Donor substrate for use in a method of light-induced component transfer

Abstract

The present document relates to a donor substrate for use in a method of light-induced component transfer to an acceptor substrate. The donor substrate comprises an optically transparent carrier and for supporting the at least one component prior to transfer, further comprises a contact layer on the optically transparent carrier configured to attach the component to the donor substrate. The contact layer comprises a release layer for being illuminated configured to release the component when exposed to the light beam. At least part of the contact layer is patterned such as to form contact elements connecting the component to the donor substrate over at least a contact area, such that a sum of the contact areas is smaller than a total area of the component's support surface.

Description

[0001] 1 P139321PC00 Title: Donor substrate for use in a method of light-induced component transfer.

[0002] Field of the invention

[0003] The present invention is directed at a donor substrate for use in a method of light-induced component transfer of a component from the donor substrate to an acceptor substrate, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam from a light source during the light-induced component transfer, wherein the donor substrate is configured to attach the component to the donor substrate, the donor substrate comprising a release layer for being illuminated through the optically transparent carrier by the light beam and configured to release the component when the release layer is exposed to optical energy from the light beam. The invention is further directed at a method of manufacturing the donor substrate.

[0004] Background

[0005] Semiconductor devices and photonics components are extremely fragile, due in part to their small sizes and high aspect ratios. As such, assembly of such devices requires complex pick-and-place equipment to transfer the components without damaging them. This equipment is expensive and intrinsically slow, and at best provides a low transfer yield.

[0006] Known transfer techniques are able to transfer small micro-components from a donor substrate to an acceptor substrate, and are applied in the manufacture of semiconductor devices and photonic devices . Such micro-components may be transferred using light-induced techniques from the donor substrate carrying the micro-components to the acceptor substrate with high yields. This typically involves illuminating a release layer of the donor substrate to which the component is attached with a light beam that carries a sufficient light beam fluence (optical energy delivered per unit of area) to induce the release of the component towards the acceptor substrate.

[0007] For a controlled and accurate transfer, the release has to occur simultaneously across the entire illuminated area. However, this can be very difficult to achieve if those components are large or if they have complex shapes. For example, maintaining a uniform distribution of light beam fluence to release the component becomes more difficult to achieve when components have high aspect ratios, or when their surface areas are larger. A further challenge when transferring larger components is that the required optical power scales with the surface area to be illuminated. Larger components thus require more powerful – and therefore more expensive – light sources.

[0008] Application of this technique is therefore limited to smaller components and cannot freely be applied to handling components of varying sizes and shapes.

[0009] Summary of the invention

[0010] It is an object of the present invention to provide a donor substrate and a method of manufacturing thereof that overcome the abovementioned drawbacks, and which allow light-induced component transfer to be applied for transferring components of any size and having any shape, in an energy-efficient manner.

[0011] To this end, there is provided herewith, in accordance with a first aspect of the invention, a donor substrate for use in a method of light-induced component transfer of a component from the donor substrate to an acceptor substrate, the component comprising a support surface facing the donor substrate prior to transfer of the component, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam from a light source during the light-induced component transfer, wherein the donor substrate for supporting the component prior to transfer thereof, further comprises a contact layer on the optically transparent carrier configured to attach the component to the donor substrate, wherein the contact layer comprises a release layer for being illuminated through the optically transparent carrier by the light beam and configured to release the component when the release layer is exposed to optical energy from the light beam, wherein at least a part of the contact layer is patterned such as to form one or more contact elements, each contact element arranged for connecting the component to the donor substrate over at least a contact area, such that a sum of the contact areas of the one or more contact elements configured for supporting the component is smaller than a total area of the support surface.

[0012] The present invention is based on the realization that the footprint of the contact layer need not match the total area of the component’s support surface. Instead, in accordance with the invention, the component is supported by the donor substrate using contact elements that cover, both individually and in total, only a portion of the component’s support surface. The invention thereby achieves a reduced area that is to be illuminated during the light-induced component transfer, since only the sum total of the contact areas needs to be illuminated. The invention in other words decouples the area to be illuminated from the shape or size of the component. This reduction allows the light beam fluence threshold required for inducing the release of the component during transfer to be reached without the need for increasing the laser power in proportion to the size of the component. As long as the contact elements have contact areas that render them suitable to support the weight of the component, the contact elements of the donor substrate of the invention advantageously do not need to comprise contact areas that cover the full support surface, and thereby advantageously do not need to increase in contact area in proportion to the size of the support surface. Contact elements may in this context be understood as (contact) structures, such as pillars, pads, ribs or other structures that cover only a portion of the support surface of the component. For attaching the support surface and for supporting the component, the contact layer may typically have materials, or at least comprises a layer with materials, that adhere to the support surface of the component. Furthermore, by reducing the area to be illuminated, the invention also avoids the need for implementing elaborate or complex beam shaping optics to yield a suitable beam spot for releasing large or complexly shaped components. Large components may for example be components that have lateral dimensions of the support surface exceeding 100 μm2. Components with complex shapes, such as high aspect ratio features (where one lateral dimension of the support surface is larger than another lateral dimension of the support surface, such as twice as large or larger), or components that include a bend along their length, may for example be supported from the donor substrate using contact elements that are strategically placed across the footprint of the component. As an example, a single contact element centrally placed with respect to the component may be used. Alternatively, multiple contact elements that may be spatially distributed (e.g. evenly distributed) across the support surface maybe employed. In this way, the invention is able to significantly reduce undesirable release dynamics when transferring the component. For example, if a large or complexly shaped component is supported from the donor substrate across its full support surface, the risk of controlled and accurate release being interfered with by a defect or imperfection that is present in the contact layer would be significantly higher. Such defects or imperfections can locally alter the threshold of required light beam fluence for inducing the release of the component from the contact layer. As a result, the component being transferred may be released unevenly or even partially, or after release assume an unintended angular orientation or tilt as it moves from the donor substrate to the acceptor substrate. Such uncontrolled release may also be caused due to non-uniform thickness of the release layer -larger areas to be illuminated have an increased risk of unevenness across that surface. This can lead to inaccurate transfer of the component, or to bouncing of the component when it is received on the acceptor substrate. Advantageously, this risk is made significantly less likely by the fact that the contact elements in total have a smaller contact area than the support surface. To achieve these advantages, the donor substrate of the present invention, rather than supporting the component across its full support surface using the contact layer, comprises a patterned contact layer, the patterning being provided across at least a part of the surface area thereof on the optically transparent carrier. The patterning forms the one or more contact elements connecting the component to the donor substrate. The contact elements yielded by the patterning in total have a contact area connecting the component to the donor substrate, which is smaller than the surface area of the support surface. For example, the sum of the contact areas may in the invention advantageously be limited to less than 70% of the total area of the support surface, preferably less than 50%, more preferably less than 30%. At the same time, the contact elements are still able to support the component from the donor substrate prior to transfer. Through patterning of the contact layer, the invention thus provides a donor substrate that enables, during the light-induced transfer method, to maintain a uniform distribution of light beam fluence, for components of any size and regardless of the component’s shape in an energy-efficient manner. The patterning of the contact layer can be achieved using several fabrication techniques. For example, lithography methods may be employed to define a desired pattern on the contact layer, followed e.g. by removal of material in specific regions, such as via etching, thereby creating the desired contact elements. By decoupling the area to be illuminated from the size of the support surface, the invention also advantageously enables to tune the topology of the contact layer on the optically transparent carrier specifically to the properties of the component, such as its shape or weight distribution, as will be further elucidated with reference to some exemplary embodiments further below. In the context of the present document, the optical energy from the light beam may induce the release layer to release the component in various ways. For example, the release layer may comprise a stack of sublayers comprising: an absorption sublayer for absorbing optical energy from the light beam, the absorption sublayer having a first melting temperature; a melting sublayer for being melted by heat from the absorption sublayer, the melting sublayer having a second melting temperature below the first melting temperature; and an adhesive sublayer for adhering the component to the melting sublayer, and for releasing the adhesion when the melting sublayer is in a molten state. The adhesive sublayer of the stack in such embodiments may typically be composed of polymeric materials, which give the sublayer a high bonding strength to components. This makes the composition of the release layer according to such embodiments highly suitable for being applied in the invention. In the absorption sublayer, the optical energy of the light beam may be absorbed, such that the absorption sublayer generates heat therein. The heat in the absorption sublayer may then melt the melting sublayer of the stack and bring it into a molten, liquid state. The melting temperature of the absorption sublayer may therefore be higher than the melting temperature of the melting sublayer, such that the absorption sublayer can remain solid while the melting sublayer is melted. Once the melting sublayer is in a molten state, release of the component, which adheres to the adhesive sublayer, may in such embodiments then occur via a process of dewetting. The surface energy of the absorption sublayer may be higher than the surface tension of the molten melting sublayer. At the same time, the surface tension of the molten melting sublayer may be higher than the surface energy of the adhesive sublayer. Therefore, when the melting sublayer is molten, adhesion between the absorption sublayer and melting sublayer would be maintained, but adhesion between the melting sublayer and the adhesive sublayer would be lost, resulting in the release of the component. To accelerate this de-wetting process, the stack may optionally also comprise a degradation layer, with a decomposition temperature closely matched to or slightly higher than a melting temperature of a melting layer. A thrust may then be induced when the degradation layer reaches its decomposition temperature, which thrust would then form a blister due to outgassing. Such a blister may be laterally confined e.g. through etching or a singulation process, to prevent it from propagating sideways, and from thereby affecting closely spaced neighboring components on the donor substrate. The light-induced release may in the present document of course also be achieved in a different way. For example, the release layer may contain photoresists including for example photoacid generators or photobase generators. The optical energy from the light beam would then catalyze a chemical reaction changing the solubility of the materials in the release layer in order to facilitate the release of the component to the acceptor substrate. The donor substrate according to the first aspect of the invention is therefore highly versatile. Regardless of by which physical mechanism the release of the component by the release layer occurs, the release layer may at the moment of release of the component in some implementations fully remain on the donor substrate. In other embodiments however, the release layer may lose attachment to the donor substrate and move to the acceptor substrate with the component. In yet further examples, part of the release layer may be released with the component (for example due to severance or breakage from the contact layer). Another advantage of the present invention is that by patterning the contact layer, such that the one or more contact elements have a contact area smaller than the area of the support surface, components with varying sizes and geometries may be packed closer together on the donor substrate, since the light beam that is to be used for releasing each component does not need to cover the full support surface anymore. This reduces the risk of regions along the sides of the component from being affected by the optical energy of the light beam.

[0013] In accordance with some embodiments of the invention, the contact areas of the one or more contact elements are arranged at one or more contact positions between the contact layer and the component, the one or more contact positions being selected, such as to yield an effective suspension point of the component from the one or more contact positions, coinciding with a center of mass of the component. In these embodiments, prior to the transfer of the component, the component may on net effectively be suspended from the center of mass of the component by the contact elements. In other words, the point or location at which the total suspension force, resulting from the suspension force(s) from the or each contact element, acts on the component in these embodiments coincides with the component’s center of mass. In components where the mass is evenly distributed, this center of mass may coincide with the geometric center of the component.

