Methods and apparatuses for transferring discrete components

Abstract

The present invention provides a method comprising transferring a plurality of discrete elements from a first substrate to a second substrate, including irradiating a plurality of regions on the top surface of a dynamic release layer, the dynamic release layer adhering the plurality of discrete elements to the first substrate, each of the irradiated regions being aligned with a corresponding one of the discrete elements. The irradiation induces a plastic deformation in each of the irradiated regions of the dynamic release layer. The plastic deformation causes at least some of the discrete elements to be simultaneously released from the first substrate.

Description

Parallel assembly of discrete components on a substrate This specification generally relates to the assembly of discrete components on a substrate. Known assembly processes use robotic pick-and-place systems, fluid self-assembly systems, light-assisted assembly systems, or other systems to automatically transfer objects from one place to another. In one aspect, a method includes transferring a plurality of discrete components from a first substrate to a second substrate, including simultaneously irradiating a plurality of regions on a top surface of a dynamic release layer that adheres the plurality of discrete components to the first substrate, with each of the irradiated regions aligned with one of the discrete components. The irradiation induces ablation of at least a portion of the dynamic release layer in each of the irradiated regions. The ablation causes at least some of the discrete components to be simultaneously released from the first substrate. Embodiments may include one or more of the following features. Irradiating the plurality of regions includes applying laser energy to irradiate the plurality of regions. The method includes dividing the laser energy into a plurality of small beams, and applying one of the small beams of the laser energy to irradiate each of the plurality of regions. The method includes using a diffractive optical device to separate the laser energy. The irradiation induces ablation of a partial thickness of a dynamic release layer in each of the irradiated regions. The ablation of the partial thickness of the dynamic release layer induces deformation of a remaining thickness of the dynamic release layer in each of the irradiated regions. The deformation includes a convex bubble in each of the irradiated regions of the dynamic release layer, and each of the convex bubbles applies a force to a corresponding discrete element. The force applied by the convex bubbles causes the discrete elements to be released from the first substrate. The ablation of the partial thickness induces plastic deformation in each of the irradiated regions. The ablation of the partial thickness induces elastic deformation in each of the irradiated regions. The irradiation induces ablation of an entire thickness of a dynamic release layer in each of the irradiated regions. The method includes reducing an adhesion force of a dynamic release layer before irradiating the plurality of regions. Reducing the adhesion force of a dynamic release layer includes exposing the dynamic release layer to a stimulus. Exposing the dynamic release layer to a stimulus includes exposing the dynamic release layer to one or more of heat and ultraviolet light. Transferring the plurality of discrete elements includes: transferring a first set of one or more discrete elements to a first target substrate, the discrete elements in the first set sharing a first common characteristic; and transferring a second set of one or more discrete elements to a second target substrate, the discrete elements in the second set sharing a second common characteristic. The discrete elements include light emitting diodes (LEDs), and wherein the characteristic includes one or more of an optical characteristic and an electrical characteristic. Transferring the plurality of discrete elements to the second substrate includes transferring less than all of the discrete elements from the first substrate to the second substrate. The method includes individually transferring each of one or more of the discrete elements from the first substrate to a destination before transferring the plurality of discrete elements. Individually transferring each of one or more of the discrete elements includes transferring discrete elements that do not meet a quality criterion. The method includes individually transferring each of one or more discrete elements remaining on the first substrate to the second substrate after transferring the plurality of discrete elements to the second substrate. The method includes individually transferring each of one or more discrete elements from a third substrate to the second substrate after transferring the plurality of discrete elements to the second substrate. The plurality of discrete elements form an array of discrete elements on the second substrate, and wherein transferring each of one or more discrete elements remaining on the first substrate includes transferring a discrete element to an empty position in the array on the second substrate. Irradiating a plurality of regions includes scanning the irradiation to a plurality of subsets of discrete elements. The plurality of discrete elements in each subset are simultaneously released, and the plurality of subsets are sequentially released. Irradiating a plurality of regions includes irradiating each region using an irradiation pattern.The method includes splitting laser energy into the illumination pattern. The method includes using a first diffractive optical device to split the laser energy into the illumination pattern. The method includes splitting the illumination pattern into a plurality of small beams of laser energy, each small beam having the illumination pattern. The method includes using a second diffractive optical device to split the illumination pattern into a plurality of small beams. The method includes scanning the plurality of small beams of laser energy to a plurality of subsets of discrete elements, each small beam having the illumination pattern. The method includes using a single diffractive optical device to split laser energy into a plurality of small beams of laser energy, each small beam having the illumination pattern. The illumination pattern includes a plurality of small beams of laser energy, each small beam corresponding to a specific location on a given discrete element. The illumination pattern includes four small beams of laser energy, each small beam corresponding to a corner of a given discrete element. Transferring the plurality of discrete elements from the first substrate to the second substrate includes transferring the plurality of discrete elements to the second substrate in a face-down orientation. The plurality of discrete elements includes light-emitting diodes (LEDs). In one aspect, an apparatus includes: a substrate assembly including a substrate, a dynamic release layer disposed on a surface of the substrate, and a plurality of discrete elements adhered to the substrate by the dynamic release layer; and an optical system including at least one optical device configured to split a laser beam from a laser energy source into a plurality of small beams, each small beam configured to illuminate a corresponding area on a top surface of the dynamic release layer. Embodiments may include one or more of the following features. The at least one optical element is configured to divide the laser beam from the source into the plurality of small beams, each small beam having an irradiation pattern. The irradiation pattern includes a plurality of small beams of laser energy, and each small beam of the irradiation pattern is configured to irradiate a specific position on a given discrete element. The optical system includes: a first optical device configured to divide the laser beam from the source into the irradiation pattern; and a second optical device configured to divide the irradiation pattern into the plurality of small beams, each small beam having the irradiation pattern. The first optical device and the second optical device each include a diffractive optical device. The optical system includes: a first optical device configured to divide the laser beam from the source into the plurality of small beams; and a second optical device configured to divide each of the plurality of small beams into the irradiation pattern. The apparatus includes a scanning mechanism configured to scan the plurality of small beams of laser energy to the plurality of regions of the dynamic release layer, each region of the dynamic release layer adhering a subset of the plurality of discrete elements to the substrate. The optical system has: (i) a first configuration in which the optical device is in the path of the laser beam between the source of laser energy and the dynamic release layer; and (ii) a second configuration in which the optical device is not in the path of the laser beam between the source of laser energy and the dynamic release layer. When the optical system is in the first configuration, the optical device divides the laser beam into the plurality of small beams. When the optical system is in the second configuration, the laser beam is incident on the top surface of the dynamic release layer at a position corresponding to a position of one of the discrete elements. The apparatus includes a controller configured to control the alignment of the laser beam with the position of the one of the discrete elements. The controller is configured to control the alignment of the laser beam based on information indicating one or more of the characteristics and one or more of the quality of one or more of the discrete elements. The optical system includes: a first optical device configured to divide the laser beam into a first number of small beams; a second optical device configured to divide the laser beam into a second number of small beams; and a switching mechanism configured to position the first optical device or the second optical device in the path of the laser beam. The apparatus includes the laser energy source. The laser energy source includes a laser. The irradiation of the regions of the dynamic release layer causes the release of the discrete elements aligned with the irradiated regions. One or more of the wavelength and the flux of each small beam of laser energy is sufficient to induce ablation of at least a portion of the thickness of the dynamic release layer in each of the irradiated regions. The wavelength or the flux of each small beam is sufficient to induce ablation of a portion of the thickness of the dynamic release layer in each of the irradiated regions, and the ablation of the portion of the thickness induces deformation in each of the irradiated regions. The wavelength or the flux of each small beam is sufficient to induce ablation of an entire thickness of the dynamic release layer in each of the irradiated regions.The adhesion of the dynamic release layer responds to a stimulus. The adhesion of the dynamic release layer responds to one or more of heat and ultraviolet light. The discrete elements include LEDs. In one aspect, a device includes: a laser energy source; a substrate holder configured to receive a substrate; an optical system including a first optical device configured to split a laser beam from the laser energy source into a plurality of small beams, wherein the optical system has a first configuration in which the first optical device is disposed in the path of the laser energy between the laser energy source and the substrate holder and at least one second configuration, the at least one second configuration being