Method and structure for transferring semiconductor devices

Abstract

The object of the present invention is a method for transferring a semiconductor device (100) by infrared laser ablation. The active layer is transferred from a donor substrate to a transfer substrate (3) made of silicon by bonding with a parting layer (20) between the active layer and the transfer substrate (3). The active layer is then formed on the transfer substrate (3) into a semiconductor device (100). The semiconductor device (100) is then assembled on a recipient substrate (2) and released onto the entire transfer substrate (3) under infrared radiation. Advantageously, the parting layer (20) comprises a metallic release layer (21) and a mineral absorption layer (22). Another object of the present invention is a transfer structure that allows the implementation of the transfer method.

Description

[Technical Field]

[0001] The present invention relates to the field of microelectronics and optoelectronics technology and finds particularly advantageous application in the mass transfer of semiconductor devices, such as light-emitting devices based on GaN-on-silicon. [Background technology]

[0002] A semiconductor device typically comprises at least one so-called "active" semiconductor layer that is involved in the operation of the device. For example, but not by way of limitation, the semiconductor device may be based on CMOS circuits, i.e., complementary metal oxide semiconductor transistors (CMOS is an acronym for "Complementary Metal Oxide Semiconductor"), or on microelectromechanical systems MEMS (an acronym for "Micro Electro Mechanical Systems"), or on LED types (an acronym for "Light Emitting Diode"). To illustrate the transfer method and structure, we now select one or more LED(s) or micro LED(s) as a non-limiting example.

[0003] Typically, different LEDs are assembled on a screen support, which may also comprise control electronics, to form a self-illuminating display screen consisting of multiple RGB pixels (an acronym for "Red Green Blue") that emit their own light.

[0004] The LEDs are typically formed on a donor or growth substrate and then individually separated before being transferred to a screen support or receiver substrate. Not all LEDs on the donor substrate are necessarily transferred to the receiver substrate.

[0005] Preferably, the LED growth substrate is silicon-based to benefit from the production capabilities of microelectronics industry equipment. To transfer multiple LEDs from a silicon-based growth substrate en masse, a glass transfer substrate is used, onto which the LEDs are attached with an organic adhesive. The growth substrate is then removed, and the LEDs are individually attached to a receiver substrate. UV laser irradiation then decomposes the organic adhesive across the glass transfer substrate, releasing the LEDs and combining them with the receiver substrate. This UV laser ablation method requires a glass transfer substrate, which is poorly compatible with microelectronics industry production equipment (substrate detection, mechanical deformation). Furthermore, organic adhesives are temperature-sensitive, potentially causing plate deformation and degradation due to temperature. As a result, performing intermediate LED technology steps after removing the growth substrate becomes more complex.

[0006] To overcome these drawbacks, WO 2022 / 111141 A1 discloses a solution that involves the use of mineral bonding, e.g., "oxide-oxide" bonding, between the transfer substrate and the device on the donor substrate. This solution involves the use of a silicon transfer substrate with an inorganic separating layer (usually aluminum-based). The separating layer can then be decomposed across the silicon transfer substrate by irradiating it with an infrared (IR) laser, releasing the assembled device on the receiving substrate. In practice, this method requires a very energy-intensive IR laser and can partially degrade the transferred device.

[0007] Another laser ablation process using inorganic partition layers is described in document US2022 / 406621 A1, which also requires a high-energy infrared laser. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2022 / 111141 A1 [Patent Document 2] US2022 / 406621 A1 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to at least partially overcome the drawbacks of the aforementioned solutions.

[0010] In particular, one object of the present invention is to provide an optimized method for transferring semiconductor devices, and another object of the present invention is to provide a transfer structure for semiconductor devices that allows the transfer method to be carried out.

[0011] Other objects, features, and advantages of the present invention will become apparent from a consideration of the following description and accompanying drawings. It is understood that other advantages may be incorporated therein. In particular, some features and some advantages of the transfer method are applicable mutatis mutandis to the transfer structure, and vice versa. [Means for solving the problem]

[0012] To achieve the above object, one aspect relates to a method for transferring at least one semiconductor device from a so-called donor first substrate to a so-called recipient second substrate using a silicon-based transfer substrate. This method involves at least providing a donor substrate on a first side, the donor substrate comprising at least one active layer intended to be integrated into a semiconductor device; providing a silicon-based transfer substrate having a second surface; forming a dividing layer on at least one of the first side and the second side, the dividing layer being inorganic; Assembling the donor substrate to the transfer substrate via the split layer; removing the donor substrate while maintaining the at least one active layer on the transfer substrate and forming at least one semiconductor device starting from the at least one active layer; providing a receptor substrate; Assembling at least one semiconductor device to a receptor substrate; and irradiating the division layer of the entire transfer substrate with infrared light to at least partially remove the division layer, thereby peeling off at least one semiconductor device from the transfer substrate.

