Through-Silicon Via Depth Measurement Using Segmented Light Paths
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Solution Overview
Problem
Existing reflectometers face challenges in accurately measuring the depth of through-silicon vias with small apertures and high depth-to-width ratios due to inconsistencies in light signal reflection, leading to inaccurate depth measurements.
Innovation Solution
A sample depth-measuring device comprising a light source unit, light modulation unit, spectrum sensing unit, and image sensing unit, which projects and modulates light paths to distinguish between microstructure bottoms and surfaces, allowing for precise depth measurement through spectrum and image analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing reflectometers use a hole mirror to measure the depth of through-silicon vias with small apertures, then the measurement can be performed, but the measurement accuracy deteriorates due to detecting surface reflections instead of actual bottom depth
Solution Approach 1:
The patent segments the reflected light into multiple paths using a light modulation unit with microlenses. Each microlens corresponds to a specific via and directs its reflected light to a dedicated detection region on the sensor, preventing cross-contamination between adjacent vias and enabling accurate depth measurement for each individual via
Solution Approach 2:
The patent introduces a light modulation unit with microlenses as an intermediary between the sample and the sensor. This intermediary component modulates the reflected light paths, ensuring that light from each via's bottom reaches the correct detection region while blocking surface reflection interference, thereby achieving accurate depth measurement
2Ease of operation
If spectrometers measure light signal reflected from the surface around the aperture, then the measurement can be performed, but the result is inconsistent with the actual depth of the through-silicon via
Solution Approach 1:
The patent applies local quality by assigning different functional regions to different areas of the sensor. The detection region is specifically configured to receive light from the via bottom, while other regions handle surface reflection. This spatial differentiation ensures that depth measurement uses only the appropriate light signal, achieving accurate and consistent results
3Shape
If the distance between the through-silicon via and another adjacent through-silicon via is greater than the aperture, then the structure is easier to measure, but the spectrometer detects more surface area and cannot accurately measure the via depth
Solution Approach 1:
The patent segments the detection space using microlenses, where each microlens is positioned to correspond to a specific via. This segmentation creates dedicated detection regions for each via, ensuring that even when vias are spaced far apart, the system only detects light from the intended via bottom and not from surrounding surface areas or adjacent vias
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
The device achieves accurate depth measurements with a signal-to-noise ratio of over 95%, effectively reducing surface reflection and enhancing bottom layer signal intensity for small-aperture and low-density microstructures.
Implementation Method 1
a light source unit configured to project a first light path to a sample and receive a second light path reflected from the sample
Implementation Method 2
The light modulation unit includes an array of light intensity reflective elements arranged in a plurality, which are configured to reflect light onto the second light path within the array. Through the arrangement, one or more light intensity reflective elements can tilt the second light path by altering the light intensity
Implementation Method 3
The spectrum sensing unit is configured to receive the third light path to capture a spectrum corresponding to the bottoms
Implementation Method 4
The image sensing unit is configured to receive the fourth light path to measure a captured image corresponding to the sample
Data Source
AI summary
A measuring device includes a light source unit, a light modulation unit, a spectrum sensing unit, an image sensing unit, and a processing unit. The light source unit projects a first light path to a sample and receives a second light path reflected from the sample. The light module unit tilts the second light path to become a third light path or a fourth light path. The spectrum sensing unit receives the third light path to capture a spectrum corresponding to the microstructures. The image sensing unit receives the fourth light path to measure a captured image that corresponds to the sample. When the processing unit identifies the position of at least one of the microstructures in the captured image, the processing unit measures the depth of at least one of the microstructures from the spectrum for the identified area.