Chiplet with integrated LED on display backplane

Abstract

The present disclosure discloses chiplet integration in a backplane display. In particular, a transferable array of microdevice loaded chiplet structure is discussed. Further, methods such as, a method of fabricating a chiplet structure with an active backplane, a method to integrate microLED loaded chiplets into cartridge wafers, and a method integrate microLED's to connect to a display backplane are also disclosed.

Description

Chiplet with Integrated LED on Display BackplaneField of the invention

[0001] The present disclosure relates to chiplet integration in a backplane display.Summary

[0002] The present invention relates to a transferable array of microdevice loaded chiplet structure comprising, a carrier substrate with a release layer, an array of chiplets where each chiplet includes at least one pixel functionality, microdevices bonded to one surface of a chiplet, singulated planarization layers covering the surface with microdevices and bonding pads on a second surface of the chiplet that is different from a first surface of the chiplet.

[0003] The present invention also relates to a transferable array of microdevice loaded chiplet structure comprising, a carrier substrate with a release layer, an array of chiplets where each chiplet includes at least one pixel functionality, microdevices bonded to one surface of a chiplet, singulated planarization layers covering the surface with microdevices, and bonding pads on the surface of a planarization layer.

[0004] The present invention also relates to a method of fabricating a chiplet structure, the method comprising, having an active backplane, having microdevices bonded to the active backplane, having pads allowing active backplane to be bonded to a carrier substrate, and having an encapsulation structure surrounding the microdevices.

[0005] The present invention also relates to a method integrate microLED’ s to connect to a display backplane the method comprising, having a chiplet active backplane and functional circuits formed on the Chiplet active backplane, forming TVS and bonding pad, integrating microLED, and forming isolated passivation / planarization on a surface of a chiplet with integrated microLED’s.

[0006] The present invention also relates to a method to integrate microLED’s to connect to a display backplane the method comprising, forming circuits on an active backplane, forming a TVS, bonding the active backplane to a carrier substrate, forming pads for integrating microdevices, transferring microdevices into the active backplane, forming an encapsulation structure as part of a cartridge, and connecting chiplets to the cartridge substrate through the encapsulation structure.

[0007] The present invention also relates to a method integrate microLED’ s to connect to a display backplane the method comprising, forming circuits on an active backplane; forming TVS, transferring microdevices into the active backplane, encapsulating microdevices on the active backplane as part of a cartridge, forming pads on the active backplane, and connecting chiplets to the cartridge substrate through the encapsulation structure.

[0008] The present invention also relates to a method integrate microLED’ s to connect to a display backplane the method comprising, forming circuits on an active backplane, forming pads on the active backplane, transferring microdevices into the active backplane, encapsulating microdevices on the active backplane as part of a cartridge, forming pads on the encapsulation structure coupled to the active backplane, and connecting chiplets to the cartridge substrate through the encapsulation structure.

[0009] The present invention also relates to a method to integrate microLED loaded chiplets into cartridge wafers, the method comprising, having inspection and testing, singulating cartridges, and loading cartridges with microLEDs for transfer.Brief description of the Drawings

[0010] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

[0011] Figure 1 shows the processes needed to integrate the microLED’s and being able to connect to the display.

[0012] Figure 2 shows chiplet integration steps.

[0013] Figure 3 shows integrated chiplets.

[0014] 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 will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of an invention as defined by the appended claims.Detailed Description Of The Invention

[0015] The present disclosure relates to structure and methods of chiplet integration on display backplane.Transfer Ready Chiplet Structure

[0016] In this description, chiplet can be fabricated using different semiconductor technologies such as CMOS, silicon-carbide, GaN, or other types. The microdevice can be microLED, microsensor, actuator or other types. The final optoelectronic arrays that include the chiplets and microdevice may be a display, a multi -function display, multi-sensor surface, sensor array or other type. The description may refer to only one type of chiplet, microdevices, or final array for explanation purposes. The following description also covers methods of fabrication and of integrating the microLED’s and also processes for being able to connect to the display backplane.