[0014] However, some components may not have an evenly distributed mass. This may for example be the case for components with more complex shapes - they may include a lateral bend along the support surface. However, even if the support surface is geometrically symmetric about at least a line crossing the geometric center of the support surface, the center of mass of the component may be positioned at an offset from the geometric center of the support surface. By supporting the component from the donor substrate in total from the center of mass of the component in these embodiments, the donor substrate may further increase its ability to facilitate controlled and accurate release of the component.

[0015] In accordance with some embodiments of the invention, the contact layer is patterned in at least the release layer. Advantageously, the release layer of the contact layer may in these embodiments advantageously have a smaller area than the support area. Consequently, the area over which the release mechanism needs to be triggered for the transfer of the component may in these embodiments be reduced. This helps provide a high degree of energy efficiency for the controlled and accurate release of components.

[0016] In accordance with some embodiments of the invention, the contact layer is provided as a plurality of release patches on the optically transparent carrier, wherein each release patch is configured for attaching a component to the donor substrate and for releasing the component to the acceptor substrate when the release patch is exposed to optical energy from the light beam. In these exemplary embodiments, the entire contact layer may be provided as a plurality of release patches that individually may be seen as equivalent to small instances of a release layer. In other words, the release patches in these embodiments may be seen as the contact elements formed by the patterning, with a spacing between all of the release patches. These release patches may cover only a portion of the component’s footprint. As explained, release layers that cover the full footprint of components have bonding strengths exceeding what is necessary for attaching the components to the donor substrate. A substantial portion of the area to be illuminated of those release layers may therefore be unnecessary for holding the component prior to being transferred. These embodiments provide an advantageous implementation that removes this unnecessary portion and significantly reduces the area to be illuminated, which greatly reduces the optical power needed to transfer components. In accordance with some embodiments of the invention, the plurality of release patches are spatially distributed on the optically transparent carrier, such as to form a release patch array, wherein the donor substrate further comprises a plurality of microlenses at an opposite side of the optically transparent carrier with respect to the release patch array, the plurality of microlenses forming a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon. These embodiments can support the component to the donor substrate using a release patch array formed by the plurality of release patches that are spatially distributed across the optically transparent carrier. The components that may be transferred in this manner may thus be much larger than the sum of the contact areas of the release patches. The area to be illuminated is thereby reduced by a factor equal to the ratio of the total component footprint and the total area covered by the release patches. These embodiments further provide the donor substrate with a microlens array. This microlens array may be provided on the optically transparent carrier, as part of the donor substrate, or alternatively may be provided separately from the donor substrate, for cooperating therewith. In other words, in the present invention the method comprises providing a plurality of microlenses at an opposite side of the optically transparent carrier with respect to the release patch array. This advantageously enables the component to be released from the donor substrate by illuminating the microlens array with a single light beam. Each microlens may then subsequently form a focused beam onto one of the release patches from the light incident on the microlens. Because the microlenses may condense the optical power they receive into focused beams having a smaller area, the effective intensity of the light used to illuminate the donor substrate can therefore advantageously be increased. This enables to illuminate the donor substrate with a less power-consuming and less expensive light source emitting a light beam, which yields a light beam fluence that would normally be insufficient for a component to be released. Each focused beam may yield a laser fluence sufficient for its respective release patch, ensuring that the component will lose attachment to each release patch after illumination. These embodiments thereby enable selective and rapid transfer of components of any size, in an energy-efficient and cost-efficient manner. The invention described in the present documents includes embodiments that comprise microlenses, and also comprises embodiments that do not comprise microlenses.

[0017] In accordance with some embodiments of the invention, each release patch is formed by a stack of layers comprising: an absorption layer for absorbing optical energy from the light beam, the absorption layer having a first melting temperature; a melting layer for being melted by heat from the absorption layer, the melting layer having a second melting temperature below the first melting temperature; and an adhesive layer for adhering the component to the melting layer, and for releasing the adhesion when the melting layer is in a molten state. In these embodiments, the adhesive layer of each release patch is typically composed of polymeric materials, providing high bonding strength to the components. This composition makes the release patches particularly well-suited for application in the method of light-induced component transfer. Each microlens focuses its respective portion of the light beam onto the absorption layer of one of the release patches, where the optical energy of the focused beam is then absorbed, generating heat within the absorption layer. Each release patch is limited in size, so that they are all surrounded by a gap that forms a thermal barrier that confines the generated heat to the respective patch. The heat in the absorption layer melts the melting layer of the release patch, bringing it into a liquid, molten state. The melting temperature of the absorption layer is higher than that of the melting layer, and consequently the absorption layer remains solid. Once the melting layer is in a molten state, a release of the components, which adhere to the release patches through the adhesion layers, occurs via a de-wetting process. The surface energy of the absorption layer is higher than the surface tension of the molten melting layer, and the surface tension of the molten melting layer is higher than the surface energy of the adhesion layer. As a result, when the melting layer is in a molten state, adhesion between the absorption and melting layers is maintained, but adhesion between the melting and adhesion layers is lost, resulting in the release of the components.

[0018] In accordance with some embodiments of the invention, each focused beam has a second beam width smaller than a first beam width of the light beam used in the step of illuminating the microlens array, wherein each release patch covers an area on the optically transparent carrier, and wherein a maximum width of the area covered by each release patch relates to the second beam widths such that each focused beam illuminates a major part of the area covered by one of the release patches. In the donor substrate according to these embodiments, each microlens is shaped to condense the light beam into a focused beam having a second beam width smaller than a first beam width of the light beam. The lenses in that case are positive lenses and may for example be shaped as plano-convex lenses. The magnification of the lenses may then be chosen in combination with the dimension of the optically transparent carrier, such that the focused beams have a second beam width at the release patches for forming spots thereon with a desired spot size. This desired spot size according to these embodiments is a major part of the area covered by a release patch.

[0019] In accordance with some embodiments of the invention, the major part of the area covered by each release patch that is illuminated by each respective focused beam is at least 50%, preferably at least 80%, more preferably at least 90% of the area covered by the release patch. Although the donor substrate would be optimally composed in the invention if the shaping of the microlenses and the areas covered by the release patches on the optically transparent carrier yield, in use in the method of light-induced component transfer, focused beams that illuminate 100% of the release patches, the donor substrate may deviate from this optimum while still being advantageously applicable in said method. The closer the focusing strength, determined by the shaping of the lens, matches the areas covered by the release patches, the more optimally the donor substrate is composed. A percentage of the areas covered by the release patches that is illuminated by the focused beams, which is higher than 100% will result in a loss in terms of efficient energy usage, while a percentage which is below 100% will result in a loss in transfer speed.

[0020] In accordance with some embodiments of the invention, prior to illuminating the microlens array, at least one of: multiple release patches adhere a same component to the donor substrate; and multiple release patches adhere a different component to the donor substrate. In some of these embodiments, multiple release patches may hold a single component to the donor substrate, thereby reducing the optical power required to release that component to the acceptor substrate. Alternatively, individual release patches may hold different components to the donor substrate. In these embodiments, illuminating the microlens array enables the simultaneous release of multiple components to the acceptor substrate with a single illumination, significantly speeding up the transfer process and increasing potential throughput in industrial applications. In other embodiments, some release patches may hold the same component to the donor substrate, while other release patches may individually hold different components or together hold another component to the donor substrate. Any combination of multiple release patches attaching the same component and individual release patches attaching different components can be advantageously used in these embodiments of the invention. Furthermore, these embodiments provide further advantage, because it enables a rapid transfer of multiple components of various sizes and shapes. Some components may have more complex shapes. They may for example be oblong, L-shaped or T-shaped. The release patch array enables to attach such components to the donor substrate 1 at specific points of coverage, and thus removes the need to provide complexly shaped release stacks, or more simply shaped release patches that are larger than the component to be transferred. The area to be illuminated is thereby reduced, improving energy efficiency.

[0021] In accordance with some embodiments of the invention, a planar surface of each microlens is one of a group comprising: circular surfaces, elliptical surfaces and polygonal surfaces. The lenses may for example be plano-convex, with spherically shaped convex surfaces. In that case, a circularly shaped planar surface would have the lowest risk of uncertainties in fabrication and may be produced with a more consistent quality. In alternative embodiments, the planar surface shape may correspond to the arrangement of the microlenses on the optically transparent carrier. For example, if the microlenses are arranged in a hexagonal lattice, the planar surfaces may still be circular, but they could also be polygonal in shape. For example, a hexagonal lattice combined with hexagonal planar surfaces would maximize the efficient use of optical energy, as it can ensure that none of the light bypasses the microlenses. Other combinations, such as square planar surfaces within a square lattice, may also be selected to achieve this advantage.

[0022] In accordance with some embodiments of the invention, each microlens is provided on the optically transparent carrier, such as to be positioned mutually adjacent to each other in one of: a hexagonal lattice, a triangular lattice, a square lattice, a rectangular lattice, a rhombic lattice, a pentagonal lattice, or an oblique lattice. A contiguous configuration offers greater energy efficiency, as it reduces the amount of optical energy that bypasses the microlenses. In some embodiments, the microlenses may be plano-convex with spherical convex surfaces and circular planar surfaces. While any of the abovementioned lattice geometries may be advantageously applied in these embodiments, a hexagonal lattice would provide additional advantage, as it minimizes the gaps between the circular surfaces, thereby reducing optical energy loss.

[0023] In accordance with some embodiments of the invention, the component is part of a plurality of components to be transferred, the support surface of each component comprising a first dimension and a second dimension, the second dimension optionally being smaller than the first dimension, the first and the second dimensions defining a surface area of the support surface, wherein the patterning defines a common contact area for each of the one or more contact elements arranged for connecting one of the plurality of components to the donor substrate, the common contact area being defined such as to substantially cover the second dimension of the support surface of a component that comprises the smallest surface area. In other words, the contact elements in these embodiments advantageously are tailored to the component that comprises the smallest dimension. The contact elements in these embodiments may for example cover between 50% and 100% of the second dimension of the component that comprises the support surface having the smallest total area, preferably between 70% and 100%, more preferably between 90% and 100%. These contact elements may then be applied to support each of the plurality of components, regardless of their shape or size, with the amount of contact elements and their positions across the optically transparent carrier being adjusted to the requirements of the individual components. In this way, these embodiments allow a uniform design of contact elements to be applied for a wide range of components. These embodiments are in other words highly versatile. Furthermore, by matching the dimensions of the contact elements to the smaller components, these embodiments also provide an advantageous implementation to pack components more closely on the donor substrate, thus yielding a more efficiently utilized component footprint on the donor substrate.

[0024] In accordance with some embodiments of the invention, the contact layer further comprises an interconnecting structure provided between the release layer and the component to be transferred, the interconnecting structure being arranged for being attached to the component, such as to provide, by the interconnecting structure, a connecting bridge between the component to be transferred and the donor substrate. These embodiments provide a further advantageous implementation that allows the area illuminated to be reduced.

[0025] In accordance with some embodiments of the invention, the contact layer is patterned in at least the interconnecting structure. Furthermore, in some embodiments both the interconnecting structure, and another part of the contact layer such as the release layer may be patterned, and the area to be illuminated may thus be advantageously reduced.

