Improving uniformity in microdevice transfer

Abstract

The present invention discloses methods and aspects to deal with microdevice wafers that include non-uniformities that can result in non-uniformity in the optoelectronic systems. In particular, use of intermixing and interfering zones in a cartridge made of arrays of microdevices is disclosed. In addition, selected transfer sub-array of microdevices and wafer or wafers divided into different donor zones is also discussed. Further, integration of donor zones with intermixing zone in the cartridge is also disclosed.

Description

IMPROVING UNIFORMITY IN MICRODEVICE TRANSFERField of the invention

[0001] The present disclosure relates to improve uniformity, a method of transferring microdevices into a system substrate from a cartridge where pixels with similar microdevices are populated with microdevices from different places in a wafer or other wafers.Summary

[0002] The present invention relates to a method of populating a system substrate, the method comprising, forming a cartridge, a substrate is developed to release microdevices into the system substrate, having a cartridge where the intermixing method is embedded in the cartridge, having arrays of microdevices in the cartridge wherein the cartridge is aligned with an area of a system substrate and transferring a selected sub-array of microdevices from the cartridge into the system substrate.Brief Description of the Drawings

[0003] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

[0004] Figure 1 shows a method of populating a system substrate with a cartridge where the intermixing method is embedded in the cartridge.

[0005] Figure 2 shows a method of populating a system substrate with a cartridge.

[0006] 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

[0007] The present invention relates to microdevice wafers that include non-uniformities that can result in non-uniformity in the optoelectronic systems. For example, microLEDs in the same wafer or different wafers may have color non-uniformities or brightness non-uniformity.

[0008] One method of addressing this problem is to divide the wafer into smaller areas so that the microdevices in the small area have close performance with variation smaller than a threshold defined by the system requirements. A set of similar small regions is used to populate the same system substrate so that the performance is identical.

[0009] While this addresses the performance uniformity in one system substrate, the performance between two systems may not be the same. The performance uniformity between two systems can be enhanced by choosing the microdevice areas used for each system with similar performance within a predefined threshold. This may limit how much a wafer can be used for specific applications.

[0010] One embodiment demonstrated in Figure 1 highlights a method of populating a system substrate with a cartridge where the intermixing method is embedded in the cartridge. Here, a cartridge includes arrays of microdevices; the cartridge is aligned with an area of the system substrate. A selected sub-array of microdevices from the cartridge is transferred into the system substrate. A wafer or wafers are divided into different donor zones. To form the cartridge, a substrate is developed to release microdevices into the system substrate. The cartridge is divided into intermixing and interfering zones. The interfering zones in the cartridge are related to the areas in the system substrate that require different types of microdevices. The intermixing zones are associated with the same kind of microdevices in the system substrate but with devices from different donor zones. A predefined set of donor zones is selected from at least one wafer. A selected set of microdevices from the first donor zone are transferred into the cartridge's first intermixing zone. A second donor zone is selected, and a set of microdevices from the second donor zone is integrated into the second intermixing zone in the cartridge.

[0011] The process continues until all intermixing zones are populated with microdevices with different donor zones. The cartridge is aligned with the system substrate, and a selected set of microdevices is transferred into the system substrate. Due to intermixing in the cartridge, themicrodevices transferred in the system substrate will be a mix of devices from different donor zones.

[0012] The selection of donor zones can be random, or it can follow a process where the microdevices of each zone are within a set of performance parameters.

[0013] The transfer can be done by bonding the microdevices from the cartridge to the system substrate, laser or thermal dissociation.

[0014] Another related embodiment demonstrated in Figure 2 highlights a method of populating a system substrate with a cartridge. The intermixing method uses several cartridges to populate a similar area in the system substrate. Here, a cartridge includes arrays of microdevices; the cartridge is aligned with an area of the system substrate. A selected sub-array of microdevices from the cartridge is transferred into the system substrate. A wafer or wafers are divided into different donor zones. To form the cartridge, a substrate is developed to release microdevices into the system substrate. The cartridge is divided into interfering zones and intermixing areas. The interfering zones in the cartridge are related to the areas in the system substrate that require different types of microdevices. The intermixing zones are associated with the same kind of microdevices in the system substrate but with devices from different donor zones. A selected set of microdevices from the first donor zone are transferred into the first cartridge's intermixing zone. A second donor zone is selected, and a set of microdevices from the second donor zone is integrated into the second cartridge intermixing zone, which differs from the first cartridge intermixing zone.

[0015] The process continues with different cartridges and different donor zones. A set of cartridges is selected where they have different intermixing areas filled by microdevices, and the combination of the intermixing areas can cover the entire area of a system substrate. The first cartridge is aligned with the system substrate, and a selected set of microdevices is transferred into the system substrate areas associated with the first intermixing zones. A second cartridge is aligned with the system substrate, and a selected set of microdevices is transferred into the system substrate areas associated with the second intermixing zones. The process continues till the microdevices fill all the intended areas in the system substrate.

[0016] The selection of donor zones can be random, or it can follow a process where the microdevices of each zone are within a set of performance parameters.

[0017] The transfer can be done by bonding the microdevices from the cartridge to the system substrate, laser or thermal dissociation.

[0018] 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.

Claims

Claims1. A method of populating a system substrate, the method comprising: forming a cartridge by developing a substrate is developed by releasing microdevices into the system substrate; having the cartridge where an intermixing method is embedded in the cartridge; having arrays of microdevices in the cartridge wherein the cartridge is aligned with an area of a system substrate; and transferring a selected sub-array of microdevices from the cartridge into the system substrate.

2. The method of claim 1, wherein a wafer or wafers are divided into different donor zones.

3. The method of claim 2, wherein the cartridge is divided into intermixing and interfering zones wherein the interfering zones in the cartridge are related to the areas in the system substrate that require different types of microdevices, and the intermixing zones are associated with the same kind of microdevices in the system substrate but with microdevices from different donor zones.

4. The method of claim 3, wherein a predefined set of donor zones is selected from at least one wafer.

5. The method of claim 4, wherein a selected set of microdevices from a first donor zone are transferred into a cartridge's first intermixing zone.

6. The method of claim 5, wherein a second donor zone is selected, and a set of microdevices from the second donor zone is integrated into the second intermixing zone in the cartridge.

7. The method of claim 6, wherein the process continues until all intermixing zones are populated with microdevices with different donor zones and the cartridge is aligned with the system substrate, and a selected set of microdevices is transferred into the system substrate wherein further the microdevices transferred in the system substrate are a mix of devices from different donor zones.

8. The method of claim 6, wherein a selection of donor zones is random, or follows a process where the microdevices of each donor zone are within a set of performance parameters.

9. The method of claim 6, wherein the transfer can be done by bonding the microdevices from the cartridge to the system substrate, laser or thermal dissociation.

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