Semiconductor Device Crack Starting Point Layer

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Solution Overview

Problem

Existing semiconductor devices face the challenge of cracks occurring due to temperature cycles, which can propagate into the electrode layer, compromising the device's integrity.

Innovation Solution

The semiconductor device incorporates a crack starting point layer with a lower joining force to the solder layer than the electrode layer, ensuring that any cracks initiated within the device preferentially propagate into the solder layer rather than the electrode layer, thereby protecting the electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a semiconductor element protection resin is provided to improve crack resistance, then the overall crack resistance of the device is improved, but cracks can still propagate into the electrode layer causing device failure

Engineering Contradiction:

Improvecrack resistanceVSAvoidcrack propagation into electrode layer

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A crack starting point layer is introduced as an intermediary between the solder layer and the electrode layer. This intermediate layer has controlled material properties (lower joining force with solder than the electrode) to serve as a designated crack initiation zone, preventing cracks from propagating into the electrode layer while maintaining overall device reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of crack formation into a beneficial outcome by providing a designated crack starting point layer. Cracks are allowed to form and propagate into this sacrificial layer, which has lower bonding strength, thereby protecting the electrode layer from crack damage. The harm of crack propagation is redirected to a controlled location that does not compromise device functionality

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If the crack starting point layer is made with material that forms alloy less easily with solder, then cracks preferentially propagate into the solder layer protecting the electrode, but the joining force between solder and crack starting point layer becomes weaker

Engineering Contradiction:

Improvecrack propagation direction controlVSAvoidjoining force between solder and crack starting point layer

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The crack starting point layer is designed with localized specific properties: it is positioned only in regions where crack initiation is desirable (peripheral regions between intermediate and solder joint layers), and its material composition is specifically selected to have lower joining force with solder compared to the electrode layer. This local differentiation in material properties ensures cracks propagate into the crack starting point layer rather than the electrode layer

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9553067B2Semiconductor device

Publication Date: 2017.01.24 DENSO CORP

AI summary

A semiconductor device includes a semiconductor layer, an electrode layer arranged on the semiconductor layer, a crack starting point layer arranged above the semiconductor layer, and a solder layer being in contact with the electrode layer and the crack starting point layer. A joining force between the solder layer and the crack starting point layer is smaller than a joining force between the solder layer and the electrode layer.