CARTUCE WITH INNER COLUMN

Abstract

The present invention discloses a method for transferring microdevices. The method includes coupling a microdevice to a donor substrate via a pillar layer, aligning the microdevice, bonding the microdevice, and fracturing the pillar layer using various techniques. Different pillar configurations within the structure, such as edges and floating layers, are also disclosed. Furthermore, the method discloses the use and formation of nanopillars to achieve the transfer of microdevices.

Description

REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 339,935, filed May 9, 2022, which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION

[0002] The present disclosure relates to a cartridge structure having an array of micro devices. SUMMARY

[0003] According to one embodiment, the invention relates to a method for transferring microdevices, the method comprising coupling a microdevice to a donor substrate through a pillar layer, aligning the microdevice to a system substrate, bonding the microdevice to the system substrate, breaking the pillar layer with the donor substrate, and transferring the microdevice to the system substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings. Fig. Figure 1A shows a microdevice connected to a substrate by a pillar. Fig. Figure 1B shows the micro device aligned with a system substrate, with a bonding layer in the system substrate. Fig. Figure 2A shows one embodiment of column development. Fig. Figure 2B shows that the new structure is bonded to a substrate. Fig. Figure 2C shows that the original substrate is removed and the buffer / community layer is etched back or removed. Fig. Figure 2D shows a related embodiment wherein the interface between column and microdevice is modified. Fig. Figure 3A shows a structure bonded to a substrate. Fig. Figure 3B shows that the original substrate has been removed. Fig. Figure 4A illustrates the formation of columns. Fig. Figure 4B shows the structure after the substrate was removed. Fig. Figure 4C shows a layer that can be deposited on the surface of the device. Fig. Figure 4D shows that the release / protective layer can be removed to leave a cavity beneath the device. Fig. Figure 4E shows the top view of the device with the floating layer coupled to a part of the column.

[0005] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown by way of example in the drawings and are described in detail herein. It is to be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is intended to include all modifications, equivalents, and alternatives falling within the spirit and scope defined by the appended claims. DETAILED DESCRIPTION

[0006] The following description provides a microdevice structure and a method for transferring microdevices.

[0007] In one embodiment, a cartridge structure comprises a substrate, with an array of microdevices coupled to the substrate by pillars. The backplate may be a substrate and may include further layers on either side of the substrate. The microdevices may be organic or inorganic optoelectronic devices, a CMOS chiplet, MEMS, actuators, sensors, or other devices. The pillars are formed at an edge of the microdevices. There may be a modified interface between the pillar and the microdevices, the modification weakening the bonding between the pillar and the microdevices. The modified interface may be weakened by chemical processes, such as solvent or acid exposure.

[0008] Another method for weakening the interface is the use of impurities in the interface. The impurities can be organic or inorganic materials.

[0009] In another case, the column may have a weak point that breaks under the compressive load. The weak point can be developed by reducing the column width.

[0010] In one process, the column is positioned at the edge, and dry etching reduces the column width. Here, the microdevice can be used as a mask for etching the column.

[0011] In a related case, the column is at the corner, so the etching thins the column from both sides.

[0012] In a related case, the columns are made of brittle material.

[0013] In a related case, the pillars have an angle that is not a right angle (90°) with respect to the surface of the microdevices. The pressure created by bonding microdevices to a substrate causes the pillar to break very easily.

[0014] Another related embodiment involves microdevices that float on a surface and are ready to be transferred to a substrate. The embodiment also includes the process of developing the floating microdevices.

[0015] The related embodiment includes a micro device connected to a floating layer, wherein the floating layer is bonded to a pillar formed on a surface.

[0016] One case of developing microdevices floating on a surface is the formation of a pillar on the surface bonded to a set of microdevices covered by a layer.

[0017] Fig. 1A shows a microdevice 102 connected to a substrate 120 by a pillar 104. A buffer / bonding layer 106 may be present between the pillar 104 and the substrate 120. The pillar 104 may be made of the same material as the buffer / bonding layer 106. The interface 108 is located between the pillars and the microdevices.