[0017] The carrier substrate includes a release layer that can be a UV release layer, thermal release layer, or other type of release layer. Chiplets are bonded to the release layer. In case of using optical power such as UV for release, the carrier substrate should be transparent to the wavelength of light.

[0018] Figure 1 shows a chiplet structure that includes active substrate, microdevice bonded to the active substrate, and pads that allows the active substrate to be bonded to a backplane (carrier substrate), and encapsulation structure surrounding the microdevices. In one related embodiment, the microdevices are microLED or micro sensor. In one related embodiment, encapsulation can be an optical structure such as a lens. In one related embodiment, the micro devices are bonded to the active backplane with an electrical bond pad. In one embodiment, the microdevices are coupled to the active backplane using through substrate VIA (TVS)

[0019] In another related embodiment, microdevices are coupled to the active backplane without TVS. In one related structure, the pads are coupled to an active backplane using TVS. In another related structure, the pads are coupled to the active backplane without TVs.

[0020] In another related embodiment, the pads are coupled to the active backplane throughencapsulation structure.

[0021] Figure 1 shows an exemplary process for forming the chiplet structure. Here, microLED are used as micro devices. However, microdevices can be microLED or microSensor or other types of microdevices. After a Chiplet active backplane is fabricated and functional circuits are formed on active backplane of the chiplet, to integrate the microLED’s and being able to connect to the display backplane following processes as shown by Figure 1, are needed:1. TVS (through substrate VIA) and bonding pad formation. TVS or through-substrate via (TVS) or through-chip via is a vertical electrical connection that passes completely through the substrate wafer or die.2. MicroLED contact pad formation.3. MicroLED integration.4. Forming isolated passivation / planarization on the surface of a chiplet with integrated microLEDs.

[0022] Another related method and process is as follows:1. Forming circuits on active backplane2. Forming TVS (through substrate VIA). This process may include wafer thinning, trench formation in substrate, filling the trench, and forming pads.3. Bonding the active backplane to a carrier substrate. The active backplane can be separated into small chiplets.4. Forming pads for integrating microdevices.5. Transferring microdevices into the active backplane (post processing may be needed to connect the microdevices to the active backplane. The post processing can be planarization and metalization).6. Forming encapsulation structure.7. Connecting chiplets to the cartridge substrate through encapsulation structure as shown in Figure 2.

[0023] Another method and related process for coupling microdevices to active backplane through TVS is as follow:1. Forming circuits on active backplane.2. Forming TVS (through substrate VIA). This process may include wafer thinning,trench formation in substrate, filling the trench, and forming pads for microdevices integration.3. Transferring microdevices into the active backplane (post processing may be needed to connect the microdevices to the active backplane. The post processing can be planarization and metalization).4. Encapsulating microdevices on the active backplane.5. Forming pads on the active backplane.6. Connecting chiplets to the cartridge substrate through encapsulation structure as shown in Figure 2.

[0024] Another related method and process steps for coupling pads through encapsulation are as follow1. Forming circuits on active backplane.2. Forming pads on the active backplane.3. Transferring microdevices into the active backplane (post processing may be needed to connect the microdevices to the active backplane. The post processing can be planarization and metalization).4. Encapsulating microdevices on the active backplane.5. Forming pads on the encapsulation structure coupled to the active backplane6. Connecting chiplets to the cartridge substrate through encapsulation structure as shown in Figure 2.

[0025] In one case, the bonding pad and microLED’s are formed on the opposite surface of chiplets. In one case, the microLED can be on the surface of a chiplet with active circuit layers and the bonding pads are on the surface with no circuit. In another case, the microLED’s are on the surface with no active circuit layers and the bonding pads are on the surface with active circuit layers.

