Via Plug Charging Effects Distribution in Semiconductor Devices
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Solution Overview
Problem
Conventional semiconductor devices face challenges in reliably connecting multiple wiring layers due to charging effects during the formation of via plugs, leading to defects such as not-open via holes, which affect the electrical connection and overall reliability of the device.
Innovation Solution
The semiconductor device incorporates a combination of real and dummy via plugs, with the number of dummy via plugs being significantly greater than real via plugs, to distribute charging effects and prevent defects, thereby enhancing the reliability of electrical connections between wiring layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via plugs are formed to connect wiring layers, then electrical connection between wiring layers is achieved, but charging effects occur during formation leading to defects such as not-open via holes
Solution Approach 1:
A dummy wiring layer is introduced as an intermediary structure between the third wiring layer and the fourth wiring layer. This dummy wiring layer includes dummy via plugs that act as charge absorption sites, mediating the charging effects that occur during via plug formation. The dummy wiring layer absorbs excess charges that would otherwise cause not-open defects in the real via plugs, thereby protecting the electrical connection reliability.
Solution Approach 2:
Dummy via plugs are created as copies of the real via plugs. These dummy via plugs replicate the structure and position of the real via plugs but serve a different function - they absorb charging effects during the formation process. By having multiple dummy via plugs (greater than real via plugs in number), the charging effects are distributed and neutralized, preventing defects in the actual functional via plugs.
2Reliability
If dummy via plugs are added to distribute charging effects, then defect occurrence is reduced, but device structure becomes more complex
Solution Approach 1:
The dummy wiring layer is merged with the existing wiring layer structure, specifically positioned between the third and fourth wiring layers. The dummy via plugs are combined with the via plug formation process, using the same etching and filling steps. This merging approach integrates the defect prevention mechanism into the existing manufacturing flow without requiring completely separate processes, thereby limiting the increase in device complexity.
Solution Approach 2:
The dummy wiring layer serves multiple functions: it provides a structural framework for the dummy via plugs, acts as a charge absorption medium, and maintains the overall wiring layer architecture. The dummy via plugs themselves serve dual purposes - they occupy space to distribute charging effects and provide additional etch stop layers during the formation process. This multi-functionality reduces the need for additional dedicated structures, limiting complexity increase.
Data Source
AI summary
A semiconductor device includes a lower insulating layer on a substrate, a lower wiring layer extending on the lower insulating layer, a lower surface of at least a part of the lower wiring layer being covered by the lower insulating layer, a plurality of via plugs extending in a first direction on the lower wiring layer, the plurality of via plugs including a real via plug and a first dummy via plug connected to the part of the lower wiring layer covered by the lower insulating layer, and an upper wiring layer overlapping the lower wiring layer and extending in a second direction different from the first direction on the real via plug, the upper wiring layer not overlapping the dummy via plug.