Multi-carrier construction

Abstract

Various methods of constructing multiple cartridges are disclosed. In particular, methods of using an adhesive-based direct build, an adhesive-based simultaneous build, a mechanical direct build, a modular anchoring direct build, and a modular anchoring direct build with color conversion and transferring a micro device from a cartridge to a release layer located on a template are discussed. In addition, the use of an intermediate substrate, alignment, use of a pocket as a template substrate, use of a pocket as a carrier substrate, a method of improving a template is also discussed.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority and the benefit of U.S. Provisional Patent Application No. 63 / 386,262, filed on December 6, 2022, and U.S. Provisional Patent Application No. 63 / 514,951, filed on July 21, 2023, the entire contents of each of which are incorporated herein by reference. Technical field

[0003] The present disclosure relates to different mechanisms for constructing multi - cylinders. Summary of the invention

[0004] The present invention relates to a method for constructing multi - cylinders using adhesive - based direct construction, the method comprising: patterning alignment marks on a highly flat substrate and cutting the flat substrate into a number of template pieces; applying an adhesive to the template; picking up the cylinders face - up using a pick - up head; aligning the back of the cylinder with the top of the template using the alignment marks or cylinder corners present on both surfaces; joining the cylinder to the template; and repeating the last three steps until all desired cylinder positions on the template are filled and the multi - cylinder construction is completed.

[0005] The present invention also relates to a method for constructing multi - cylinders using mechanical direct construction, the method comprising: completing patterning and etching a precision recess into a ceramic template in two patterning and etching steps (one step for the recessed walls and one step for the vacuum holes); placing a stainless - steel compression spring or a V - shaped torsion spring into the recess; and manually or using a fixture loading the cylinders face - up into each recess such that each cylinder is oriented the same as the other cylinders and is tensioned against the recessed walls.

[0006] The present invention also relates to a method for constructing multi - cylinders using adhesive - based simultaneous construction, the method comprising: patterning alignment marks on a highly flat substrate; patterning adhesive bumps on a highly flat temporary bonding substrate to selectively transfer micro - LEDs from the cylinders; holding the temporary bonding substrate to a tool carrier; picking up the cylinders face - down using a pick - up head; aligning the top of the cylinder with the adhesive bumps on the substrate using fiducials or other features (e.g., cylinder corners) present on both surfaces; joining the cylinder to the substrate; and repeating the last three steps until all desired cylinder positions on the substrate are filled.

[0007] The present invention also relates to a method for constructing a multi-cartridge using modular anchor-based direct construction, the method comprising: patterning a sacrificial layer on a template, the sacrificial layer having openings for anchor points in a structural layer; having alignment marks to allow integration into a pick-and-place tool; depositing a structural layer anchored to the template substrate and then patterning the structural layer to allow tuning of mechanical breakage during micro-device printing; cutting the template into a number of template pieces; patterning adhesive bumps on top of the structural layer to transfer all micro-devices from the cartridge to the template; vacuum-adsorbing the template pieces onto a pick-and-place tool stage; picking up the cartridge face-down using a vacuum pick-up head; aligning the top of the cartridge with the adhesive bumps on the template using fiducials or cartridge corners present on both surfaces; bonding the cartridge to the template such that only the pick-up head applies heat to prevent curing of the adhesive of the entire template; and repeating the last three steps until all desired cartridge positions on the template are filled, thereby producing a multi-cartridge.

[0008] The present invention also relates to a method for constructing a multi-cartridge, the method comprising: forming a release layer on a template, the release layer having openings for anchor points in a diaphragm layer; forming fiducials to improve alignment accuracy during integration of micro-devices into the template; depositing a diaphragm layer anchored to the template substrate; and then patterning the diaphragm layer into individual diaphragms associated with each micro-device, thereby allowing individual micro-devices to be spaced apart from the template during the transfer process, wherein the template substrate comprises more than one template piece and will be separated into a number of template pieces by mechanical cutting or laser cutting; patterning bonding pads / bumps on top of the diaphragm layer to transfer all micro-devices from the cartridge to the template; aligning a donor substrate with the fixed micro-devices, the fixed micro-devices facing the template bonding pads in the positions in the template, wherein the devices are fixed to the donor substrate by different means such as adhesives or mechanical release layers, and wherein further, the micro-devices of the donor are bonded to the template; and repeating the last three steps until all desired positions on the template are filled, thereby producing a multi-cartridge.

[0009] The present invention also relates to a method of constructing a multi-tube using color conversion-based adhesive direct construction, the method comprising: forming a release layer on the template, the release layer having openings for anchors in the diaphragm layer; forming fiducials to improve alignment accuracy during integration of the micro-devices into the template; depositing a diaphragm layer anchored to the template substrate; and then patterning the diaphragm layer into individual diaphragms associated with each micro-device to allow the individual micro-devices to be spaced apart from the template during the transfer process, wherein the template substrate comprises more than one template piece; integrating a functional layer on top of the diaphragm, wherein the functional layer comprises one or more of a passivation layer, a color conversion layer, and a color filter; patterning bonding pads on top of the diaphragm structure layer to transfer the micro-devices from a donor substrate to the template; integrating the micro-devices into the bonding pads of the template by aligning the donor substrate with the regions of the template; bonding a selected set of micro-devices into the bonding pads; and repeating the process until all selected regions of the template are filled with micro-devices.

[0010] The present invention also relates to a method of loading micro-devices into a tube, the method comprising: loading the micro-devices from a donor substrate into the tube, wherein the process comprises: forming a release layer on the substrate; forming a diaphragm on the release layer, wherein the diaphragm is connected to the substrate through an opening in the release layer; and bonding the micro-devices to the diaphragm through an adhesive layer or a bonding layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In this specification, the terms "micro-LED" and "micro-device" may be used interchangeably.

[0012] The foregoing and other advantages of the present disclosure will become apparent by reading the following detailed description and referring to the accompanying drawings:

[0013] Figure 1 A process flow for inspecting and metering a set of tubes to determine their binning categories is shown.