one or more of (i) a configuration in which a second optical device is disposed in the path of the laser energy and (ii) a configuration in which neither the first optical device nor the second optical device is in the path of the laser energy; and a controller configured to control the configuration of the optical system. Embodiments may include one or more of the following features. The device includes a scanning device configured to scan the laser beam or small beams output from the optical system relative to the substrate holder. The controller is configured to move the first optical device into and out of the path of the laser energy. The device includes a stimulus application device configured to output a stimulus including one or more of ultraviolet light and heat. When a substrate is present in the substrate holder, the stimulus application device is positioned to apply the stimulus to the substrate. In one aspect, a device includes: a laser energy source; a first substrate holder configured to receive at least one first substrate; an optical system including a first optical device configured to split a laser beam from the laser energy source into a plurality of sub-beams, wherein the optical system has a first configuration in which the first optical device is disposed in the path of the laser energy between the laser energy source and the first substrate holder and at least one second configuration, the at least one second configuration being one or more of (i) a configuration in which a second optical device is disposed in the path of the laser energy and (ii) a configuration in which neither the first optical device nor the second optical device is in the path of the laser energy; a first controller configured to control the configuration of the optical system; a second substrate holder configured to hold at least one second substrate, at least a portion of the second substrate holder being disposed below the first substrate holder; and a second controller configured to control the positioning of the second substrate holder relative to the first substrate holder. The device includes a scanning device configured to scan the laser beam or sub-beams output from the optical system relative to the substrate holder. The device includes a stimulus application device configured to output a stimulus including one or more of ultraviolet light and heat. The device includes a control system including the first controller and the second controller. The second substrate holder is configured to hold a plurality of second substrates. The device includes a substrate rack configured to hold a plurality of second substrates; and a transfer mechanism controllable by the second controller to transfer one of the plurality of second substrates from the substrate rack to the second substrate holder. The first substrate holder is configured to hold a plurality of first substrates. The device includes a substrate rack configured to hold a plurality of first substrates; and a transfer mechanism controllable by a third controller to transfer one of the plurality of first substrates from the substrate rack to the first substrate holder. In one aspect, a method includes transferring a plurality of discrete elements from a substrate, the discrete elements being adhered to the substrate by a dynamic release layer, the transfer including: using a first laser-assisted transfer process to individually transfer each of one or more first discrete elements from the substrate to a first destination, the first discrete elements not meeting a quality criterion; and using a second laser-assisted transfer process to transfer a plurality of second discrete elements from the substrate to a second destination, the second discrete elements meeting the quality criterion. Embodiments may include one or more of the following features. Transferring a plurality of second discrete elements includes transferring less than all of the second discrete elements such that one or more second discrete elements remain adhered to the substrate. The method includes individually transferring each of one or more of the second discrete elements that remain adhered to the substrate to the second destination. The plurality of second discrete elements form an array of discrete elements at the second destination, and individually transferring each of one or more of the remaining second discrete elements includes transferring each of the remaining second discrete elements to an empty position in the array. The second laser-assisted transfer process includes irradiating a plurality of regions on a top surface of the dynamic release layer, each of the irradiated regions being aligned with a corresponding one of the second discrete elements, wherein the irradiation causes the second discrete elements to be simultaneously released from the substrate. The first laser-assisted transfer process includes, for each of the first discrete elements, irradiating a region on a top surface of the dynamic release layer that is aligned with the first discrete element, wherein the irradiation causes the first discrete element to be released from the substrate. The method includes reducing an adhesion force of the dynamic release layer prior to transferring the one or more first discrete elements. Reducing the adhesion force of the dynamic release layer includes exposing the dynamic release layer to one or more of heat and ultraviolet light. The second destination includes a target substrate, and transferring the plurality of second discrete elements to the second destination includes transferring a set of second discrete elements onto an attachment device disposed on a top surface of the target substrate. The method includes curing the attachment device to bond the transferred second discrete elements to the target substrate. Curing the attachment device includes exposing the attachment device to one or more of heat, ultraviolet light, and mechanical pressure. The method includes applying the attachment device to the target substrate. The second destination includes a target substrate and includes bonding the transferred second discrete elements to the target substrate. The second destination includes a target substrate having circuit elements, and wherein the method includes interconnecting the circuit elements of the transferred second discrete elements with the circuit elements of the target substrate. The method includes transferring the discrete elements from a donor substrate to the substrate. Transferring the discrete elements from the donor substrate to the substrate includes bringing the dynamic release layer on the substrate into contact with the discrete elements on the donor substrate. The method includes singulating the discrete elements on the donor substrate. The donor substrate includes a dicing tape. The donor substrate includes a wafer. The method includes applying the dynamic release layer to the substrate. In one aspect, a method includes transferring discrete components from a carrier substrate to each of a plurality of target substrates, the discrete components being adhered to the carrier substrate by a dynamic release layer, the transfer including: using a laser-assisted transfer process to transfer a first set of the discrete components to a first target substrate, the discrete components in the first set sharing a first characteristic; and using the laser-assisted transfer process to transfer a second set of the discrete components to a second target substrate, the discrete components in the second set sharing a second characteristic different from the first characteristic. Embodiments may include one or more of the following features. The method includes transferring the discrete components from a plurality of carrier substrates to the plurality of target substrates. The method includes successively transferring the discrete components from each of the plurality of carrier substrates. The transfer includes transferring discrete components from a first carrier substrate to one or more of the target substrates in a transfer system; removing the first carrier substrate from a transfer position in the transfer system; placing a second carrier substrate in the transfer position; and transferring discrete components from the second carrier substrate to one or more of the target substrates. The transfer includes transferring the first set of discrete components to the first target substrate in a transfer system; removing the first target substrate from a transfer position in the transfer system; and placing the second target substrate in the transfer position for transferring the second set of discrete components. The discrete components include LEDs, and wherein the first and second characteristics include one or more of an optical characteristic and an electrical characteristic. Transferring each set of the discrete components to the corresponding target substrate includes individually transferring each of the discrete components in the set to the target substrate. Transferring each set of the discrete components to the corresponding target substrate includes transferring some or all of the discrete components in the set to the target substrate. Transferring a set of discrete components to the corresponding target substrate includes transferring the discrete components in the set to a die capture material layer disposed on a top surface of the target substrate. The method includes applying die acceptance material to each target substrate. The method includes reducing an adhesion force of the dynamic release layer. Reducing an adhesion force of the dynamic release layer includes exposing the dynamic release layer to one or more of heat and ultraviolet light. The method includes transferring the discrete components from a donor substrate to the carrier substrate. Transferring the discrete components from the donor substrate to the carrier substrate includes contacting the dynamic release layer on the carrier substrate with the discrete components on the donor substrate. The donor substrate includes a dicing tape. The donor substrate includes a wafer. The method includes applying the dynamic release layer to the carrier substrate. In one aspect, an apparatus includes a substrate, a plurality of cavities formed in a top surface of the substrate; a spectral shift material disposed in each of the plurality of cavities, the spectral shift material configured to emit light at one or more emission wavelengths in response to absorbing light at an excitation wavelength; and an LED disposed in each of the plurality of cavities, each LED configured to emit light at the excitation wavelength, each LED oriented such that light emitted from the micro-LED irradiates the spectral shift material disposed in the corresponding cavity. Embodiments may include one or more of the following features. The spectral shift material includes a first spectral shift material configured to emit light at a first emission wavelength; and a second spectral shift material configured to emit light at a second emission wavelength. The first spectral shift material is disposed in a first subset of the plurality of cavities and the second spectral shift material is disposed in a second subset of the plurality of cavities. The cavities are arranged in a two-dimensional array, and wherein the first spectral shift material is disposed in cavities in a first column of the array and the second spectral shift material is disposed in cavities in a second column of the array. The spectral shift material includes a third spectral shift material configured to emit light at a third emission wavelength, and wherein the first emission wavelength corresponds to red light, the second emission wavelength corresponds to green light, and the third