[0013] Preferably, forming the dividing layer comprises forming a metallic release layer on the active layer side and a mineral absorbing layer on the transfer substrate side, whereby the dividing layer comprises a metallic release layer and a mineral absorbing layer, the mineral absorbing layer being configured to absorb at least 20% of infrared radiation when irradiated. The dividing layer is thus in the form of a dual layer, which has the advantage of separating the respective functions of the metallic release layer and the mineral absorbing layer.

[0014] The metallic release layer is intended to melt or vaporize under the effect of heat transmitted by the infrared absorbing layer, which also protects the at least one semiconductor device from infrared radiation by reflecting the infrared radiation back toward the absorbing layer.

[0015] The mineral absorption layer can efficiently absorb infrared radiation and generate enough heat to partially or completely melt or vaporize the metal release layer, thus reducing the energy of the infrared radiation.

[0016] In connection with the development of the present invention, it was observed that theoretical considerations would require very high laser powers in order to use a simple aluminum layer as a splitting layer due to the reflectivity of aluminum, and in practice, picosecond (ps) pulsed infrared lasers cannot be used.

[0017] By adding a mineral absorber layer, for example based on transitional refractory nitrides, the energy required to melt / vaporize the metal peel layer can be reduced sufficiently to allow the use of pulsed infrared lasers delivering energies of 10 microjoules (μJ) or less.

[0018] Instead of a dividing layer, document WO 2022 / 111141 A1 provides either an aluminum layer or a light / heat conversion layer. In the first case, the reflectivity of aluminum makes the energy required very high. In the second case, the reflectivity of the layer decreases and the device is no longer protected from infrared rays.

[0019] Practical developments carried out in connection with the development of the present invention have led to the consideration of a combination of an absorber layer and a release / reflector layer, which is not considered in the alternative proposed by document WO2022 / 111141 A1.

[0020] This combination advantageously allows for a reduction in the required energy delivered by the pulsed infrared laser while protecting the device being transferred.

[0021] Preferably, the metal release layer is in direct contact with the mineral absorber layer. There is no intermediate layer between the metal release layer and the mineral absorber layer. This allows all of the energy absorbed by the mineral absorber layer to be directly transferred to the metal release layer, thereby melting / evaporating the metal release layer with locally reduced energy. This allows for a reduced energy density to be used to delaminate the semiconductor device from the transfer substrate via the melting / evaporation of the metal release layer. Unlike the laser ablation process disclosed in US2022 / 406621 A1, which requires the insertion of a silicon-based layer between the metal release layer and the mineral absorber layer, this process typically requires a lower energy density of 10 watts / cm. 2 The following power densities are sufficient:

[0022] Another aspect is, a so-called donor first substrate; at least one active layer intended to be integrated into at least one semiconductor device; A dividing layer; The present invention relates to a transfer structure comprising a silicon-based transfer substrate, stacked on top of one another. The laminate is configured such that when the entire transfer substrate is irradiated with infrared (IR) light, the dividing layer is at least partially removed and the transfer substrate is peeled off from the laminate. Preferably, the dividing layer comprises: a metallic release layer on the side of the active layer; The mineral absorbing layer on the side of the transfer substrate is configured to absorb at least 20% of the infrared radiation when irradiated.

[0023] Such a transfer structure makes it possible to advantageously carry out the transfer method described above.

[0024] The stack of layers does not include any organic layers and can therefore be advantageously handled by conventional process steps in the microelectronics industry, for example to form semiconductor devices starting from the active layer after removing the donor substrate and before peeling off the transfer substrate.

[0025] The objects, aims, features and advantages of the present invention will be better understood from the following detailed description of the embodiments illustrated by the accompanying drawings, in which: [Brief explanation of the drawings]

[0026] [Figure 1A] 1A-1D are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 1B] 1A-1D are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 2] 1A to 1C are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 3] 1A to 1C are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 4]1A to 1C are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 5] 1A to 1C are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 6] 1A to 1C are diagrams illustrating steps of a transfer method according to one embodiment of the present invention. [Figure 7] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 8] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 9] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 10] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 11] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 12] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 13] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. [Figure 14] 5A to 5C are diagrams illustrating steps of a transfer method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The drawings are illustrative and not limiting of the invention. They are general schematic representations intended to facilitate understanding of the invention and are not necessarily scaled to a practical application. In particular, the dimensions of the different layers and parts of the transfer structure and the LED do not necessarily represent reality.