[0026] In accordance with some embodiments of the invention, the interconnecting structure is further arranged for maintaining attachment to the component when the release layer is exposed to optical energy of the light beam. Thus, the donor substrate of these embodiments allows to transfer components with predetermined additional structures on top of them. The interconnecting structure may then also influence the trajectory of the component towards the acceptor substrate, or have a function on the acceptor substrate itself. These embodiments thus potentially can make assembly of semiconductor or photonic devices more efficient. For example, in embodiments where the component is released via a process of de-wetting where the release layer comprises a stack of sublayers as explained above, the adhesive sublayer may be attach the component to the donor substrate via the interconnecting structure prior to transfer of the component. In examples where the interconnecting structure does not serve a function after transfer of the component, the interconnecting structure may be provided from materials that allow it to be selectively removed from the component after transfer, such as solvent-soluble polymers or etchable metals.

[0027] In accordance with some embodiments of the invention, the interconnecting structure comprises a shape for guiding the component from the donor substrate to the acceptor substrate along a predetermined trajectory or for maintaining a predetermined orientation of the component upon release of the component to the acceptor substrate. When transferring large amounts of components to a single acceptor substrate, it can become difficult to release components onto specific positions on the acceptor substrate, particularly in the vicinity of previously released components in the vicinity of that position, which can form obstructions. This shape of the interconnecting structure may be adapted to – or in other words tailored for – the component to be released and thereby enables to control the trajectory and orientation of the component as it moves from the donor substrate to the acceptor substrate. In these embodiments the shape of the interconnecting structure may include a deflection surface that can influence the trajectory or orientation of the component as it moves from the donor substrate to the acceptor substrate upon release by interacting with the air that it deflects. Through this aerodynamic control provided by the interconnecting structure in these embodiments, it can be made easier to precisely transfer components regardless of their geometries. For example, the component may have an asymmetric weight distribution. This may for example be due to mutually different weights of n- and p-contacts on the component. This asymmetric weight distribution then risks the component to tilt upon being released from the donor substrate. In another example, larger components may ordinarily tilt as they are being released from the donor substrate, due to for example imperfections or defects in an (unpatterned) contact layer, which can cause the release thrust imparted onto the component as a consequence of illuminating the contact layer to be asymmetric. The shape of the interconnecting structure may advantageously counteract this effect and compensate for or prevent such tilt, allowing these larger components to be received more securely and e.g. with a face-on orientation relative to the acceptor substrate, meaning that the primary surface of the component intended to contact the acceptor substrate would be oriented substantially parallel to that substrate at the moment of impact. This reduces the likelihood of bouncing or rotations after making contact with the acceptor substrate. These embodiments in other words provide improved positional accuracy on the acceptor substrate and minimize the risk of damage, surface contamination, or misalignment during subsequent processing steps. Furthermore, in another example a component may have a complex shape, and its center of mass may for example he at an offset from the geometric center of the component. Moreover, optionally the contact areas may in the invention be connected to the component at contact positions on the support surface that are remote from the component’s center of mass, and which in combination may optionally also yield an effective suspension point remote from the component’s center of mass. In such cases, the component may experience an unbalanced distribution of inertial forces at the moment of release, which can generates a torque that initiates unwanted rotation. This unintended rotation can result in the component landing at an incorrect angle, leading to misalignment, incomplete bonding, or physical damage to either the component or adjacent structures. By compensating for or preventing this rotational tendency, the shape of the interconnecting structure of these embodiments can increase the probability that the component arrives in the correct position and orientation for reliable integration.

[0028] In accordance with some embodiments of the invention, the shape of the interconnecting structure comprises at least one of: a wing portion arranged to generate a lift on the component with the interconnecting structure attached thereto during the movement to the acceptor substrate, a fin portion arranged to maintain a predetermined orientation of the component during the movement to the acceptor substrate, a rudder portion arranged to provide a rotational motion of the component about a predefined rotation axis during the movement to the acceptor substrate, a deflector portion arranged to provide a drag on the component with the interconnecting structure attached thereto during the movement to the acceptor substrate. In these embodiments, the interconnecting structure may be shaped to fulfil various roles in yielding the predetermined trajectory and / or orientation, and these roles may be selected individually or in combination to address the specific requirements of the component transfer scenario. In order to provide these roles, the shape may include a deflection surface that is shaped or oriented for those functions. A wing portion may then for example help stabilise the vertical descent of a flat component by generating counteracting lift, while a rudder portion may deliberately induce a small rotation to match alignment features on the acceptor substrate. A deflector portion or skirt that provides drag may help decelerate the component as it moves to the acceptor substrate. Such deceleration may be achieved, for example, by aerodynamic drag resulting from the geometry, surface area, or texture of the interconnecting structure, or by interaction with the surrounding atmosphere. By lowering the velocity prior to impact, the kinetic energy transferred to the component upon contact is reduced, which decreases the likelihood of breakage or deformation of fragile features, such as high- aspect-ratio projections or microstructures. Another advantage provided by the invention is thus that more fragile components may be transferred with a lower risk of damage thereto caused by impact.

[0029] In accordance with some embodiments of the invention, the support surface is provided with one or more functional areas, and wherein the contact areas of the one or more contact elements are arranged outside the one or more functional areas. In these embodiments, specific regions of the support surface can advantageously be protected from interactions with both the contact layer and with the light beam. These specific regions in these embodiments comprise functional areas on the component that provide the component with a predetermined function. This function can differ between components depending on the specific application. The functional areas may thus for example be photosensitive, or may be prone to chemically react with the contact layer if physical contact were established. These functional areas, or active areas, may for example include biosensitive materials, such that it may be responsive or reactive to biological stimuli or conditions. For example, the functional layer may change in its properties or interact with biological molecules, such as proteins, enzymes, or cells, or when the functional layer is exposed to certain biological factors such as the pH value of the contact layer, temperatures of the contact layer (which can change during the transfer process as a consequence of illumination with the light beam). In other examples, the functional layers may include a membrane, e.g. for providing (selective) permeability. Such a membrane may be very fragile and could be very vulnerable to damage. By forming the contact elements outside of the functional layers, the donor substrate in these embodiments advantageously allows transfer components that include such functional layers on their support surfaces while avoiding undesired effects of either the donor substrate or of the light beam on the functional layers. These embodiments thus allow to protect the pristinity of the component during transfer.

[0030] In accordance with some embodiments of the invention, wherein the patterning is such that, when the contact layer is illuminated by the light beam, the one or more contact elements are configured to impart a total thrust onto the component away from the donor substrate, the total thrust having a predetermined thrust magnitude and / or thrust direction.

[0031] In other words, the patterning may be such, that the geographic arrangement of the one or more contact elements on the support surface (i.e., the positions and properties of the contact elements relative to each other) results in the total thrust having the predetermined thrust magnitude and / or thrust direction. In this way, by illuminating the contact layer with the light beam, the incoming optical energy may be translated by the patterned contact layer into a thrust onto the component that has a desired strength and / or that is oriented in a desired direction. As a result, a flight or trajectory of the component from the donor substrate to the acceptor substrate may be advantageously controlled. For example, the thrust magnitude may be proportional to the light beam fluence provided to the contact layer, but inversely proportional to the area being illuminated. The thickness of the contact elements may also be tuned to control the thrust magnitude. A thicker contact element may impart a greater thrust onto the component than a thinner contact element. Consequently, the one or more contact elements may, upon illumination with the light beam, at that moment impart a total thrust with a reduced magnitude compared to a case where the contact layer would be unpatterned. In this way these embodiments advantageously allow to receive the component on the acceptor substrate with a softer landing. This reduces the risk that the component bounces from the intended destination position on the acceptor substrate upon impact, and thereby increases the control and accuracy with which the transfer process can be performed. Similarly, the total thrust direction may be controlled by the patterning, since each contact element at the moment of illumination locally imparts a thrust onto the component with a magnitude specific to that contact element, and at a position of the support surface where that respective contact element is connected to the component. Since each contact element then pushes the component in a specific direction, the total thrust direction can advantageously send the component to a desired destination position on the acceptor substrate, including for example at positions located at an offset from the position on the acceptor substrate which is aligned with the component at and prior to the moment of illumination with the light beam. These embodiments thereby further increase the control over the component transfer process.

[0032] In accordance with some embodiments of the invention, the one or more contact elements are formed at predetermined contact positions, having predetermined thicknesses and / or having predetermined contact areas, such as to yield the thrust onto the component having the predetermined thrust magnitude and / or thrust direction. This is an advantageous means of achieving the predetermined thrust magnitude and / or thrust direction onto the component at the moment of illuminating the contact layer with the light beam. By forming the one or more contact elements with predetermined contact areas, the thrust magnitude imparted onto the component by each contact element may advantageously be controlled. By forming the one or more contact elements at predetermined contact positions, each contact element is in these embodiments configured to impart its individual thrust, at the moment of illumination, onto the component at that predetermined contact position.

[0033] In accordance with some embodiments of the invention, the patterning further forms one or more further contact elements, wherein the one or more further contact elements are formed at predetermined further contact positions and / or having predetermined further contact areas, such that the one or more contact elements in combination with the one or more further contact elements yield the thrust onto the component having the predetermined thrust magnitude and / or thrust direction. These embodiments provide an advantageous further implementation for yielding the predetermined thrust magnitude and / or thrust direction. In particular, in these embodiments the one or more contact elements may impart first thrusts onto the component having first predetermined thrust magnitudes and / or first predetermined thrust directions. At the same time the one or more further contact elements may impart second thrusts onto the component having second predetermined thrust magnitudes and / or second predetermined thrust directions. In some of these embodiments, the first thrusts may be different from the second thrusts. The contact elements may be formed having smaller or larger contact areas than further contact areas of the further contact elements, and consequently the first thrust magnitudes may be smaller or larger than the second thrust magnitudes. Furthermore, the patterning may form a larger or smaller amount of contact elements than the amount of further contact elements formed.

[0034] In accordance with some embodiments of the invention, the contact layer is patterned by spatially distributing a plurality of release patches on the optically transparent carrier, such as to form a release patch array, wherein each release patch is configured for attaching a component to the donor substrate and for releasing the component to an acceptor substrate when the release patch is exposed to optical energy from the light beam; providing an opposite side of the transparent carrier with respect to the release patch array with a plurality of microlenses, such as to form a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon. By providing the optically transparent carrier with a plurality of release patches at spatially distributed spots on a side thereof, these embodiments greatly reduce the area to be illuminated during the process of releasing components from the donor substrate to an acceptor substrate. The donor substrate manufactured in the method according to these embodiments of the invention is able to carry components with the release patch array which only covers a portion of the components’ footprints. This reduces the optical power that is required for releasing the components carried by the donor substrate onto the acceptor substrate. The method of light-induced component transfer can then be executed using a light source that emits significantly less optical power and that can therefore be significantly less expensive. When illuminating the microlenses of the donor substrate manufactured according to these embodiments of the invention, each microlens focuses light onto a release patch of the release patch array. These microlenses then increase the effective intensity delivered to each release patch. A light beam having significantly lower overall optical power can therefore be used to trigger the release mechanism of the donor substrate, because each focused beam yields a light beam fluence sufficiently high to activate its designated release patch, ensuring that each component is successfully detached from the release patch. The donor substrate manufactured by the method according to these embodiments allows for a controlled and efficient transfer of components, regardless of size, in an energy-efficient and cost-efficient manner. The method according to these embodiments may involve providing the donor substrate with release patches which support various methods of light-induced component transfer. For example, the optical energy may generate heat in the release patches, which then triggers a de-wetting process that releases adhesion between the components and the donor substrate. In alternative embodiments however, the release patches may include photoresist materials, such as photoacid generators or photobase generators, enabling a chemical reaction upon exposure to focused light. The optical energy from the focused beams would then catalyze a chemical reaction changing the solubility of the materials in the release patches in order to facilitate the release of the components to the acceptor substrate. The method according to these embodiments of the invention therefore provides a high degree of versatility.