[0018] As in Fig. As shown in Figure 1B, the microdevice may be aligned with a system substrate 400, with a bonding layer 402 located within the system substrate 400. The microdevice 102 is bonded to the system substrate 400, and the donor substrate 120 and the system substrate 400 are removed. Either of the processes of bonding or separating the two substrates may break the column layers or separate the column layer 104 from the microdevices 102, thereby inserting the microdevice 102 into the system substrate 400.

[0019] In one case, pressure or temperature is used during the bonding process of a microdevice to the system substrate. Here, the pressure can be adjusted to break the pillars. In another related case, the temperature is adjusted during bonding to reduce the adhesion between the pillar and the microdevice.

[0020] In another related case, the process of separating the system substrate and the donor substrate separates the column from the microdevice. Here, temperature can be used to reduce the adhesion between the column and the microdevices. The system substrate 400 can include drive circuitry for the pixels. The bonding layer can be either bond pads or adhesive layers.

[0021] In a related embodiment, the interfaces 108 between columns and microdevices are modified to enable transfer. In one case, the interface provides an adhesive force between the column and the microdevices. The adhesion can be modified by temperature or illumination to reduce the force. In another related embodiment, temperature can decompose the material at the interfaces, thus separating the microdevices.

[0022] In other related cases, chemicals can be used to reduce the interfaces between microdevices and columns. In a related embodiment, residue material can be formed at the interface. For example, a thin polymer layer can be formed on the surface so that, under temperature or with chemicals, the adhesion of the microdevice to the column is reduced. Some implementations of embodiments in Fig. 1A and Fig. 1B will be explained in the next embodiments.

[0023] Fig. Figure 2A shows a related embodiment of pillar development. Here, the microdevices are formed on a substrate 240. A layer 204 may be present between the microdevice 202 and the substrate 240. The layer 204 may be part of the microdevice 202. After the device is formed, a protective layer 206 may be formed on top of the device 202. The protective layer 206 is etched to create openings 208. The etching may be dry etching or wet etching.

[0024] As in Fig. As shown in Figure 2B, the new structure is bonded to a substrate 220. The bonding layer 210 can consist of different layers and materials. In one case, it can be BCB, polyamide, and other bonding materials.

[0025] As in Fig. As shown in Figure 2C, the original substrate 240 may be removed, and if a buffer / common layer 204 is present, it may be etched back or removed. The protective layer 206 may be removed or modified. This process may be performed by wet etching, light-induced deformation, or other processes. Layer 210 may be etched back to clear the materials around the microdevice so that the materials around the microdevice do not interfere with the system substrate during transfer. The etching back may occur behind the column base or near the microdevice 202 (in Fig. 2C).

[0026] Fig. Figure 2D illustrates a related embodiment wherein the interface 212 between the pillar 208 and the microdevice 202 is modified. Here, light, temperature, pressure, or residue material is used to create a weathering bond between the microdevice 202 and the pillar 212. Here, the bond between the pillar and the microdevice is modified so that the microdevice can be separated from the donor substrate during transfer using the bonding force between the microdevice and the system substrate. The bond is modified either by the application of pressure, temperature, or the exposure to chemicals. In another related case, a different material is used as the interface of the pillar to make it more easily modified. The material can be a mixture of adhesive or residue material that can be removed by exposure to chemicals.

[0027] In another related embodiment, the pillar 208 is developed through an opening in the protection / separation layer 206 on the microdevice 202 at least at one edge of the microdevice. The process may be used for embodiments of Fig. 2A-2D and Fig. 3A and Fig. 3B. Here is the structure as in Fig. 3A, bonded to a substrate 220. A structure such as planarization, soft material, and other structures may be present on the substrate 220.

[0028] As in Fig. 3B, the original substrate 240 is removed. The buffer / common layer may be etched back. Here, layer 210 is etched back. The microdevice may act as a mask (or another mask may be formed on top of the microdevice 202). By etching back layer 210, the pillar may also be etched so that it is self-aligned to the edge of the device 202. Through the self-alignment process, the size of the pillar 208 may be reduced beyond the original pattern formed by the opening of the protection / isolation layer. This may allow the size of the pillar to be smaller than the patterning capability. The pillar(s) 208 may be formed at the corner of the device 202 and are therefore self-aligned from two sides.