[0028] Before starting a detailed discussion of the embodiments of the invention, it should be recalled that the invention, according to a first aspect thereof, consists in particular in any of the following features that may be used in combination or alternatively:

[0029] According to one embodiment, the at least one semiconductor device comprises a plurality of semiconductor devices each having a characteristic dimension of 100 μm or less, preferably 10 μm or less, more preferably 5 μm or less.

[0030] According to one embodiment, the irradiation is configured to separate only some of the semiconductor devices of the plurality of semiconductor devices, thus allowing the localized transfer of micro-components.

[0031] According to one embodiment, a semiconductor device comprising a plurality of semiconductor devices is separated from one another prior to irradiation, with the semiconductor devices remaining held together by a separating layer on the transfer substrate. The semiconductor devices are typically separated prior to separation by laser irradiation.

[0032] According to one embodiment, irradiation is performed using a pulsed infrared laser emitting infrared radiation with a duration between 100 femtoseconds (fs) and 10 picoseconds (ps) and an energy between 0.1 μJ and 10 μJ, preferably between 1 μJ and 10 μJ. Advantageously, such lasers emit "low" energy radiation and can be shaped to target individual semiconductor devices.

[0033] According to one embodiment, the infrared (IR) radiation has a wavelength of 2.5 μm or less. According to one embodiment, the irradiation is performed using a pulsed infrared laser that generates the IR radiation in the form of pulses, the energy of one pulse being comprised between 0.1 μJ and 10 μJ. According to one embodiment, the duration of one pulse is comprised between 100 femtoseconds (fs) and 10 picoseconds (ps).

[0034] For example, the separation of the semiconductor devices from one another is achieved by anisotropic etching in a direction perpendicular to the second surface. According to one embodiment, the anisotropic etching extends to the metallic release layer, preferably to the mineral absorber layer, preferably to the second surface. Removal of the separation layer advantageously allows for a clearer or more precise debonding. The semiconductor devices are locally separated from the transfer substrate. The semiconductor devices can be removed individually or in small groups. The transfer of the semiconductor devices is not collective. Multiple semiconductor devices are not transferred to the receiving substrate. According to one embodiment, the mineral absorber layer has a resistivity between 50 μ.ohm.cm (micro-ohm-centimeter) and 1 m.ohm.cm (milli-ohm-centimeter). Such an absorber layer can conduct charge carriers generated upon absorption of infrared radiation. Advantageously, these charge carriers are conducted toward the metallic release layer, increasing the heat transferred to the metallic release layer.

[0035] According to one embodiment, the mineral absorber layer is selected from refractory materials having a melting point above 1500° C. This allows most, and potentially all, thermal processes in the microelectronics industry to be carried out without degradation of the mineral absorber layer, thus limiting thermal degradation under infrared radiation to the metallic release layer.

[0036] According to one embodiment, the mineral absorption layer is selected from transition materials, preferably refractory materials based on Ti, V, Zr, Ta, Hf, Nb, W.

[0037] According to one embodiment, the mineral absorber layer is selected from transition metals such as Ti, V, Zr, Ta, Hf, Nb, W, etc.

[0038] According to one embodiment, the mineral absorption layer is selected from transition metal-based refractory nitrides such as TiN, VN, ZrN, TaN, HfN, NbN, or alloys thereof. According to another embodiment, the mineral absorption layer is selected from transition metal-based refractory carbides. According to another embodiment, the mineral absorption layer is selected from transition metal-based refractory borides.

[0039] According to one embodiment, the thickness of the mineral absorbing layer ranges from 10 nm to 100 nm.

[0040] According to one embodiment, the mineral absorbing layer has an extinction coefficient k>1 for radiation wavelengths below 2.5 μm.

[0041] According to one embodiment, the metallic release layer has an infrared reflectivity of 97% or greater, thereby protecting the semiconductor device from infrared radiation when irradiated.

[0042] According to one embodiment, the metallic release layer has a resistivity between 2.5 μOhm·cm (microohm·centimeter) and 50 μOhm·cm (microohm·centimeter).

[0043] According to one embodiment, the thickness of the metallic release layer ranges from 30 nm to 200 nm.

[0044] According to one embodiment, the metallic release layer is based on elemental metals such as aluminum, tin, zinc, or metal alloys with a melting point below 700°C.