[0014] Figure 2 How misalignment (low precision) during the multi-tube assembly process can lead to poor alignment of micro-LEDs is described.

[0015] Figure 3 A case of constructing a multi-tube using adhesive-based direct construction is shown.

[0016] Figure 4A and Figure 4B A case of constructing a multi-tube using adhesive-based simultaneous construction is shown.

[0017] Figure 5 An optical alignment process for adhesive-based simultaneous construction is shown.

[0018] Figure 6An adhesive based build utilizing spacer beads is shown.

[0019] Figure 7 A case where mechanical direct construction is used to build a multi-barrel is shown.

[0020] Figure 8A , Figure 8B and Figure 8C A photovoltaic system is shown with a pad on one surface.

[0021] Figure 9 An intermediate substrate including alignment marks and a temporary adhesive layer is shown.

[0022] Figure 10 An intermediate substrate comprising recesses is shown.

[0023] Figure 11 The cartridge is shown placed in a recess and using vibration for accurate placement.

[0024] Figure 12 It is shown that a tool with vacuum holes aligned with the cylinders in the carrier substrate can be used.

[0025] Figure 13A , Figure 13B and Figure 13C A case where mechanical direct construction is used to build a multi-barrel is shown.

[0026] Figure 14 Modular anchored direct construction using color conversion layers is shown.

[0027] Figure 15 , Figure 16 and Figure 17 The same implementation as that of modular anchored direct construction is shown, but the color conversion layer is embedded into the structure layer.

[0028] Although the present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown in the drawings by way of example and will be described in detail herein. However, it should be understood that the present disclosure is not intended to be limited to the specific forms disclosed. On the contrary, the present disclosure will cover all modifications, equivalents and substitutes that fall within the spirit and scope of the present invention defined by the appended claims. DETAILED DESCRIPTION

[0029] Selective transfer and binning of high-quality LED tubes is a highly desired feature for Micro-LED display manufacturers. A more selective binning process requires scaling down the die size, which also scales down the productivity of each die when filling a Micro-LED display.

[0030] The multi-tube is an invention composed of a highly flat template with a number of micro-LED tubes. These micro-LED tubes have been binned through an inspection process to ensure high quality and are fixed to the template. Binning involves classifying the tubes into different categories based on the presence of defects (such as particles or damaged microstructures) and optical properties (such as emission wavelength) for eventual use in appropriate end applications. These categories can be determined through an inspection process that may involve optical image recognition and evaluation by a number of thin film or semiconductor metrology tools.

[0031] The tubes are fixed to the template with high accuracy and precision to ensure that the misalignment of the micro-LEDs during the printing process is below the desired tolerance, which depends on the micro-LED size and the backplane contact size. Since the micro-LED contacts must be aligned with the backplane contacts within the desired tolerance to ensure proper device performance, the precision of the multi-tube assembly process should keep the fixing of the tubes in the 2D space below the desired tolerance. The fiducials (or alignment marks) on both the tubes and the template will allow active alignment according to the assembly process and allow measurement to verify accurate alignment after assembly. Transfer using the multi-tube will double the productivity of the display filling process according to the number of tubes that can be successfully attached to the template.

[0032] The present invention relates to the following aspects: accurately and precisely fixing the tube height to the template (or vice versa) to achieve higher display productivity and limit repairs after display filling, and changing the profile of a number of binned die from a wafer to any arrangement on the template, thus customizing the solution according to the needs of the final micro-LED display.

[0033] Method for constructing multi-tubes

[0034] There are various methods of constructing the multi-tube.

[0035] Grading and inspection

[0036] Figure 1 A process flow for inspecting and metering a set of tubes to determine their binned categories is shown. Tubes in the holder / waffle box that do not meet the specifications of any category (such as those with a significant particle count or device defects) can be scrapped. The remaining tubes are binned and spaced for the desired application. The process starts with a set of tubes from the manufacturing step. Then visual / optical inspection is carried out. Then a metrology step is performed, where the tubes are profiled (by a profiler as an example only) and defective structures are scrapped. After that, the remaining tubes are binned according to various parameters or characteristics of them.

[0037] Expected tolerance

[0038] Figure 2Describes how misalignment (low precision) during the multi-tube assembly process can lead to poor alignment of micro-LEDs during transfer to the backplane. For successful multi-tube assembly, the misalignment between tubes must be below the desired tolerance to ensure device functionality after transfer.

[0039] Direct construction based on adhesive

[0040] Figure 3 Shows the case of building multi-tubes based on adhesive-based direct construction. This specific implementation involves the active alignment of the backside of the tubes with the top surface of the template (receptor substrate). The template is coated with an adhesive so that the tubes are fixed (bonded) to its surface once placed. The misalignment in this process mainly stems from the placement accuracy of the pick-and-place die bonding tool used.

[0041] A typical process for adhesive-based direct construction can be as follows:

[0042] 1. Pattern alignment marks on a highly flat substrate and cut the flat substrate into several template pieces.

[0043] 2. Apply a thermally curable adhesive to the template by spin coating, spraying, dip coating, or bar coating.

[0044] 3. Vacuum adsorb the template to the pick-and-place tool stage.

[0045] 4. Pick up the tubes face up using a vacuum bonding head.

[0046] 5. Align the back of the tubes with the top of the template using fiducials (alignment marks) or other features (e.g., tube corners) present on both surfaces.

[0047] 6. Bond the tubes to the template such that only the bonding head applies heat to prevent curing of the adhesive across the entire template.

[0048] 7. Repeat steps 4 to 6 until all desired tube positions on the template are filled and the multi-tube construction is complete.

[0049] Some possible advantages of the adhesive-based direct construction method are a lower degree of misalignment, which can be actively corrected by the bonding tool.