emission wavelength corresponds to blue light. The LEDs are oriented such that a light-emitting surface of each LED faces away from the top surface of the substrate. Each LED includes a contact formed on a second surface of the LED, the second surface being opposite the light-emitting surface. The apparatus includes electrical connection lines in electrical contact with the contacts of the LEDs. The substrate is transmissive to light at the one or more emission wavelengths. The substrate absorbs light at the excitation wavelength. The apparatus includes a planarization layer formed on the top surface of the substrate. The planarization layer may be transmissive to the one or more emission wavelengths. The spectral shift material includes one or more of phosphors, quantum dots, and organic dyes. The apparatus includes a display device. Each cavity, the spectral shift material disposed therein, and the corresponding LED correspond to a sub-pixel of the display device. The apparatus includes a solid-state lighting device. In one aspect, a method includes: disposing a spectral shift material in each of a plurality of cavities formed in a top surface of a substrate, the spectral shift material configured to emit light at one or more emission wavelengths in response to absorbing light at an excitation wavelength; and assembling an LED into each of the plurality of cavities, each LED configured to emit light at the excitation wavelength, each LED oriented such that light emitted from the LED irradiates the spectral shift material disposed in the corresponding cavity. Embodiments may include one or more of the following features. The method includes forming the plurality of cavities in the top surface of the substrate. The method includes forming the plurality of cavities by one or more of imprinting and lithography. Disposing the spectral shift material includes: disposing a first spectral shift material in a first subset of the plurality of cavities, the first spectral shift material being configured to emit light at a first emission wavelength; and disposing a second spectral shift material in a second subset of the plurality of cavities, the second spectral shift material being configured to emit light at a second emission wavelength. Assembling an LED into each of the plurality of cavities includes assembling the LEDs such that a light emitting surface of each micro-LED faces away from the top surface of the substrate. Assembling an LED into each of the plurality of cavities includes simultaneously transferring a plurality of LEDs into corresponding cavities. Simultaneously transferring a plurality of LEDs includes transferring the plurality of LEDs by a large scale parallel laser assisted transfer process. The method includes forming an electrical connection to each LED. The method includes forming an electrical connection to a contact on a second surface of each LED, the second surface being opposite a light emitting surface of each LED. The method includes forming a planarization layer on the top surface of the substrate. Priority Claim This application claims the benefit of priority of PCT Application No. PCT / US2018 / 029347, filed Apr. 25, 2018, and U.S. Patent Application No. 62 / 518,270, filed Jun. 12, 2017, the contents of which are incorporated herein by reference in their entirety. We describe herein a method for large scale parallel laser assisted transfer of discrete components onto a target substrate. This process can allow for ultra-fast, high throughput, low cost assembly of large numbers of discrete components. For example, light emitting diodes (LEDs) can be rapidly placed on a substrate, thus creating LED arrays for use in devices such as displays or solid state lighting devices. Referring to FIGS. 1A and 1B, a laser assisted transfer process is used for high throughput, low cost, contactless assembly of discrete components onto rigid or flexible substrates. The term discrete component generally refers to any single unit that will become part of a product or electronic device, such as an electronic, electromechanical, photovoltaic, photonic or optoelectronic component, module or system, such as any semiconductor material having circuitry formed on a portion of the semiconductive material. The discrete component can be ultrathin, meaning having a maximum thickness of 50 microns or less, 40 microns or less, 30 microns or less, 25 microns or less, 20 microns or less, 10 microns or less or 5 microns or less. The discrete component can be ultrasmall, meaning having a maximum length or width dimension of less than or equal to 300 microns per side, 100 microns per side, 50 microns per side, 20 microns per side or 5 microns per side. The discrete component can be both ultrathin and ultrasmall. Specifically referring to FIG. 1A, the discrete component 12 is adhered to the carrier substrate 16 by the dynamic release layer 22. The term carrier substrate generally refers to any material that includes, for example, one or more discrete components, such as, for example, an assembly of discrete components assembled by a manufacturer, such as a wafer including one or more semiconductor dies. The discrete component 12 includes an active face 32, which includes integrated circuit devices. In the examples of FIGS. 1A and 1B, the active face 32 of the discrete component 12 faces away from the dynamic release layer 22; in some examples, the active face 32 may face the dynamic release layer 22. Also referring to FIG. 1B, in the blister transfer process, the energy of the laser beam 24 is applied to the back side 30 of the carrier substrate 16. The carrier substrate 16 is transmissive to the wavelength of the laser energy. The laser energy 24 thus passes through the carrier substrate 16 and impinges on an area of the dynamic release layer 22, thereby causing ablation of a partial thickness of the dynamic release layer in the area (which we refer to as the irradiation area) on which the laser energy 24 impinges. This ablation generates a confined gas, which expands and creates a pressure in the non-ablated remaining portion of the dynamic release layer 22. This pressure causes the material of the dynamic release layer to elastically deform, thereby forming a blister 26. If the pressure caused by the elastic deformation exceeds the yield strength of the dynamic release layer material, the dynamic release layer plastically deforms. The blister 26 applies a mechanical force on the discrete component 12. When the mechanical force applied by the blister 26 is sufficient to overcome the adhesion between the discrete component 12 and the dynamic release layer 22, the mechanical force (combined with gravity) applied by the blister 26 pushes the discrete component away from the carrier substrate 16, for example for transfer to a target substrate 28. In the ablation transfer process, the energy of the laser beam 24 is applied to the back side 30 of the transmissive carrier substrate, as shown in FIG. 1B. The laser energy 24 incident on the area of the dynamic release layer 22 causes ablation of the entire thickness of the dynamic release layer 22 in the irradiation area, thereby ablating any adhesion between the discrete component 12 and the carrier substrate 16. The gas generated by the ablation, combined with gravity, propels the discrete component 12 away from the carrier substrate 16, for example for transfer to a target substrate 28. A further description of the laser-assisted transfer process by blistering of the dynamic release layer can be found in U.S. Patent Publication No. US2014 / 0238592, the content of which is incorporated herein by reference in its entirety. In some examples, the laser-assisted transfer process can be used to transfer multiple discrete components simultaneously or almost simultaneously. We sometimes use the term simultaneously to mean generally simultaneously or almost simultaneously. This process (sometimes referred to as large-scale parallel laser-assisted transfer) can achieve ultrafast, high-throughput transfer of discrete components onto a target substrate. Referring to FIG. 2A, a plurality of discrete components 112 are adhered to a single carrier substrate 116 by a dynamic release layer 122. The plurality of discrete components 112 can be arranged in an array, such as a one-dimensional array or a two-dimensional array. The dynamic release layer 122 of FIG. 2A can include one or more layers. Also referring to FIG. 2B, the energy of a laser beam 124 is used to simultaneously laser-assisted transfer a plurality of discrete components 112 onto a target substrate 128. The carrier substrate 116 transmits the wavelength of the laser beam 124. The laser beam 124 is split into a plurality of small beams 140a, 140b, 140c by an optical device 142 (such as a diffractive optical device, e.g., a beam splitter). By a small beam, we mean a light beam, such as a light beam having a smaller size (e.g., diameter) than the laser beam 124. Each of the plurality of small beams 140a, 140b, 140c is incident on a corresponding region of the dynamic release layer 122 simultaneously with each of the other small beams, and the corresponding region is aligned with one of the plurality of discrete components 112. In a pop-up transfer, the laser energy of each of the plurality of small beams 140a, 140b, 140c induces the simultaneous formation of bumps 126 at each of these regions of the dynamic release layer 122. The simultaneous formation of the plurality of bumps 126 causes all the discrete components 112 aligned with the irradiated region of the dynamic release layer 122 to separate from the dynamic release layer 122 simultaneously, e.g., for transfer to the target substrate 128. Referring to FIG. 2C, in some examples, ablation transfer can be used for the simultaneous laser-assisted transfer of a plurality of discrete components 112 onto a target substrate. In simultaneous ablation transfer, the laser energy of each of the small beams 140a, 140b, 140c induces the simultaneous ablation of the entire thickness of the dynamic release layer 122 in the irradiated region, thereby causing the discrete components 112 aligned with the irradiated region to separate from the dynamic release layer 122 simultaneously, e.g., for transfer to the target substrate 128. In the example of FIG. 2B, the laser beam 124 is split into three small beams incident on the discrete components 112 arranged in a one-dimensional array. In some examples, the laser beam 124 is split into a plurality of small beams incident on the discrete components arranged in a two-dimensional array. The laser beam 124 can be split into a larger number of small beams, such as 10 small beams, 100 small beams, 500 small beams, 1000 small beams, 5000 small beams, 10,000 small beams or another number of small beams. The number of small beams into which the laser beam 124 can be split can depend on the energy of the laser generating the laser beam 124. The number of small beams can depend on the size of the discrete components 112 to be transferred. For example, compared with smaller discrete components, larger discrete components may require a larger amount of energy to be transferred, and thus, compared with that used for transferring smaller discrete components, the laser beam 124 can be split into fewer small beams for transferring larger discrete components. In some instances, the laser beam 124 is split into fewer sub-beams 140 compared to the number of discrete elements 112. The laser beam 124 can be scanned across the carrier substrate 116 to sequentially transfer subsets of the plurality of discrete elements 112, where the discrete elements in each subset are transferred simultaneously. For example, the laser beam 124 can be split into a two-dimensional pattern, such as to transfer a