Crack Stop Ring Trench for GaN-on-Si Substrate Crack Isolation

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Solution Overview

Problem

The challenge in semiconductor manufacturing is the propagation of cracks in stacked semiconductor substrates due to thermal expansion mismatch between silicon and gallium nitride layers, which can lead to yield loss and reliability issues in device regions.

Innovation Solution

A crack stop ring trench is introduced around the central device region, extending in a closed path between the central and peripheral regions, preventing cracks from propagating into the device area by separating the peripheral region cracks from the central region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stacked semiconductor substrate structure is used to achieve high performance devices, then device performance is improved, but crack propagation occurs due to thermal expansion mismatch

Engineering Contradiction:

Improvedevice performanceVSAvoidcrack propagation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the semiconductor substrate into distinct regions by introducing a trench structure. The trench segments the substrate into a first region (containing device regions) and a second region (peripheral region), preventing crack propagation from the peripheral region into the device regions while maintaining the overall stacked substrate structure for high performance devices.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If the substrate is cooled from growth temperature, then crystal structure stabilizes, but cracks form and propagate in the peripheral region

Engineering Contradiction:

Improvecrystal structure stabilityVSAvoidcrack formation

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent performs preliminary action by forming the trench structure before cracks can propagate into the device regions. The trench is created as a preventive measure during the manufacturing process, establishing a barrier that stops crack propagation from the peripheral region where cracks naturally form during cooling, thereby protecting the device regions while maintaining crystal structure stability.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If peripheral region is allowed to contain cracks, then manufacturing process is simpler, but yield and reliability are reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidyield

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent uses segmentation to isolate the peripheral region (which can contain cracks) from the device regions. By creating a trench that divides the substrate into distinct first and second regions, the patent allows the peripheral region to maintain its simpler manufacturing characteristics while preventing cracks from affecting the device regions, thereby preserving both manufacturing ease and high yield.

Inventive Principle:

Principle #1Segmentation

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 effectively prevents cracks from reaching the device regions, enhancing yield, reliability, and performance by isolating the device area from crack propagation, thereby improving the stability and functionality of semiconductor devices.

Implementation Method 1

one or more sidewalls defining a crack stop ring trench that continuously extends in a closed path between the central region and the peripheral region... configured to prevent a plurality of cracks within the peripheral region from propagating to the central region

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

thermal expansion mismatch between silicon and gallium nitride layers... base silicon substrate having a first coefficient of thermal expansion and the III-N semiconductor material having a second coefficient of thermal expansion that is different than the first coefficient of thermal expansion

Methodology Applied

Scientific EffectThermal expansion mismatch: Thermal Expansion

Data Source

PatentUS12094838B2Crack stop ring trench to prevent epitaxy crack propagation

Publication Date: 2024.09.17 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In some embodiments, the present disclosure relates to a semiconductor structure. The semiconductor structure includes a stacked semiconductor substrate having a semiconductor material disposed over a base semiconductor substrate. The base semiconductor substrate has a first coefficient of thermal expansion and the semiconductor material has a second coefficient of thermal expansion that is different than the first coefficient of thermal expansion. The stacked semiconductor substrate includes one or more sidewalls defining a crack stop ring trench that continuously extends in a closed path between a central region of the stacked semiconductor substrate and a peripheral region of the stacked semiconductor substrate surrounding the central region. The peripheral region of the stacked semiconductor substrate includes a plurality of cracks and the central region is substantially devoid of cracks.