[0050] On the other hand, the disadvantages of adhesive-based direct construction may include: fiducial or feature detection of the active area via an optical camera may be challenging within the thickness of the barrel (deformation, refraction, etc.), corner detection on the back side of the barrel may be sufficient, but testing is required. Sensitive features on the surface of the micro-LEDs may be damaged due to direct contact with the bonding head, and the exclusion area can be avoided by including a custom recess in the bonding head. A protective coating can be added to the barrel, but the solvent or etchant required to remove this protection must be compatible with the stencil adhesive. The temperature difference between the bonding head and the tool carrier may cause additional stress or misalignment due to CTE mismatch, and this can be offset by fully cooling the parts during bonding, but this increases the assembly time.

[0051] Simultaneous construction based on adhesive

[0052] Figure 4A and Figure 4B The case of constructing multiple barrels based on adhesive-based simultaneous construction is shown. This specific implementation involves actively aligning the top surface of the barrel with a temporary bonding substrate and placing it onto the temporary bonding substrate. Once all the barrels are placed in the desired positions on the substrate, a stencil coated with adhesive is aligned and simultaneously bonded to the back side of all the barrels. The misalignment in this process mainly stems from the placement accuracy of the pick-and-place die bonding tool used, and is the sum of the misalignments introduced during both the barrel placement step and the stencil bonding step.

[0053] A typical process for adhesive-based simultaneous construction can be as follows:

[0054] 1. Pattern alignment marks on a highly flat substrate and cut the flat substrate into several stencil pieces.

[0055] 2. Pattern adhesive bumps on a highly flat temporary bonding substrate to selectively transfer some but not all of the micro-LEDs from the barrel.

[0056] 3. Vacuum-adsorb the temporary bonding substrate to the pick-and-place tool carrier.

[0057] 4. Pick up the barrel face down using a vacuum bonding head.

[0058] 5. Align the top of the barrel with the adhesive bumps on the substrate using fiducials or other features (e.g., barrel corners) present on both surfaces.

[0059] 6. Bond the barrel to the substrate such that only the bonding head applies heat to prevent the adhesive of the entire substrate from curing.

[0060] 7. Repeat steps 4 to 6 until all the desired barrel positions on the substrate are filled.

[0061] 8. Apply the thermosetting adhesive to the template by spin coating, spraying, dip coating, or bar coating.

[0062] 9. Pick up the template face down using a vacuum chuck.

[0063] 10. Align the template with the top of the temporary substrate using fiducials present on both surfaces.

[0064] 11. Simultaneously bond the template to the back side of all the barrels and remove it from the tool carrier. Transfer some of the micro-LEDs onto the adhesive bumps to complete the multi-barrel.

[0065] This process has many advantages: such as avoiding contact with the sensitive active regions of the barrels, all barrels will have the same misalignment relative to the template, so this misalignment is canceled - leaving only the misalignment caused by bonding the barrels to the temporary substrate, and reducing the CTE mismatch by assembling the multi-barrel with the chuck and tool carrier at the same temperature. On the other hand, additional steps may be required compared to direct construction.

[0066] Figure 5 An optical alignment process for adhesive-based simultaneous construction is shown.

[0067] Adhesive-based construction using spacer beads

[0068] Figure 6 A case of adhesive-based construction using spacer beads is shown. To enhance the x-axis and y-axis alignment achieved in the above embodiments, the z-axis depth can also be controlled by maintaining a consistent bond line thickness on the template adhesive at all barrel positions. Introducing spacer beads composed of dimensionally controllable spherical glass or ceramic particles into the adhesive (the adhesive has the beads before application) allows the bond line thickness of all the barrels fixed to the template to remain uniform. The thickness can be set by the largest bead present under each barrel during bonding. This addition will ensure that all points on the multi-barrel will have a uniform landing during the filling of the micro-LED display, thus reducing defects.

[0069] Mechanical direct construction

[0070] Figure 7 A case of mechanically direct construction to build a multi-barrel is shown. In mechanically direct construction, the template will serve as the temporary substrate because the barrels are not permanently bonded to the template. This embodiment does not involve active alignment and relies on loading the barrels into pre-defined depressions on the template (temporary substrate). To hold the barrels in place against the depression walls, thin springs can be used to tension the barrels. Vacuum holes located on the bottom surface of the depression can further strengthen the barrels by allowing the vacuum of the chuck to hold the barrels in place. The misalignment in this process mainly stems from the precise dimensions of each barrel and the wall roughness (depending on cutting) as well as the wall roughness of the template depressions.

[0071] A typical process for such construction may be as follows:

[0072] 1. Patterning and etching the precision recess into the ceramic template is completed in two patterning and etching steps (one step for the recess walls and one step for the vacuum holes). Here, deep recesses can be micromachined in silicon using the Bosch process, which will have negligible wall roughness (RMS in the tens of nanometers) (this is the most common way, but there are many other ways to micromachine the recess) (deep recesses can be micromachined in silicon, ceramic, or glass).

[0073] 2. Place a stainless - steel compression spring or a V - shaped torsion spring into the recess.

[0074] 3. Manually or using a fixture, load the barrels face - up into each recess such that each barrel is oriented the same as the others and is tensioned against the recess walls.

[0075] Some advantages of this process include: Assembly does not require precision tools. Once all the barrels are consumed, the template can be reused. The absence of polymer materials enables good chemical resistance, thus providing greater flexibility in the process sequence (wet etching or cleaning the barrels can still be carried out after loading). In this case, Elgiloy alloy springs are good candidates.

[0076] On the other hand, the disadvantages may be: Cutting sapphire (a typical micro - LED substrate) is uncommon and may be more variable than glass or silicon, making this particular implementation infeasible for some substrates due to non - uniformity. Finding suitable springs with the desired dimensions can be challenging. To overcome this, custom - made micro - springs made of chemical - resistant alloys can be provided, or polymer springs made by two - photon lithography can be used.

[0077] Modular anchored direct construction

[0078] Figure 8A 、 Figure 8B and Figure 8C The case of modular - anchored direct construction for building multiple barrels is shown. This particular implementation involves transferring the micro - devices from the barrels to a release layer located on the template. To facilitate the transfer, a laser - activated release layer is initially present on the barrels. The back side of the micro - device is bonded to the release layer of the template via an adhesive, and then the micro - device is peeled off the barrel using laser excitation. In this scenario, the barrels will act as donor substrates while the template is the acceptor substrate.

