Semiconductor Substrate Contact Plug in Seal Ring Region
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Solution Overview
Problem
The formation of an insulating altered layer at the bottom of deep trenches in semiconductor devices during the dry etching process for substrate contact plugs leads to connection failures between the substrate contact plug and the semiconductor substrate, causing operational issues in semiconductor devices.
Innovation Solution
The substrate contact plug is formed in the seal ring region, which increases the substrate contact opening ratio during the dry etching process, preventing the formation of an insulating altered layer and ensuring reliable electrical connection by forming a pseudo substrate connection portion that does not contribute to the circuit, thereby enhancing the reliability of the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If dry etching is used to form deep trenches for substrate contact plugs in the circuit region, then the trench depth is sufficient to reach the semiconductor substrate, but an insulating altered layer is formed at the bottom of the trench causing connection failure
Solution Approach 1:
The patent extracts the substrate contact plug formation from the circuit region and relocates it to the seal ring region. This separation removes the problematic interaction between deep trench etching and circuit functionality, allowing the seal ring region to accommodate the altered layer without affecting electrical connections in the circuit region.
Solution Approach 2:
The patent applies different functional requirements to different regions: the circuit region maintains high electrical quality for active devices, while the seal ring region accepts the altered layer as a acceptable trade-off for achieving sufficient trench depth and moisture protection. This local differentiation resolves the contradiction by allowing connection formation where it is least critical.
2Reliability
If the substrate contact opening ratio is increased to prevent insulating altered layer formation, then connection reliability improves, but chip area increases
Solution Approach 1:
The seal ring region serves multiple functions: it provides moisture protection, prevents metallic contamination during dicing, and accommodates substrate contact plugs. By making the seal ring multi-functional, the patent avoids needing additional dedicated area for substrate contacts, thus preventing chip area increase while maintaining connection reliability.
Solution Approach 2:
The patent merges the substrate contact function with the seal ring structure. The seal ring region, which would otherwise be non-functional space, is combined with the substrate contact plug formation, eliminating the need for separate area allocation and resolving the area-reliability contradiction.
3Reliability
If substrate contact plugs are formed in the circuit region, then electrical connection is achieved, but circuit layout flexibility is reduced
Solution Approach 1:
The patent segments the substrate contact function from the circuit region and places it in the seal ring region. This segmentation allows independent optimization of circuit layout without being constrained by substrate contact requirements, thereby maintaining layout flexibility while ensuring electrical connection through the seal ring region.
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 improves the reliability of semiconductor devices by preventing increased resistance values and connection failures, while maintaining the chip area and layout flexibility, and effectively prevents moisture and metallic contamination.
Implementation Method 1
it is conceivable to form the trench, which reaches a deep position of the semiconductor substrate from an upper surface of an interlayer insulating film on the semiconductor substrate, by dry etching
Data Source
AI summary
A substrate contact plug which is connected to a wiring and a semiconductor substrate and does not form a circuit is formed in a seal ring region in a peripheral portion of a semiconductor chip region. The substrate contact plug is buried in a trench which is deeper than an element isolation trench.