Semiconductor Die Strain Detection via BEOL Metallic Structures

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Solution Overview

Problem

Thinning semiconductor dies to reduce IC package thickness poses a challenge in maintaining structural integrity, as existing methods lack accurate strain measurement techniques to ensure the semiconductor die can withstand applied stress.

Innovation Solution

A method involving a metallic structure in the BEOL metallization of semiconductor dies, where a measurement signal is transmitted to detect resistance changes, allowing for the determination of strain, with multiple meandering conductive paths in different layers enabling strain measurement around orthogonal axes, utilizing a Wheatstone Bridge configuration for resistance detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If semiconductor die thickness is reduced to decrease IC package thickness, then IC package thickness is reduced, but structural integrity of the semiconductor die deteriorates

Engineering Contradiction:

ImproveIC package thicknessVSAvoidstructural integrity of semiconductor die

Core Design Contradiction:

Length of stationary objectVSStrength

Solution Approach 1:

The patent applies preliminary action by incorporating strain gauge structures (meandering metallic pathways) into the BEOL metallization layers before the semiconductor die is thinned. This allows strain measurement capabilities to be established in advance, enabling real-time monitoring of structural integrity during and after the thinning process, thus facilitating safe reduction of die thickness while maintaining structural assurance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional mechanical strain measurement methods with an electrical resistance-based measurement system. The meandering metallic pathways in the BEOL metallization serve as strain gauges whose electrical resistance changes in response to mechanical strain, allowing non-contact, precise strain measurement that does not add mechanical complexity to the thinned die structure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Length of stationary object

If semiconductor die thickness is reduced to decrease IC package thickness, then IC package thickness is reduced, but measurement capability to ensure structural integrity is insufficient

Engineering Contradiction:

ImproveIC package thicknessVSAvoidstrain measurement capability

Core Design Contradiction:

Length of stationary objectVSMeasurement precision

Solution Approach 1:

The patent applies universality by designing the BEOL metallization layers to serve dual functions: their primary function as electrical interconnects and their secondary function as strain gauge structures for measurement. The meandering pathways in the metallization layers simultaneously conduct electrical signals and provide strain measurement capability, eliminating the need for separate measurement infrastructure and enabling precise strain monitoring in thinned dies

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces the meandering metallic pathways as an intermediary element that mediates between the mechanical strain on the thinned die and the electrical measurement system. These pathways convert mechanical deformation into measurable electrical resistance changes, providing a reliable measurement mechanism that works effectively in thinned die structures where traditional measurement methods would be insufficient

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

Enables accurate measurement of strain on semiconductor dies, allowing for safe thinning without compromising structural integrity, thereby supporting the continuous reduction of IC package thickness while ensuring the semiconductor die can withstand applied stress.

Implementation Method 1

determining a strain of the semiconductor die based on the resistance of the metallic structure

Methodology Applied

Scientific EffectStrain: Deformation

Implementation Method 2

detecting a resistance of the metallic structure in response to the transmission of the measurement signal

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS20240426682A1Semiconductor die level stress detection in package utilizing strain gauge structures

Publication Date: 2024.12.26 QORVO US INC

AI summary

In some embodiments, a method of measuring strain on a semiconductor substrate of a semiconductor die is disclosed. The semiconductor die further includes a Back End of Line (BEOL) positioned on the semiconductor substrate that includes a metallic structure. In some embodiments, the method includes transmitting a measurement signal into the metallic structure. In some embodiments, the method further includes detecting a resistance of the metallic structure in response to the transmission of the measurement signal. In some embodiments, the method includes determining a strain of the semiconductor die based on the resistance of the metallic structure.