Wafer-Integrated Test Coupler for Photonic Device Alignment
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Solution Overview
Problem
Wafer-level testing of photonic devices, such as silicon photonics, is slow and costly due to difficulties in coupling optical test signals in and out of numerous devices, requiring complex optical alignment for each device under test.
Innovation Solution
A wafer configuration with a test coupler that allows for a single alignment step to couple optical test signals between a tester and multiple photonic devices, using structures like cascade tap couplers and on-chip switches for parallel testing, enabling efficient and reliable testing of multiple devices simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional individual device testing is used, then measurement precision is maintained, but productivity deteriorates due to slow testing speed
Solution Approach 1:
The patent segments the testing process by providing individual access ports for each photonic device on the wafer, allowing each device to be tested independently through its own dedicated test coupler while maintaining measurement precision. This enables parallel testing of multiple devices without compromising the accuracy of individual measurements.
Solution Approach 2:
The test coupler structure serves multiple functions: it provides optical coupling for individual device testing, enables parallel testing of multiple devices, and maintains measurement precision through dedicated access ports. This multi-functional design resolves the contradiction by allowing both high productivity through parallel testing and high measurement precision through individual device access.
2Measurement precision
If complex optical alignment is performed for each device, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The test coupler is pre-integrated into the wafer structure during fabrication, with each coupler positioned and configured before testing. This preliminary action eliminates the need for complex real-time optical alignment during testing, as the couplers are already precisely positioned to interface with the photonic devices. The alignment is performed once during manufacturing rather than repeatedly during testing.
3Measurement precision
If individual testing of each photonic device is performed, then measurement precision is maintained, but device complexity increases due to multiple alignment steps
Solution Approach 1:
The patent merges the test coupler functionality directly into the wafer structure, combining the testing interface with the device substrate. This integration reduces testing system complexity by eliminating separate alignment components while maintaining measurement precision through dedicated access ports for each device. The test coupler array is fabricated as part of the wafer, creating a unified structure that simplifies the overall testing system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables fast and reliable wafer-level testing of photonic devices with separate measurement of individual devices using a single alignment, reducing testing time and cost by simplifying the alignment process and allowing for parallel testing.
Implementation Method 1
The test coupler is disposed on the wafer and is configured to couple an optical test signal between a tester and the multiple ports of the multiple photonics devices
Data Source
AI summary
A wafer includes a semiconductor substrate, multiple photonics devices and a test coupler. The multiple photonics devices are fabricated on the substrate and have multiple respective ports. The test coupler is disposed on the wafer and is configured to couple an optical test signal between a tester and the multiple ports of the multiple photonics devices during testing of the photonics devices.