[0045] According to one embodiment, the metallic release layer has a melting point below 700° C. According to one example, the mineral absorption layer is made from a refractory material having a melting point above 2500° C.

[0046] According to one embodiment, the mineral absorbing layer is based on a transition refractory nitride selected from TiN, VN, ZrN, TaN, HfN, NbN or alloys of these transition refractory nitrides.

[0047] Except where incompatible, technical features described in detail for a particular embodiment may be combined with technical features described in the context of other embodiments described as non-limiting examples to form further embodiments not necessarily shown or described, and of course such embodiments are not excluded from the present invention.

[0048] In the present invention, the method is particularly specialized for transferring semiconductor devices, in particular devices with dimensions in the micrometer range, such as light emitting diodes (LEDs), where LEDs or individual semiconductor devices typically have projected dimensions on the base surface xy in the range of 2.5 μm x 2.5 μm to 100 μm x 100 μm.

[0049] The invention is more broadly applicable to a variety of microelectronic or optoelectronic devices, as well as electromechanical devices or microsystems (MEMS). For example, the invention is applicable in the context of laser devices or photovoltaic devices.

[0050] Unless explicitly stated, in the context of the present invention, the relative positioning 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 rather that the third layer is either in direct contact with the first layer and the second layer or is separated therefrom by at least one other layer or at least one other element.

[0051] Thus, the terms and phrases "having," "covering," and "overlapping" do not necessarily mean "in contact with."

[0052] The steps of the methods recited in the claims should be understood in a broad sense and may be divided into several substeps for implementation.

[0053] In this patent application, the terms "light emitting diode," "LED," or simply "diode" are used synonymously. "LED" may also be understood as "micro LED" or "smart LED" where appropriate.

[0054] A portion or element described as "sacrificial" means that the element is intended to be "sacrificed," ie, removed, in a subsequent step in the method.

[0055] A substrate, layer, or device "based on" a material M means a substrate, layer, or device composed solely of that material M, or of that material M and possibly other materials, such as alloying elements, impurities, doping elements, etc. Thus, a GaN-based diode is typically composed of GaN and an AlGaN or InGaN alloy.

[0056] A reference frame with axes x, y and z, preferably orthonormal, is depicted in some of the accompanying figures, which reference frame is extendible to other figures of the same figure.

[0057] This patent application preferably describes the thickness of layers and the height of structures or devices. Thickness is considered along a direction perpendicular to the layer's main extension plane, and height is considered along a base plane xy. Thus, a layer typically has a thickness along z when extending primarily along the plane xy, and a protruding element, e.g., a device, has a height along z. The relative terms "above," "below," and "base" preferably refer to a position considered along the z direction. Dimensional values ​​should be understood within the scope of manufacturing and measurement tolerances. The terms "substantially," "about," and "within" refer to values ​​and, when referring to angular directions, to within 10° of the value. Thus, a direction substantially perpendicular to a plane refers to a direction at an angle of 90±10° to the plane.

[0058] The optical absorption coefficient, denoted in this patent application as α or a, is the ratio between the absorbance and the optical path length (m -1 or cm -1 It is defined by the ratio between

[0059] The extinction coefficient (also called attenuation coefficient) of a medium is denoted by k and measures the energy loss of electromagnetic radiation as it traverses the medium. Like the absorption coefficient, it takes into account the effects of diffusion and emission as well as absorbance. It is material and wavelength dependent. It is k=n'', the imaginary part of the complex refractive index n=n′+in″. Transparent materials have low extinction coefficients, while opaque materials have high extinction coefficients.

[0060] In the context of the present invention, the irradiation is carried out in the infrared wavelength range, preferably in the near infrared range, with wavelengths comprised between 1 μm and 2.5 μm.

[0061] One objective of the present invention is to transfer a semiconductor or optoelectronic device onto a receiving substrate, such as a screen support, via a transfer structure and an IR laser ablation process. The principle of the present invention is to perform the transfer and bonding via a split layer consisting of a metallic release layer and a mineral absorber layer, preferably in direct contact with each other. In the context of the transfer method, the metallic release layer is a sacrificial layer. Specifically, the absorber layer absorbs infrared light and converts it into heat. Specifically, this heat diffuses toward the metallic release layer. This typically causes partial meltdown or partial evaporation of the metallic release layer at the interface between the two layers. This can lead to degradation of the interface between the two layers and separation of the two layers. The unmelted portion of the release layer may remain on the side of the transferred device.