[0079] The typical process for modular - anchored direct construction includes:

[0080] 1. Pattern the sacrificial layer on the template, which has openings for the anchor points in the structural layer.

[0081] 2. Alignment marks are allowed to be integrated into the pick-and-place tool.

[0082] 3. Deposit the structural layer anchored to the template substrate and then pattern the structural layer to allow tuning of mechanical fracture during microdevice printing.

[0083] 4. Cut the template into a number of template pieces.

[0084] 5. Pattern adhesive bumps on top of the structural layer to transfer all the microdevices from the cartridge to the template.

[0085] 6. Vacuum-adsorb the template pieces to the pick-and-place tool stage.

[0086] 7. Use a vacuum pick-up head to pick up the cartridge face down.

[0087] 8. Use fiducials or other features (e.g., cartridge corners) present on both surfaces to align the top of the cartridge with the adhesive bumps on the template.

[0088] 9. Bond the cartridge to the template such that only the pick-up head applies heat to prevent curing of the adhesive across the entire template.

[0089] 10. Repeat steps 4 to 6 until all desired cartridge positions on the template are filled, resulting in a multi-cartridge.

[0090] 11. Laser-process the cartridge to peel the microdevices from the cartridge substrate and transfer them to the template.

[0091] 12. If needed, coat the template with a protective resist and pattern the protective resist to protect the device during etching of the sacrificial layer.

[0092] 13. Etch the sacrificial layer to peel off the freestanding structures that can be used to print microdevices from the multi-cartridge.

[0093] A method for improved template development applicable to the above method is to fix the cartridge (or donor substrate) in an intermediate substrate. Then, use the template to bond, hold, or adhere to all the cartridges at once.

[0094] Figure 9 An intermediate substrate including alignment marks and a temporary adhesive layer is shown. In this structure, although patterning the adhesive layer allows for better alignment, the adhesive layer does not need to be patterned.

[0095] In one method, alignment marks are formed on an intermediate substrate and an adhesive layer is added to the substrate. The barrel is aligned with the position in the carrier substrate and bonded to the carrier substrate (the micro device faces the carrier substrate). After all barrels are bonded to the carrier substrate, a template is used to bond to all barrel substrates. The template has a bonding layer that will adhere to the barrel substrate. The bonding layer can be a patterned adhesive, metal or other type of polymer. After bonding, the barrel is debonded from the carrier substrate.

[0096] Applicable to the above methods Figure 10 An intermediate substrate including grooves is shown. These grooves match a structure in the barrel (e.g., a pedestal holding a microdevice) or a barrel substrate. The barrel is placed face down in these grooves (the microdevice faces the intermediate carrier substrate). After the barrel is in position, vibration or air or liquid can be used to place the barrel in the perfect position. After all barrels are in the perfect position, a template is used to bond to all barrel substrates. The template has a bonding layer that will adhere to the barrel substrate. The bonding layer can be a patterned adhesive, metal, or other type of polymer. After bonding, the barrel is debonded from the carrier substrate.

[0097] Using cavities as template substrates for the above method

[0098] Prepare the template substrate: Etch a cavity in the substrate of the same size as the tube substrate. Alignment marks are required. Suction forces are needed to hold the tube in place (selective vacuum, ESD or adhesive can be used). The structure can be used directly to fill the display.

[0099] Figure 12 It is shown that a tool with vacuum holes aligned with the cartridges in the carrier substrate can be used. In this way, we can pick up the cartridges without a second adhesive or bonding.

[0100] Using cavities as carrier substrates for the above method

[0101] Prepare a carrier substrate and etch a cavity in it with the same size as the active layer of the active tube. We need alignment marks (selective vacuum can be used to enhance the process).

[0102] The cartridge is placed on top of a structure that bonds the template substrate to a mounting structure (which can be sapphire with SU8 or sapphire with Kapton tape at bonding temperature).

[0103] Figure 11 It is shown that the cartridge can be placed in the recess and vibration used for accurate placement (which will be faster).

[0104] Figure 13A , Figure 13B and Figure 13C A case of a method of constructing a multi-barrel is shown.

[0105] This specific implementation involves transferring a micro-device from a cylinder to a release layer located on a template. To facilitate the transfer, a laser-activated release layer is initially present on the cylinder. The back side of the micro-device is bonded to the release layer of the template via an adhesive, and then the micro-device is peeled off the cylinder using laser excitation. In this scenario, the cylinder will act as a donor substrate, while the template is the recipient substrate.

[0106] Here, the template has individual bonding pads to which the micro-devices are bonded. The micro-devices are bonded to the template such that the face connected to the system substrate faces away from the template. The density of micro-devices in the template is higher than that of the system substrate. The template is a plurality of donor substrates for filling the template with micro-devices. The bonding pads can be formed on a diaphragm anchored to the template.

[0107] A typical process for this construction includes:

[0108] 1. Form a release layer on the template, which has openings for the anchors in the diaphragm layer.

[0109] 2. Form fiducials to improve alignment accuracy during the integration of the micro-devices into the template.

[0110] 3. Deposit a diaphragm layer anchored to the template substrate, and then pattern the diaphragm layer into individual diaphragms associated with each micro-device to allow the individual micro-devices to be spaced apart from the template during the transfer process.

[0111] 4. The template substrate can include more than one template piece, and thus the template substrate can be spaced into several template pieces by mechanical cutting, laser cutting, or other means. This step can be carried out after the micro-devices are integrated into the template.

[0112] 5. Pattern bonding pads / bumps on top of the diaphragm layer to transfer all the micro-devices from the cylinder to the template - depending on the micro-device structure, the pads of the micro-devices can face the diaphragm or away from the diaphragm. - The bonding pads can be an adhesive polymer, a metal layer, or other materials. In a related structure, the template can include only bonding pads. The bonding pads can be temporary bonding members. The bonding pads can be larger than, equal to, or smaller than the micro-devices. In a related case, the bonding pads can be smaller than the micro-devices by more than multiple times, and thus multiple bonding pads in the bonding pads contact one micro-device.