[0026] The bonding pads allow connection to the display (system) substrate. In one case, the bonding pads also connect to the system substrate electrically to the chiplet.Cartridge Structure

[0027] The microLED loaded chiplets can be integrated into cartridge wafers and get prepared for transfer with the following steps (as shown in Figure 2):1) Inspection and testing2) Singulation of cartridges3) Loading for transfer

[0028] In Figure 2, cartridge formation is shown with cartridge layers on cartridge backplane allowing selective transfer of chiplets with integrated microLEDs. The cartridge layers can be MEMS, adhesive, or other types of layers. The passivation / planarization layer or layers protect the microdevices from damage during transfer. It also enables cartridge layers to have more surface to be connected with microdevices. In the case of microdevices, such as a microLED or sensor, the planarization layer or layers need to be transparent to the wavelength of the microLED or microsensor. The planarization layer(s) can also provide some optical functions such as color filter, color conversion, lens, etc.

[0029] In one embodiment there is a transferable array of microdevice loaded chiplet structure comprising, a carrier substrate with a release layer, an array of chiplets where each chiplet includes at least one pixel functionality, microdevices are bonded to one surface of a chiplet. There are singulated planarization layers covering the surface with microdevices and bonding pads on a second surface of the chiplet that is different from a first surface of the chiplet. Here the cartridge layers are bonded to the surface with planarization layers and the carrier substrate is removed by activating the release layer.

[0030] In another embodiment there is a transferable array of microdevice loaded chiplet structure comprising, a carrier substrate with a release layer, an array of chiplet where each chiplet include at least one pixel functionality, microdevices bonded to one surface of chiplet, singulated planarization layers covering the surface with microdevices, and bonding pads on the surface of a planarization layer. Here cartridge layers are bonded to the surface with planarization layers and the carrier substrate is removed by activating the release layer.

[0031] The array of loaded chiplets in which cartridge layers bonded to the surface with planarization layers and the carrier substrate is removed by activating release layer.

[0032] The Figure 3 shows Chiplets with Integrated LED on Display Backplane. Here the chiplets may have microLED’s for RGB on a CMOS with PADs beneath. The chiplets are spaced apart on a backplane with interconnections. The chiplets may have a passivation layer that may further include optical layers such as lens, color conversion, etc.

[0033] The chiplet on the carrier substrate comprises a transparent backplane with a release layer on it. The pads are placed along with TSV. The other set of pads are chiplet where microLED’s are placed on top. The passivation layer encapsulates the chiplet.

[0034] While particular 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 can be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

Claims1. A transferable array of microdevices loaded chiplet structure comprising: a carrier substrate with a release layer; an array of chiplets where each chiplet includes at least one pixel functionality; microdevices bonded to one surface of a chiplet; singulated planarization layers covering the surface with microdevices; and bonding pads on a second surface of the chiplet that is different from a first surface of the chiplet.

2. The transferable array of microdevices loaded chiplet structure in claim 1 wherein cartridge layers are bonded to the surface with planarization layers and the carrier substrate is removed by activating release layer.

3. A transferable array of microdevices loaded chiplet structure comprising: a carrier substrate with a release layer; an array of chiplets where each chiplet includes at least one pixel functionality; microdevices bonded to one surface of a chiplet; singulated planarization layers covering the surface with microdevices; and bonding pads on the surface of a planarization layer.

4. The transferable array of microdevices loaded chiplet structure in claim 3 wherein cartridge layers are bonded to the surface with planarization layers and the carrier substrate is removed by activating release layer.

5. A method of fabricating a chiplet structure, the method comprising: having an active backplane; having microdevices bonded to the active backplane; having pads allowing active backplane to be bonded to a carrier substrate; and having an encapsulation structure surrounding the microdevices.

6. The method of claim 5, wherein the microdevices are microLED’s or micro sensors.

7. The method of claim 5, wherein the encapsulation structure is an optical structure such as a lens.

8. The method of claim 5, wherein the microdevices are bonded to the active backplane with an electrical bond pad.

9. The method of claim 5, wherein the microdevices are coupled to the active backplane using a TVS.

10. The method of claim 5, wherein the microdevices are coupled to the active backplane without a TSV,11. The method of claim 5, wherein the pads are coupled to the active backplane using a TSV.

