Wafer Bonding Trenches for Thermal Expansion Management
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Solution Overview
Problem
During the bonding of wafers, air bubbles or elevations in the bonding material can cause damage or warping due to thermal expansion and contraction, posing a challenge in miniaturizing electronic products.
Innovation Solution
Incorporating trenches in at least one of the substrates, which are filled with an adhesive layer, allowing air bubbles or elevations to be temporarily stored or removed, thereby reducing distortion and warping during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a continuous adhesive layer is used for bonding wafers, then bonding strength is improved, but thermal expansion and contraction cause air bubbles or elevations that lead to wafer damage and warping
Solution Approach 1:
The adhesive layer is segmented into discrete adhesive units distributed across the bonding surface, rather than forming a continuous layer. This segmentation allows each unit to independently manage thermal expansion and contraction, preventing the formation of large air bubbles or elevations that could damage the wafer, while still providing adequate bonding strength through the distributed array of adhesive units
Solution Approach 2:
The adhesive units are designed with specific local characteristics including controlled size, shape, and spacing to optimize both bonding performance and thermal management. Each adhesive unit's dimensions and distribution pattern are tailored to provide sufficient adhesion while creating voids or spaces that accommodate thermal expansion and contraction, thus preventing wafer warping and damage
2Reliability
If the adhesive layer is made thicker to ensure complete coverage, then bonding reliability is improved, but thermal expansion causes more significant distortions and warping
Solution Approach 1:
Rather than using a single thick continuous adhesive layer that would cause significant thermal distortion, the adhesive is divided into multiple smaller discrete units. This segmentation maintains adequate adhesive coverage for reliable bonding while the spaces between units provide relief for thermal expansion, preventing excessive warping and maintaining wafer flatness
Solution Approach 2:
The segmented adhesive structure creates a porosity-like effect with spaces between adhesive units that can accommodate thermal expansion and contraction. This porous configuration allows the adhesive layer to manage thermal stresses without requiring excessive adhesive material, thus maintaining both bonding reliability and wafer flatness
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
The use of trenches in the substrates effectively prevents damage and warping by dispersing forces and allowing the adhesive layer to expand and contract without causing harm, enhancing the reliability of the bonding structure.
Implementation Method 1
The wafer may be burst or cracked because of thermal expansion and contraction of the bonding material
Data Source
AI summary
A bonding structure including a first substrate, a second substrate, and an adhesive layer is provided. The first substrate has a plurality of first trenches. The adhesive layer is located between the first substrate and the second substrate, and the first trenches are filled with the adhesive layer.