Double Guard Ring for Die Fracture Detection and Humidity Protection
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Solution Overview
Problem
Compound semiconductor devices, particularly GaAs devices, face challenges with moisture penetration through plastic packaging leading to chip-level failures during THB testing and are susceptible to fractures during the manufacturing process, which can result in unpredictable failures at the customer site.
Innovation Solution
A double guard ring arrangement is implemented around the semiconductor substrate, comprising an outer guard ring for humidity protection and an inner guard ring for die crack detection, using segmented metal layers to satisfy fabrication process conditions and provide a unique resistance signature for authentication and identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic packaging is used to reduce cost, then manufacturing cost is reduced, but moisture protection capability deteriorates
Solution Approach 1:
The guard ring structure is segmented into multiple discrete regions around the periphery of the semiconductor die. These segments are electrically connected to form a continuous protective barrier, allowing moisture protection without requiring a complete continuous metal ring that would be difficult to fabricate
Solution Approach 2:
The guard ring structure is formed during the semiconductor fabrication process before packaging, creating a pre-established moisture protection barrier at the die level. This preliminary protection is built into the device structure itself, eliminating the need for additional protective packaging measures
2Measurement precision
If rigorous inspections are implemented at each process step to detect fractures, then fracture detection capability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The semiconductor die itself provides fracture detection functionality through its guard ring structure. The electrical properties of the guard ring change when fractures occur, allowing the device to self-diagnose structural integrity issues without requiring external inspection equipment or additional test structures
Solution Approach 2:
The guard ring structure serves multiple functions simultaneously: it provides moisture protection during operation and serves as a fracture detection mechanism during testing and quality control. This multi-functionality eliminates the need for separate inspection systems
3Object-affected harmful factors
If a continuous metal ring is used for guard ring protection, then moisture protection is improved, but fabrication process compliance deteriorates
Solution Approach 1:
The continuous metal ring is divided into multiple discrete segments that are easier to fabricate using standard semiconductor manufacturing processes. The segments are positioned around the periphery of the die and electrically connected to form a continuous protective barrier, satisfying both fabrication constraints and protection requirements
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 double guard ring arrangement effectively prevents moisture penetration and detects die cracks, enhancing the reliability of semiconductor devices by integrating humidity protection and crack detection functions while maintaining fabrication process compliance, thus reducing the likelihood of failures and enabling effective authentication.
Implementation Method 1
Ohmic fences have been used to provide moisture protection in GaAs devices and products with plastic packaging
Implementation Method 2
The gaps of the outer guard ring are laterally offset from the gaps of the inner guard ring such that the Ohmic metal layers of the outer and inner guard rings laterally overlap
Implementation Method 3
provide a unique resistance signature for authentication and identification
Data Source
AI summary
An electronic apparatus includes a semiconductor substrate, outer and inner guard rings disposed along a periphery of the semiconductor substrate, and first and second contact pads electrically coupled to the outer and inner guard rings, respectively. The outer and inner guard rings are electrically coupled to one another to define a conduction path between the first and second contact pads. Each of the outer and inner guard rings includes an Ohmic metal layer having a plurality of gaps and further includes conductive bridges across the gaps. The gaps of the outer guard ring are laterally offset from the gaps of the inner guard ring such that the Ohmic metal layers of the outer and inner guard rings laterally overlap.