two-dimensional array of discrete elements, and the pattern can be scanned across the carrier substrate to simultaneously release a two-dimensional array of discrete elements. In some instances, the pattern can vary for different scan positions, such as to account for variations in the type, size, or both of the discrete elements on the carrier substrate. FIG. 3 shows a perspective view of a portion of the discrete element 112 and the dynamic release layer 322 aligned with the discrete element 112. For simplicity, the carrier substrate to which the dynamic release layer 322 adheres is not shown. A laser beam 324 is used to transfer the discrete element 112 onto a target substrate. An optical device 342 splits the laser beam 324 into a multi-sub-beam pattern 326 incident on the dynamic release layer aligned with the discrete element 112. Each sub-beam pattern causes ablation of a partial thickness of the dynamic release layer and the formation of a convex bubble, or ablation of the entire thickness of the dynamic release layer, thereby causing a force to be applied to the discrete element at multiple locations. In the particular example of FIG. 3, the multi-sub-beam pattern 326 includes four sub-beams 326a, 326b, 326c, 326d, which are oriented such that the sub-beams are incident on the dynamic release layer aligned with the four corners of the discrete element 112. This configuration causes substantially equal forces to be applied to each corner of the discrete element 112. Using a multi-sub-beam pattern of laser energy to transfer discrete elements can help achieve a high yield of discrete elements and precise placement on the target substrate. FIG. 4 is a perspective view of a plurality of discrete elements 112 and the dynamic release layer 422. For simplicity, the carrier substrate to which the discrete elements 112 adhere is not shown. A laser beam 424 is used to simultaneously transfer the plurality of discrete elements 112 onto a target substrate. The laser beam 424 is split into a multi-sub-beam pattern 426 by a first optical device 428 of an optical system (such as a diffractive optical device, e.g., a beam splitter). The multi-sub-beam pattern 426 includes a plurality of sub-beams in a configuration to be incident on the dynamic release layer aligned with a single discrete element. For example, the multi-sub-beam pattern 426 can include four sub-beams of laser energy, which are oriented to be incident on the dynamic release layer aligned with the four corners of the discrete element. The multi-small beam pattern 426 undergoes a second splitting at a second optical device 430 of the optical system, such as a diffractive optical device, e.g., a beam splitter. The second splitting produces multiple groups 432 of the multi-small beam pattern 426 of the laser beam. Each group 432 is incident on an area of the dynamic release layer aligned with one of the discrete elements 112. The multiple small beams within each group 432 cause multiple convex bubbles to form in the irradiated area of the dynamic release layer, or alternatively, cause ablation of the entire thickness to form in the irradiated area of the dynamic release layer. This method enables the simultaneous transfer of multiple discrete elements 112, while the use of multiple small beams for each discrete element can help achieve a high yield of discrete elements and precise placement on the target substrate. In the specific example of FIG. 4, the laser beam 424 is split by a first optical device 428 into a pattern 426 including four small beams, one small beam for each corner of the discrete element. The pattern 426 is split by a second optical device 430 into three groups 432a, 432b, 432d, each group including four small beams of laser energy. Each group 432 is incident on an area of the dynamic release layer 422 aligned with a corresponding one of the multiple discrete elements 112, and within each group, the four small beams are incident on the dynamic release layer aligned with the four corners of the corresponding discrete element 112. In the example of FIG. 4, the optical system includes two optical devices 428, 430. In some examples, the optical system may include a single optical device that splits the laser beam 424 into multiple patterns, each pattern including multiple small beams of laser energy. In some examples, the pattern 426 of laser small beams is split into groups 432 that are fewer in number than the discrete elements 112. The set of groups 432 can be scanned across an entire carrier substrate (not shown in the figure) to sequentially transfer a subset of multiple discrete elements, where the discrete elements within each subset are transferred simultaneously. In an example where a laser beam is scanned across a carrier substrate, the energy density incident on the dynamic release layer can change as the laser energy is scanned, for example, due to changes in the distance the laser energy travels from its source and the angle at which the laser energy strikes the dynamic release layer. Differences in energy density can affect the positional accuracy of discrete element transfer onto a target substrate and the yield of the transfer process. In some examples, the energy density (e.g., laser fluence) can be adjusted to compensate for changes in the angle at which the layer energy strikes the dynamic release layer or changes in the distance between the source of the laser energy and the point where the laser energy strikes the dynamic release layer. In some examples, the energy density can be adjusted based on changing the pattern of the sub-beams (e.g., due to a change in the number of discrete elements being transferred simultaneously or due to a change in the number of sub-beams incident on a single discrete element). In some examples, an optical device such as a lens (e.g., a telecentric lens) can be used to reduce the change in the angle at which the laser energy strikes the dynamic release layer, thus reducing the difference in energy density. In some examples, the output power of the laser can be adjusted based on the release process, for example, by the scan position or by the pattern of the sub-beams or by another aspect of the release process. In some examples, the optical system is configured to switch between a single-element mode in which individual discrete elements are transferred one by one and a multi-element mode in which multiple discrete elements are transferred simultaneously. In one example, the multiple discrete elements 112 on the carrier substrate can be discrete elements from a wafer. The single-element mode can be used to transfer one or more unwanted discrete elements to a destination, such as a test substrate or discard. For example, an unwanted discrete element can be a discrete element having a circuit that fails a test. The multi-element mode can then be used to transfer one or more of the remaining discrete elements to the target substrate. In some examples, after the multi-element mode transfer of one or more of the remaining discrete elements to the target substrate, the single-element mode can be used again to transfer additional discrete elements to the location of a missing discrete element on the target substrate (e.g., because the discrete element at that location has been removed as unwanted, was initially missing from the source substrate, or for another reason). For example, the single-element mode can be used to transfer discrete elements that were not transferred during the multi-element transfer, such as discrete elements from the circumferential region of the wafer. The ability to transfer discrete elements in the single-element mode can help increase the yield, for example, by enabling the transfer of discrete elements (such as elements near the edge of the wafer, which can be difficult to include in a group of simultaneously transferred discrete elements). In some instances, non-desired discrete components can be identified based on a wafer map indicating the characteristics of each of one or more of the discrete components on a carrier substrate. In some instances, a wafer map can be generated based on testing prior to the discrete components being adhered to the carrier substrate. For example, the wafer map can be generated based on testing of each discrete component after manufacture, and the non-desired discrete components can be those components having circuitry that fails a post-manufacture test. Testing can include electrical testing of the circuitry of the discrete component, optical testing of the optical output of an LED discrete component, or other types of testing (e.g., testing the functionality of a sensor on the discrete component or the operation of a microelectromechanical (MEMS) device on the discrete component). In some instances, a wafer map can be generated based on in-situ testing of the discrete components on the carrier substrate. For example, when the discrete component is an optoelectronic device, a photoluminescence (PL) test can be performed, where low-power laser energy is used to excite each discrete component and the optical response after relaxation to the ground state is detected. The optical response can be used to characterize the component. FIGS. 5A-5C and 6A-6C illustrate examples of this multi-transfer process, which we sometimes refer to as a "good die only" transfer process. Specifically referring to FIG. 5A, discrete components 550 arranged in an array are adhered to a carrier substrate 552 by a dynamic release layer. A map indicates the characteristics of each of one or more of the discrete components 550 in the array. For example, the map can indicate the results of post-manufacture testing, quality control testing, or in-situ testing (e.g., as described above), and can indicate whether each discrete component passed the test or failed the test. Discrete components that pass the test (e.g., discrete components that meet quality criteria) are sometimes referred to as "good die" and discrete components that fail the test (e.g., components that do not meet quality criteria) are sometimes referred to as "bad die". In the example map of FIG. 5A, the bad die (e.g., discrete component 550a) is shaded dark gray and the good die (e.g., discrete component 550b) is shaded light gray. In a first transfer step, the bad die are transferred in a single-component mode to a destination, such as a test substrate or discarded. Referring to FIG. 5B, after the bad die have been transferred in a single-component mode transfer, there are empty positions in the array on the carrier substrate 552 where each of the bad die was initially located. For example, the empty position 554 in the array corresponds to the position of the bad die 550a. At least a portion of the remaining discrete components, which are good die, are transferred in a second multi-component transfer step to a target substrate 556, thus forming a second array of transferred discrete components 550' on the target substrate. The transfer field 558 can define an area of a desired size, an area surrounding a desired number of array positions, or an area surrounding a desired number of discrete components on the carrier substrate 552. The multi-component transfer process can transfer only some or all of those discrete components enclosed within the transfer field 558. Any discrete components outside the transfer field 558 are not transferred to the target substrate 556 and remain on the carrier substrate 552 as remaining discrete components 560. In the example of FIG. 5B, the transfer field 558 is sized to surround a 10×10 array, and the multi-component transfer process transfers all of the discrete components enclosed within the transfer field. The array of transferred discrete components 550' on the target substrate 556 is thus a 