[0035] There is provided herewith a method of light-induced component transfer from a donor substrate according to the first aspect, to an acceptor substrate. The method comprises: providing the donor substrate, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam. In some embodiments, the donor substrate is provided comprising a plurality of release patches on the optically transparent carrier. The method may comprise providing, using a light source, the light beam for illuminating the plurality of release patches through the optically transparent carrier; wherein each release patch is configured for attaching the component to the donor substrate and for releasing the component to the acceptor substrate when the release patch is exposed to optical energy from the light beam, wherein the plurality of release patches are spatially distributed on the optically transparent carrier, such as to form a release patch array, wherein the donor substrate is further provided comprising a plurality of microlenses at an opposite side of the optically transparent carrier with respect to the release patch array, the plurality of microlenses forming a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon, wherein the method further comprises illuminating the microlens array with the light beam from the light source, wherein optical energy from the focused beams causes a release of attachment of the component, for releasing the component to the acceptor substrate.

[0036] In these embodiments, components are attached to the donor substrate using release patches that cover only a portion of the components’ footprints.

[0037] Release stacks that cover the full footprint of components have bonding strengths far exceeding what is necessary for attaching the components to the donor substrate. A substantial portion of the area to be illuminated of those release stacks is therefore unnecessary for holding the components prior to being illuminated. The present invention removes this unnecessary portion and significantly reduces the area to be illuminated, which greatly reduces the optical power needed to transfer components. Rather than attaching components to the donor substrate using a release stack that covers the full footprint of the components, the method of these embodiments may instead attach the components to the donor substrate using a release patch array formed by a plurality of release patches that are spatially distributed across the optically transparent carrier. The components that may be transferred in this manner may thus be much larger than the size of a release stack, which immediately enables the possibility to transfer large components (i.e. components that are much larger than the size of a single release patch). Each release patch may be viewed as equivalent to a small release stack attaching a point or small area of a component’s footprint to the donor substrate, with a spacing between all of the release patches. The area to be illuminated is thereby reduced by a factor equal to the ratio of the total component footprint and the total area covered by the release patches. These embodiments further provide the donor substrate comprising a microlens array. The method of these embodiments then involves illuminating the microlens array with a light beam having an intensity and a beam width suitable for release of a specific component or specific components. Each microlens subsequently forms a focused beam onto one of the release patches from the light incident on the microlens. Because the microlenses condense the optical power it receives into a focused beam having a smaller area, the effective intensity of the light used to illuminate the donor substrate is therefore increased. This enables to illuminate the donor substrate with a less power-consuming and less expensive light source emitting a light beam, which yields a light beam fluence that would normally be insufficient for a component to be released. Each focused beam yields a laser fluence sufficient for its respective release patch, ensuring that the component will lose attachment to each release patch after illumination. The method according to these embodiments thereby enables selective and rapid transfer of components of any size, in an energy-efficient and cost-efficient manner. This method may be applied to many light-induced transfer techniques; the release patches may utilize various processes to facilitate the binding and release of the components. For example, the optical energy may generate heat in the release patches and subsequently initiate a process of de-wetting that causes a loss of adhesion between the components and the donor substrate. Alternatively, the release patches may contain photoresists including for example photoacid generators or photobase generators. The optical energy from the focused beams would then catalyze a chemical reaction changing the solubility of the materials in the release patches in order to facilitate the release of the components to the acceptor substrate. The method of these embodiments is therefore highly versatile.

[0038] In accordance with some embodiments of the invention, each release patch is formed by a stack of layers comprising: an absorption layer for absorbing optical energy from the light beam, the absorption layer having a first melting temperature; a melting layer for being melted by heat from the absorption layer, the melting layer having a second melting temperature below the first melting temperature; and an adhesive layer for adhering the component to the melting layer, and for releasing the adhesion when the melting layer is in a molten state. The adhesive layer of each release patch in these embodiments typically is composed of polymeric materials, which give the layer a high bonding strength to components. This makes the composition of the release patches according to these embodiments highly suitable for being applied in the invention. The light beam is incident on the microlens array and each microlens focuses its respective portion of the light beam, such that a more converging light beam emerges from each microlens, propagates through the optically transparent carrier, and is focused onto an absorption layer of one of the release patches. In each of the absorption layers, the optical energy of the light beam is then absorbed, such that each absorption layer generates heat therein. Each of the release patches is limited in size, and is consequently surrounded by a gap forming a thermal barrier ensuring that the generated heat substantially remains confined to that respective release patch. The heat in each absorption layer then melts the melting layer of the respective release patch and brings it into a molten, liquid state. The melting temperature of the absorption layer is higher than the melting temperature of the melting layer, such that the absorption layer can remain solid while the melting layer is melted. Once the melting layer is in a molten state, release of the component, which adheres to the release patches via the adhesion layers, occurs via a process of de-wetting. The surface energy of the absorption layer is higher than the surface tension of the molten melting layer. At the same time, the surface tension of the molten melting layer is higher than the surface energy of the adhesion layer. Therefore, when the melting layer of the release patches is molten, adhesion between the absorption layers and melting layers will be maintained, but adhesion between the melting layers and the adhesion layers will be lost, resulting in the release of the component.

[0039] In accordance with some embodiments of the invention, each focused beam has a second beam width smaller than a first beam width of the light beam used in the step of illuminating the microlens array, wherein each release patch covers an area on the optically transparent carrier, and wherein a maximum width of the area covered by each release patch relates to the second beam widths such that each focused beam illuminates a major part of the area covered by one of the release patches. The first beam width is the width of the light beam prior to the beam being focused by the microlens array. Thus, in other words, each focused beam exhibits a second beam width, which is narrower than the initial beam width of the light beam applied in the illumination step of the microlens array. Each release patch occupies a defined area on the optically transparent carrier, wherein the maximum width of the area covered by each release patch is proportionate to the second beam widths. This proportion ensures that each focused beam illuminates a substantial portion of the area encompassed by a respective release patch. Substantial in this connection means that at least a major part of the area of the patch is thereby illuminated. The term ‘major’ is further elaborated upon below. Notably, the first beam width denotes the width of the light beam before it is focused by the microlens array.

[0040] The fact that the second beam width is smaller than the first beam width means that the optical energy from the light beam is concentrated into a smaller area, increasing the intensity or optical energy per unit area. This focusing effect allows the energy to be more effective in triggering the release mechanism in the patches, while advantageously requiring a lower overall energy input. Based on the area covered by each release patch, the proportion of each release patch that is exposed to optical energy from a focused beam may vary. All else being equal, a smaller patch area means a greater proportion of the patch will be illuminated by the focused beam, leading to a more efficient use of the optical energy for triggering the release. The area covered by each release patch in combination with the focusing strength of the microlenses may thus be optimized to maximize this energy efficiency.

[0041] In accordance with some embodiments of the invention, the major part of the area covered by each release patch that is illuminated by one of the focused beams is at least 50%, preferably at least 80%, more preferably at least 90% of the area covered by each release patch. The method is able to function if the focused beams illuminate a percentage below 100% of the areas covered by the release patches, although the downward deviation from 100% will come with a cost in transfer speed, because some additional time will be needed for the release mechanism to be triggered outside of the illuminated part of the release patches. The closer the percentage is to 100% of the area covered by each release patch, the closer the performance of the method is to optimal performance in terms of energy usage and transfer speed, where optimal performance lies at 100%. In general, the higher the percentage is, the more quickly the components can be transferred, as the release mechanism will be instantaneously triggered in a higher proportion of the release patches. Above 100%, this relation ceases to hold, and although the method would still be able to function in those embodiments, the optical energy of the focused beams is essentially lost energy to the extent that the focused beams illuminated areas outside of the release patches.

[0042] In accordance with some embodiments of the invention, prior to illuminating the microlens array, at least one of: multiple release patches adhere a same component to the donor substrate; and multiple release patches adhere a different component to the donor substrate. Multiple release patches may for example hold a single component to the donor substrate, in order to reduce the optical power needed to release that single component to an acceptor substrate. Alternatively however, individual release patches may hold different components to the donor substrate. Illumination of the microlens array in those embodiments then enables to simultaneously release multiple components to the acceptor substrate with a single act of illuminating. This greatly increases the speed with which multiple components may be transferred using the method, thus increasing the throughput that may be achieved with this method in industrial settings. In some other of these embodiments, some release patches may hold a same component to the donor substrate, while at the same time other release patches may each individually hold different components to the donor substrate, or together hold another component to the donor substrate. Any combination of multiple release patches attaching a same component to the donor substrate and individual release patches attaching different components to the donor substrate may be advantageously applied in these embodiments of the invention.

[0043] Furthermore, these embodiments provide further advantage, because it enables a rapid transfer of multiple components of various sizes and shapes. Some components may have more complex shapes. They may for example be oblong, L-shaped or T-shaped. The release patch array enables to attach such components to the donor substrate 1 at specific points of coverage, and thus removes the need to provide complexly shaped release stacks, or more simply shaped release patches that are larger than the component to be transferred. The area to be illuminated is thereby reduced, improving energy efficiency.

[0044] In accordance with some embodiments of the invention, a planar surface of each microlens is one of a group comprising: circular surfaces, elliptical surfaces and polygonal surfaces. The lenses may for example be plano-convex lenses, and the convex surface of each lens may then for example be spherical. Choosing a circular surface as the planar surface of the lens would introduce the fewest design and fabrication complications and uncertainties. In alternative embodiments, the shape of the planar surfaces may be based on the configuration in which the microlenses are placed on the optically transparent carrier. For example, if the microlenses are positioned in a hexagonal lattice, the microlenses may also have circular surfaces, but in alternative embodiments the planar surfaces of the microlenses may be polygonal surfaces. In particular they may be hexagonal surfaces. The combination of a hexagonal lattice and a hexagonal planar surface is an example of an embodiment that maximizes the optical energy that is efficiently utilized in the invention, because in this combination none of the light passes through the optically transparent carrier without entering one of the microlenses. Other combinations, such as square planar surfaces and square lattices, may similarly be chosen to gain this advantage.

