrate 3, the infrared radiation transmitted by the mineral absorption layer 22 is thus reflected by the metallic release layer 21. This makes it possible to protect the semiconductor layer 10 and / or a semiconductor device formed from the semiconductor layer 10 from IR radiation. The metallic release layer 21 may be based on a simple metal, for example Al, Sn, Zn.The metallic release layer 21 preferably has a melting temperature of less than or equal to 700°C. The difference in melting temperature between the metallic release layer 21 and the mineral absorption layer 22 is thus sufficiently large to ensure partial (not shown) or complete melting / vaporization of the metallic release layer 21 while maintaining the integrity of the mineral absorption layer 22.

[0092] The characteristics of the different layers 10, 11, 21, 22, in particular of the mineral absorption layer 22 and of the metallic release layer 21, are common to the other embodiments described below.

[0093] According to a second example illustrated in Figure 1B, the splitting layer 20 is formed on a face 201 of the donor substrate 1. The exposed face 204 of the splitting layer 20 corresponds here to a face of the mineral absorption layer 22. The mineral bonding between the transfer substrate 3 and the donor substrate 1 is done here between the faces 202, 204. According to a possibility not illustrated, one or more layers of silicon oxide are formed on the face 204 of the splitting layer 20 and on the face 202 of the transfer substrate 3. The bonding is then done by a molecular bonding of the SiO2-SiO2 type.

[0094] In this example, the metal release layer 21 is formed on the side of the donor substrate 1, for example directly on the face 201. The mineral absorption layer 22 is formed on the metal release layer 21, so that the metal release layer 21 is interposed between the donor substrate 1 and the mineral absorption layer 22.

[0095] As illustrated in Figure 2, regardless of the face 201 or 202 on which the split layer 20 is formed, the donor substrate 1 and the transfer substrate 3 are assembled via the split layer 20, typically by molecular bonding.

[0096] As illustrated in Figure 3, the donor substrate 1 is then removed, for example partly by trimming and partly by chemical mechanical polishing (CMP) or by selective chemical etching with respect to the active layer 10. The active layer 10 and the oxide layer 11 are retained on the transfer substrate 3.

[0097] As illustrated in Figure 4, the active layer 10 and the oxide layer 11 are then structured so as to form and individualize semiconductor devices 100, for example LEDs. This structuring may include annealing steps at temperatures of a few hundred degrees Celsius. Advantageously, the layers 21, 22 of the splitting layer 20 withstand these temperatures. The structuring can therefore be done after transfer of the initial layers 10, 11 onto the transfer substrate 3. The transfer method is thus less restrictive for the sequence of steps for forming the devices 100. In the example illustrated in Figure 4, the semiconductor devices 100 comprise an insulating and transparent part 111, an active part 110 typically configured to emit light, and contact pads 112. The formation of the individual devices 100 may in particular comprise one or more anisotropic etchings along z.The etching of the oxide layer 11 is typically selective with respect to the metallic release layer 21. According to a possibility not illustrated, the anisotropic etchings intended to separate the devices 100 from each other are extended to the mineral absorption layer 22, or even to the transfer substrate 3. The splitting layer 20 can thus be etched along z along all or part of its thickness.

[0098] As illustrated in Figure 5, after formation of the devices 100, the transfer substrate 3 is brought opposite the receiving substrate 2, for example a screen support, intended to receive at least some of the devices 100. The face 205 of the receiving substrate 2 typically has contact pads 211 at the locations provided for receiving the devices 100. After alignment of the contact pads 112 and 211, bonding is carried out, for example by thermocompression or by Cu-Cu bonding between the contact pads 112, 211. Illumination of the split layer 20 is then carried out by IR radiation through the transfer substrate 3. This IR radiation is typically located only above the devices 100 to be transferred. At least 20%, preferably at least 30% or at least 40%, of the IR radiation is typically absorbed by the layer 22.The energy of the IR radiation thus absorbed is transmitted in the form of heat to the metallic release layer 21.

[0099] As illustrated in Figure 6, the metal release layer 21 melts or vaporizes locally under the effect of the heat induced by the IR radiation, thus releasing certain devices 100a assembled on the receiving substrate 2. The IR radiation being localized, other devices 100b can be retained on the transfer substrate 3, via parts 21p of the metal release layer 21 which have not melted. The transfer substrate 3 can then be brought to another location to carry out another transfer, for example for the device(s) 100b.

[0100] The IR radiation typically has a wavelength of between 1 pm and 2.5 pm, preferably between 1.5 pm and 2 pm. It is preferably produced in the form of pulses by a pulsed laser. The energy of an IR radiation pulse is preferably between 0.1 pJ and 10 pJ, preferably between 1 pJ and 10 pJ, for example of the order of 7 or 8 pJ. The duration of an IR radiation pulse is preferably between 100 fs and 10 ps, ​​preferably between 1 ps and 10 ps. A single IR radiation pulse may be sufficient to detach the device 100a from the transfer substrate 3. The illumination may be carried out by a beam, typically a laser beam, having a power less than or equal to 10 E 11 watts / cm 2 .