[0062] 1A and 1B show two variants in which the dividing layer 20 is formed directly on the transfer substrate 3 (FIG. 1A) or directly on the donor substrate 1 (FIG. 1B), respectively.

[0063] According to a first embodiment shown in Figure 1A, a donor substrate 1 is provided, which typically comprises an active layer 10 covered by a mineral bonding layer 11. Preferably, the donor substrate 1 is silicon-based.

[0064] For example, the active layer 10 can be based on GaN (p-GaN and / or n-GaN), AlGaN, and / or InGaN, epitaxially grown on the donor substrate 1. Typically, the active layer comprises, for example, a p-n junction or quantum wells, and is adapted to form a semiconductor device, such as one or more LEDs. The active layer 10 can also comprise adjacent three-dimensional structures based on InGaN, such as nanowires or nanopyramids. The active layer 10 can also comprise sublayers structured and intended to form, for example, electrical contacts, on the p-GaN or n-GaN, for example, based on transparent conductive oxides (TCOs).

[0065] The mineral bonding layer 11 is typically silicon oxide SiO2. In particular, the active layer 10 can be planarized to provide a flat surface 201 suitable for mineral bonding, allowing direct SiO2 to SiO2 bonding.

[0066] The transfer substrate 3 is silicon-based. In this example, a parting layer 20 is formed above a surface 202 of the transfer substrate 3. The exposed surface 203 of the parting layer 20 is essentially flat and suitable for mineral bonding. For example, the mineral bonding may consist of molecular bonding. The mineral bonding between the transfer substrate 3 and the donor substrate 1 is achieved by surfaces 201, 203.

[0067] The dividing layer 20 comprises at least one mineral absorption layer 22 and at least one metallic release layer 21. The mineral absorption layer 22 is formed directly on a side surface, for example, face 202, of the transfer substrate 3. The metallic release layer 21 is formed on the mineral absorption layer 22, with the mineral absorption layer 22 being interposed between the transfer substrate 3 and the metallic release layer 21. Here, the exposed face 203 of the dividing layer 20 corresponds to the face of the metallic release layer 21. According to a possibility not shown, a silicon oxide layer is formed on face 203 of the dividing layer 20. Then, bonding is performed by SiO2-SiO2 type molecular bonding.

[0068] The mineral absorber layer 22 is typically at least partially conductive, preferably with a resistivity in the range of 50 μOhm·cm to 1 mOhm·cm. This optimizes heat and electron transfer between the mineral absorber layer 22 and the metallic release layer 21. The thickness of the mineral absorber layer 22 is preferably in the range of 10 nm to 100 nm, depending on z. Typically, in the near-infrared region, the optical extinction coefficient k is greater than 1 for wavelengths of 2.5 μm or less. This allows for absorption of at least 20%, and in some cases at least 30%, or even at least 40% of infrared radiation in the near-infrared region. The mineral absorber layer 22 may be based on transition metals, such as Ti, Ta, W, Zr, Nb, or Hf. Alternatively, it may be based on nitrides of these transition metals (called transition refractory nitrides), such as TiN, TaN, VN, ZrN, HfN, or NbN. Alternatively, it may be based on carbides of these transition metals, called transition refractory carbides, such as TiC, TaC, or VC. Alternatively, the mineral absorber layer 22 may be based on a boride of one of these transition metals (called transition refractory borides), such as TiB2, TaB, TaB2, VB2, or HfB2. The mineral absorber layer 22 may also be based on a combination or alloy of these materials, such as C5HfTa4. Preferably, the mineral absorber layer 22 has a melting point of 1500°C or higher. This prevents thermal degradation of the mineral absorber layer 22 during irradiation. Therefore, the integrity of the mineral absorber layer 22 is maintained after irradiation.

[0069] The metallic release layer 21 is typically electrically conductive, preferably with a resistivity of 2.5 μΩ·cm to 50 μΩ·cm. Preferably, the thickness of the metallic release layer 21 is 30 nm to 200 nm in Z. The metallic release layer 21 typically has an optical reflectivity of 97% or more in the near-infrared region at wavelengths of 2.5 μm or less. Therefore, when light is irradiated onto the entire transfer substrate 3, the infrared light transmitted through the mineral absorption layer 22 is reflected by the metallic release layer 21. This protects the semiconductor layer 10 and / or the semiconductor device formed therefrom from the infrared light. The metallic release layer 21 can be based on a simple metal, such as Al, Sn, or Zn. Preferably, the melting point of the metallic release layer 21 is 700°C or less. Therefore, the melting point difference between the metallic release layer 21 and the mineral absorption layer 22 is large enough to ensure partial (not shown) or complete melting / evaporation of the metallic release layer 21 while maintaining the integrity of the mineral absorption layer 22.