[0113] 6. Align the donor substrate with the fixed microdevices facing the template bonding pads in position in the template. The devices can be fixed to the donor substrate in different ways such as adhesives, mechanical peel layers, or other means. Bond the donor microdevices to the template. Bonding can include heat and pressure. Heat and pressure can be applied only to the donor substrate. Bonding can be performed for all microdevices in the donor substrate or a selected group of microdevices in the donor substrate.

[0114] 7. Repeat steps 4 to 6 until all desired locations on the template are filled, thereby producing multiple barrels.

[0115] 8. The donor substrate can be removed individually after the bonding process or after all bonding. The removal process can be done by mechanical force, laser, heat or chemical release agent to leave the microdevices in the template. After or before removing the donor substrate, curing can be further performed to further fix the microdevices. The peeling process can be performed selectively for a group of microdevices in the donor substrate or for all microdevices in the donor substrate.

[0116] 9. Removing the release layer. One approach is to etch a sacrificial layer to release a free-standing membrane that can be used to print microdevices from multiple cylinders.

[0117] To perform the steps associated with transferring the microdevice to the template, the template can be secured to a flat stage tool stage such that the membrane and adhesive layer are facing away from the stage, and a donor substrate (having the microdevice secured thereto by various means) is picked up by a flat transfer head such that the microdevice can face the template.

[0118] Figure 14 It is shown that a tool with vacuum holes aligned with the cartridge in the carrier substrate can be used. In this way, we can pick up the cartridge without a second adhesive or bonding. Removing the backing plate from the cartridge makes bonding easier.

[0119] Modular anchored direct construction using color conversion

[0120] Figure 15 , Figure 16 and Figure 17 The same implementation as the modular anchor direct build implementation is shown, but the color conversion layer is embedded in the structural layer and will be transferred with the micro devices (especially micro LEDs) to allow RGB color printing directly from multiple cylinders. This is shown in Figure 8, Figure 9 , Figure 10 and Figure 11 Shown in.

[0121] A typical process for direct construction using modular anchors with color transformations would be as follows:

[0122] 1. Form a release layer on the template, the release layer having openings for the anchor points in the diaphragm layer.

[0123] 2. Form fiducials to improve alignment accuracy during integration of the micro-devices into the template.

[0124] 3. Deposit a diaphragm layer anchored to the template substrate and then pattern the diaphragm layer into individual diaphragms associated with each micro-device to allow the individual micro-devices to be spaced apart from the template during the transfer process.

[0125] 4. The template substrate may include more than one template piece, and thus the template substrate can be spaced into a number of template pieces by mechanical cutting or laser cutting or other means. This step can be carried out after the micro-devices are integrated into the template.

[0126] 5. Functional layers such as color conversion layers can be integrated on top of the diaphragm. The functional layer can include one or more of a passivation layer, a color conversion layer, a color filter, and other layers. For different colors, there can be different types of color conversion layers.

[0127] 6. Pattern bonding pads on top of the diaphragm structure layer to transfer the micro-devices from the donor substrate to the template - depending on the micro-device structure, the pads of the micro-device can face the diaphragm or be back-to-back with the diaphragm. - The bonding pads on the template can be an adhesive polymer, a metal layer, or other materials. In a related structure, the template can include only the bonding pads. The bonding pads can be temporary bonding members. In this case, the functional layer is formed on the template. The bonding pads can be larger than, equal to, or smaller than the micro-devices. In a related case, the bonding pads can be smaller than the micro-devices by more than a multiple, and thus a number of bonding pads in the bonding pads contact one micro-device.

[0128] 7. The micro-devices can be integrated into the bonding pads of the template by aligning the donor substrate with the area of the template and bonding a selected group of micro-devices to the bonding pads. This process can be repeated until all the selected areas of the template are filled with micro-devices. After each individual bonding or at the end, the donor substrate can be removed by different means (laser, mechanical force, chemical release, or other means).

[0129] 8. A reflective layer is formed around a part of the sidewall of the bonding pads on the template or around a part of the sidewall of the micro-devices to guide the input light or out-coupled light through the bonding pads.

[0130] 9. The bonding pads are transparent or semi-transparent to the wavelength generated by the micro-devices or the light intended to enter the micro-devices.

[0131] In another related structure, the functional layer is formed on top of the bonding pads, where the bonding pads can have an opening to embed the functional layer. The opening can be formed by photolithography, wet etching, or dry etching.

[0132] The following table outlines the various advantages of the materials used in the combination of the structural layer and the sacrificial layer:

[0133]

[0134]

[0135] In another related structure, a functional layer is formed on top of the bonding pad, where the bonding pad may have an opening to embed the functional layer. The opening can be formed by photolithography, wet etching, or dry etching.

[0136] Transfer head

[0137] The following aspects apply to all methods of multi-tube construction as mentioned above where appropriate.

[0138] The present invention relates to a transfer head that loads multiple tubes with high alignment accuracy while selectively transferring micro-devices from each tube into a substrate, where the tube includes a substrate, a transfer layer, and a micro-device coupled to the tube substrate through the transfer layer.

[0139] One method of loading multiple tubes into a transfer head is to precisely fix the tubes face down into a template (with the micro-devices facing the template) and lift the tubes from the back of the tube substrate with the transfer head.

[0140] The transfer head holds multiple tubes by an adhesive layer, vacuum, electrostatic force, or other forces.

[0141] The present invention also relates to loading micro-devices from a donor substrate into a tube, where the process includes: forming a release layer on the substrate; forming a diaphragm on the release layer, where the diaphragm is connected to the substrate through an opening in the release layer; and bonding the micro-devices to the diaphragm through an adhesive layer or a bonding layer.

[0142] The diaphragm can be patterned to hold only a single micro-device or multiple micro-devices.

[0143] Removing the release layer reduces the force holding the diaphragm to the substrate.

