Optical Probe With Diffraction Grating For Wafer Inspection
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Solution Overview
Problem
High-density optical integrated circuits on silicon wafers are challenging to inspect efficiently due to the need for precise alignment and adjustment of optical fibers with silicon wire waveguides, which requires complex and inaccurate processes.
Innovation Solution
An optical probe with a diffraction grating at its end is used to contact and inspect the diffraction gratings of optical circuits on the wafer, eliminating the need for inclination angle adjustments and allowing for efficient evaluation of optical characteristics by changing the direction of the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffraction grating is formed within a plane of a silicon wafer and an optical fiber is provided to face the diffraction grating at an inclination of approximately 10 degrees, then optical coupling between the optical fiber and the silicon wire waveguide can be achieved, but it necessitates a troublesome process of aligning the optical fiber and the silicon wire waveguide with high alignment accuracy
Solution Approach 1:
The patent introduces a diffraction grating as an intermediary component between the optical fiber and the silicon wire waveguide. The diffraction grating changes the direction of the optical axis, enabling optical coupling without requiring the optical fiber to be inclined at approximately 10 degrees. This eliminates the troublesome alignment process while maintaining reliable optical coupling.
2Reliability
If the optical fiber is provided to face the diffraction grating at an inclination of approximately 10 degrees, then optical coupling can be achieved, but it requires accurate adjustment of relative position in XY direction, Z direction, and inclination angle
Solution Approach 1:
The diffraction grating serves as a mediator that redirects the optical axis without requiring the optical fiber to be inclined. This eliminates the need for complex adjustment mechanisms for XY position, Z position, and inclination angle, while ensuring reliable optical coupling.
3Measurement precision
If conventional methods are used to inspect optical circuits on silicon wafers, then measurement can be conducted for each measured portion, but inspection efficiency is reduced due to the need to cut end surfaces into chips and conduct measurement for each portion
Solution Approach 1:
The patent makes the diffraction grating universal by forming it within the plane of the silicon wafer, allowing a single wafer structure to serve multiple functions: optical coupling, light direction changing, and inspection of multiple optical circuits. This enables simultaneous or sequential inspection of multiple circuits without cutting chips, significantly improving inspection efficiency while maintaining measurement precision.
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 method enables efficient and accurate inspection of high-density optical circuits on silicon wafers without the need for precise alignment adjustments, improving inspection efficiency and reliability.
Implementation Method 1
a diffraction grating which changes a direction of an optical axis in a range between a direction of light propagated by the optical waveguide core and a direction of input/output of light to/from the input/output surface
Data Source
AI summary
Provided is an optical probe that includes an optical waveguide having a core layer and a cladding layer formed so as to cover the core layer, and a support member that supports an end portion of the optical waveguide. In the core layer, an optical waveguide core and a diffraction grating are provided. The diffraction grating is provided at an end of the optical waveguide core, has an input/output surface through which light is output to the outside or input from the outside, and converts the optical axis direction in a range between a light propagation direction in which light is propagated through the optical waveguide core and the input/output direction of light to/from the input/output surface. The support member supports the diffraction grating in such a manner that the input/output surface faces toward a predetermined direction.