Microdevice Substrate Integration With Patterned Protective Layer Bonding
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Solution Overview
Problem
The challenge lies in efficiently integrating millions of microdevices with circuits for every pixel with proper yield, particularly due to issues with transfer processes and bonding repeatability and reliability at small pad sizes, which affect system yield and lifetime.
Innovation Solution
A method involving the transfer of microdevices to a system substrate, followed by forming a protective layer, patterning it for conductive electrodes, and connecting backplane elements to the microdevices, enhancing integration efficiency and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microdevices are transferred to a system substrate using conventional transfer processes, then integration of millions of microdevices with circuits is achieved, but bonding repeatability and reliability deteriorate at small pad sizes
Solution Approach 1:
The patent applies preliminary action by forming a protective layer over the microdevices before the transfer process. This protective layer is patterned to expose only the bonding pads, ensuring that the pads are protected during transfer while remaining accessible for bonding. This pre-preparation resolves the contradiction by enabling reliable bonding at small pad sizes through advance protection and exposure configuration.
Solution Approach 2:
The protective layer serves as an intermediary element between the microdevice and the external environment during transfer. It mediates the transfer process by providing mechanical protection while allowing precise exposure of bonding pads through patterning, thus maintaining bonding reliability without compromising transfer productivity.
2Productivity
If conventional transfer and bonding processes are used, then microdevices are integrated with circuits, but system yield deteriorates due to bonding reliability issues
Solution Approach 1:
By forming and patterning the protective layer before transfer, the patent ensures that bonding pads are pre-protected and pre-positioned for optimal bonding. This preliminary configuration maintains high system yield by preventing bonding defects that would otherwise occur with conventional processes.
3Area of moving object
If small pad sizes are used for microdevice integration, then device density is improved, but bonding reliability deteriorates
Solution Approach 1:
The protective layer is selectively patterned to provide different properties in different locations: it protects the bonding pads with precise local exposure while leaving other areas exposed or covered as needed. This local differentiation enables reliable bonding at small pad sizes by providing targeted protection and exposure configuration.
Data Source
AI summary
An integrated optical display system includes a backplane with appropriate electronics, and an array of micro-devices. A touch sensing structure may be integrated into the system. In one embodiment, an integrated circuit and system is integrated on top of micro-devices transferred to a substrate. Openings in a planarization layer (or layers) may be provided to connect the micro-devices with electrodes and other circuitry. Light reflectors may be used to redirect the light, and color conversion layers or color filters may be integrated before the micro-devices or on the substrate surface opposite to the surface of micro-devices.