Guard Ring Moisture Protection for Semiconductor Chips
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Solution Overview
Problem
Compound semiconductor devices, particularly GaAs, face humidity penetration issues during THB testing due to inadequate moisture barriers in plastic packaging, leading to chip-level failures, despite efforts like ohmic fences and metallic layers, which fail to prevent moisture ingress from the edges and tops of chips.
Innovation Solution
The implementation of a guard ring with conductive structures and atomic layer deposition (ALD) dielectric films to create a humidity protection barrier around the chip and bond pads, preventing moisture penetration by forming an ohmic fence and electrostatically trapping ions, while also addressing the lack of adhesion layers on metal line sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic packaging is used to reduce packaging cost, then packaging cost is reduced, but moisture barrier performance deteriorates
Solution Approach 1:
The patent applies preliminary action by forming a moisture barrier structure on the chip surface before packaging. The guard ring and dielectric layer are deposited in advance during chip fabrication, creating a pre-established moisture barrier that protects the chip even when packaged in non-hermetic plastic packages. This eliminates the need for expensive hermetic packaging while ensuring moisture protection.
2Reliability
If metallic layers are configured to block moisture, then bond pad protection is improved, but moisture penetration from edges and top still occurs
Solution Approach 1:
The patent applies segmentation by dividing the moisture protection function into multiple components: a guard ring structure that blocks moisture at the chip periphery, a dielectric layer that covers and protects the metal interconnects, and bond pad structures that protect specific contact areas. This segmented approach ensures comprehensive coverage of all potential moisture ingress paths including edges, tops, and bond pads.
3Ease of manufacture
If conventional fabrication processes are used, then manufacturing simplicity is maintained, but adhesion layers on metal line sidewalls are lacking
Solution Approach 1:
The patent applies parameter changes by modifying the deposition process parameters to achieve conformal coverage of the dielectric layer on metal sidewalls. By controlling deposition conditions (such as using atomic layer deposition with appropriate temperature and pressure parameters), the process achieves complete sidewall coverage without requiring additional adhesion layer materials or complex multi-step processes, thus maintaining fabrication simplicity while ensuring reliable adhesion.
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 solution effectively minimizes moisture penetration at chip edges and bond pads, preventing damage to metal and dielectric layers, and enhances humidity protection without adding significant fabrication costs or relying solely on physical barriers.
Implementation Method 1
depositing an atomic layer deposition (ALD) dielectric film along an edge of a first metal layer to cover a sidewall
Implementation Method 2
electrostatically trapping ions
Implementation Method 3
form an ohmic fence
Data Source
AI summary
An electronic apparatus includes a semiconductor substrate, a device structure supported by the semiconductor substrate, and a guard ring surrounding the device structure. The guard ring includes a plurality of conductive structures spaced apart from one another, supported by the semiconductor substrate, and coupled to a voltage source to establish an operating voltage for the guard ring.