[0045] In accordance with some embodiments of the invention, each microlens is provided on the optically transparent carrier, such as to be positioned mutually adjacent to each other in one of: a hexagonal lattice, a triangular lattice, a square lattice, a rectangular lattice, a rhombic lattice, a pentagonal lattice, or an oblique lattice. Although in alternative embodiments of the invention, the microlenses may not be positioned to be mutually adjacent to each other, and may instead leave some space in between them, a configuration in which they are contiguous is more advantageous in terms of energy efficiency, because it minimizes the amount of optical energy that is lost because it does not enter any of the microlenses. In some embodiments then, the microlenses may be plano-convex lenses with spherically shaped convex surfaces and circular planar surfaces. In those embodiments, any of the abovementioned lattice geometries may be advantageously applied, but a hexagonal lattice would minimize the size of the areas in between the circular surfaces and thereby minimize the lost optical energy. Furthermore, although the microlenses may be provided on the optically transparent carrier as part of the donor substrate, they may alternatively be provided separately from the donor substrate and positioned on or just over the optically transparent carrier.

[0046] Brief description of the drawings

[0047] The invention will further be elucidated by description of some specific embodiments thereof, making reference to the attached drawings. The detailed description provides examples of possible implementations of the invention, but is not to be regarded as describing the only embodiments falling under the scope. The scope of the invention is defined in the claims, and the description is to be regarded as illustrative without being restrictive on the invention. In the drawings:

[0048] Figures 1A-1D schematically illustrates a donor substrate in accordance with some embodiments of the invention.

[0049] Figure IE schematically illustrates a top down view of a component being supported from a donor substrate in accordance with some embodiments of the invention.

[0050] Figures 2A-2B schematically illustrate some embodiments of patterned contact layers.

[0051] Figures 3A-3E schematically illustrate some embodiments of an interconnecting structure of the contact layer.

[0052] Figures 4A and 4B schematically illustrate a donor substrate with a component attached to a plurality of release patches, respectively before and after being released from the donor substrate to an acceptor substrate, in accordance with an embodiment of the invention.

[0053] Figure 5 schematically illustrates an exemplary application of a donor substrate in accordance with some embodiments of the invention.

[0054] Figures 6A and 6B schematically illustrate a donor substrate with a plurality of components attached to a plurality of release patches, respectively before and after being released from the donor substrate to an acceptor substrate, in accordance with an embodiment of the invention.

[0055] Figure 7 schematically illustrates a configuration of a microlens array on a donor substrate in accordance with an embodiment of the invention.

[0056] Figures 8A-8C schematically illustrate an embodiment of the method in accordance with the third aspect of the invention. Figure 9 schematically illustrates a further embodiment of the invention, wherein the component comprises a functional area on its support surface.

[0057] Figures 10A-10B schematically illustrate some yet further embodiments of the invention, wherein the one or more contact elements are arranged to provide a predetermined thrust onto the component at the moment of release.

[0058] Detailed description

[0059] Figure 1A schematically shows a donor substrate 1 for use in a method of light-induced component transfer of a component 2 from the donor substrate 1 to an acceptor substrate 3. The component 2 comprises a support surface 4 that faces the donor substrate 1 prior to transfer of the component 2. The donor substrate 1 comprises an optically transparent carrier 5 for transmitting a light beam 6 from a light source 7 during the light-induced component transfer. In this figure, a multitude or plurality of light sources 7 is used. It will be appreciated that this is optional. When using a plurality of light sources 7, the light sources 7 can be synchronized with each other in order to be able to simultaneously expose multiple release patches 13, as shown in figure 1A. Alternatively however, simultaneous exposure can also be achieved by using one (or more) light source(s) 17 and a microlens array (as will be further explained further below, with reference to figures 4A-4B and 6A-6B), or with a strong light source in combination with a grid, a mask, and / or optics that are arranged to form a multitude of beams 6. Optics may also be used for beam shaping purposes, such as diffractive optical elements, depending on the components to be transferred. In other words, the invention also includes embodiments where only a single light source 7 is used. For supporting the component 2 prior to transfer thereof to the acceptor substrate 3, the donor substrate 1 further comprises a contact layer 8 on the optically transparent carrier 5. The contact layer 8 is configured to attach the component 2 to the donor substrate 1. The contact layer 8 comprises a release layer 9 for being illuminated through the optically transparent carrier 5 by the light beam 6. The release layer 9 is further configured to release the component 2 when the release layer 9 is exposed to optical energy from the light beam 6. This may for example occur via a process of de-wetting, or via alternative release mechanisms, such as alteration of the solubility of a photoresist layer, as explained above. Furthermore, at least a part of the contact layer 8 is patterned. This patterning forms one or more contact elements 10 on the optically transparent carrier 5. Each contact element 10 connects the component 2 to the donor substrate 1 over at least a contact area 11, such that the sum of the contact areas 11 of the one or more contact elements 10 that are configured to support the component 2, is smaller than a total area 12 of the support surface 4. The contact areas 11 of the one or more contact elements 10 may be arranged at one or more respective contact positions between the contact layer 8 and the component 2. In figure 1A, three components 2 are supported by the donor substrate 1. The left-most component 2 is supported from a contact layer 8 not according to the invention, since the contact area 11 of the contact layer 8 on the left is equal to the area of the support surface 4 of that component 2. The middle component 2 and the right-most component 2 are however supported by the donor substrate 1 by contact layers 8 according to the invention: the contact layers 8 attaching these components 2 to the donor substrate 1 are patterned to form contact elements 10 at respective contact positions. These contact positions may be selected, in order to yield an effective suspension point of the component 2 from the contact positions that coincides with the center of mass of the component 2. For example, the middle component 2 in figure 1A is supported by a contact layer 8 forming a single, centrally positioned contact element 10. The component 2 on the right is supported by multiple contact elements 10 (three are shown here for simplicity, but the skilled person will appreciate that any other number of contact elements 10 may likewise be applied). The contact layer 8 may be patterned in at least the release layer 9, as shown in figure IB. Additionally or alternatively however, other parts of the contact layer may be patterned, as shown in figures 1C and ID. The contact layer 8 may for example be patterned in at least an interconnecting structure 20 (figure 1C) or in both the release layer 9 and an interconnecting structure (figure ID), further discussed below with reference to the exemplary embodiments shown in figures 3A-3E.

[0060] In figure IE, a component 2 can be seen that is supported by contact elements 10 of a contact layer of a donor substrate (rest of the donor substrate not shown here). Ordinarily, when supported from a donor substrate over a contact layer that covers the full support surface 4, the component 2 would have to be released from the donor substrate by illumination using a light beam 6-1 that is both wide enough to illuminate the total area of the support surface 2, in this example with width 12, and with sufficient light beam fluence to induce the release mechanism uniformly across that total area. In the invention however, the contact layer is patterned, and the component 2 advantageously is supported from contact elements 10 that cover only a portion of the support surface 4. In this particular example, the contact elements 10 have a contact area 11; these contact areas 11 yield a sum of contact areas 11 of each contact element 10, that is smaller than the total area of support surface 4. Moreover, release of the component 2 from the donor substrate may then involve illuminating these contact elements 10 with light beams 6, which therefore each require a substantially smaller beam width than would be required if the component 2 were supported over its full contact surface. This figure thus exemplifies how the invention advantageously decouples the area to be illuminated from the size of the component 2.

[0061] Figures 2A-2B schematically illustrate respectively a group of components 2 with various sizes and shapes (figure 2A), and a component 2 with a complex shape (figure 2B). The component 2 may, as shown in figure 2Abe a part of a plurality of components 2 to be transferred, each of the plurality of components 2 comprising a support surface 4 facing the donor substrate prior to transfer of the plurality of components 2. The components 2 shown in this figure maybe arranged or distributed on the donor substrate 1 in the configuration illustrated, prior to transfer. The support surface 4 of each component 2 may comprise a first dimension 18 and a second dimension 19 smaller than the first dimension 18. The first and the second dimensions 18 and 19 may define a surface area 12 of the respective component. The patterning may form the one or more contact elements 10 for each respective one of the plurality of components 2, and the contact area 11 of each contact element 10 may be selected such as to substantially cover the second dimension 19 of the component 2 that comprises the smallest surface area. In this way, the same design for the contact elements 10 may be used for multiple components 2 that comprise widely varying sizes and shapes.

[0062] In a quantitative experimental example, the middle component 2 shown in figure 1A may comprise dimensions of 200 pm x 300 pm x 75 pm. In that case the total area of the support surface 12 may be 200 pm x 300 pm or 60,000 pm2. The contact area 11 of the patterned contact layer 8 attaching this component 2 to the donor substrate 1 may however for example be only 135 pm x 135 pm, or 18,225 pm2. Consequently, the component 2 may be released here, by way of example, using a light beam 6 that has a beam diameter of 168 pm, which is sufficiently large to cover the patterned contact layer 8, but would not be wide enough to illuminate the entire support surface 12. For reference, under standard transfer conditions (where the entire support surface 4 would be covered by the contact area with the donor substrate 1, the contact layer 8 may have a beam diameter of 420 pm in order to illuminate the full area of the support surface 4 and induce the release of the component 2. This reduction in area also allows components to be transferred with a lower light beam fluence, as discussed above. In this particular example, while unpatterned contact layers (which cover the full support surface of the component) may need to be illuminated with a light source that provides 3600 pJ (or 2.6109 J / cm2), the patterned contact area may only need 189 pJ (or 0.8536 J / cm2). The invention in this particular example thus advantageously is able to achieve a reduction of approximately 67% in the required light beam fluence for inducing the component release.

[0063] Turning to figure 2B, the component 2 shown here comprises a bend along its length and serves as an example of a component 2 with a complex shape. The component 2 shown here may likewise be included in the group of components 2 from figure 2A. Furthermore, the contact elements 10 configured to attach the present component 2 to the donor substrate 1 may likewise have the same design as for the components of figure 2A, further highlighting the versatility of such embodiments. The contact elements 10 shown here may also be strategically positioned, such as to yield an effective suspension point of the component 2 from the donor substrate 1, which coincides with the component’s 2 center of mass 2- 1, thus preventing rotation of the component upon release and improving the control over the component transfer.