[0029] Fig. 4A-4E show microdevices floating on pillars formed on a surface. Fig. Figure 4A illustrates the formation of pillars. Here, after the formation of the micro device 202 on a substrate 240, a separation / protection layer 206 is formed, covering the micro device 202. A buffer or common layer 204 may be present. After the formation of the protection layer 206, the structure is bonded to another substrate 220 using the bonding layer 210. The bonding layer 210 may consist of multiple layers of different materials. The substrate 240 may be removed, and the protection layer 206 may be removed from a portion of the surface, exposing a portion of the pillars formed with the bonding layer(s) 210.

[0030] Fig. Figure 4B shows the structure after removal of the substrate 240, removal of the community layer (buffer layer) 204, and removal of a portion of the protection / separation layer 206. And a portion of the pillar 210-P is exposed 266.

[0031] As in Fig. As shown in Figure 4C, a layer 264 may be deposited on the surface of the device and covers at least a portion of the sidewall of the device 202 and a portion of the exposed pillar 210-P. The layer 264 may be patterned to provide access to the protection / release layer 206.

[0032] As in Fig. As shown in Figure 4D, the release / protection layer 206 may be removed to leave a cavity beneath the microdevice, and the microdevice remains floating with a layer 264 covering at least the top surface of the microdevice and connected to a portion 268 of the pillar 210-P. The layer 264 may be patterned to provide access to some layers in the microdevice 202. Pads 270 may be formed on the floating layer 264, which couples to some of the layers in the device 202. Empty space 262 may be present between the microdevices.

[0033] Fig. Figure 4E shows the top view of the device with the floating layer 264 coupled to the part 268 of the column.

[0034] In a related embodiment, the pillar can be formed externally on a substrate and bonded to the microdevices. The pillar can be buried in a separation layer, and after bonding, the separation layer is removed. Or it can be bonded to the microdevices independently.

[0035] In a related embodiment, more than one pillar can be bonded to the microdevice. Here, the pillar can be a nanopillar to easily separate it from the microdevice. The nanopillars can be evenly distributed throughout the microdevice, or they can be grouped in small areas. The nanopillar can be a nanowire, a nanotube, or another form of one-dimensional nanostructure. They can be formed on top of microdevices, or they can be formed on separate substrates and bonded to the microdevices.

[0036] While certain embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein, and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 339,935

[0001]

