Segmented Guard Ring and Edge Seal for RFSOI Reliability
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Solution Overview
Problem
Segmented guard rings are incompatible with RFSOI chips using low-K SiCOH or p-SiCOH materials at the middle of the line (MOL) and back end of the line (BEOL) processing levels, leading to reliability issues due to moisture ingress and cracking.
Innovation Solution
A guard ring structure formed in low-k dielectric material with an edge seal structure extending through the MOL and BEOL, using a silicon on insulator substrate and low-k dielectric material, and employing a segmented guard ring and edge seal structure compatible with RFSOI chips, which can be manufactured using photolithographic processes and thin film deposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a segmented guard ring structure is used in low-k dielectric material, then parasitic coupling and inductive coupling are avoided, but moisture ingress causes SiCOH cracking and degraded copper reliability
Solution Approach 1:
The guard ring is divided into multiple discrete segments rather than a continuous structure. This segmentation prevents inductive coupling between adjacent guard ring portions while maintaining the electrostatic shielding function. Each segment is electrically isolated, eliminating the harmful inductive effects that would occur in a continuous guard ring structure.
Solution Approach 2:
An edge seal structure is introduced as an intermediary element between the segmented guard ring and the external environment. This edge seal prevents moisture ingress that would otherwise penetrate through gaps in the segmented guard ring and cause SiCOH cracking or copper reliability degradation. The edge seal acts as a protective barrier that mediates between the segmented guard ring structure and the harmful moisture environment.
2Productivity
If low-k porous dielectric material is used in MOL or BEOL processing, then RF circuitry performance is improved, but segmented guard ring causes reliability fails
Solution Approach 1:
The guard ring structure is segmented into discrete sections that are electrically isolated from each other. This segmentation allows the use of low-k porous dielectric material in the MOL or BEOL processing levels while preventing the reliability failures associated with continuous guard rings. The segmented structure maintains RF circuitry performance by preventing inductive coupling while being compatible with the porous dielectric material.
Solution Approach 2:
The edge seal structure serves as an intermediary that protects the low-k porous dielectric material and segmented guard ring combination from moisture ingress. This enables the use of low-k material for improved RF performance while the edge seal prevents the moisture-related reliability failures that would otherwise occur with segmented guard rings in porous dielectric environments.
3Object-affected harmful factors
If a continuous guard ring is used, then moisture barrier protection is provided, but inductive coupling occurs
Solution Approach 1:
The continuous guard ring is divided into multiple discrete segments that are electrically isolated from each other. This segmentation eliminates inductive coupling between adjacent guard ring portions while maintaining the moisture barrier function. The segments collectively provide protection against moisture ingress through the edge seal structure, which prevents moisture from penetrating through the gaps between segments.
Solution Approach 2:
The edge seal structure acts as an intermediary that provides continuous moisture barrier protection even though the guard ring itself is segmented. The edge seal fills the gaps between segmented guard ring portions and prevents moisture ingress, thereby maintaining the protective function of a continuous guard ring while allowing the segmentation that eliminates inductive coupling.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to segmented guard-ring and chip edge seals and methods of manufacture. The structure includes: a guard ring structure formed in a low-k dielectric material; and an edge seal structure formed through the low-k dielectric material to at least a substrate underneath the low-k dielectric material.