[0064] Figures 3A-3E schematically show some embodiments of an interconnecting structure 20 as may be applied in some exemplary implementations of the invention. Such an interconnecting structure 20 comprised by the contact layer 8 provided between the release layer 9 and the component to be transferred may be arranged for being attached to the component 2, such as to provide, by the interconnecting structure 20, a connecting bridge between the component 2 to be transferred and the donor substrate 1. Furthermore, the interconnecting structure 20 may further be arranged for maintaining attachment to the component 2 when the release layer 9 is exposed to optical energy of the light beam 6. Turning now to the figures at hand, in figure 3A the component 2 is shown in two states: a first state (dashed) in which the component 2 is attached to the donor substrate 1 via the contact elements 10, and a second state after the component 2 has been released from the donor substrate 1 while the contact elements 10, which in this particular figure are formed by the interconnecting structure 20, maintain attachment to the component 2. The interconnecting structure 20 may comprise a shape for guiding the component 2 from the donor substrate 1 to the acceptor substrate 3 along a predetermined trajectory or for maintaining a predetermined orientation of the component 2 upon release of the component 2 to the acceptor substrate 3. The shape of the interconnecting structure 20 may for this purpose comprise a fin portion arranged to maintain a predetermined orientation of the component 2 during the movement to the acceptor substrate 3. An example is shown in figure 3A. Additionally or alternatively, the interconnecting structure 20 may include a wing portion arranged to generate a lift on the component 2 with the interconnecting structure 20 attached thereto during the movement to the acceptor substrate 3. By generating counteracting lift to air flowing over and against the interconnecting structure 20, a wing portion may then for example help stabilise the vertical descent of a component 2. A top-down view and a side view of an example are shown schematically in figures 3B and 3C, respectively. Additionally or alternatively, the shape of the interconnecting structure 20 may comprise a rudder portion arranged to provide a rotational motion of the component 2 about a predefined rotation axis (such as an axis coinciding with a vertical motion of a component 2 towards the acceptor substrate) during the movement to the acceptor substrate 3 (a top-down view of an example is schematically shown in figure 3D). This may help match alignment of the component 2 with features on the acceptor substrate 3. Additionally or alternatively, the shape of the interconnecting structure 20 may comprise a deflector portion arranged to provide a drag on the component 2 with the interconnecting structure 20 attached thereto during the movement to the acceptor substrate 3. A top-down view of an example is shown schematically in figure 3E. The drag generated by such a deflector portion can help slow the component 2 down as it moves toward the acceptor substrate 3 upon release. This can help prevent bouncing or damage to the component 2 or to the acceptor substrate 3. Figures 4A-4B schematically illustrates a further embodiment of a donor substrate 1 in accordance with an exemplary implementation of the invention. In this figure, the contact layer 8 is provided as a plurality of release patches 13 on the optically transparent carrier 5. Each release patch 13 may be configured for attaching a component 2 to the donor substrate 1 and for releasing the component 2 to the acceptor substrate 3 when the release patch 13 is exposed to optical energy from the light beam 6. Furthermore, in the present figure, the plurality of release patches 13 are spatially distributed on the optically transparent carrier 5, such as to form a release patch array 14. The donor substrate 1 may then further comprise a plurality of microlenses 15 at an opposite side of the optically transparent carrier 5 with respect to the release patch array 14. The plurality of microlenses 15 in turn then may form a microlens array 16 for being illuminated with the light beam 6 and for focusing the light beam 6 onto the release patch array 14, such as to form a plurality of focused beams 17 thereon. In this embodiment, each release patch 14 may have an absorption sublayer 29, a melting sublayer 30 and an adhesive sublayer 31. In alternative embodiments, the release patches 14 may be alternatively composed and may be used to release components 2 to an acceptor substrate 3 through different physical processes than will the release patches 14 illustrated here. For example, the patches 14 may contain photoresists which, upon being exposed to optical energy, catalyze a chemical reaction for facilitating the release of components 2 from the donor substrate 1 to an acceptor substrate 3. In this embodiment, a component 2 may be attached to the adhesive sublayers 31 of the release patches 14. In use, the microlenses 15 maybe illuminated with a light beam 6. The light beam 6 may be used to illuminate the microlenses 15 directly from a light source 7, but alternatively may be led through beam shaping optics for obtaining a suitable beam shape, such as a collimated light beam. The microlenses 15 may focus the light beam 6, which propagates through the optically transparent carrier 5 before being incident on the absorption sublayers 29 of the release patches 14. The focused light beams 17 may have beam widths when incident on the absorption sublayers 29, which may be smaller than the widths of the release patches 13, such that each focused beam 17 covers only a major part of its respective release patch 14, such as at least 50%, 80% or 90% of the surface area, as long as the focused beam 17 provides enough light beam fluence to induce the release of the component 2. Alternatively the focused beam 17 may be wide enough to cover the full surface area of the release patches 14. The absorption sublayers 29 may absorb optical energy from the focused beams 17 and consequently generate heat. The release patches 14 may have a confined width, with the air surrounding the release patches 14 forming thermal barriers. The heat generated in the absorption sublayers 29 thus may be conducted to the melting sublayers 30, which may be in direct thermal contact with the absorption sublayers 29. The melting sublayers 30 may have a melting temperature that is lower than the melting temperature of the absorption sublayers 29. Therefore, as long as the light beam 6 illuminating the microlenses 15 provides sufficiently high light beam fluence to induce the release of the component 2 to the acceptor substrate 3, the melting sublayers 30 will be melted by the heat conducted from the absorption sublayers 29, while the absorption sublayers 29 can remain solid. Upon illumination, a process of de-wetting will in these exemplary embodiments result in the release of the component 2 to the acceptor substrate 3, as previously explained. The component 2 illustrated in this figure is a large component attached to the donor substrate 1 with release patches 14 that cover only a portion of the component’s footprint. Because the large component 2 is held by the donor substrate 1 using a patterned plurality of release patches 14, rather than a release layer 9 covering the full footprint of the component 2, the area to be illuminated and therefore the required optical power from the light source 7 for triggering the release of the component 2 is significantly reduced. Upon illumination of the microlens array 16, the microlenses 15 form the plurality of focused beams 17. The focused beams 17 may be incident on the plurality of release patches 14. The absorption sublayer 29 of each release patch 14 may receive the optical energy from the beam 17 focused thereon and consequently generate heat. When referring to layers 29, 30 or 31 in the present document, it is understood that such layers may also be referred to as sublayers 29, 30 or 31.

[0065] In another quantitative example, the microlens array may for example have a pitch between microlenses of ca. 150 micrometer, in combination with a microlens height or thickness of 270 micrometer. This implies that a component of roughly 0.5 mm x 0.7 mm would be effectively covering the area of 25 microlenses. The microlenses would then funnel the light beam into (in this case) ca. 25 separate spots from the focused beams, effectively concentrating the light fluence locally by a factor of 50. With further reference to figure 4A,the donor substrate 1 comprises an optically transparent carrier 5. The optically transparent carrier 5 is provided with microlenses 15 and corresponding release patches 13. In alternative embodiments however, the microlenses 3-1 – 3-8 may instead be provided separately from the donor substrate 1. In this embodiment, each release patch has an absorption layer 29, a melting layer 30 and an adhesive layer 31 (only the layers 29, 30 and 31 are pointed out explicitly in the figure for readability). In alternative embodiments, the release patches may be alternatively composed and may be used to release components to an acceptor substrate through different physical processes than will the release patches illustrated here. For example, the patches may contain photoresists which, upon being exposed to optical energy, catalyze a chemical reaction for facilitating the release of components from the donor substrate to an acceptor substrate. In this embodiment, a component 2 is attached to the adhesive layers 31 of the release patches 13. In use, the microlenses 15 may be illuminated with a light beam 6. The light beam 6 may be used to illuminate the microlenses 15 directly from a light source, but alternatively may be led through beam shaping optics for obtaining a suitable beam shape, such as a collimated light beam. The microlenses 15 focus the light beam 6, which propagates through the optically transparent carrier 5 before being incident on the absorption layers 29 of the release patches 13.

[0066] The focused light beams 17 have beam widths when incident on the absorption layers 29, which may be smaller than the widths of the release patches, such that each focused beam covers only a major part of its respective release patch, such as at least 50%, 80% or 90% of the surface area, as long as the focused beam provides enough light beam fluence to induce the release of the component 2. Alternatively the focused beam may be wide enough to cover the full surface area of the release patches 13. The absorption layers 29 absorb optical energy from the focused beams 17 and consequently generate heat. The release patches 13 have a confined width, with the air surrounding the release patches forming thermal barriers. The heat generated in the absorption layers 29 thus is conducted to the melting layers 30, which is in direct thermal contact with the absorption layers 30. The melting layers 30 have a melting temperature that is lower than the melting temperature of the absorption layers 29. Therefore, as long as the light beam 6 illuminating the microlenses 15 provides sufficiently high light beam fluence to induce the release of the component 2 to the acceptor substrate 3, the melting layers 30 will be melted by the heat conducted from the absorption layers 29, while the absorption layers 29 remain solid. When the melting layers 30, which are typically provided as metallic layers, are in a molten state, the surface tension of the melting layers 30 will be below the surface energy of the absorption layers 29, which are typically also provided as metallic layers, but it will be higher than the surface energy of the typically polymeric adhesive layers 31. As a consequence, dewetting will occur, wherein adhesion between the absorption layers 29 and the melting layers 30 will be preserved, but adhesion between the melting layers 30 and the adhesion layers 31 will be lost. This will result in the release of the component 2 to the acceptor substrate 3, as shown in figure 4B. The component 2 illustrated in this figure is a large component attached to the donor substrate 1 with release patches 13 that cover only a portion of the component’s footprint. Because the large component 2 is held by the donor substrate 1 using a patterned plurality of release patches 13, rather than a release stack covering the full footprint of the component 2, the area to be illuminated and therefore the required optical power from the light source for triggering the release of the component 2 to the acceptor substrate 3 is significantly reduced. Upon illumination of the microlens array, the microlenses form the plurality of focused beams 17. The focused beams are incident on the plurality of release patches 13. The absorption layer 29 of each release patch receives the optical energy from the beam 6a focused thereon and consequently generates heat. The gaps between the release patches 13 form thermal barriers, forcing the heat generated in each absorption layer 29 to be conducted into the melting layer 30 of the same release patch 13. The melting layer 30 in each release patch 13 reaches its melting temperature and enters a molten state. Once the melting layers 30 are in a molten state, de-wetting occurs, causing each release patch 13 to lose adhesion with the component 2, allowing the component 2 to be released onto the acceptor substrate 3, as shown in figure 4B.