10×10 array of discrete components (and empty positions, if any), with the relative positioning of the remaining discrete components and empty positions retained. The transfer field can be sized based on the desired size or number of discrete components for a downstream application, such as a light-emitting diode (LED)-based display. Referring to FIG. 5C, in some examples, the empty positions in the array of transferred discrete components 550' on the target substrate are filled by a third transfer step. In the third transfer step, each of one or more of the remaining discrete components 560 (e.g., the remaining good discrete components) is transferred to one of the empty positions (e.g., referring to FIG. 5B, the empty position 554') on the target substrate 556 in a single-component mode transfer process. In some examples, for instance, if there are not enough discrete components remaining on the carrier substrate 552 or if different types of discrete components are needed, the empty positions can be filled by transferring discrete components from a different carrier substrate. Upon completion of the third transfer process, the array of transferred discrete components 550' on the target substrate 556 is a complete array of good discrete components with no empty positions. Referring to FIGS. 6A-6C, in some examples, only the good die transfer process transfers a specified pattern of discrete components from the carrier substrate to the target substrate. Specifically referring to FIG. 6A, discrete components 580 configured in an array are adhered to the carrier substrate 582 by a dynamic release layer. A map of the characteristics of the discrete components 580 indicates dark gray bad die (e.g., discrete component 580a) and light gray good die (e.g., discrete component 580b). In the first transfer step, the bad die are transferred to a destination, such as a test substrate or discarded, in a single-component mode. Referring to FIG. 6B, after the defective die has been transferred in the single die mode transfer, there are empty positions in the array on the carrier substrate 582 where each defective die was initially positioned. The pattern of the remaining discrete components, which are good dies, is transferred to the target substrate 586 in a second plurality of die transfer steps, thereby forming a second transfer array of transferred discrete components 580' on the target substrate. For example, the pattern of discrete components enclosed within the transfer field 588 can be transferred. In the example of FIG. 6B, discrete components are transferred at every other position in the array on the carrier substrate 582; if there is an empty position at one of these positions, that empty position also remains in the transfer array. Referring to FIG. 6C, in some examples, the empty positions in the array of transferred discrete components 580' on the target substrate are filled by a third transfer step (e.g., by transferring the remaining discrete components from the carrier substrate 582 or from another carrier substrate). In some examples, the third transfer step is not performed and the empty positions in the array of transferred discrete components are retained when the target substrate is provided to a downstream application. For example, if the density of the discrete components in the array is sufficient, the third transfer step can be eliminated and a small number of empty positions will not substantially affect the performance of the array in the downstream application. In some examples, the third transfer step is optional and can be implemented based on whether the array of transferred discrete components meets (or does not meet) a quality characteristic. For example, the third transfer step can be performed when there are more than a threshold number or percentage of empty positions, or when a threshold number of empty positions are adjacent to other empty positions. Referring to FIG. 7, only the good die processes (such as the processes shown in FIGS. 5A to 5C and FIGS. 6A to 6C) can be implemented on a transfer device 750 capable of switching between a multi-die mode and a single-die mode. For example, the transfer device 750 can include an automated optical device changer 752 that, depending on the type of transfer process (e.g., multi-die mode or single-die mode), enables various optical systems 754a, 754b, 754c to move into alignment with the laser 753. In one example, the optical system 754a can be a single beam system and the optical systems 754b, 754c can be multi-beam systems with different beam configurations. Other configurations of the optical systems are also possible. In some examples, the transfer device 750 can include a plurality of optical devices in the path of the laser beam or the small beam, and the automated optical device changer 752 can move one of the plurality of optical devices into or out of the path. The transfer device can include a scanning mechanism (not shown in the figure) that can scan the laser beam or the small beam output from each optical system across the entire surface of the carrier substrate 758 to transfer one or more discrete components 760. The device can be a computer controlled by one or more local or remote computers or controllers 762, enabling the end-to-end multi-transfer process to be automated. For example, the controller can control the alignment of the laser beam or small beam with each discrete component transferred in the first single-component mode transfer. The controller can control the alignment of the laser beam or small beam with the discrete components to be transferred in the second multi-component transfer. The controller can control the alignment of the laser beam or small beam with each of the remaining discrete components to be transferred in the third transfer in the single-component mode, and can control the alignment of the carrier substrate with the target substrate during the third transfer in the single-component mode. The device can include a stimulus application device 764 configured to output a stimulus (such as ultraviolet light or heat) to be applied to the carrier substrate, for example, to reduce the adhesion of the dynamic release layer. The transfer device can include a target substrate holder 766 for holding the target substrate. In some examples, the target substrate holder 766 can hold multiple target substrates. In some examples, such as in the exemplary device 750 of FIG. 7, the target substrate holder 766 can hold a single target substrate 768' in place to receive the discrete components transferred from the carrier substrate 758. The transfer rack 770 configured to hold one or more target substrates 768 can be controlled by the controller 772 to move individual target substrates from the transfer rack 770 to the target substrate holder 766. As an example, a first target substrate can be held by the target substrate holder 766 to receive the first transfer (e.g., defective die) from the carrier substrate 758. A second target substrate can then be transferred from the transfer rack 770 into the target substrate holder 766 to receive the second transfer (e.g., good die) from the carrier substrate 758. The transfer device can include a carrier substrate holder 774 for holding the carrier substrate 758. In some examples, the carrier substrate holder 774 can hold multiple carrier substrates. In some examples, such as in the exemplary device 750 of FIG. 7, the carrier substrate holder 774 can hold a single carrier substrate. In some examples, a transfer rack (not shown in the figure) configured to hold one or more carrier substrates can be controlled to move individual substrates from the transfer rack to the carrier substrate holder 774. Referring to FIG. 8, in some examples, a single-component mode or a multi-component mode can be used to sort discrete components 600 held on a carrier substrate 602 by one or more characteristics of the discrete components. For example, when the discrete component is an LED, the characteristics can be emission wavelength, quantum output, turn-on voltage, light intensity, voltage-current characteristics, or another characteristic, or any combination of two or more of them. The characteristics can be indicated in a map indicating the characteristics of each of one or more of the discrete components to be held on the carrier substrate 602. In the sorting process, each set of discrete components sharing a common characteristic or combination of characteristics is transferred to a corresponding target substrate, resulting in a set of target substrates, each target substrate having a set of discrete components sharing a common characteristic (e.g., a characteristic falling within a common range) or combination of characteristics. The discrete components sharing a common characteristic or combination of characteristics can be transferred individually in the single-component mode or simultaneously in the multi-component mode. The transfer device 750 of FIG. 7 can be used to sort discrete components by the characteristics of the discrete components. In some examples, the target substrate holder 766 can hold multiple target substrates, and discrete components from a single carrier substrate 758 can be transferred to respective target substrates held in the target substrate holder 766 based on the characteristics of the discrete components. In some examples, the target substrate holder 766 can hold a single target substrate. A first set of discrete components sharing a common characteristic or combination of characteristics from the carrier substrate 758 can be transferred to a first target substrate held in the target substrate holder 766. A second target substrate can then be transferred into the target substrate holder 766 and a second set of discrete components having a different common characteristic or combination of characteristics can be transferred to the second target substrate. In the example of FIG. 8, discrete components 604 (e.g., LEDs having an emission wavelength in a first range) sharing a first characteristic are transferred from the carrier substrate 602 to a first target substrate 606 in a first multi-component mode transfer. Discrete components 608 (e.g., LEDs having an emission wavelength in a second range) sharing a second characteristic are transferred from the carrier substrate 602 to a second target substrate 610 in a second multi-component mode transfer. Discrete components 612 (e.g., LEDs having an emission wavelength in a third range) sharing a third characteristic are transferred from the carrier substrate 602 to a third target substrate 614 in a third multi-component mode transfer. Although three target substrates are shown in FIG. 8, the sorting process can transfer sets of discrete components to any number of target substrates. Referring to FIG. 9, in an example process for transferring discrete components, the singulated discrete components are provided on a temporary substrate such as a dicing tape; or on a donor substrate (700) such as a wafer (e.g., a silicon wafer or a sapphire wafer). For example, a wafer can be adhered to a dicing tape and diced into discrete components. Before adhering the wafer to the dicing tape, the wafer can be thinned, for example, to a thickness of about 50 microns. Further description of dicing a wafer into discrete components is provided in PCT Application No. PCT / US2017 / 013216, filed on January 12, 2017, the content of which is incorporated herein by reference in its entirety. The singulated discrete components are transferred from the temporary substrate to a transparent carrier substrate (702) having a dynamic release layer disposed thereon. In some examples, the carrier substrate can be provided with a dynamic release layer that has already been