Hole Depth Measurement via Phase Extraction from Reflectance Spectrum

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Solution Overview

Problem

Accurately measuring the depth of holes in high aspect ratio TSV structures is challenging due to their structural features, which affects the overall TSV process accuracy.

Innovation Solution

A method using phase extraction information from a reflectance spectrum to measure hole depth, involving acquiring a reflectance spectrum, converting intensity-wave number data into phase-wave number data, and determining hole depth from the slope of straight lines in the phase-wave number distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional measurement methods are used for high aspect ratio hole structures, then the measurement process is simple, but the measurement precision and resolution are insufficient

Engineering Contradiction:

Improvehole depth measurement precisionVSAvoidmeasurement process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the measurement approach by changing from direct intensity-based depth measurement to phase-based measurement. By extracting phase information from the reflectance spectrum and analyzing the linear relationship between phase and wave number, the measurement precision is significantly improved while maintaining a manageable process complexity through systematic data transformation steps.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional direct physical measurement methods with optical spectrum analysis. By using phase extraction from reflectance spectrum instead of direct geometric measurement, the system achieves higher precision for high aspect ratio structures without requiring complex mechanical measurement apparatus.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If direct intensity-based measurement is used, then the measurement process is straightforward, but the measurement resolution is insufficient for high aspect ratio structures

Engineering Contradiction:

Improvedepth size measurement resolutionVSAvoidmeasurement difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces phase information as an intermediary parameter between the reflectance spectrum and the hole depth measurement. By extracting phase from the spectrum and using the linear phase-wave number relationship, the measurement resolution is enhanced while the systematic approach keeps the measurement process manageable despite increased complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances measurement resolution and accuracy for hole depth measurements in TSV structures, allowing for precise control of TSV processes.

Implementation Method 1

acquiring a reflectance spectrum from a target region, the target region having therein a hole structure with a high aspect ratio

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

performing a Hilbert transform to obtain an analytical signal having a real part term in a cosine form and an imaginary part term in a sine form

Methodology Applied

Scientific EffectHilbert transform:

Implementation Method 3

converting the first distribution data into intermediate data having a real part term and an imaginary part term; performing a Fourier transform

Methodology Applied

Scientific EffectFourier transform:

Data Source

PatentUS20250172384A1Method, measurement system, and computer-readable medium for measuring hole depth using phase extraction information from reflectance spectrum

Publication Date: 2025.05.29 CHROMA ATE INC

AI summary

A method, measurement system and computer-readable medium for measuring a hole depth using phase extraction information from a reflectance spectrum. The method includes a step of acquiring a reflectance spectrum, a step of obtaining the correlation between the intensity and a wave number of a reflected light, a step of phase extraction and a step of determining a hole depth. By converting first distribution data between the intensity and the wave number of the reflected light into second distribution data between a phase and the wave number, information of the hole depth of a hole structure is obtained by calculating a slope value. Thus, a measurement resolution can be increased and the accuracy can be enhanced.