Seal Ring Structure for IC Noise Shielding
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Solution Overview
Problem
Noise coupling from digital circuits to analog and/or RF circuits in integrated circuit chips is a significant challenge, as it adversely affects the performance of sensitive analog and/or RF circuitry, despite advances in fabrication technology integrating these circuits onto a single IC.
Innovation Solution
A seal ring structure comprising a continuous outer seal ring and a discontinuous inner seal ring with a conductive rampart or gap positioned in front of the analog and/or RF circuit block to shield noise, while maintaining protection from moisture and corrosive substances, utilizing a stack of metal and contact/via layers manufactured during IC fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous seal ring structure is used to protect the IC from moisture and ionic contamination, then protection reliability is improved, but noise coupling from digital circuits to analog circuits worsens
Solution Approach 1:
The seal ring is divided into two distinct portions: a first seal ring portion that is continuous and provides moisture/ionic contamination protection, and a second seal ring portion that is discontinuous with gaps positioned between digital and analog circuits to block noise coupling paths. This segmentation allows the seal ring to simultaneously provide protection while preventing noise interference.
Solution Approach 2:
Different portions of the seal ring are designed with different structural characteristics to perform different functions. The first portion maintains continuity for environmental protection, while the second portion introduces discontinuities (gaps) specifically at locations where noise blocking is needed. This local differentiation enables the seal ring to address multiple concerns with a single integrated structure.
2Productivity
If digital and analog circuits are integrated onto a single IC to improve productivity, then manufacturing efficiency is improved, but noise interference from digital to analog circuits worsens
Solution Approach 1:
The seal ring structure is segmented into continuous and discontinuous portions to simultaneously support integrated circuit functionality while preventing noise interference. The discontinuous second portion creates electrical isolation barriers that prevent noise coupling between digital and analog circuits, enabling their co-integration on a single chip without performance degradation.
Solution Approach 2:
The seal ring structure acts as an intermediary element between digital and analog circuits. By positioning the discontinuous second seal ring portion between these circuit types, it serves as a noise-blocking mediator that allows both circuit types to coexist on the same chip while preventing harmful electromagnetic coupling.
3Object-affected harmful factors
If a discontinuous inner seal ring with gaps is introduced to block noise propagation, then noise shielding is improved, but structural complexity increases
Solution Approach 1:
The seal ring is segmented into two functional portions with distinct continuity characteristics. The first portion remains continuous for environmental sealing, while the second portion is deliberately discontinuous with gaps positioned to interrupt noise propagation paths. This segmentation achieves noise shielding without requiring completely complex redesign of the entire seal ring structure.
Solution Approach 2:
Rather than making the entire seal ring discontinuous or complex, the invention applies discontinuity only in specific local regions (the second portion) where noise blocking is required. The first portion maintains its simple continuous structure for environmental protection, thereby minimizing overall structural complexity while achieving the noise shielding objective.
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
The proposed seal ring structure effectively reduces noise coupling between digital and analog/RF circuits, enhancing the performance of sensitive analog and/or RF circuit blocks by isolating noise propagation and providing independent grounding or supply voltage for the inner seal ring portion.
Implementation Method 1
The second portion is situated in front of the analog and/or RF circuit block for shielding a noise from interfering the analog and/or RF circuit block
Data Source
AI summary
An integrated circuit chip includes an analog and/or RF circuit block and a seal ring structure surrounding the analog and/or RF circuit block. The seal ring structure comprises a continuous outer seal ring and an inner seal ring, wherein the inner seal ring comprises a gap that is situated in front of the analog and/or RF circuit block.