Optical Interference Microscope for Non-Destructive TSV Inspection
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Solution Overview
Problem
Current methods for inspecting three-dimensional laminated semiconductor wafers are either destructive, time-consuming, or unable to effectively detect minute and three-dimensional changes in the wafer surface, particularly in deep portions of Through-Silicon Vias (TSVs), limiting their ability to ensure high inspection accuracy and efficiency.
Innovation Solution
A method and apparatus that utilize illumination light with specific wavelengths to irradiate and detect diffracted light from the wafer surface, allowing for non-destructive inspection of the entire wafer surface, including deep portions, by adjusting the incidence and outgoing angles to satisfy diffraction conditions and using image processing to compare with non-defective wafer data for abnormality detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission image observation is used, then the observable area is extremely small, but it is impractical to inspect the TSVs of the entire wafer surface
Solution Approach 1:
The patent creates an inspection system that can simultaneously observe both surface and subsurface features across the entire wafer surface. The optical interference microscope achieves this by utilizing light reflection and refraction properties, allowing single-shot full-wafer inspection while maintaining the ability to detect TSV profiles, thereby eliminating the need for sequential multi-step inspection processes.
2Measurement precision
If destructive inspection methods are used, then the actual shape of the cross section can be observed, but the inspection is destructive and time-consuming
Solution Approach 1:
The patent replaces mechanical destructive sectioning methods with optical non-destructive inspection. By using optical interference to visualize internal structures through the wafer surface, the system obtains cross-section-like information without physically cutting or destroying the sample, thereby eliminating time-consuming preparation steps and enabling rapid inspection.
Solution Approach 2:
The patent introduces optical interference patterns as an intermediary to reveal internal structures. The interference fringes act as a mediator that encodes three-dimensional profile information, allowing indirect observation of TSV cross-sections through the intact wafer surface without requiring physical sectioning.
3Measurement precision
If infrared light microscopes are used, then transmission images can be obtained, but the region observable at one time is extremely small
Solution Approach 1:
The patent extends the observable area by utilizing optical reflection and refraction in three dimensions. The optical interference microscope captures information from the entire wafer surface simultaneously by analyzing light path differences, effectively expanding the observable area from microscopic regions to the full wafer diameter in a single measurement.
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 rapid and sensitive detection of abnormalities in TSVs across the entire wafer surface, including deep portions, improving inspection accuracy and efficiency while avoiding the limitations of traditional methods.
Implementation Method 1
detecting a light reflected from or transmitted through the substrate due to irradiation of the illumination light; and inspecting the substrate by utilizing information based on the pattern obtained from detection of the light reflected from or transmitted through the substrate
Data Source
AI summary
There is provided a method for inspecting a substrate including: irradiating an illumination light onto a first surface or a second surface opposite to the first surface, of a substrate in which a pattern having a periodicity and extending from the first surface to an inside of the substrate is formed in the first surface, the illumination light having a permeability to permeate the substrate to a predetermined depth; detecting a light reflected from or transmitted through the substrate due to irradiation of the illumination light; and inspecting the substrate by utilizing information based on the periodicity of the pattern obtained from detection of the light reflected from or transmitted through the substrate.