Vertically Separated TSV Openings for Flexible Metal Layer Distribution
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Solution Overview
Problem
The existing TSV nested hole structure in semiconductor manufacturing faces limitations in flexibility of wafer design due to restricted metal layer distribution and difficulties in filling and removing the filling layer from deep holes, especially affecting the photolithography process with thick photoresists.
Innovation Solution
A manufacturing method involving bonded wafers with a passivation layer, trenches, and separate shallow openings that do not communicate, allowing for flexible metal layer distribution and eliminating the need for thick photoresists, thereby simplifying the photolithography process and improving exposure effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a TSV nested hole structure with vertical communication is used to connect metal layers, then metal interconnection between upper and lower wafers is achieved, but the lateral distance between metal layers is restricted and effective area is wasted
Solution Approach 1:
The patent divides the single vertical communication hole into multiple separate openings (first opening, second opening, third opening) that do not communicate with each other. Each opening connects to a corresponding metal layer independently, allowing metal layers to be distributed more flexibly across the wafer surface without being constrained by a single vertical path, thereby increasing the effective area for metal layer placement.
2Length of moving object
If the aspect ratio of the deep hole increases in TSV nested hole structure, then vertical connection capability is improved, but filling and removing filling layer becomes difficult
Solution Approach 1:
The patent segments the deep vertical hole into multiple shallower openings (first opening penetrating first substrate, second opening penetrating second substrate, third opening in first dielectric layer). Each opening has a reduced aspect ratio compared to a single deep hole, making it easier to fill with filling layer and subsequently remove, while collectively achieving the same vertical connection depth through stacked wafer structure.
3Reliability
If upper opening penetrating through wafer substrate is deep to meet thickness requirements, then device performance is improved, but photoresist thickness increases and photolithography exposure deteriorates
Solution Approach 1:
The patent segments the deep upper opening into multiple separate openings at different depths and locations (first opening, second opening, third opening). Each opening requires a thinner photoresist for filling compared to a single deep opening, resulting in smoother photoresist surfaces and better photolithography exposure. The segmented structure maintains the necessary vertical penetration depth through the stacked wafer configuration while improving manufacturing precision.
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
Enhances the flexibility of wafer design, simplifies the photolithography process, and improves exposure effects by eliminating the need for thick photoresists and reducing the complexity of filling and removing filling layers from deep holes.
Implementation Method 1
performing a dry etching process to expose the first metal layer below the first opening and the second metal layer below the second opening
Data Source
AI summary
A semiconductor device and a manufacturing method thereof are disclosed. In which a first opening and a second opening are vertically separated, and are no longer restricted by the condition that a deep upper opening needs to be filled with a thick photoresist when a TSV nested hole in vertical communication forms a middle opening and lower opening, thereby satisfying devices with different thicknesses requirements. The design is no longer restricted by the lateral process of the TSV nested hole, thereby enhancing the flexibility of the design. In the photolithography process, the deep hole does not need to be filled with the photoresist, the photoresist does not need to be thick, thereby reducing the complexity of the photolithography process and improving the exposure effect. The first metal layer and the second metal layer are directly led out via a first trench, thereby simplifying the process and reducing the production cost.