[0070] The properties of the different layers 10, 11, 21, 22, in particular the mineral absorption layer 22 and the metal release layer 21, are common to the other embodiments described below.

[0071] 1B, the dividing layer 20 is formed on the surface 201 of the donor substrate 1. Here, the exposed surface 204 of the dividing layer 20 corresponds to the surface of the mineral absorption layer 22. The mineral bond between the transfer substrate 3 and the donor substrate 1 is formed between the surfaces 202, 204. According to a possibility not shown, one or more silicon oxide layers are formed on the surface 204 of the dividing layer 20 and on the surface 202 of the transfer substrate 3. The bond is then formed by a molecular bond of the SiO2-SiO2 type.

[0072] In this example, metallic release layer 21 is formed on a side surface of donor substrate 1, e.g., directly above face 201. Mineral absorption layer 22 is formed on metallic release layer 21, such that metallic release layer 21 is interposed between donor substrate 1 and mineral absorption layer 22.

[0073] As shown in FIG. 2, regardless of the surface 201 or surface 202 on which the dividing layer 20 is formed, the donor substrate 1 and the transfer substrate 3 are assembled via the dividing layer 20, typically by molecular bonding.

[0074] 3, the donor substrate 1 is then removed, for example by partial trimming, partial chemical mechanical polishing (CMP) or selective chemical bonding to the active layer 10. The active layer 10 and oxide layer 11 are retained on the transfer substrate 3.

[0075] As shown in FIG. 4, the active layer 10 and the oxide layer 11 are subsequently structured to form and separate the semiconductor devices 100 (e.g., LEDs). This structure may include annealing at temperatures of several hundred degrees Celsius. Advantageously, the layers 21 and 22 of the dividing layer 20 can withstand these temperatures. Therefore, the structure can be performed after the initial layers 10 and 11 have been transferred to the transfer substrate 3. This transfer method therefore places fewer constraints on the ordering of the steps for forming the devices 100. In the example shown in FIG. 4, the semiconductor device 100 comprises an insulating and transparent portion 111, an active portion 110 that is typically configured to emit light, and contact pads 112. In particular, the formation of the individual devices 100 may include one or more anisotropic etches in z. The etching of the oxide layer 11 is essentially selective to the metallic release layer 21. According to a possibility not shown, the anisotropic etching for separating the devices 100 from one another may be extended to the mineral absorption layer 22 or to the transfer substrate 3. Thus, the dividing layer 20 can be engraved along the z axis depending on all or part of its thickness. As shown in FIG. 5 , after forming the devices 100, the transfer substrate 3 faces a receiver substrate 2 (e.g., a screen support) for receiving at least some of the devices 100. The receiver substrate 2 typically has contact pads 211 on its surface 205, positioned to receive the devices 100. After aligning the contact pads 112 and 211, they are bonded together, for example, by thermocompression bonding or Cu-Cu bonding between the contact pads 112 and 211. The entire transfer substrate 3 is then irradiated with IR radiation. This IR radiation is typically localized only above the devices 100 to be transferred. Typically, at least 20%, preferably at least 30%, or even at least 40% of the IR radiation is absorbed by the layer 22. The energy of the absorbed IR radiation is transferred to the metallic release layer 21 in the form of heat.

[0076] 6, the metal release layer 21 is affected by the heat from the infrared irradiation and melts or vaporizes locally, thereby peeling off a portion of the device 100a assembled on the receptor substrate 2. Because the infrared irradiation is localized, another device 100b is held on the transfer substrate 3 via the unmelted portion 21p of the metal release layer 21. The transfer substrate 3 is then moved to another location, and, for example, the device 100b is transferred.

[0077] The wavelength of the infrared light is usually 1 μm to 2.5 μm, preferably 1.5 μm to 2 μm. Preferably, the infrared light is generated in pulses by a pulsed laser. The energy of the infrared pulse is preferably in the range of 0.1 μJ to 10 μJ, preferably 1 μJ to 10 μJ, for example 7 μJ or 8 μJ. The duration of the infrared pulse is preferably 100 fs to 10 ps, ​​preferably 1 ps to 10 ps. A single infrared pulse is sufficient to peel the device 100a from the transfer substrate 3. The irradiation is 10 watts / cm. 2 This can be done by a beam, usually a laser beam, with the following power:

[0078] 7 to 14 show another embodiment of the transfer method. In this embodiment, a first transfer of the semiconductor layer 10 is performed from a growth substrate 1a to an intermediate substrate 1b, for example based on silicon. After growing the active layer 10 on the substrate 1a (FIG. 7), the intermediate substrate 1b is bonded onto the active layer 10 via one or more oxide layers 11, for example based on silicon oxide (FIG. 8). The growth substrate 1a is then partially removed, for example by trimming, by chemical mechanical polishing (CMP), or by selective chemical attack on the active layer 10, exposing a face 200 of the active layer 10 (FIG. 9).