[0067] Figure 5 schematically illustrates an exemplary embodiment of a method of light-induced component transfer. As will be appreciated from the present document, the invention comprises embodiments that include microlenses, yet the invention further comprises embodiments not including microlenses. The method in this particular figure involves a step 36 of providing the donor substrate 1. The donor substrate 1 is provided with a plurality of release patches on the optically transparent carrier 5. Furthermore, the donor substrate is provided with a plurality of microlenses 15 at an opposite side of the optically transparent carrier 5 with respect to the release patches. Before release of a component 2 from a donor substrate 1 to an acceptor substrate 3 can begin, it may be that the component 2 first has to be attached to the donor substrate 1. In that case, the method first comprises a preparatory step 37, which involves aligning 38 the donor substrate 1 with a component 2 to de deposited onto an acceptor substrate 32. Components 2 should be precisely aligned with the donor substrate 1, which means among other things that the orientation of the donor substrate 1 should be well matched to that of a component 22. Components 2 can then be firmly attached to the donor substrate 1 across its footprint with a uniform distribution of adhesive force. Once the donor substrate 1 and the component 2 are properly aligned, the method can move onto attaching 39 the component 2 to the donor substrate. Depending on the materials that the adhesive layers 31 of the release patches 13 are composed of, this attaching 39 may involve curing through UV exposure, heat or other means to achieve full bonding strength. Once the component 2 to be transferred is attached to the donor substrate 1, the method can move on to transferring the component 2 to the acceptor substrate 3. In order to ensure proper placement of the component 2 on the acceptor substrate 3, a step 40 of alignment is first performed. The method may thus first determine the location on the acceptor substrate 3 where the component 2 is to be deposited and subsequently position 41 the component 2 relative to the acceptor substrate. Afterward, a step 42 of optically aligning the light source with the donor substrate may be performed, such that upon illumination of the microlenses 15 the release patches will be properly exposed to optical energy from the light beam for triggering the release mechanism. It is advantageous to perform the optical alignment after the step of positioning 41 of the component 2 relative to the acceptor substrate, because in embodiments where the step 42 of optical alignment is performed first, additional positioning uncertainty could be introduced by moving the donor substrate and light source to their desired locations using separate motors or actuators. The method further comprises a step 43 of illuminating the microlenses 15. Each microlens 15 focuses the incoming light beam 6 into a narrower, intensified beam 17 directed onto the release patches 13 in their optical paths. As the focused beams hit the release patches 13, the optical energy causes the release of the components to the acceptor substrate. This may for example happen through a process of de-wetting. In that case, the optical energy may be absorbed by absorption layers 29, generating heat. This heat may then be transferred to a melting layer 30, causing it to reach its melting temperature and subsequently melt. The melting of this layer may disrupt the bond between an adhesive layer 31 and the melting layer 30. The component 2 is thus freed from the donor substrate 1 and transferred to the acceptor substrate 3 positioned below. The focusing mechanism of the microlenses 15 ensures that the transfer of components occurs only in the targeted areas where the light beams 17 are concentrated, allowing for controlled transfer processes of components of a broad range of sizes without the need for much more powerful light sources. As the microlenses 15 concentrate the initially broader light beam 6 into narrower, intensified focused beams 17, the beams 17 may illuminate a substantial portion of the release patches’ 13 covered areas. This may cause the concentrated beams 17 to distribute optical energy across a major part of the release patches 13, such as at least 50%, 80% or 90% of the area covered by the release patches. This allows for efficient absorption of the optical energy by the absorption layer 29, generating sufficient heat to melt the underlying melting layer 30.

[0068] Rather than a large component, a donor substrate 1 comprising a plurality of release patches 13 and microlenses 15 may also be used to simultaneously release a large number of components 2 to an acceptor substrate 3. This case is illustrated in figures 6A and 6B. Using a microlens array and a release patch array provides an advantageous means of rapidly transferring a large number of components. In some embodiments, some release patches may individually be attached with components, while at the same time other release patches may together be attached with a single, larger component. In such embodiments, the use of a microlens array and a release patch array further provides advantage, because it enables a rapid transfer of multiple components of various sizes and shapes. Some components may have more complex shapes. They may for example be oblong, L-shaped or T-shaped. The release patch array enables to attach such components to the donor substrate 1 at specific points of coverage, and thus removes the need to provide complexly shaped release patches, or more simply shaped release patches that are larger than the component to be transferred. The area to be illuminated is thereby reduced, improving energy efficiency. Figure 7 schematically illustrates how a microlens array may be arranged on the optically transparent carrier 5 of a donor substrate 1. In this figure, the microlenses 15 are plano-convex lenses attached to the optically transparent carrier 5 of a donor substrate 1 along their planar surfaces. The microlenses 15 are aligned with the release patches 13, such that the release patches 13 can receive the light beams 17 focused by the microlenses 15 from the light beam 6. Normally (contrary to the present invention), the component 2 would be attached to the donor substrate with a release stack that covers the full surface of the component 2 (in this case a surface area denoted 12). In that case, as the size of the component 2 increases, so does the required beam width 44 of the light beam 6 and therefore also the required optical power. However, in the present invention, the microlenses 15 focus the optical energy incident thereon onto the release patches 13. By condensing the optical power onto the release patches 13 from a larger area, the effectively required optical power for providing sufficient light beam fluence for triggering the release of the component 2 is significantly reduced. The component is thus able to be transferred using a light source that consumes less energy. In this figure, the microlenses 15 are arranged in a hexagonal lattice. This minimizes the unused space where optical energy from the light beam 6 is not focused onto a release patch 13. In other embodiments of the invention, the unused space maybe reduced further by forming the planar surfaces of the microlenses as polygonal surfaces. For example, in this hexagonal lattice, the unused space would be completely eliminated by microlenses having planar surfaces that are shaped as hexagons. This embodiment further increases the energy efficiency of the invention by utilizing all of the optical power from the light beam 6. The radius of curvature of the convex surface of the microlenses 15 may be chosen in accordance with the size of the release patches 13, such that the focused beams have a final beam width suitable for triggering the release. The smaller the radius of curvature is, the stronger the curvature of the lens and therefore the smaller the width w of the release patches may be. With smaller release patches in turn comes a higher effective increase in the provided light beam fluence. The advantage gained by the use of a microlens array and a release patch array may thereby be tuned by varying the radius of curvature and the width 45 of the microlenses according to case-specific requirements. Figures 8A-8C schematically illustrate three points in a method in accordance with an embodiment of the invention. In figure 8A, an optically transparent carrier 5 is shown, as provided in the method. The transparent carrier 5 may serve as a base or foundation of the donor substrate 1 for carrying the other parts of the donor substrate. Accordingly, the method as shown in the figures further involves providing the transparent carrier 5 with a plurality of release patches 13 on spatially distributed spots of one side of the transparent carrier 5, as shown in figure 8B. Each of the release patches 13 may receive optical energy from a light beam. The release patches 13 may all together carry a same component 2 to be transferred until they are exposed to optical energy from the light beam, or in alternative embodiments may each carry a separate component. In yet further embodiments, a combination of these two cases may occur, wherein some release patches share a same component 2, while other release patches carry separate components. In the method shown, the release patches 13 may receive optical energy from focused beams, meaning that the effective intensity of the light beam will be increased via focusing for each of the release patches 13. Accordingly, figure 8C shows the donor substrate 1 after having been provided, in accordance with the method, with microlenses 15 on the opposite side of the transparent carrier 5 with respect to the release patches 13. When used in a method according to the first aspect of the invention, the microlenses 15 may be illuminated with a light beam. Each of the microlenses 15 may then receive a portion of that light beam and focus its respective portion of the optical energy onto the release patches 13. The microlenses 15 focus the light beam and thereby effectively intensify the beam that is incident on the release patches 13. The combination of this effective intensification of the light beam with the spatial distribution of release patches 13 enables the light-induced transfer of components 2 to be performed using the method of transfer described above, regardless of the size of the component 2, and with a light source that emits a lower amount of optical power and which can therefore be significantly less expensive. Alternatively, the donor substrate 1 manufactured in the method discussed here may be used to simultaneously transfer a large amount of small components that are attached to separate release patches 13. As will be appreciated, the microlenses described with reference to figures 4A-4B, 5, 6A-6B, 7, 8A-8C are entirely optional and are not essential to the invention. The embodiments described with reference to figures 1A-1E, 2A-2B, 3A- 3E, 9 and 10A-10B provide some examples of embodiments that do not require such microlenses.

[0069] Turning now to figure 9, in the here illustrated example, the donor substrate 1 has a component 2 attached thereto which includes a functional area 32. Such a functional area 32 may serve a predetermined function even after being released to an acceptor substrate, and may be vulnerable to interactions with either the light beam 6 or with the materials of the contact elements 10. Therefore, in these embodiments, the patterning of the contact layer is such, that the contact elements 10 are arranged outside of the functional area 32. This advantageously allows to protect the pristineness of critical parts of the component, such as the functional area 32 shown here.

[0070] In figure 10A, two components 2 are shown being attached to a donor substrate 1 prior to being transferred to an acceptor substrate. As illustrated by way of example in this figure, the patterning may be such that, when the contact layer is illuminated by the light beam 6, the one or more contact elements 10 are configured to impart a total thrust onto the component 2 away from the donor substrate 1, the total thrust having a predetermined thrust magnitude and / or thrust direction. In the here illustrated example, the component 2 on the left is held by contact elements 10 that have contact areas which are considerably larger than the contact areas covered by the contact elements 10 of the component 2 on the right in the figure. As explained, the thrust magnitude may be proportional to the optical power delivered to the contact layer 8, and thus also proportional to the total contact area of the contact elements 10. Consequently, the total thrust magnitude for the component 2 shown on the left may be considerably higher than the thrust magnitude imparted to the component 2 shown on the right, as indicated by the arrows. Likewise, the one or more contact elements 10 may be formed at predetermined contact positions, or have predetermined thicknesses for yielding the thrust onto the component 2 having the predetermined thrust magnitude and / or thrust direction. As an example, one of the two shown contact elements 10 holding the component 2 on the left may in other embodiments be positioned at another position on the support surface of the component 2. Consequently, the resulting thrust direction on the component 2, defined by the sum of the individual thrusts imparted thereto by each contact element 10, may be controlled. Moreover, the patterning may further form one or more further contact elements 10. These further contact elements 10 may be formed at predetermined further contact positions and / or having predetermined further contact areas. The contact elements 10 and the further contact elements 10 may differ from each other in at least one of their thicknesses; their contact areas; or they may otherwise differ in their geographic arrangements on the component 2. As a result, the contact elements 10 in combination with the further contact elements 10 may yield the thrust onto the component having the predetermined thrust magnitude and / or thrust direction.

[0071] The present invention has been described in terms of some specific embodiments thereof. It will be appreciated that the embodiments shown in the drawings and described herein are intended for illustrated purposes only and are not by any manner or means intended to be restrictive on the invention. It is believed that the operation and construction of the present invention will be apparent from the foregoing description and drawings appended thereto. It will be clear to the skilled person that the invention is not limited to any embodiment herein described and that modifications are possible which should be considered within the scope of the appended claims. Also kinematic inversions are considered inherently disclosed and to be within the scope of the invention. Moreover, any of the components and elements of the various embodiments disclosed may be combined or may be incorporated in other embodiments where considered necessary, desired or preferred, without departing from the scope of the invention as defined in the claims.

