Alignment Key Structure With Contact Pattern for Thermal Stress Relief
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Solution Overview
Problem
Semiconductor wafers face stress issues due to thermal expansion differences between alignment key structures and insulating layers, leading to potential separation and adhesion problems during the semiconductor integration process.
Innovation Solution
Incorporating a contact pattern layer that extends upward from the alignment key structure and a connection pattern layer covering the contact pattern layer, which alleviates stress by increasing the contact area and improving adhesion between the alignment key structure and the insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin film alignment key structure is formed prior to lithography, then alignment functionality is achieved, but thermal stress causes separation and adhesion problems during integration
Solution Approach 1:
The alignment key structure is extended vertically by forming a contact pattern layer that protrudes upward from the top surface of the alignment key structure. This vertical extension into the third dimension increases the contact area with the insulating layer, thereby improving adhesion and reducing thermal stress separation.
Solution Approach 2:
The alignment key structure is formed as a composite of multiple materials including a first conductive layer (e.g., tungsten nitride), a second conductive layer (e.g., tungsten), and an insulating layer (e.g., silicon oxide). This multi-material composite structure provides both mechanical stability and thermal stress management through coordinated thermal expansion properties of different materials.
2Stability of the object's composition
If alignment key structure is formed as thin film layer, then fabrication simplicity is maintained, but structural stability under thermal deformation is insufficient
Solution Approach 1:
The alignment key structure is divided into multiple functional layers: a first conductive layer (tungsten nitride) providing thermal stress resistance, a second conductive layer (tungsten) providing mechanical strength, and an insulating layer (silicon oxide) providing electrical isolation. This segmentation allows each layer to contribute specific properties that collectively enhance structural stability.
Solution Approach 2:
The physical and chemical parameters of the alignment key structure are optimized by selecting materials with specific thermal expansion coefficients and mechanical properties. The multi-layer structure with controlled thicknesses (e.g., 50-200 nm for conductive layers, 100-500 nm for insulating layer) enables the structure to withstand thermal deformation while maintaining structural integrity.
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 stress alleviation structure effectively reduces thermal deformation-induced stress by up to 54%, enhancing the structural stability and adhesion between the alignment key structure and the insulating layer, thereby improving the semiconductor wafer's integrity.
Implementation Method 1
Semiconductor wafers face stress issues due to thermal expansion differences between alignment key structures and insulating layers
Data Source
AI summary
In an embodiment, a semiconductor wafer includes an alignment key structure disposed over a substrate, a contact pattern layer disposed on the alignment key structure to extend upward of the alignment key structure, and an insulating layer in contact with the alignment key structure and the contact pattern layer over the substrate.