[0079] As shown in Figure 10, an intermediate substrate 1b having an active layer 10 is bonded to a transfer substrate 3 via a dividing layer 20. The dividing layer 20 may be pre-formed on a surface 200 of the active layer 10 or on a surface 202 of the transfer substrate 3. This intermediate substrate 1b corresponds to the donor substrate 1 in the previous embodiment. A mineral absorption layer 22 is formed so as to be located on the transfer substrate 3 side. A metal release layer 21 is formed so as to be located on the active layer 10 side.

[0080] After bonding, the intermediate substrate 1b is removed, for example by cutting and / or polishing and / or chemical attack, as shown in Figure 11. Preferably, the oxide layer 11 is also removed, for example by polishing and / or chemical attack, to expose the active layer 10.

[0081] As shown in FIG. 12, the active layer 10 may then be configured to form individual devices 100. In this example, the devices 100 typically include an active portion 110 configured to emit light, and contact pads 112. As before, forming the individual devices 100 may comprise one or more anisotropic etches, particularly in z. The etching of the active layer 10 is typically selected with consideration given to the underlying metal release layer 21. As before, the anisotropic etching intended to separate the devices 100 from one another can extend to the mineral absorber layer 22 and the transfer substrate 3. Thus, the separation layer 20 can be sculpted along z according to all or part of its thickness.

[0082] As before, after forming the devices 100, the transfer substrate 3 is brought against the receptor substrate 2. The contact pads 112 and 211 are aligned and bonded together. The parting layer 20 is then locally irradiated with infrared (IR) radiation across the entire transfer substrate 3 (FIG. 13). The metal release layer 21 locally melts or vaporizes under the influence of the heat induced by the IR radiation, releasing the assembled devices 100a on the receptor substrate 2 and retaining the other devices 100b on the receptor substrate 2 (FIG. 14). The transfer substrate 3 can then be brought to another location to perform another transfer for the remaining devices 100b.

[0083] Thus, as shown in the examples above, the transfer structure and method according to the present invention advantageously enables the formation of unitary semiconductor devices after removal of the donor substrate and their local transfer to a recipient substrate.

[0084] However, the present invention is not limited to the above-described embodiment.

[0085] In particular, the number, shape, and arrangement of semiconductor devices may be adjusted depending on the target application.

Claims

1. A method for transferring at least one semiconductor device (100, 100a) from a so-called donor first substrate (1, 1b) to a so-called recipient second substrate (2) using a silicon-based transfer substrate (3), comprising: providing a donor substrate (1, 1b) comprising, on a first side (201, 200), at least one active layer (10) intended to be integrated into said semiconductor device (100, 100a, 100b); providing said silicon-based transfer substrate (3) having a second surface (202); forming a dividing layer (20) on at least one of the first surface (201, 200) and the second surface (202), wherein the dividing layer (20) is inorganic; assembling the donor substrate (1, 1b) to the transfer substrate (3) via the dividing layer (20); removing the donor substrate (1, 1b) while the at least one active layer (10) is maintained on the transfer substrate (3), to form a plurality of semiconductor devices (100, 100a, 100b) starting from the at least one active layer (10); separating the plurality of semiconductor devices (100a, 100b) from one another, the semiconductor devices remaining held on the transfer substrate (3) by the dividing layer (20); providing said receptor substrate (2); Assembling the semiconductor device (100, 100a, 100b) to the receptor substrate (2); irradiating the dividing layer (20) of the entire transfer substrate (3) with infrared rays (IR) so as to at least partially remove the dividing layer (20), and peeling only some of the semiconductor devices (100a) of the plurality of semiconductor devices (100, 100a, 100b) from the transfer substrate (3); The method is characterized in that forming the dividing layer (20) includes forming a metal release layer (21) on the side of the active layer (10) and forming a mineral absorbing layer (22) on the side of the transfer substrate (3), whereby the dividing layer (20) comprises the metal release layer (21) and the mineral absorbing layer (22), and is configured to absorb at least 20% of the infrared light when irradiated.