12. The method of claim 5, wherein the pads are coupled to the active backplane without a TSV.

13. The method of claim 5, wherein the pads are coupled to the active backplane through encapsulation structure.

14. The method of claim 5, wherein the microLED is on a surface of a chiplet with active circuit layers and the bonding pads are on a surface with no circuit.

15. The method of claim 5, wherein the bonding pad and microLED’s are formed on the opposite surface of chiplets.

16. The method of claim 5, wherein the microLED’s are on the surface with no active circuit layers and the bonding pads are on the surface with active circuit layers.

17. The method of claim 5, wherein the bonding pads allow connection to the display (system) substrate.

18. The method of claim 17, wherein the bonding pads also connect to the system substrate electrically to the chiplet.

19. A method integrate microLED’s to connect to a display backplane the method comprising; having a chiplet active backplane and functional circuits formed on the Chiplet active backplane; forming a TVS and bonding pad; integrating microLED; and forming isolated passivation / planarization on a surface of a chiplet with integrated microLED’s.

20. A method to integrate microLED’s to connect to a display backplane the method comprising; forming circuits on an active backplane; forming a TVS; bonding the active backplane to a carrier substrate; forming pads for integrating microdevices; transferring microdevices into the active backplane; forming an encapsulation structure as part of a cartridge; and connecting chiplets to the cartridge substrate through the encapsulation structure.

21. The method of claim 20, wherein forming TVS includes wafer thinning, a trench formation in substrate, filling the trench, and forming pads.

22. The method of claim 20, wherein the active backplane is separated into small chiplets.

23. The method of claim 20, wherein post processing is needed to connect the microdevices to the active backplane and wherein the post processing is planarization and metalization.

24. A method integrate microLED’s to connect to a display backplane the method comprising; forming circuits on an active backplane; forming a TVS; transferring microdevices into the active backplane; encapsulating microdevices on the active backplane as part of a cartridge; forming pads on the active backplane; and connecting chiplets to the cartridge substrate through the encapsulation structure.

25. The method of claim 24, wherein forming TVS includes wafer thinning, a trench formation in substrate, filling the trench, and forming pads.

26. The method of claim 24, wherein post processing is needed to connect the microdevices to the active backplane and wherein the post processing is planarization and metalization.

27. A method integrate microLED’s to connect to a display backplane the method comprising; forming circuits on an active backplane; forming pads on the active backplane; transferring microdevices into the active backplane; encapsulating microdevices on the active backplane as part of a cartridge; forming pads on the encapsulation structure coupled to the active backplane; and connecting chiplets to the cartridge substrate through the encapsulation structure.

28. The method of claim 27, wherein post processing is needed to connect the microdevices to the active backplane and wherein the post processing is planarization and metalization.

29. A method to integrate microLED loaded chiplets into cartridge wafers, the method comprising: having inspection and testing; singulating cartridges; and loading cartridges with microLEDs for transfer.

30. The method of claim 29, wherein a cartridge comprises cartridge layers on a cartridge backplane allowing selective transfer of chiplet with integrated microLEDs.

31. The method of claim 30, wherein the cartridge layers are MEMS or adhesive layers.

32. The method of claim 30, wherein a passivation / planarization layer or layers protect the microdevices from damage during transfer and enable cartridge layers to have more surface to be connected with microdevices.

33. The method of claim 32, wherein in the case of a microLED or a microsensor, the planarization layer or layers are transparent to the wavelength of the microLED or microsensor and the planarization layer(s) provide optical functions such as color filter, color conversion and / or lens, singularly or in combination.

34. The method of claim 27, wherein the chiplets have microLED’s for RGB on a CMOS with PADs beneath.

35. The method of claim 34, wherein the chiplets are spaced apart on the backplane with interconnections.

36. The method of claim 34, wherein the chiplets have a passivation layer that includes optical layers such as lens or color conversion.

37. The method of claim 27, wherein the chipl et on the carrier substrate comprises a transparent backplane with a release layer on it wherein the pads are placed along with a TSV.

38. The method of claim 37, wherein another set of pads are chiplet where microLED’s are placed on top wherein further a passivation layer encapsulates the chiplet.

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