Trench-Via-Merged Alignment Marks for Semiconductor Layer Overlay
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices is the precise alignment of layers with step differences in substrates, where existing alignment marks become difficult to detect due to covering by additional material layers, leading to potential overlay failures and reduced reliability.
Innovation Solution
A method involving the formation of trench-via-merged-type alignment marks, where a light reflection material is used to create alignment marks that communicate with trenches and vias, allowing for precise alignment despite step differences, and additional alignment marks are formed in subsequent layers to maintain detectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If additional material layers are formed on the substrate, then the device structure becomes more complex and functional layers are added, but the alignment marks become difficult to detect due to being covered by these layers
Solution Approach 1:
The alignment mark structure is segmented into multiple components: a trench structure, a via structure, and a light reflection material layer. This segmentation allows the alignment mark to maintain detectability through multiple material layers by creating distinct reflective interfaces at different depths, enabling detection even when covered by additional functional layers.
Solution Approach 2:
The alignment mark is extended into the vertical dimension by forming trenches and vias that penetrate through material layers, and by depositing light reflection material at specific depths. This three-dimensional structure allows the alignment mark to be detected through optical means even when covered by additional planar material layers, effectively adding a depth dimension to the traditionally two-dimensional alignment mark.
2Adaptability or versatility
If step differences exist in the substrate, then device functionality is achieved, but alignment precision deteriorates due to the step differences affecting alignment mark quality
Solution Approach 1:
The alignment mark structure is locally optimized to compensate for step differences. The trench and via structures are formed at specific locations where step differences occur, and the light reflection material is deposited selectively in these regions. This local quality enhancement ensures that alignment marks maintain high detectability and precision even in areas with substrate step differences, while other regions can maintain their standard structure for device functionality.
3Ease of manufacture
If conventional alignment marks are used, then the manufacturing process is simple, but overlay failures occur due to reduced alignment precision
Solution Approach 1:
The alignment mark structure merges the trench structure, via structure, and light reflection material into a single integrated alignment mark system. This merged structure combines the advantages of each component: the trench provides a defined boundary, the via extends the mark through layers, and the light reflection material enhances detectability. This integration maintains manufacturing simplicity while significantly improving overlay accuracy and reducing overlay failures.
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 approach ensures high-quality alignment marks that remain detectable even after etching, reducing overlay failures and maintaining alignment precision across layers, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
forming a trench-via-merged-type first alignment mark by at least partially filling the first alignment mark trench and the first alignment mark via with a light reflection material layer
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a first alignment mark trench in a first material layer on a substrate. A first alignment mark via may then be formed by etching a second material layer that is underneath the first material layer, where the first alignment mark via is positioned to communicate with the first alignment mark trench. Then, a trench-via-merged-type first alignment mark may be formed by filling the first alignment mark trench and the first alignment mark via with a light reflection material layer.