[0144] Aligning the micro-devices in the substrate with a system substrate and selectively bonding the micro-devices to a bonding area in the system substrate can remove the micro-devices from the tube substrate. After transferring the micro-devices to the system substrate, the diaphragm and the bonding layer can be removed. In one case, the bonding layer and the diaphragm are transparent, and thus both can continue to remain on the micro-device.

[0145] The present invention also relates to a multi-tube structure, wherein the multi-tube structure comprises: a template substrate, a release layer or a sacrificial layer having an opening, a diaphragm layer coupled to the substrate through the opening in the release layer, and micro-devices from different donor substrates are coupled to the diaphragm layer through an adhesive layer on the diaphragm layer, wherein the diaphragm can be patterned into an array of individual diaphragms.

[0146] In addition, the adhesive layer can be patterned into an array matching the array of micro-devices coupled to the adhesive layer. A functional layer is formed on top of the diaphragm layer, wherein the functional layer comprises one or more of a passivation layer, a color conversion layer, a color filter layer, and an optical structure.

[0147] The functional layer is patterned into an array of functional layers. A reflective layer around a part of the template bonding pad, the functional layer, or the micro-device is used to guide light through the functional layer.

[0148] The release layer or the sacrificial layer can be removed, and the diaphragm layer is freestanding. A group of micro-devices bonded to the freestanding diaphragm can be bonded to a bonding pad on a system substrate through a system substrate bonding pad. A selected group of freestanding diaphragms with the associated micro-devices are spaced apart from the template and remain on the system substrate.

[0149] The present invention also relates to a method of constructing a multi-tube, wherein the method comprises: forming a release layer on a template, the release layer having an opening for an anchor point in the diaphragm layer; forming a fiducial to improve alignment accuracy during integration of the micro-devices into the template; depositing a diaphragm layer anchored to the template substrate; and patterning bonding pads / bumps on top of the diaphragm layer.

[0150] The micro-devices are further transferred from at least one donor to an area in the template by: aligning the donor substrate with the fixed micro-devices, the fixed micro-devices facing the template bonding pad in the position in the template; bonding the donor substrate to the position in the template; and peeling the micro-devices into the template.

[0151] The micro-devices are fixed to the donor substrate by different means such as an adhesive or a mechanical release layer, wherein further, the micro-devices of the donor are bonded to the template.

[0152] In a related embodiment, the diaphragm can be patterned into individual diaphragms associated with each micro-device, thereby allowing the individual micro-devices to be spaced apart.

[0153] In a related embodiment, the pad of the micro-device faces the diaphragm or faces away from the diaphragm, and the bonding pad is an adhesive polymer or a metal layer.

[0154] In related embodiments, only the template may include the bonding pad, where the bonding pad is a temporary bonding member and is larger than, equal to, or smaller than the microdevice.

[0155] In related embodiments, the bonding pad is smaller than the microdevice by more than an order of magnitude, and thus multiple bonding pads in the bonding pad contact one microdevice.

[0156] In related embodiments, the donor substrate may be removed separately or after all bondings after the bonding process, and the removal process is accomplished by mechanical force, laser, heat, or chemical release aids to leave the microdevice in the template.

[0157] In related embodiments, the peeling process is selectively performed for a group of microdevices in the donor substrate or for all microdevices in the donor substrate.

[0158] In related embodiments, curing is further performed after or before removing the donor substrate to further fix the microdevice.

[0159] In related embodiments, the release layer is moved by etching a sacrificial layer to release a freestanding diaphragm for the multi-barrel printed microdevice.

[0160] In related embodiments, a functional layer is formed on top of the diaphragm, where the functional layer includes one or more of a passivation layer, a color conversion layer, a color filter, and an optical structure.

[0161] In related embodiments, the donor substrate is removed by laser, mechanical force, or chemical release after each individual bonding or at the end.

[0162] In related embodiments, a reflective layer is formed around a part of the sidewall of the bonding pad on the template or around a part of the sidewall of the microdevice to guide input light or out-coupled light through the bonding pad.

[0163] In related embodiments, the bonding pad is transparent or translucent to the wavelength generated by the microdevice or the light intended to enter the microdevice.

[0164] In related embodiments, a functional layer is formed on top of the bonding pad, where further, the bonding pad has an opening to embed the functional layer, and the opening is formed by photolithography, wet etching, or dry etching.

[0165] In related embodiments, the release layer or the sacrificial layer is removed, and the diaphragm is a freestanding structure.

[0166] In related embodiments, the microdevices are selectively transferred from the template to the system substrate by selectively aligning a set of the microdevices in the template with bonding pads on the system substrate and removing the septum from the template, where the septum includes template bonding pads and the microdevices.

[0167] While particular embodiments and applications of the invention have been illustrated and described, it should be understood that the invention is not limited to the precise structures and components disclosed herein, and that various modifications, alterations, and variations will be apparent from the foregoing description without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for constructing a multi-tube using adhesive-based direct construction, the method comprising: Patterning alignment marks on a highly flat substrate and cutting the flat substrate into a number of template pieces; Applying an adhesive to the template; Picking up the tube with the face up using a bonding head; Aligning the back of the tube with the top of the template using the alignment marks or tube corners present on both surfaces; Bonding the tube to the template; And Repeating the last three steps until all desired tube positions on the template are filled and the multi-tube construction is completed.

2. The method according to claim 1, wherein the adhesive is thermally cured.

3. The method according to claim 1, wherein only the bonding head applies temperature.

4. The method according to claim 1, wherein misalignment is actively corrected by a bonding tool.

5. The method according to claim 1, wherein there is testing of the back side of the tube and corner detection.

6. The method according to claim 1, wherein there are custom depressions in the bonding head.

7. A method for constructing a multi-tube using adhesive-based simultaneous construction, the method comprising: Patterning alignment marks on a highly flat substrate; Patterning adhesive bumps on a highly flat temporary bonding substrate to selectively transfer micro-LEDs from the tube; Holding the temporary bonding substrate to a tool carrier; Picking up the tube with the face down using a bonding head; Aligning the top of the tube with the adhesive bumps on the substrate using fiducials or other features (e.g., tube corners) present on both surfaces; Bonding the tube to the substrate; And Repeating steps 4 to 6 until all desired tube positions on the substrate are filled.

