Wafer-Integrated μ-LED Test Structure for Faster Reliability Screening
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Solution Overview
Problem
Current methods for reliability testing of μ-LEDs on wafers require extensive additional work and time, involving removal, transfer, and further processing steps, which hinder efficient determination of selection probability and delay further processing of other components.
Innovation Solution
Integrating test structures onto the production wafer, allowing for direct testing or easy detachment without additional manufacturing steps, with contact elements already formed, thus minimizing complex procedures and error-influencing variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If μ-LEDs are removed from production wafer and transferred to carrier wafer for testing, then reliability testing can be performed, but additional work and time are required
Solution Approach 1:
The patent merges the production wafer and test structure into a single integrated system. The test structure is formed directly on the production wafer, eliminating the need to transfer μ-LEDs to a separate carrier wafer. This combining of production and testing functions on one substrate directly resolves the time loss associated with multiple transfer and preparation steps.
Solution Approach 2:
The test structure is prepared in advance on the production wafer during the manufacturing process, before the μ-LEDs are fully processed. Contact elements are pre-formed and test structures are pre-configured, so that when testing is needed, the components are already in the correct state for immediate testing without additional preparation time.
2Reliability
If μ-LEDs are removed and transferred to carrier wafer, then testing can be conducted, but additional production steps are required
Solution Approach 1:
The production wafer and test structure are merged into a single integrated system. The test structure includes contact elements and test components that are formed directly on the production wafer, eliminating the need for separate carrier wafers and reducing the number of production steps required for testing.
Solution Approach 2:
The production wafer serves multiple functions: it acts as both the manufacturing substrate for μ-LEDs and the test platform for reliability testing. The contact elements on the test structure can serve both production and testing purposes, making the system multi-functional and reducing overall process complexity.
3Productivity
If test structures are added to production wafer, then testing can be performed without transfer, but wafer structure becomes more complex
Solution Approach 1:
The wafer is segmented into distinct functional regions: production areas for manufacturing μ-LEDs and test areas with integrated test structures. The test structure itself is segmented into contact elements, test components, and connection regions. This segmentation allows the test structures to be added without significantly complicating the overall wafer design, as each region maintains a clear, simple function.
Solution Approach 2:
The test structures are localized to specific regions of the wafer rather than being distributed throughout. This allows the majority of the wafer to maintain its simple production-oriented structure, while only localized areas have the additional test structure complexity. The contact elements are locally formed where needed for testing specific μ-LEDs.
4Reliability
If conventional testing method is used, then reliability testing can be performed, but other components on wafer cannot be processed during testing preparation
Solution Approach 1:
Test structures are prepared in advance during the manufacturing process, before the wafer is ready for final testing. Contact elements are pre-formed and test structures are pre-configured on the production wafer, so that when testing is needed, no additional preparation time is required and other components can continue to be processed without interruption.
Data Source
AI summary
In an embodiment a wafer includes a plurality of optoelectronic components and means for testing at least one of the optoelectronic components for at least one parameter, wherein the plurality of optoelectronic components includes at least one light-emitting layer, which is arranged between an insulating layer and a light emission layer, wherein the insulating layer of at least one optoelectronic component comprises a first contact and a second contact arranged on the light emission layer of the at least one optoelectronic component, and wherein the second contact is arranged outside a light emission surface of the at least one optoelectronic component.