applied. In some examples, the dynamic release layer is applied to the carrier substrate. The carrier substrate is formed of a material such as glass or a transparent polymer that at least partially transmits at least some wavelengths of the ultraviolet, visible, or infrared electromagnetic spectrum, including the wavelengths used during subsequent laser-assisted transfer processes. In some examples, the components of the singulated wafer are transferred directly to the carrier substrate without using a temporary substrate. For example, direct transfer of singulated components can be used to transfer an epitaxial layer thick micro-LED from a growth substrate to a carrier substrate using a laser lift-off process. In some examples, the singulated discrete components are transferred to the carrier substrate in a good die only transfer process, where "bad dies" are first removed from the temporary substrate and the remaining "good dies" are then transferred to the carrier substrate. The discrete components are transferred from the temporary substrate to the carrier substrate by contacting the discrete components on the temporary substrate with the dynamic release layer on the carrier substrate. In some examples, when the temporary substrate is a dicing tape, the dicing tape can be formed of a material that experiences a decrease in adhesion in response to a stimulus such as heat or ultraviolet light. When the dicing tape is exposed to the stimulus, the adhesion of the dicing tape decreases, thereby facilitating the transfer of the discrete components to the carrier substrate. Further description of transferring discrete components onto a carrier substrate is provided in PCT Application No. PCT / US2017 / 013216, filed on January 12, 2017, the content of which is incorporated herein by reference in its entirety. In some examples, the discrete components can be transferred to the carrier substrate, for example, as an entire or partial wafer, before dicing. For example, a wafer or a partial wafer can be mounted on the carrier substrate and then the wafer can be diced into discrete components. In some examples, the wafer can be partially diced before being transferred to the carrier substrate and the dicing can be completed after being transferred to the carrier substrate. In some examples, the dynamic release layer can be a material with controllable adhesion, such as a material with adhesion that can be reduced after exposure to a stimulus (such as heat, ultraviolet light, or another stimulus). When the discrete element is transferred to the carrier substrate, the highly adhesive dynamic release layer facilitates the transfer and helps to secure the discrete element onto the carrier substrate. However, the less adhesive dynamic release layer can facilitate the subsequent laser-assisted transfer of the discrete element to the target substrate. Accordingly, in some examples, after the discrete element has been transferred to the carrier substrate, the adhesion of the dynamic release layer is reduced (704), for example, by exposing the dynamic release layer to a stimulus (such as heat or ultraviolet light). The reduced adhesion promotes the reduced adhesion for the entire dynamic release layer and facilitates the subsequent laser-assisted transfer. The reduction of adhesion is optional, as indicated by the dashed boundary in FIG. 8. For example, in an ablation laser-assisted transfer process, the reduction of adhesion is typically not performed. A further description of the dynamic release layer with controllable adhesion is provided in PCT application No. PCT / US2017 / 013216, filed on January 12, 2017, the content of which is incorporated herein by reference in its entirety. In some examples, in a sorting process, the discrete elements are transferred from the carrier substrate to multiple target substrates in multiple laser-assisted transfer processes (706). For example, the discrete elements can be transferred to the target substrates based on the characteristics of the discrete elements, thereby sorting the discrete elements by those characteristics. The result of the sorting process is a set of target substrates, each target substrate having a set of discrete elements that share a common characteristic. In some examples, each target substrate can have a die capture material disposed thereon. The die capture material (DCM) can be a material that接纳the discrete element when it is transferred from the carrier substrate and holds it in its target position when reducing the post-transfer movement of the discrete element on the target substrate. The DCM can be selected based on characteristics such as surface tension, viscosity, and rheology. For example, the DCM can provide viscous drag force to prevent the movement of the discrete element, or can prevent the movement of the discrete element by another externally applied force (such as electrostatic force, magnetic force, mechanical force, or any combination of two or more of them). It should be noted that there is an unclear word "接纳" in the original Chinese text which is translated as "接纳" here. You may need to check and correct it according to the actual situation.In some instances, the target substrate is provided with a die capture material that has already been applied. In some instances, DCM is applied to the target substrate before transferring the discrete components. The DCM can be applied as a continuous film using a film deposition method such as spin coating, dip coating, line coating, knife over roll, or another film deposition method, for example having a thickness between about 3 microns and about 20 microns. Alternatively, the DCM can be applied as a discrete patterned film, for example, in the locations where the discrete components will be placed. The patterned DCM film can be formed by a material printing technique such as stencil printing, screen printing, spraying, inkjet printing, or other techniques. The patterned DCM film can also be formed by pre-treating the target substrate with a pattern of a material that attracts DCM, a material that repels DCM, or both, and then depositing the DCM using a continuous film deposition method (resulting in DCM in the areas with DCM attracting material (or in the areas without DCM repelling material)). For example, the target substrate can be patterned with a hydrophilic material, a hydrophobic material, or both. In some instances, the discrete components on each target substrate are transferred to a corresponding second substrate, such as a tape (708). Since the discrete components are sorted by characteristics during transfer to the target substrate, each tape will thus also receive discrete components sharing a common characteristic. The tape can be provided for downstream applications, such as to a final product manufacturer. The transfer of the discrete components to the second substrate can be a contact transfer. When the target substrate includes a die capture material layer having a controllable adhesion, the attachment device can be exposed to a stimulus to reduce the adhesion, thereby facilitating the transfer of the discrete components. In some instances, the discrete components are transferred to a device substrate (710) in a laser-assisted transfer process. The transfer of the discrete components to the device substrate can include only the good die transfer process as described above, where the bad dies are first transferred from the carrier substrate to discard, and then an array of good dies is transferred from the carrier substrate to the device substrate simultaneously. In some instances, the device substrate can have conductive attachment devices disposed thereon to effect die capture and interconnection. The attachment device cures in response to an applied stimulus (such as a material that can be thermally cured, cured after exposure to ultraviolet light, or cured in response to another type of stimulus, or a combination of any two or more of them). In some instances, the device substrate is provided with attachment devices that have already been applied. In some instances, the attachment devices are applied to the target substrate before the discrete components are transferred. In some instances, the device substrate can have attachment devices disposed thereon that act as a flux during soldering, and the die capture material is activated by heating to facilitate soldering as a process for interconnection of the discrete components. A further description of the attachment device is provided in PCT application No. PCT / US2017 / 013216 filed on January 12, 2017, the content of which is incorporated herein by reference in its entirety. Discrete components are bonded to a device substrate (712). For example, an attachment device can be cured, for example, by exposure to a stimulus such as heat, ultraviolet light, or another stimulus, or any combination of two or more of them, thereby increasing the adhesion of the attachment device. The stimulus can be removed after a time sufficient to allow the attachment device to cure, thus forming a mechanical bond, an electrical bond, or both between the device substrate and the discrete component. Further description of bonding discrete components to a device substrate is provided in PCT application No. PCT / US2017 / 013216 filed on January 12, 2017, the content of which is incorporated herein by reference in its entirety. The discrete components are interconnected (714) with the device substrate to establish an electrical connection between the circuit elements on the discrete components and the circuit elements on the device substrate. In some examples, the discrete components are interconnected with the device substrate in a face-up orientation, where the active face of the discrete component faces away from the device substrate. The active face of the discrete component is the surface on which the circuit of the discrete component is formed. For face-up discrete components, the interconnection can include wire bonding, coplanar printing (where a conductive material is printed on the active faces of the device substrate and the discrete component), direct write material deposition, thin film lithography, or other interconnection methods. In some examples, the discrete components are interconnected with the device substrate in a face-down orientation (sometimes referred to as "flip chip"), where the active face of the discrete component faces the device substrate. Flip chip interconnection can include adhesive bonding, soldering, thermocompression bonding, ultrasonic bonding, or other flip chip interconnection methods. Referring to FIG. 10, in an example process 800 for transferring discrete components such as micro LEDs, the singulated discrete components are provided on a substrate (802), such as a wafer, for example, a sapphire wafer. In some examples, the discrete components are transferred to an intermediate substrate (804), for example, by contacting the discrete components on the donor substrate with the intermediate substrate. For example, the intermediate substrate can be used in cases where the discrete components will be flipped (i.e., rotated 180°) for a final downstream application. The intermediate substrate can sometimes also improve metrics associated with the transfer process, such as yield, accuracy, or another metric. The discrete components are then transferred from the intermediate substrate to a transparent carrier substrate having a dynamic release layer disposed thereon (806). In some instances, no intermediate substrate is used and the discrete components are transferred directly from the donor substrate to the transparent carrier substrate. In this case, aspect 804 of the transfer process is skipped and aspect 806 of the transfer process is the direct