[0072] In the claims, any reference signs shall not be construed as limiting the claim. The term 'comprising' and ‘including’ when used in this description or the appended claims should not be construed in an exclusive or exhaustive sense but rather in an inclusive sense. Thus the expression ‘comprising’ as used herein does not exclude the presence of other elements or steps in addition to those listed in any claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. Features that are not specifically or explicitly described or claimed may be additionally included in the structure of the invention within its scope. Any of the claimed or disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise, without departing from the claimed invention. Expressions such as: "means for...” should be read as: "component configured for..." or "member constructed to..." and should be construed to include equivalents for the structures disclosed. The use of expressions like: "critical", "preferred", "especially preferred" etc. is not intended to limit the invention. Additions, deletions, and modifications within the purview of the skilled person may generally be made without departing from the spirit and scope of the invention, as is determined by the claims. The invention may be practiced otherwise then as specifically described herein, and is only limited by the appended claims. List of reference numerals

[0073] 1. Donor substrate

[0074] 2. Component

[0075] 2-1. Center of mass of component

[0076] 3. Acceptor substrate

[0077] 4. Support surface

[0078] 5. Optically transparent carrier

[0079] 6. Light beam

[0080] -16. Light beam

[0081] 7. Light source

[0082] 8. Contact layer

[0083] 9. Release layer

[0084] 10. Contact element

[0085] 11. Contact area

[0086] 12. Area of the support surface

[0087] 13. Release patch

[0088] 14. Release patch array

[0089] 15. Microlens

[0090] 16. Microlens array

[0091] 17. Focused beam

[0092] 18. First dimension

[0093] 19. Second dimension

[0094] 20. Interconnecting structure

[0095] 29. Absorption sublayer

[0096] 30. Melting sublayer

[0097] 31. Adhesive sublayer

[0098] 32. Functional area

[0099] 33. First material

[0100] 34. Second material

[0101] 36. Providing a donor substrate

[0102] 37. Preparatory step

[0103] 38. Aligning the donor substrate with the component 39. Attaching the component to the donor substrate 40. Alignment 41. Positioning the component relative to the acceptor substrate 42. Optically aligning the light source with the donor substrate 43. Illuminating the microlenses

[0104] 44. Beam width

[0105] 45. Width of microlenses

[0106] 46. Width of release patches Clauses

[0107] 1. Method of light-induced component transfer from a donor substrate to an acceptor substrate, the method comprising:

[0108] providing the donor substrate, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam, wherein the donor substrate is provided comprising a plurality of release patches on the optically transparent carrier; and

[0109] providing, using a light source, the light beam for illuminating the plurality of release patches through the optically transparent carrier;

[0110] wherein each release patch is configured for attaching a component to the donor substrate and for releasing the component to the acceptor substrate when the release patch is exposed to optical energy from the light beam,

[0111] wherein the plurality of release patches are spatially distributed on the transparent carrier, such as to form a release patch array, wherein the donor substrate is further provided comprising a plurality of microlenses at an opposite side of the transparent carrier with respect to the release patch array, the plurality of microlenses forming a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon,

[0112] wherein the method further comprises illuminating the microlens array with the light beam from the light source, wherein optical energy from the focused beams causes a release of attachment of the component, for releasing the component to the acceptor substrate.

[0113] 2. Method according to clause 1, wherein each release patch is formed by a stack of layers comprising:

[0114] - an absorption layer for absorbing optical energy from the light beam, the absorption layer having a first melting temperature;

[0115] - a melting layer for being melted by heat from the absorption layer, the melting layer having a second melting temperature below the first melting temperature; and

[0116] - an adhesive layer for adhering the component to the melting layer, and for releasing the adhesion when the melting layer is in a molten state. 3. Method according to clause 1 or 2, wherein each focused beam has a second beam width smaller than a first beam width of the light beam used in the step of illuminating the microlens array,

[0117] wherein each release patch covers an area on the optically transparent carrier, and wherein a maximum width of the area covered by each release patch relates to the second beam widths such that each focused beam illuminates a major part of the area covered by one of the release patches.

[0118] 4. Method according to clause 3, wherein the major part of the area covered by each release patch that is illuminated by one of the focused beams is at least 50%, preferably at least 80%, more preferably at least 90% of the area covered by each release patch.

[0119] 5. Method according to any of the preceding clauses, wherein, prior to illuminating the microlens array, at least one of:

[0120] - multiple release patches adhere a same component to the donor substrate; and

[0121] - multiple release patches adhere a different component to the donor substrate.

[0122] 6. Method according to any of the preceding clauses, wherein a planar surface of each microlens is one of a group comprising: circular surfaces, elliptical surfaces and polygonal surfaces.

[0123] 7. Method according to any of the preceding clauses, wherein each microlens is provided on the optically transparent carrier, such as to be positioned mutually adjacent to each other in one of: a hexagonal lattice, a triangular lattice, a square lattice, a rectangular lattice, a rhombic lattice, a pentagonal lattice, or an oblique lattice.

[0124] 81. Donor substrate for use in a method according to any one or more of the preceding clauses, for a light-induced component transfer to an acceptor substrate, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam, wherein the donor substrate comprises a plurality of release patches on the optically transparent carrier, wherein each release patch is configured for attaching a component to the donor substrate and for releasing the component to the acceptor substrate when the release patch is exposed to optical energy from the light beam,

[0125] wherein the plurality of release patches are spatially distributed on the optically transparent carrier, such as to form a release patch array, wherein the donor substrate further comprises a plurality of microlenses at an opposite side of the optically transparent carrier with respect to the release patch array, the plurality of microlenses forming a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon.

[0126] 91. Donor substrate according to clause 8, wherein each release patch is formed by a stack of layers comprising:

[0127] - an absorption layer for absorbing optical energy from the light beam, the absorption layer having a first melting temperature;

[0128] - a melting layer for being melted by heat from the absorption layer, the melting layer having a second melting temperature below the first melting temperature; and

[0129] - an adhesive layer for adhering the component to the melting layer, and for releasing the adhesion when the melting layer is in a molten state.

[0130] 101. Donor substrate according to clause 8 or 9, wherein each focused beam has a second beam width smaller than a first beam width of the light beam used in the step of illuminating the microlens array,

[0131] wherein each release patch covers an area on the optically transparent carrier, and wherein a maximum width of the area covered by each release patch relates to the second beam widths such that each focused beam illuminates a major part of the area covered by one of the release patches.

[0132] 111. Donor substrate according to clause 10, wherein the major part of the area covered by each release patch that is illuminated by each respective focused beam is at least 50%, preferably at least 80%, more preferably at least 90% of the area covered by the release patch. 121. Donor substrate according to any of the clauses 8-11, wherein, prior to illuminating the microlens array, at least one of:

[0133] - multiple release patches adhere a same component to the donor substrate; and

[0134] - multiple release patches adhere a different component to the donor substrate.

[0135] 131. Donor substrate according to any of the clauses 8-12, wherein a planar surface of each microlens is one of a group comprising: circular surfaces, elliptical surfaces and polygonal surfaces.

[0136] 141. Donor substrate according to any of the clauses 8-13, wherein each microlens is provided on the optically transparent carrier, such as to be positioned mutually adjacent to each other in one of: a hexagonal lattice, a triangular lattice, a square lattice, a rectangular lattice, a rhombic lattice, a pentagonal lattice, or an oblique lattice.

[0137] 15. Method of manufacturing a donor substrate according to any one or more of the clauses 8-14, wherein the method comprises:

[0138] providing an optically transparent carrier for transmitting a light beam; spatially distributing a plurality of release patches on the optically transparent carrier, such as to form a release patch array, wherein each release patch is configured for attaching a component to the donor substrate and for releasing the component to an acceptor substrate when the release patch is exposed to optical energy from the light beam;

[0139] providing an opposite side of the transparent carrier with respect to the release patch array with a plurality of microlenses, such as to form a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon.

Claims

1. Claims11. Donor substrate for use in a method of light-induced component transfer of a component from the donor substrate to an acceptor substrate, the component comprising a support surface facing the donor substrate prior to transfer of the component, wherein the donor substrate comprises an optically transparent carrier for transmitting a light beam from a light source during the light-induced component transfer,3.wherein the donor substrate for supporting the component prior to transfer thereof, further comprises a contact layer on the optically transparent carrier configured to attach the component to the donor substrate, wherein the contact layer comprises a release layer for being illuminated through the optically transparent carrier by the light beam and configured to release the component when the release layer is exposed to optical energy from the light beam,4.wherein at least a part of the contact layer is patterned such as to form one or more contact elements, each contact element arranged for connecting the component to the donor substrate over at least a contact area, such that a sum of the contact areas of the one or more contact elements configured for supporting the component is smaller than a total area of the support surface.

21. Donor substrate according to claim 1, wherein the contact areas of the one or more contact elements are arranged at one or more contact positions between the contact layer and the component, the one or more contact positions being selected, such as to yield an effective suspension point of the component from the one or more contact positions, coinciding with a center of mass of the component.

31. Donor substrate according to claim 1 or 2, wherein the contact layer is patterned in at least the release layer.

41. Donor substrate according to claim 3, wherein the contact layer is provided as a plurality of release patches on the optically transparent carrier, wherein each release patch is configured for attaching a component to the donorsubstrate and for releasing the component to the acceptor substrate when the release patch is exposed to optical energy from the light beam.

51. Donor substrate according to claim 4, wherein the plurality of release patches are spatially distributed on the optically transparent carrier, such as to form a release patch array, wherein the donor substrate further comprises a plurality of microlenses at an opposite side of the optically transparent carrier with respect to the release patch array, the plurality of microlenses forming a microlens array for being illuminated with the light beam and for focusing the light beam onto the release patch array, such as to form a plurality of focused beams thereon.

61. Donor substrate according to any of the preceding claims, wherein the component is part of a plurality of components to be transferred, the support surface of each component comprising a first dimension and a second dimension, the second dimension optionally being smaller than the first dimension, the first and the second dimensions defining a surface area of the support surface,10.wherein the patterning defines a common contact area for each of the one or more contact elements arranged for connecting one of the plurality of components to the donor substrate, the common contact area being defined such as to substantially cover the second dimension of the support surface of a component that comprises the smallest surface area.

71. Donor substrate according to any of the preceding claims, wherein the contact layer further comprises an interconnecting structure provided between the release layer and the component to be transferred, the interconnecting structure being arranged for being attached to the component, such as to provide, by the interconnecting structure, a connecting bridge between the component to be transferred and the donor substrate.

81. Donor substrate according to claim 7, wherein the contact layer is patterned in at least the interconnecting structure.

91. Donor substrate according to claim 7 or 8, wherein the interconnecting structure is further arranged for maintaining attachment to the component when the release layer is exposed to optical energy of the light beam.

101. Donor substrate according to claim 9, wherein the interconnecting structure comprises a shape for guiding the component from the donor substrate to the acceptor substrate along a predetermined trajectory or for maintaining a predetermined orientation of the component upon release of the component to the acceptor substrate.

111. Donor substrate according to claim 10, wherein the shape of the interconnecting structure comprises at least one of:15.a wing portion arranged to generate a lift on the component with the interconnecting structure attached thereto during the movement to the acceptor substrate,16.a fin portion arranged to maintain a predetermined orientation of the component during the movement to the acceptor substrate,17.a rudder portion arranged to provide a rotational motion of the component about a predefined rotation axis during the movement to the acceptor substrate,18.a deflector portion arranged to provide a drag on the component with the interconnecting structure attached thereto during the movement to the acceptor substrate.

121. Donor substrate according to any of the preceding claims, wherein the support surface is provided with one or more functional areas, and wherein the contact areas of the one or more contact elements are arranged outside the one or more functional areas.

131. Donor substrate according to any of the preceding claims, wherein the patterning is such that, when the contact layer is illuminated by the light beam, the one or more contact elements are configured to impart a total thrust onto the component away from the donor substrate, the total thrust having a predetermined thrust magnitude and / or thrust direction.

141. Donor substrate according to claim 13, wherein the one or more contact elements are formed at predetermined contact positions; having predetermined thicknesses and / or having predetermined contact areas, such as to yield the thrust onto the component having the predetermined thrust magnitude and / or thrust direction.

151. Donor substrate according to claim 14, wherein the patterning further forms one or more further contact elements, wherein the one or more further contact elements are formed at predetermined further contact positions and / or having predetermined further contact areas, such that the one or more contact elements in combination with the one or more further contact elements yield the thrust onto the component having the predetermined thrust magnitude and / or thrust direction.

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