Claims

[1] A method for transferring micro devices, the method comprising: coupling a microdevice to a donor substrate through a pillar layer; Aligning the micro device to a system substrate; Bonding the micro device to the system substrate; Breaking the column layer with the donor substrate and Transferring the micro device to the system substrate. [2] The method of claim 1, wherein pressure or temperature is used during the bonding process of the micro device to the system substrate. [3] The method of claim 2, wherein the pressure for breaking the column layer is adjusted. [4] The method of claim 2, wherein the temperature during bonding is adjusted to reduce the adhesion between the column and the microdevice. [5] The method of claim 1, wherein a bonding / buffer layer is located between a column and the donor substrate. [6] The method of claim 5, wherein the column is made of the same material as the buffer / bonding layer. [7] The method of claim 1, wherein a further bonding layer is present in the system substrate, the system substrate comprises drive circuits for pixels, and the bonding layer comprises either bond pads or adhesive layers. [8] The method of claim 1, wherein an interface between the column layer and the microdevices is modified to enable transfer, forming a residue material at the interface. [9] The method of claim 8, wherein the interface provides an adhesive force between the column and the microdevices. [10] The method of claim 9, wherein the adhesion is modified by temperature or illumination to reduce the force. [11] The method of claim 10, wherein the temperature decomposes the material at the interfaces, thereby separating the microdevices. [12] The method of claim 9, wherein a chemical may be used to reduce the interface between the microdevice and the column. [13] A method according to claim 8, wherein another material which is a mixture of adhesive or residue material is used as the interface of the column which is removed by exposure to chemicals. [14] The method of claim 8, wherein a thin polymer layer is formed on a surface such that, under a temperature or with a chemical, the adhesion of the microdevice to the column is reduced. [15] The method of claim 1, wherein microdevices are formed on a first substrate, with a first layer between the microdevices and the first substrate, the first layer being part of the microdevice. [16] The method of claim 15, wherein a protective layer is formed on top of the micro device. [17] The method of claim 16, wherein the protective layer is etched to create openings. [18] The method of claim 17, wherein the micro device is bonded to a second substrate via a first bonding layer. [19] The method of claim 18, wherein the first bonding layer consists of different layers and materials. [20] The method of claim 19, wherein the first bonding layer is made of BCB or polyamide. [21] The method of claim 18, wherein the first substrate and the first layer are removed. [22] The method of claim 21, wherein the protective layer is removed or modified and the first bonding layer is etched back beyond a column base. [23] The method of claim 15, wherein the first substrate is removed and a buffer / common layer is etched back and the micro device acts as a mask. [24] The method of claim 17, wherein the protective layer is removed or modified by wet etching or light-induced deformation. [25] The method of claim 17, wherein the column is developed in an opening in the protective / separating layer on the microdevice at at least one edge of the device. [26] The method of claim 25, wherein the interface between the column and the microdevice is modified. [27] The method of claim 26, wherein a light, a temperature, a pressure or the residue material is used to create a weaker adhesion between the microdevice and the column. [28] The method of claim 27, wherein the adhesion between the column and the microdevice is modified such that the microdevice is separated from the donor substrate during transfer with the bonding force between the microdevice and the system substrate. [29] A method according to claim 28, wherein the adhesion is modified either by the application of pressure, temperature or by the action of chemicals. [30] The method of claim 26, wherein the interface material is a mixture of adhesive or residue material that is removed by exposure to chemicals. [31] The method of claim 25, wherein the bonding layer is bonded to the donor substrate. [32] The method of claim 31, wherein the donor substrate is removed and the bonding layer is etched back, whereby the microdevice acts as the mask. [33] The method of claim 32, wherein etching back the bonding layer also etches the pillar so that it is self-aligned to the edge of the microdevice. [34] The method of claim 32, wherein the self-alignment reduces a size of the pillar beyond an original pattern formed by the opening of the protection / separation layer, thereby allowing the size of the pillar to be smaller than the patterning capability. [35] The method of claim 32, wherein the pillars are formed at the corner of the micro device. [36] The method of claim 16, wherein the first substrate is removed and the protective layer is removed from a portion of the surface, thereby exposing a portion of the pillars formed with the bonding layer. [37] The method of claim 36, wherein a floating layer is deposited on the surface of the microdevice covering at least a portion of the sidewall of the microdevice and a portion of the exposed column. [38] The method of claim 37, wherein the floating layer is structured to provide access to the protection / release layer. [39] The method of claim 38, wherein the protective / separating layer is removed to leave a cavity beneath the device, and the device remains floating with the layer covering at least one upper surface of the device and connected to a portion of the exposed column. [40] The method of claim 39, wherein the floating layer is patterned to provide access to the protection / separation layers in the micro device. [41] The method of claim 40, wherein pads are formed on the floating layer coupled to some of the layers in the device. [42] The method of claim 40, wherein there are empty spaces between the microdevices. [43] The method of claim 32, wherein the pillar is formed externally on a substrate and bonded to the microdevices. [44] The method of claim 43, wherein the column is buried in a separation layer and after bonding, the separation layer is removed or it is independently bonded to the microdevices. [45] The method of claim 43, wherein more than one pillar is bonded to the micro device. [46] The method of claim 45, wherein the pillars are nanopillars to easily separate them from the microdevice. [47] The method of claim 46, wherein the nanopillars are evenly distributed throughout the microdevice or grouped in small areas. [48] The method of claim 46, wherein the nanopillars are nanowires, nanotubes or other forms of one-dimensional nanostructure. [49] The method of claim 47, wherein the nanopillars are formed on top of microdevices or formed on separate substrates and bonded to the microdevices.

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