Ring Oscillator Strain Measurement via TSV Frequency Difference
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Solution Overview
Problem
Existing methods, such as micro-Raman spectroscopy and X-ray diffraction, are difficult to implement for measuring strain effects on transistors caused by through-silicon-vias (TSVs) due to their complexity and incompatibility with IC products, making it challenging to determine the impact of TSVs on transistor performance characteristics.
Innovation Solution
A ring oscillator system comprising two ring oscillators with different distances from a TSV, where a logic difference circuit detects the frequency difference between the two oscillators to quantify strain effects, allowing for sensitive measurement of TSV-induced stresses without delayering or breaking the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If micro-Raman spectroscopy or X-ray diffraction is used to measure strain effects, then measurement capability is provided, but device complexity and ease of operation deteriorate due to implementation difficulty and incompatibility with IC products
Solution Approach 1:
The patent replaces complex external measurement systems (micro-Raman spectroscopy, X-ray diffraction) with an integrated electrical measurement approach using ring oscillators. The strain measurement function is transferred from external sophisticated equipment to simple on-chip electronic circuits that can be fabricated alongside the TSV structure, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent introduces ring oscillators as intermediary elements that convert mechanical strain into measurable electrical frequency signals. These oscillators act as mediators between the physical strain field and the measurement system, enabling indirect but compatible measurement within the IC fabrication context without requiring complex external equipment
2Measurement precision
If micro-Raman spectroscopy or X-ray diffraction is used to measure strain effects, then strain measurement is enabled, but ease of operation worsens due to difficulty in implementation on IC products
Solution Approach 1:
The patent merges the strain sensing function with the IC fabrication process itself by integrating ring oscillator circuits directly into the substrate alongside the TSV structures. This combination allows strain measurement to be performed using standard IC manufacturing techniques, dramatically improving ease of operation and implementation compared to external measurement methods
Solution Approach 2:
The ring oscillator system is self-contained and operates autonomously on the IC substrate without requiring external specialized equipment. The oscillators generate their own test signals and the frequency differences directly indicate strain levels, enabling the system to serve itself for measurement purposes and eliminating operational complexity
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 approach effectively monitors strain-induced changes in transistors by measuring the frequency difference between ring oscillators closer and farther from a TSV, providing a sensitive and non-invasive method to assess the quality and robustness of TSV formation processes.
Implementation Method 1
characterizing strain effects introduced by through-silicon-vias (TSV) using Vernier ring oscillators
Data Source
AI summary
A ring oscillator system for characterizing substrate strain including, a substrate including a through-substrate-via, at least two ring oscillators, wherein a first ring oscillator is closer to the through-substrate-via than a second ring oscillator, and a logic difference circuit that is configured to receive an input from at least the first ring oscillator and the second ring oscillator, and detect a difference between the signal frequency of the first ring oscillator and the signal frequency of the second ring oscillator.