transfer of the discrete components from the donor substrate to the transparent carrier substrate. The transfer of discrete components from a substrate (such as a sapphire wafer) to an intermediate substrate or a carrier substrate can be performed by a laser lift-off process. In the laser lift-off process, the active (functional) layer of the component is separated from the substrate by changing the material composition at the interface layer between the functional layer and the substrate. For example, in the laser lift-off process of GaN micro-LEDs epitaxially grown on a sapphire substrate, a laser (such as an ultraviolet laser) is focused on the interface between the GaN layer of the micro-LED and the sapphire substrate. The high temperature in the area where the laser is focused causes a thin (such as less than 1 μm thick) layer of GaN to decompose into gallium and nitrogen gas. The melting point of gallium is extremely low (about 30 °C), which enables the functional GaN layer of the micro-LED to be easily removed by the molten gallium layer. The adhesion of the dynamic release layer is reduced (808) by applying a stimulus such as heat, ultraviolet light, or another type of stimulus. Then, the discrete components are transferred to the device substrate (810) using a laser-assisted transfer process. In the example of FIG. 10, the discrete components are shown to be transferred individually in a single-component mode. In some instances, multiple discrete components can be transferred simultaneously in a multi-component mode. In some instances, the discrete component transfer includes only a good die process, where the bad dies are removed from the carrier substrate in a first transfer process and the good dies are then transferred to the device substrate in a second transfer process. The discrete components on the device substrate are bonded to the device substrate and interconnected to the circuit components on the device substrate (812). The method described above for large-scale parallel laser-assisted transfer of multiple discrete components can be used to assemble micro-LEDs for use in micro-LED-based devices such as displays, such as a TV screen or a computer monitor; or solid-state lighting devices. A micro-LED-based device includes an array of micro-LEDs, with each micro-LED forming an individual pixel or sub-pixel device. In some instances, color can be achieved by using micro-LEDs that emit different wavelengths. In some instances, color can be achieved by using micro-LEDs in combination with spectral-shifting materials (such as organic dyes, phosphors, quantum dots) or by using color filters. By a micro-LED, we mean an LED having at least one lateral dimension of at most 100 micrometers. By a spectral shift material, we mean a material that emits light at a second wavelength (sometimes referred to as the emission wavelength) different from the excitation wavelength upon optical excitation at a first wavelength (sometimes referred to as the excitation wavelength). When the spectral shift material is implemented by a color filter, the color of the spectral shift material is the color corresponding to the wavelength of the light emitted by the spectral shift material. When the spectral shift material is implemented by quantum dots, the color of the spectral shift material depends on the size of the quantum dots. When the spectral shift material is implemented by an organic dye or a phosphor, the color of the spectral shift material depends on the composition of the dye or the phosphor. Referring to FIGS. 11A and 11B, the micro-LED device 500 includes a substrate 502 having an array of cavities 504 formed in the top surface of the substrate 502. Each cavity 504 corresponds to a sub-pixel of the device 500. The cavities 504 can be formed by imprinting, lithography, or another manufacturing method. The spectral shift material 506 is disposed in at least some of the cavities 504. The color of the spectral shift material 506 can vary in the entire array of cavities 504, for example, column by column, row by row, in another pattern, or randomly. In the examples of FIGS. 11A and 11B, the color of the spectral shift material 506 varies by row of the array of cavities 504 such that the first row 508a has red spectral shift material in its cavities 504, the second row 508b has green spectral shift material in its cavities 504, and the third row 508c has blue spectral shift material in its cavities. The substrate 502 can be made of a material that transmits the color of the spectral shift material. For example, the substrate 502 can be glass or a transparent polymer. The micro-LEDs 510 are placed in each cavity 504 of the substrate 502. For example, the micro-LEDs 510 can be placed in the cavities 504 using the method described above for large-scale parallel laser-assisted transfer of multiple discrete components. The micro-LEDs 510 are placed in the cavities 504 having the spectral shift material 506 surrounding the light-emitting surface and the side surfaces of the micro-LEDs 510. The micro-LEDs 510 emit light of a wavelength that can excite the spectral shift material 506 to emit light. For example, the micro-LEDs can emit ultraviolet light. In the examples of FIGS. 11A and 11B, the micro-LED 510 is controlled by a passive matrix in which the electrical contacts 512 on opposite sides of the micro-LED 510 are exposed towards the top surface 514 of the substrate 502. The column electrodes 516 and the row electrodes 518 are connected to the electrical contacts 512 of the micro-LED 510, providing a way to individually address each micro-LED 510 to excite a given pixel or sub-pixel of the spectral shift material 506. A planarization layer 520 is formed above the top surface 514. The planarization layer 520 may transmit or not transmit light from the spectral shift material 506. In some examples, the micro-LEDs are controlled by active matrix technology in which each micro-LED is individually controlled using electronic components such as thin film transistors and capacitors. The transparent substrate transmits the light emitted by the spectral shift material but absorbs the light emitted by the micro-LED. The planarization layer may transmit or not transmit the light emitted by the spectral shift material. In some examples, the walls of the substrate 502 between the cavities 504 absorb the light emitted by the micro-LED 510, thereby preventing the light from one micro-LED from exciting the spectral shift material 506 in different cavities 504 and thus reducing or eliminating crosstalk and color contamination between adjacent sub-pixels. The presence of the spectral shift material 506 surrounding the light-emitting and side surfaces of the micro-LED 510 may also help to reduce or eliminate crosstalk and color contamination. In some examples, the walls of the substrate 502 between the cavities 504 may be metallized to reduce or eliminate crosstalk, to improve the quantum efficiency by reflecting light that might otherwise have been lost by absorption by the walls, and to improve the directionality of the emitted light. The micro-LED 510 can be assembled into the device 500 using the methods described above for large-scale parallel laser-assisted transfer of multiple discrete components. Using these methods, the micro-LED 510 can be assembled quickly, enabling high-throughput manufacturing. For example, assembling the micro-LEDs into a full HD display using the methods described above would take less than about ten minutes, such as about 1 minute, about 2 minutes, about 4 minutes, about 6 minutes, about 8 minutes, or about 10 minutes. In contrast, individually transferring each micro-LED to assemble the same display using modern conventional methods would take one or more hours of a much longer magnitude, such as about 100 hours, about 200 hours, about 400 hours, about 600 hours, or about 800 hours. In some instances, the methods described herein for simultaneously transferring multiple discrete components can be used to assemble other devices, such as micro solar cells or microelectromechanical (MEMS) devices. For example, to assemble the components of a MEMS mirror, the pattern of a small beam of laser energy can be dynamically changed according to the specifications of the mirror. Another example is the heterogeneous integration of system-on-chip (SoC) or system-in-package (SIP) components, where a large number of chiplets need to be transferred to an interposer substrate, where the large number of chiplets are brought together to form the SoC / SiP component. Numerous embodiments of the invention have been described. Nevertheless, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. For example, some of the steps described above can be independently sequenced and thus can be performed in an order different from the order described. Other implementations are also within the scope of the following claims. 10: Back side 12: Discrete component 16: Carrier substrate 22: Dynamic release layer 24: Laser beam 26: Convex bubble 28: Target substrate 32: Active surface 112: Discrete component 116: Carrier substrate 122: Dynamic release layer 124: Laser beam 126: Convex bubble 128: Target substrate 140a: Small beam 140b: Small beam 140c: Small beam 142: Optical device 322: Dynamic release layer 324: Laser beam 326: Multi - small - beam pattern 326a: Small beam 326b: Small beam 326c: Small beam 326d: Small beam 342: Optical device 422: Dynamic release layer 424: Laser beam 426: Multi - small - beam pattern 428: First optical device 430: Second optical device 432: Group 432a: Group 432b: Group 432c: Group 500: Micro - LED device 502: Substrate 504: Cavity 506: Spectrum - shifting material 508a: First row 508b: Second row 508c: Third row 510: Micro - LED 512: Electrical contact 514: Top surface 516: Column electrode 518: Row electrode 520: Planarization layer 550: Discrete component 550a: Discrete component 550b: Discrete component 550': Transferred discrete component 552: Carrier substrate 554: Empty position 554': Empty position 556: Target substrate 558: Transfer field 560: Remaining discrete component 580: Discrete component 580': Transferred discrete component 580a: Discrete component 580b: Discrete component 582: Carrier substrate 586: Target substrate 588: Transfer field 600: Discrete component 602: Carrier substrate 604: Discrete component 606: First target substrate 608: Discrete component 610: Second target substrate 612: Discrete component 614: Third target substrate 750: Transfer equipment 752: Automated optical device converter 753: Laser 754a: Optical system 754b: Optical system 754c: Optical system 758: Carrier substrate 760: Discrete component 762: Local or remote computer or controller 764: Stimulus application device 766: Target substrate holder 768: Target substrate 768': Target substrate 770: Transfer rack 772: Controller 774: Carrier substrate holder 800: Process Figures 1A and 1B are diagrams of a laser - assisted transfer process. Figures 2A through 2C are diagrams of a laser - assisted transfer process. Figure 3 is a diagram of a laser - assisted transfer process. Figure 4 is a diagram of a laser - assisted transfer process. Figures 5A through 5C are diagrams of a process for transferring only good grains. Figures 6A to 6C are diagrams of only the good grain transfer process. Figure 7 is a diagram of the equipment. Figure 8 is a diagram of the component sorting process. Figure 9 is a flowchart. Figure 10 is a diagram of the laser-assisted transfer process. Figures 11A and 11B are diagrams of a micro light-emitting diode (LED) device. 112: discrete component 116: carrier substrate 122: dynamic release layer 124: laser beam 126: convex bubble 128: target substrate 140a: small beam 140b: small beam 140c: small beam 142: optical device

