Microdevice Cartridge Bonding Structure for Sub-10 µm Pad Alignment
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Solution Overview
Problem
The challenge in micro-device integration lies in the difficulty of handling and bonding small bond pads, which requires precise alignment and can compromise bonding quality due to their small surface area, particularly for devices smaller than 10 micrometers.
Innovation Solution
The integration method involves forming extension layers around the micro-devices to expand the bonding area, with conductive pads extended to these layers, and using sacrificial and planarization layers to facilitate bonding to a backplane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of micro devices is reduced to produce more devices in one wafer substrate, then the cost per micro-device is reduced, but the handling and bonding becomes more challenging due to smaller bond pads
Solution Approach 1:
The patent extends the bonding area from the traditional planar pad surface to include vertical sidewalls by forming extension layers that protrude from the device surface. This dimensional transition from 2D to 3D bonding surfaces increases the effective bonding area without increasing the device footprint, thereby maintaining high device density while improving bonding ease.
Solution Approach 2:
The patent performs preliminary actions by forming extension layers and transferring pads to the backplane before final device bonding. The backplane is pre-prepared with receiving pads and alignment features, and extension layers are pre-formed on device sidewalls, enabling more robust and alignment-tolerant bonding operations.
2Length of moving object
If the bond pad size is reduced for sub 10 micrometer devices, then the device size is reduced, but the alignment precision requirement increases significantly
Solution Approach 1:
The patent transitions from 2D planar pad bonding to 3D bonding by extending pads and forming extension layers on sidewalls. This provides multiple bonding contact points (top surface and sidewalls) that collectively increase the effective bonding area, thereby reducing the stringency of alignment precision requirements while maintaining small device dimensions.
Solution Approach 2:
The patent employs composite structures combining extension layers (conductive or insulating materials) with the device body, creating a multi-material bonding interface. This composite bonding structure provides both mechanical robustness and electrical functionality, tolerating larger alignment variations compared to traditional small pad bonding.
3Length of moving object
If the bond pad surface area is reduced, then the device size is reduced, but the bonding quality is compromised
Solution Approach 1:
The patent enhances bonding quality by adding vertical dimension to the bonding interface through extension layers on sidewalls. This transforms the bonding from a single small planar contact to multiple distributed contacts across top and sidewall surfaces, significantly improving bonding strength and reliability while maintaining small device size.
Solution Approach 2:
The patent performs preliminary pad transfer to the backplane and forms extension layers before final bonding. This preliminary preparation creates a more robust bonding interface with increased contact area and improved mechanical interlocking, thereby enhancing bonding quality and device reliability.
Data Source
AI summary
What is disclosed is structures and methods of integrating micro devices into system substrate. Further, the disclosure, also relates to methods and structures for enhancing the bonding process of micro-devices into a substrate. More specifically, it relates to expanding the micro device area or bonding area of micro devices.