8. The method according to claim 7, wherein only the bonding head applies heat to prevent curing of the adhesive of the entire substrate.

9. The method according to claim 7, wherein the method further comprises applying an adhesive to the template via spin coating, spraying, dip coating, or bar coating.

10. The method according to claim 9, wherein the method further comprises picking up the template with the face down using a vacuum bonding head.

11. The method according to claim 10, wherein the method further comprises aligning the top of the template with the temporary substrate using fiducials present on both surfaces.

12. The method according to claim 11, wherein the method further comprises simultaneously bonding the template to the back sides of all tubes and removing it from the tool carrier.

13. The method according to claim 12, wherein removing the template transfers some micro-LEDs onto the adhesive bumps to complete the multi-tube.

14. The method according to claim 1, using adhesive-based construction utilizing spacer beads, the method comprising: Controlling the z-axis depth and thus enhancing the x-axis alignment and y-axis alignment by using spacer beads comprising dimensionally controllable spherical glass or ceramic particles in the template adhesive to allow the bonding line thickness for fixing to all tubes on the template to remain uniform, thereby maintaining a consistent bonding line thickness on the adhesive at all tube positions.

15. The method according to claim 14, wherein the bond line thickness is set by the maximum bead present under each cartridge at the time of bonding.

16. The method according to claim 7, using an adhesive-based build utilizing spacer beads, the method comprising: Controlling the z-axis depth and thus enhancing the x-axis alignment and y-axis alignment by using spacer beads comprising dimensionally controlled spherical glass or ceramic particles in a template adhesive to allow the bond line thickness for all cartridges fixed to the template to remain uniform, thereby maintaining consistent bond line thickness on the adhesive at all cartridge positions.

17. The method according to claim 16, wherein the bond line thickness is set by the maximum bead present under each cartridge at the time of bonding.

18. A method of building a multi-cartridge using mechanical direct build, the method comprising: Completing patterning and etching a precision recess into a template in two patterning and etching steps (one step for the recessed wall and one step for the vacuum holes); Placing a compression spring or a V-shaped torsion spring into the recess; And Manually or using a fixture, loading the cartridges face-up into each recess such that each cartridge is oriented the same as the other cartridges and is tensioned against the recessed wall.

19. The method according to claim 18, wherein the deep recess is micromachined in silicon, ceramic, or glass.

20. A method of building a multi-cartridge using modular anchoring direct build, the method comprising: Patterning a sacrificial layer on a template, the sacrificial layer having openings for anchor points in a structural layer; Having alignment marks to allow integration; Depositing a structural layer anchored to the template substrate; Patterning adhesive bumps on top of the structural layer; Holding the template piece to a tool carrier; Bonding at least one cartridge to the template by pick-up of the cartridge face-down using a bonding head; Aligning the top of the cartridge with the adhesive bumps on the template using fiducials or cartridge corners present on two surfaces; And Bonding the cartridge to the template using the bonding head.

21. The method according to claim 20, wherein the last three steps are further repeated until all desired cartridge positions on the template are filled, thereby producing a multi-cartridge.

22. The method according to claim 20, wherein the method further comprises removing the cartridge substrate and peeling the micro-device into the template.

23. The method according to claim 22, wherein the peeling process is using light or laser.

24. The method according to claim 20, wherein the method further comprises: If desired, applying a protective resist on the template and patterning the protective resist to protect the device during etching of the sacrificial layer.

25. The method according to claim 20, wherein the method further comprises etching the sacrificial layer to peel the freestanding structure.

26. The method according to claim 20, wherein the method further comprises fixing the cartridge (or donor substrate) in an intermediate substrate, wherein the template is then used to bond, hold, or adhere to all cartridges at once.

27. The method according to claim 26, wherein the method further comprises an intermediate substrate, the intermediate substrate comprising alignment marks and a temporary adhesive layer, and wherein further, the temporary adhesive layer does not require patterning.

28. The method according to claim 26, wherein the alignment marks are formed on the intermediate substrate, and an adhesive layer is added to the substrate, and wherein further, all cylinders are aligned with positions in the carrier substrate and bonded to the carrier substrate.

29. The method according to claim 28, wherein further, after all cylinders are bonded to the carrier substrate, a template is used to bond to all the cylinder substrates, and wherein further, the template has a bonding layer that will adhere to the cylinder substrate, and the bonding layer is a patterned adhesive, metal, or other type of polymer.

30. The method according to claim 28, wherein further, after bonding, the cylinders are de-bonded from the carrier substrate.

31. The method according to claim 26, wherein the method further comprises the intermediate substrate having grooves, wherein the grooves match one of the structures in the cylinders or the cylinder substrates, and wherein further, the cylinders are placed face-down in these grooves.

32. The method according to claim 31, wherein after the cylinders are in place, vibration or air or liquid is used to place the cylinders in place, and after all cylinders are in place, a template is used to bond to all the cylinder substrates, wherein the template has a bonding layer that adheres to the cylinder substrates, and the bonding layer is a patterned adhesive, metal...

33. The method according to claim 31, wherein after bonding, the cylinders are de-bonded from the carrier substrate.

34. The method according to claim 22, wherein the template substrate is prepared by etching cavities in the substrate that are the same size as the cylinder substrates, the cavities having the required alignment marks and having an adsorption force to hold the cylinders in place.

35. The method according to claim 26, wherein the template substrate is prepared by etching cavities having alignment marks in the substrate that are the same size as the active layer of the active cylinder, and placing the cylinder on top of the structure that will bond the template substrate to the assembly structure.

36. The method according to claim 35, wherein the method further comprises placing the cylinder in the cavity and using vibration for placement.