2. 2. The method of claim 1, wherein the metal release layer (21) is in direct contact with the mineral absorption layer (22).

3. 3. The method of claim 1 or 2, wherein each semiconductor device (100) of the plurality of semiconductor devices (100a, 100b) has a characteristic dimension of 10 [mu]m or less.

4. 4. The method according to claim 1, wherein the irradiation is carried out by a pulsed infrared laser generating infrared radiation with an energy comprised between 0.1 μJ and 10 μJ for a duration comprised between 100 femtoseconds (fs) and 10 picoseconds (ps).

5. The irradiation is 10 watts / cm 2 The method according to any one of claims 1 to 4, carried out by a beam having the following power:

6. 6. The method according to any of claims 1 to 5, wherein the separation of the semiconductor devices (100, 100a, 100b) from each other is effected by anisotropic etching in a direction perpendicular to the second face (202), the anisotropic etching extending to the metal release layer (21), preferably the mineral absorption layer (22), preferably the second face (202).

7. The method according to any one of the preceding claims, wherein the mineral absorption layer (22) has a resistivity comprised between 50 μOhm-cm (microohm-centimeter) and 1 mOhm-cm (milliohm-centimeter).

8. The method according to any one of claims 1 to 7, wherein the mineral absorption layer (22) is selected from refractory materials having a melting point above 1500°C.

9. The method according to any of the preceding claims, wherein the mineral absorption layer (22) is selected from refractory materials based on transition metals, preferably Ti, V, Zr, Ta, Hf, Nb, W.

10. The method according to any of the preceding claims, wherein the mineral absorption layer (22) is selected from among transition refractory nitrides based on transition metals such as TiN, VN, ZrN, TaN, HfN, NbN or alloys thereof.

11. The method according to any one of claims 1 to 10, wherein the metallic release layer (21) has an infrared reflectance of 97% or more.

12. The method according to any of the preceding claims, wherein the metallic release layer (21) has a resistivity comprised between 2.5 μOhm.cm (microohm centimeter) and 50 μOhm.cm (microohm centimeter).

13. The method according to any one of claims 1 to 12, wherein the metallic release layer (21) has a melting point of 700°C or less.

14. A transfer structure laminated together, further comprising: a silicon-based transfer substrate (3); A dividing layer (20); a plurality of semiconductor devices (100a, 100b) separated from one another, each of which comprises at least an active layer (110) and contact pads (112) intended to be bonded to contact pads (211) arranged on a receiving substrate (2); The transfer structure is configured such that when the entire transfer substrate (3) is irradiated with infrared (IR) radiation, the dividing layer (20) is at least partially removed and some semiconductor devices (100a) of the plurality of semiconductor devices (100, 100a, 100b) are peeled off from the transfer substrate (3); The dividing layer (20) is a metal release layer (21) provided on the side of the plurality of semiconductor devices (100a, 100b); a mineral absorbing layer (22) on the transfer substrate (3) side, the mineral absorbing layer (22) being configured to absorb at least 20% of infrared radiation when irradiated.

15. 15. The transfer structure of claim 14, wherein the metal release layer (21) is in direct contact with the mineral absorption layer (22).

16. 16. Transfer structure according to claim 14 or 15, wherein said mineral absorption layer (22) has a resistivity comprised between 50 μ.ohm.cm (micro-ohm centimeter) and 1 m.ohm.cm (milli-ohm centimeter).

17. The transfer structure according to any one of claims 14 to 16, wherein the mineral absorption layer (22) is a refractory material having a melting point of 1500°C or higher.

18. Transfer structure according to any of claims 14 to 17, wherein said mineral absorption layer (22) is selected from refractory materials based on transition metals, preferably Ti, V, Zr, Ta, Hf, Nb, W.

19. Transfer structure according to any of claims 14 to 18, wherein the mineral absorption layer (22) is based on a transition refractory nitride of the following group: TiN, VN, ZrN, TaN, HfN, NbN or an alloy of said transition refractory nitrides.

20. The transfer structure of any of claims 14 to 19, wherein the metallic release layer (21) has an infrared reflectance of 97% or more.

21. Transfer structure according to any of claims 14 to 20, wherein the metallic release layer (21) has a resistivity comprised between 2.5 μ ohm.cm (micro-ohm centimeter) and 50 μ ohm.cm (micro-ohm centimeter).

22. Transfer structure according to any of claims 14 to 21, wherein the metallic release layer (21) has a melting point of 700°C or less.

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