Optical Probe Facet Total Reflection Wafer Testing
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Solution Overview
Problem
Current methods for detecting wafer-level planar optical components are inefficient, costly, and time-consuming, particularly due to challenges in coupling efficiency and alignment accuracy, which hinder the analysis of device process yield and increase production costs and product development cycles.
Innovation Solution
An optical probe with a facet at the bottom of the optical fiber, forming a specific angle for total reflection, coupled with a microlens system and positioning block, allows for accurate and efficient testing of uncut wafers, improving alignment and coupling efficiency before wafer cutting and polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface light coupling with grating structure is used, then optical detection can be achieved, but coupling efficiency is difficult to improve and alignment complexity increases
Solution Approach 1:
The patent extracts the grating structure from the coupling system and replaces it with a facet-based total internal reflection mechanism. The grating is completely removed from the optical path, and instead a simple facet at the optical fiber end face performs the coupling function through total internal reflection, significantly simplifying the system.
Solution Approach 2:
The patent introduces a microlens as an intermediary element between the optical fiber and the wafer. This microlens focuses the reflected light onto the wafer surface, enabling efficient coupling without requiring complex grating structures or precise angular alignment mechanisms.
2Measurement precision
If vertical coupling accuracy is ensured with special structure, then alignment precision improves, but cost and size of test element increase substantially
Solution Approach 1:
The optical fiber's own facet structure performs the alignment function. By forming a facet at a specific angle (40-45 degrees) on the optical fiber end face, the system uses the fiber's geometry itself to achieve precise angular alignment through total internal reflection, eliminating the need for external alignment structures.
Solution Approach 2:
The patent changes the geometric parameter of the optical fiber end face by creating a facet at a specific angle range (40-45 degrees). This parameter change enables total internal reflection and provides inherent angular alignment, achieving precise vertical coupling without additional mechanical alignment structures.
3Ease of manufacture
If wafer cutting and polishing is performed before detection, then standard end-coupling testing can be used, but detection timing is delayed and process yield analysis is postponed
Solution Approach 1:
The patent performs optical detection at the wafer level before cutting and polishing the individual chips. By implementing facet-based coupling that works on the uncut wafer surface, the system enables early detection and process yield analysis, allowing corrective actions to be taken before final chip fabrication is complete.
4Adaptability or versatility
If manual coupling is used for testing, then flexibility is maintained, but testing efficiency decreases and productivity is limited
Solution Approach 1:
The patent replaces manual mechanical coupling operations with an automated optical system. The facet-based total internal reflection mechanism combined with microlens focusing creates a system that can be easily automated, enabling high-speed parallel testing of multiple chips on a wafer without manual intervention.
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 early analysis of component process yield, reduces production costs and development cycles, enhances detection accuracy, and ensures high-speed, reliable inspection of optical chips on uncut wafers with improved alignment and coupling efficiency.
Implementation Method 1
the bottom of the optical fiber of the optical probe is provided with a facet having a first angle to cause total reflection of the optical signal transmitted by the optical fiber
Implementation Method 2
The optical signal after total reflection enters the optical waveguide of the optical chip through a microlens
Data Source
AI summary
An optical probe for optoelectronic integrated circuits is provided, applicable to a test environment for testing a plurality of optical chips on a wafer. The optical chips include at least one optical waveguide, and the optical probe includes a substrate and an optical fiber. The facet of the optical fiber has a first angle, and the first angle causes the optical signal transmitted by the optical fiber to generate total reflection, and the optical signal after total reflection enters the optical waveguide of the optical chip. Thereby, an optical probe able to perform testing before wafer cutting and polishing is provided, and a high-speed, effective and reliable detection is achieved.