Semiconductor Grounding Structure for Mechanical Strain Management

Solution Overview

Problem

Semiconductor devices experience mechanical stress and cracking issues due to plastic moulding, leading to shear forces and potential short circuits, especially in isolation and passivation layers near bond pads and vias, which can result in device failure.

Innovation Solution

A supporting structure comprising a grounding structure with a harder material than the neighbouring layers, such as thermal oxide or silicon dioxide, is used to connect upper isolation and passivation layers to lower layers or the substrate, providing mechanical fixation and absorbing shear forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If plastic moulding is applied to the semiconductor device, then the device is protected and sealed, but mechanical stress and shear forces are induced into the isolation and passivation layers causing cracks and potential short circuits

Engineering Contradiction:

Improvedevice protection and sealingVSAvoidmechanical strength of isolation and passivation layers

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent introduces separate grounding structures that segment the mechanical stress path, creating independent support points for the isolation and passivation layers. These grounding structures divide the continuous stress field into discrete regions, preventing crack propagation across the entire layer while maintaining the protective sealing function of the plastic moulding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structures by combining the isolation and passivation layers with grounding structures made of different materials having complementary mechanical properties. The grounding structures provide enhanced mechanical strength and stress distribution, creating a composite system that maintains layer integrity under plastic moulding stress while the isolation layers provide their intended electrical functions.

Inventive Principle:

Principle #40Composite materials

2Length of moving object

If the isolation and passivation layers are made thinner to reduce device size, then the device dimensions are reduced, but the layers become more susceptible to mechanical stress and cracking

Engineering Contradiction:

Improvedevice dimensionsVSAvoidresistance to mechanical stress and cracking

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent applies local quality enhancement by introducing grounding structures specifically at critical locations where the isolation and passivation layers are most vulnerable to stress. Rather than uniformly thickening all layers, the grounding structures provide localized mechanical support precisely where needed, maintaining thin overall dimensions while reinforcing stress-prone regions to prevent cracking.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional grounding structures with similar hardness to neighbouring layers are used, then the fabrication is simpler, but the grounding structures cannot effectively absorb mechanical stress and prevent cracks

Engineering Contradiction:

Improvefabrication simplicityVSAvoidstress absorption capability

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the material parameter of hardness for the grounding structures, making them significantly harder than the neighbouring isolation and passivation layers. This parameter change enables the grounding structures to effectively absorb and distribute mechanical stress, preventing crack initiation and propagation in the softer isolation layers while maintaining compatibility with standard fabrication processes.

Inventive Principle:

Principle #35Parameter changes

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 solution significantly reduces the risk of cracks and enhances the lifespan of semiconductor devices by mechanically stabilizing the isolation and passivation layers, even under varying thermal conditions, by transferring mechanical strain into the substrate.

Implementation Method 1

A supporting structure comprising a grounding structure with a harder material than the neighbouring layers, such as thermal oxide or silicon dioxide, is used to connect upper isolation and passivation layers to lower layers or the substrate, providing mechanical fixation and absorbing shear forces.

Methodology Applied

Scientific EffectStress absorption:

Implementation Method 2

This solution significantly reduces the risk of cracks and enhances the lifespan of semiconductor devices by mechanically stabilizing the isolation and passivation layers, even under varying thermal conditions, by transferring mechanical strain into the substrate.

Methodology Applied

Scientific EffectMechanical stress transfer:

Data Source

PatentUS8062974B2Semiconductor device with grounding structure

Publication Date: 2011.11.22 NEXPERIA BV

AI summary

Conductions and vias between different, stacked metallic layers of a semiconductor device may be mechanically damaged by mechanical strain. According to an exemplary embodiment of the present invention, this mechanical strain may be transferred through the layer structure to the substrate by a grid of grounding structures and isolation and passivation layers which are connected by the grounding structures. This may provide for an enhancement of the lifetime of the semiconductor devices.