37. A method of constructing a multi-cylinder, the method comprising: forming a release layer on a template, the release layer having openings for anchor points in a diaphragm layer; forming fiducials to improve alignment accuracy during integration of a micro-device into the template; depositing a diaphragm layer anchored to a template substrate; patterning bonding pads / bumps on top of the diaphragm layer; transferring a micro-device from at least one donor to an area in the template by: aligning a donor substrate with a fixed micro-device, the fixed micro-device facing the template bonding pads in the positions in the template; Bond the donor substrate to the position in the template; and Release the microdevice into the template.

38. The method according to claim 37, wherein the microdevice is fixed to the donor substrate by different means such as an adhesive or a mechanical release layer, and further wherein the microdevice of the donor is bonded to the template.

39. The method according to claim 37, wherein the diaphragm is patterned into individual diaphragms associated with each microdevice, thereby allowing the individual microdevices to be spaced apart.

40. The method according to claim 37, wherein further, the pad of the microdevice faces the diaphragm or faces away from the diaphragm, and the bonding pad is an adhesive polymer or a metal layer.

41. The method according to claim 40, wherein only the template includes the bonding pad, and the bonding pad is a temporary bonding member and is larger than, equal to, or smaller than the microdevice.

42. The method according to claim 40, wherein the bonding pad is smaller than the microdevice by more than a multiple, and thus a plurality of bonding pads in the bonding pad contact one microdevice.

43. The method according to claim 40, wherein further, the donor substrate is removed individually or after all bondings, and the removal process is accomplished by mechanical force, laser, heat, or chemical release aids to leave the microdevice in the template.

44. The method according to claim 37, wherein the release process is selectively performed for a group of microdevices in the donor substrate or for all the microdevices in the donor substrate.

45. The method according to claim 43, wherein further, curing is performed after or before removing the donor substrate to further fix the microdevice.

46. The method according to claim 45, wherein further, the release layer is moved by etching a sacrificial layer to release the freestanding diaphragm for the multi-barrel printed microdevice.

47. The method according to claim 37, wherein a functional layer is formed on top of the diaphragm, and the functional layer includes one or more of a passivation layer, a color conversion layer, a color filter, and an optical structure; 48. The method according to claim 37, wherein the donor substrate is removed by laser, mechanical force, or chemical release after each individual bonding or at the end.

49. The method according to claim 47, wherein a reflective layer is formed around a part of the sidewall of the bonding pad on the template or around a part of the sidewall of the microdevice to guide the input light or out-couple the light through the bonding pad.

50. The method according to claim 47, wherein the bonding pad is transparent or translucent to the wavelength generated by the microdevice or the light intended to enter the microdevice.

51. The method according to claim 47, wherein a functional layer is formed on top of the bonding pad, and further, the bonding pad has an opening to embed the functional layer, and the opening is formed by photolithography, wet etching, or dry etching.

52. The method according to claim 47, wherein the release layer or the sacrificial layer is removed, and the diaphragm is a freestanding structure.

53. The method according to claim 47, wherein the microdevices are selectively transferred from the template to the system substrate by selectively aligning a set of microdevices in the template with bonding pads on the system substrate and removing the diaphragm from the template, wherein the diaphragm includes template bonding pads and microdevices.

54. A method of loading a transfer head, the transfer head loading a plurality of cartridges with high alignment accuracy while selectively transferring microdevices from each cartridge into a substrate, wherein the cartridges include a substrate, a transfer layer, and microdevices coupled to the cartridge substrate through the transfer layer.

55. The method according to claim 54, the method further comprising precisely fixing the cartridge face down in a template (the microdevices facing the template) and lifting the cartridge from the back of the cartridge substrate with the transfer head.

56. The method according to claim 54, the method further comprising the transfer head holding a plurality of cartridges by an adhesive layer, vacuum, or electrostatic force.

57. A method of loading microdevices with a cartridge, the method comprising: loading the microdevices from a donor substrate into the cartridge, wherein the process includes forming a release layer on the substrate; forming a diaphragm on the release layer, wherein the diaphragm is connected to the substrate through one or more openings in the release layer; and bonding the microdevices to the diaphragm through an adhesive layer or a bonding layer.

58. The method according to claim 57, wherein the diaphragm is patterned to hold only a single microdevice or a plurality of microdevices.

59. The method according to claim 57, the method further comprising removing the release layer to reduce the force holding the diaphragm to the substrate.

60. The method according to claim 59, the method further comprising: aligning the microdevices in the substrate with a system substrate; and selectively bonding the microdevices to bonding regions in the system substrate to remove the microdevices from the cartridge substrate.

61. The method according to claim 59, wherein the diaphragm and the bonding layer are removed after transferring the microdevices to the system substrate.

62. The method according to claim 57, wherein the bonding layer and the diaphragm are transparent.

63. A multi-cartridge structure, the multi-cartridge structure comprising: a template substrate; a release layer or a sacrificial layer having openings; a diaphragm layer, the diaphragm layer being coupled to the template substrate through the openings in the release layer; and microdevices from different donor substrates, the microdevices being coupled to the diaphragm layer through an adhesive layer on the diaphragm layer.

64. The structure according to claim 63, wherein the diaphragm layer is patterned into individual diaphragm arrays.

65. The structure according to claim 63, wherein the adhesive layer is patterned into an array matching the array of microdevices coupled to the adhesive layer.

66. The structure according to claim 63, wherein the structure further includes a functional layer formed on top of the diaphragm layer.

67. The structure according to claim 66, wherein the functional layer comprises one or more of a passivation layer, a color conversion layer, a color filter layer, and an optical structure.

68. The structure according to claim 66, wherein the functional layer is patterned into a functional layer array.

69. The structure according to claim 66, wherein a reflective layer around the template bonding pad, the functional layer, or a portion of the microdevice is configured to direct light through the functional layer.

70. The structure according to claim 66, wherein the release layer or the sacrificial layer is removed and the diaphragm layer is freestanding.

71. The structure according to claim 66, wherein a set of microdevices bonded to the freestanding diaphragm are bonded to pads on a system substrate via system substrate bonding pads.

72. The structure according to claim 71, wherein a selected set of freestanding diaphragms with associated microdevices are spaced apart from the template and remain on the system substrate.

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