Claims

1. A transfer apparatus for transferring a plurality of discrete elements from a first substrate, comprising: a substrate holder configured to receive the first substrate, the discrete elements being adhered to the first substrate via a dynamic release layer; a laser energy source configured for a laser-assisted transfer process to transfer a first set of the discrete elements from the first substrate to a second substrate; and at least one optical system configured to split a laser beam from the laser energy source into a plurality of beamlets, wherein the transfer apparatus is further configured to irradiate a plurality of regions of at least one of the discrete elements using the beamlets, and wherein the beamlets are oriented to incident on the dynamic release layer aligned with a plurality of corners of the at least one discrete element.

2. The transfer device of claim 1 further includes another substrate holder that holds the second substrate, the second substrate being a target substrate.

3. The transfer device as claimed in claim 1, wherein the first set of such discrete elements shares a first common characteristic.

4. The transfer device as claimed in claim 3, wherein the first common characteristic includes one or more of an optical characteristic and an electrical characteristic.

5. The transfer equipment as requested in item 3, wherein the first common characteristic is a quality criterion.

6. The transfer device of claim 1, wherein the transfer device is further configured to transfer a second set of the discrete elements, wherein the second set of the discrete elements shares a second common characteristic.

7. The transfer device as claimed in claim 6, wherein the transfer device is further configured to individually transfer each discrete element in the second set of such discrete elements.

8. A method for transferring a plurality of discrete elements from a first substrate, comprising: simultaneously irradiating a plurality of regions on a dynamic release layer, the dynamic release layer adhering the discrete elements to the first substrate, each of the irradiated regions being aligned with a corresponding discrete element; and the irradiation of the regions of the dynamic release layer causing the release of a first set of the discrete elements aligned with the irradiated regions; wherein the irradiation step comprises splitting a laser beam of laser energy into a plurality of smaller beams, and irradiating a plurality of regions of at least one of the discrete elements with the smaller beams, and wherein the smaller beams are oriented to be incident on the dynamic release layer aligned with a plurality of corners of the at least one discrete element.

9. The method of claim 8, wherein the first set of such discrete elements shares a first common characteristic.

10. The method of claim 9, wherein the first common characteristic comprises one or more of an optical characteristic and an electrical characteristic.

11. The method of claim 9, wherein the first common characteristic is a quality criterion.

12. The method of claim 9, further comprising transferring a second set of the discrete elements, wherein the second set of the discrete elements shares a second common characteristic.

13. The method of claim 12, wherein the irradiation causes the individual release of the second set of discrete elements.

14. A transfer apparatus for transferring a plurality of discrete elements from a first substrate, comprising: a substrate holder configured to receive the first substrate, the discrete elements being adhered to the first substrate by a dynamic release layer; a laser energy source configured for a laser-assisted transfer process to: (i) transfer a first set of the discrete elements from the first substrate to a second substrate, wherein the first set of the discrete elements shares a first common characteristic; and (ii) transfer a second set of the discrete elements from the first substrate to a third substrate, wherein the second set of the discrete elements shares a second common characteristic different from the first common characteristic; and at least one optical system configured to split a laser beam from the laser energy source into a plurality of smaller beams, wherein the transfer apparatus is further configured to irradiate a plurality of regions of at least one discrete element with the smaller beams, wherein the smaller beams are oriented to be incident on the dynamic release layer aligned with a plurality of corners of the at least one discrete element.

15. The transfer device of claim 14 further includes another substrate holder that holds one or more of the second substrate and the third substrate, wherein the second substrate is a first target substrate and the third substrate is a second target substrate.

16. The transfer device of claim 14, wherein the first common characteristic includes one or more of an optical characteristic and an electrical characteristic.

17. The transfer device as claimed in claim 14, wherein the first common characteristic is a quality criterion.

18. The transfer device of claim 14, wherein the transfer device is further configured to individually transfer each discrete element of a second set of such discrete elements.

19. A method for transferring a plurality of discrete elements from a first substrate, comprising: using a laser-assisted transfer process to transfer a first set of the discrete elements from the first substrate to a first target substrate, the discrete elements in the first set sharing a first common characteristic, the transfer comprising using at least one optical system configured to split a laser beam from a laser energy source into a plurality of smaller beams to irradiate a plurality of regions of at least one discrete element, wherein the smaller beams are oriented to be incident on a dynamically released layer aligned with a plurality of corners of the at least one discrete element; and transferring a second set of the discrete elements to a second target substrate, the discrete elements in the second set sharing a second common characteristic, the second common characteristic being different from the first common characteristic.

20. The method of claim 19, wherein the first common characteristic comprises one or more of an optical characteristic and an electrical characteristic.

21. The method of claim 19, wherein the first common characteristic is a quality criterion.

22. The method of claim 19, wherein each discrete element of the first set of discrete elements is transferred individually.

23. A transfer apparatus for transferring a plurality of discrete elements from a first substrate, comprising: a substrate holder configured to receive the first substrate, the discrete elements being adhered to the first substrate via a dynamic release layer; and a laser energy source for a laser-assisted transfer process; wherein the laser-assisted transfer process includes splitting a laser beam from the laser energy source into a plurality of smaller beams, wherein the transfer apparatus is further configured to irradiate at least one of the discrete elements with the smaller beams, and wherein the smaller beams are oriented to incident on the dynamic release layer aligned with a plurality of corners of the at least one discrete element.

24. A method for transferring a plurality of discrete elements from a first substrate, comprising: irradiating a region on a dynamic release layer corresponding to a discrete element, the dynamic release layer adhering the plurality of discrete elements to the first substrate; wherein the irradiation comprises: splitting a laser beam of laser energy into a plurality of smaller beams, and irradiating the discrete element with the smaller beams, wherein the smaller beams are oriented to be incident on the dynamic release layer aligned with a plurality of corners of the at least one discrete element.

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