[0101] Figures 7 to 14 illustrate another embodiment of the transfer method. In this embodiment, a first transfer of the semiconductor layer 10 is carried out from the growth substrate 1 a to an intermediate substrate 1 b, for example based on silicon. After growth of the active layer 10 on the substrate 1 a (figure 7), the intermediate substrate 1 b is bonded to the active layer 10 via one or more oxide layers 11, for example based on silicon oxide (figure 8). The growth substrate 1 a is then removed, for example partly by trimming and partly by chemical mechanical polishing (CMP) or by selective chemical etching with respect to the active layer 10, so as to expose a face 200 of the active layer 10 (figure 9).

[0102] As illustrated in Figure 10, the intermediate substrate 1b carrying the active layer 10 is bonded to the transfer substrate 3 via the splitting layer 20. The splitting layer 20 can be formed beforehand on the face 200 of the active layer 10 or on the face 202 of the transfer substrate 3. The intermediate substrate 1b here corresponds to the donor substrate 1 of the embodiment described previously. The mineral absorption layer 22 is formed so as to be positioned on the side of the transfer substrate 3. The metal release layer 21 is formed so as to be positioned on the side of the active layer 10.

[0103] As illustrated in Figure 11, after bonding the intermediate substrate 1b is removed, for example by trimming and / or polishing and / or chemical etching. The oxide layer(s) 11 are preferably also removed so as to expose the active layer 10, for example by polishing and / or chemical etching.

[0104] As illustrated in Figure 12, the active layer 10 can then be structured so as to form the individual devices 100. In this example, the devices 100 typically comprise an active part 110, for example configured to emit light, and contact pads 112. As previously, the formation of the individual devices 100 can in particular comprise one or more anisotropic etchings along z. The etching of the active layer 10 is typically selective with respect to the underlying metal release layer 21. As previously, the anisotropic etchings intended to separate the devices 100 from each other can be extended to the mineral absorption layer 22, or even to the transfer substrate 3. The splitting layer 20 can thus be etched along z over all or part of its thickness.

[0105] As previously, after formation of the devices 100, the transfer substrate 3 is brought opposite the receiving substrate 2. The contact pads 112 and 211 are aligned and bonded together. A localized illumination of the splitting layer 20 is then carried out by IR radiation through the transfer substrate 3 (figure 13). The metal release layer 21 melts or vaporizes locally under the effect of the heat induced by the IR radiation, thus releasing the devices 100a assembled on the receiving substrate 2, and retaining other devices 100b on the transfer substrate 3 (figure 14). The transfer substrate 3 can then be brought to another location to carry out another transfer, for example for the remaining device(s) 100b.

[0106] As illustrated through the previous examples, the transfer structure and method according to the invention therefore advantageously make it possible to form unitary semiconductor devices during the transfer, after removal of the donor substrate, and to transfer them in a localized manner onto the receiving substrate.

[0107] The invention is however not limited to the embodiments previously described.

[0108] In particular, the number, shape and arrangement of the semiconductor devices can be adapted according to the intended applications.

Claims

Claims Method for transferring at least one semiconductor device (100, 100a), from a first substrate (1, 1b) called donor to a second substrate (2) called receiver, using a silicon-based transfer substrate (3), said method comprising at least the following steps: • providing said donor substrate (1, 1b) comprising at least one active layer (10) intended to be integrated into said semiconductor devices (100, 100a, 100b), at a first face (201, 200), • providing said silicon-based transfer substrate (3), having a second face (202), • forming a split layer (20) on at least one of said first face (201, 200) and said second face (202), said split layer (20) being inorganic, • assembling said donor substrate (1, 1 b) with said transfer substrate (3), via said splitting layer (20), • removing said donor substrate (1, 1b), while retaining said at least one active layer (10) on the transfer substrate (3), and forming a plurality of semiconductor devices (100, 100a, 100b) from said at least one active layer (10), • separating the semiconductor devices of said plurality of semiconductor devices (100a, 100b) from each other, said semiconductor devices remaining held by the splitting layer (20) on the transfer substrate (3), • provide said receiving substrate (2), • assembling the semiconductor devices (100, 100a, 100b) with said receiving substrate (2), • illuminating, by infrared radiation (IR), the splitting layer (20) through said transfer substrate (3), so as to at least partially eliminate said splitting layer (20), to detach from the transfer substrate (3) only certain semiconductor devices (100a) of the plurality of semiconductor devices (100, 100a, 100b), said method being characterized in that the formation of said splitting layer (20) comprises a formation of a metallic release layer (21) on the side of said active layer (10), and a formation of a mineral absorption layer (22) on the side of said transfer substrate (3), so that said splitting layer (20) comprises said metallic release layer (21) and said mineral absorption layer (22), said mineral absorption layer (22) being configured to absorb at least 20% of said infrared radiation during illumination.Method according to the preceding claim in which the metallic release layer (21) is directly in contact with the mineral absorption layer (22). Method according to any one of the preceding claims in which each semiconductor device (100) of the plurality of semiconductor devices (100a, 100b) has a characteristic dimension less than or equal to 10 μm.

