Photonic IC Layout for Same-Side Optical and Electrical Testing
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Solution Overview
Problem
The challenge of simultaneously testing electrical and optical functions in integrated circuits (ICs) is complicated by the misalignment of input/output points, leading to significant optical signal loss due to diffraction and scattering, rendering optical testing less effective.
Innovation Solution
The integration of a grating coupler, inverse grating coupler, and reflector structure within the IC device facilitates same-side electrical and optical testing by directing light from both sides to a photodetector, enhancing optical signal power and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical and optical I/O points are positioned on opposite sides of the device, then operational optical functionality is supported, but optical signal loss occurs during testing due to diffraction and scattering effects
Solution Approach 1:
The patent implements an inverse grating coupler that operates in reverse of the operational grating coupler. While the operational grating coupler directs light from the top surface through the waveguide to the photodetector, the inverse grating coupler receives test light from the bottom surface and directs it through the same waveguide path to the photodetector, enabling same-side testing without compromising signal integrity
Solution Approach 2:
The patent introduces a reflector structure as an intermediary component that reflects light between the inverse grating coupler and the photodetector. This reflector enables the test light path to navigate around obstacles and reach the photodetector from the bottom surface, facilitating same-side testing while maintaining optical signal integrity
2Productivity
If same-side testing is implemented, then testing efficiency is improved, but optical signal loss due to diffraction and scattering increases
Solution Approach 1:
The patent positions the inverse grating coupler and reflector at specific locations on the bottom surface of the device, creating localized test access points. This allows same-side testing to be performed without affecting the operational optical paths on the top surface, maintaining signal integrity while improving testing efficiency
Solution Approach 2:
By implementing the inverse grating coupler that operates in reverse of the operational coupler, the patent enables test light to enter from the bottom surface and traverse the same high-quality waveguide path used during operation, minimizing diffraction and scattering losses while enabling same-side testing
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
This approach enables more accurate and precise simultaneous electrical and optical testing, improving chip yield determination and process monitoring.
Implementation Method 1
a grating coupler configured to receive first light via the optical lens and to direct the first light to the photodetector
Implementation Method 2
an inverse grating coupler configured to receive second light via a backside surface and to direct the second light to the photodetector
Implementation Method 3
a reflector configured to receive third light from the inverse grating coupler and to direct the third light back to the inverse grating coupler
Data Source
AI summary
Some embodiments relate to an integrated circuit (IC) device that includes a first substrate including an optical lens at a frontside surface of the first substrate, an electrical IC structure disposed proximate a backside surface of the first substrate, and a photonic IC structure disposed proximate a backside surface of the electrical IC structure. The photonic IC structure includes a second substrate providing a backside surface of the photonic IC structure; a photodetector, a grating coupler, and an inverse grating coupler disposed over a frontside surface of the second substrate; and a reflector disposed at a frontside surface of the photonic IC structure. The grating coupler and the inverse grating coupler are configured to direct light from the optical lens and the backside surface of the second substrate, respectively, to the photodetector. The reflector is configured to direct light from the inverse grating coupler back to the inverse grating coupler.