Semiconductor Fuse Seal Ring Moisture Ingress Prevention
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Solution Overview
Problem
The existing semiconductor devices face reliability issues due to moisture entering through fuse opening portions, causing fluctuations in IC characteristics and negative bias temperature instability (NBTI) in PMOS transistors, especially in analog ICs like voltage detectors.
Innovation Solution
A semiconductor device design that includes a metal seal ring surrounding the fuse opening portion, with a fuse terminal extending to the seal ring and a specific length inequality for the seal ring to prevent moisture entry, ensuring the SOG layer is disconnected from the internal IC, thereby preventing moisture ingress and stabilizing transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fuse opening portion is formed to allow laser irradiation for trimming, then laser trimming can be performed to adjust circuit characteristics, but moisture enters through the opening causing reliability degradation and NBTI
Solution Approach 1:
A seal ring structure is introduced as an intermediary element between the fuse opening portion and the internal IC structures. This seal ring acts as a barrier that prevents moisture from reaching the SOG layer and internal components, while still allowing the laser trimming function to operate through the opening portion.
Solution Approach 2:
The seal ring is formed using a thin film structure that can effectively block moisture penetration. The seal ring is positioned to disconnect the SOG layer from internal IC regions, creating a protective barrier that maintains reliability while preserving the fuse opening functionality.
2Manufacturing precision
If the SOG layer is used for planarization in multi-layered wiring, then surface flatness is improved, but moisture enters through the SOG layer causing characteristic fluctuations
Solution Approach 1:
The seal ring serves as an intermediary barrier that blocks moisture from reaching the SOG layer. This allows the SOG layer to maintain its planarization function while preventing moisture-induced characteristic fluctuations in the IC.
Solution Approach 2:
The seal ring thin film structure effectively prevents moisture penetration to the SOG layer, maintaining both the surface flatness provided by the SOG and the stability of IC characteristics by disconnecting the moisture path.
3Reliability
If a seal ring is formed to prevent moisture entry, then reliability is improved, but the fuse terminal connection and laser irradiation access become more complex
Solution Approach 1:
The seal ring structure is designed to serve multiple functions: it prevents moisture entry, maintains the fuse opening portion accessibility for laser irradiation, and ensures proper fuse terminal connections. This multi-functionality reduces the need for additional separate structures.
Solution Approach 2:
The seal ring is positioned in a specific spatial arrangement that allows it to block moisture paths while maintaining vertical and horizontal connectivity for fuse terminals and laser access. The dimensional positioning resolves the complexity by utilizing spatial relationships rather than adding structural complexity.
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 design effectively interrupts the moisture path between interlayer insulating films, enhancing the long-term reliability of ICs by preventing NBTI and maintaining desired output voltage characteristics.
Implementation Method 1
a seal ring made of a first layer of a metal wiring layer and provided on the intermediate insulating film so as to surround the opening portion
Implementation Method 2
Fuses for laser trimming, which are formed of thin film resistors such as polycrystalline silicon, are disposed, and the fuses are selectively burned and cut by laser irradiation
Data Source
AI summary
A semiconductor device has a field insulating film provided on a semiconductor substrate, and a fuse provided on the field insulating film and having a fuse trimming laser irradiation portion and fuse terminals. The semiconductor device further includes an intermediate insulating film covering the fuse, a first TEOS layer on the intermediate insulating film, an SOG layer for planarizing the first TEOS layer, a second TEOS layer on the SOG layer and on the first TEOS layer, a protective film on the second TEOS layer, and an opening portion above the fuse trimming laser irradiation portion in a region from the protective film to the first TEOS layer. A seal ring is provided on the intermediate insulating film so as to surround the opening portion. The seal ring is disposed over the fuse so as to overlap each of the fuse terminals in plan view.