4. Method according to any one of the preceding claims wherein said illumination is carried out by a pulsed IR laser producing IR radiation of energy between 0.1 J and 10 pJ, for a duration between 100 femtoseconds (fs) and 10 picoseconds (ps).

5. Method according to any one of the preceding claims in which the illumination is carried out by a beam having a power less than or equal to 10 E 11 watts / cm 2 .

6. Method according to any one of the preceding claims in which the separation of the semiconductor devices (100, 100a, 100b) from each other is carried out by anisotropic etching in a direction normal to the second face (202), said anisotropic etching extending to the metallic release layer (21), preferably to the mineral absorption layer (22), preferably to the second face (202).

7. Method according to any one of the preceding claims wherein said mineral absorption layer (22) has a resistivity of between 50 p. ohm. cm (micro-ohm-centimeter) and 1 m. ohm. cm (milli-ohm-centimeter).

8. Method according to any one of the preceding claims in which said mineral absorption layer (22) is chosen from a refractory material having a melting temperature greater than or equal to 1500°C.

9. Method according to any one of the preceding claims in which said mineral absorption layer (22) is chosen from a refractory material based on a transition metal, preferably based on Ti, V, Zr, Ta, Hf, Nb, W.

10. Method according to any one of the preceding claims wherein said mineral absorption layer (22) is chosen from refractory transition nitrides based on a transition metal such as TiN, VN, ZrN, TaN, HfN, NbN, or their alloys.

11. Method according to any one of the preceding claims wherein said metallic release layer (21) has an infrared reflectivity greater than or equal to 97%.

12. A method according to any preceding claim wherein said metal release layer (21) has a resistivity of between 2.5 p. ohm. cm (micro-ohm-centimeter) and 50 p. ohm. cm (micro-ohm-centimeter).

13. Method according to any one of the preceding claims in which said metallic release layer (21) has a melting temperature less than or equal to 700°C.

14. Transfer structure comprising in stack, in the following order: • a transfer substrate (3) based on silicon, • a splitting layer (20), • a plurality of semiconductor devices (100a, 100b) separated from each other, each semiconductor device comprising at least one active part (110) and contact pads (112) intended to be bonded to contact pads (211) arranged on a receiving substrate (2), said transfer structure being configured so that, under illumination by infrared radiation (IR) through said transfer substrate (3), said layer of splitting (20) is at least partially eliminated, so as to detach certain semiconductor devices (100a) from the plurality of semiconductor devices (100, 100a, 100b) from said transfer substrate (3), said splitting layer (20) comprising: - a metallic release layer (21) on the side of the plurality of semiconductor devices (100a, 100b), - a mineral absorption layer (22) on the side of said transfer substrate (3), said mineral absorption layer (22) being configured to absorb at least 20% of the infrared radiation during illumination.

15. Structure according to the preceding claim in which the metallic release layer (21) is directly in contact with the mineral absorption layer (22).

16. Structure according to any one of claims 14 to 15 wherein said mineral absorption layer (22) has a resistivity of between 50 p. ohm. cm (micro-ohm-centimeter) and 1 m. ohm. cm (milli-ohm-centimeter).

17. Structure according to any one of claims 14 to 16 wherein said mineral absorption layer (22) is made of a refractory material having a melting temperature greater than or equal to 1500°C.

18. Structure according to any one of claims 14 to 17 in which said mineral absorption layer (22) is chosen from a refractory material based on a transition metal, preferably based on Ti, V, Zr, Ta, Hf, Nb, W.

19. Structure according to any one of claims 14 to 18 wherein said mineral absorption layer (22) is based on a refractory transition nitride taken from TiN, VN, ZrN, TaN, HfN, NbN, or an alloy of said refractory transition nitrides.

20. Structure according to any one of claims 14 to 19 wherein said metallic release layer (21) has an infrared reflectivity greater than or equal to 97%.

21. Structure according to any one of claims 14 to 20 wherein said metallic release layer (21) has a resistivity of between 2.5 p. ohm. cm (micro-ohm-centimeter) and 50 p. ohm. cm (micro-ohm-centimeter).

22. Structure according to any one of claims 14 to 21 wherein said metallic release layer (21) has a melting temperature less than or equal to 700°C.

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