TSV Guard Ring Structure for Lower Parasitic Capacitance
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Solution Overview
Problem
The increased device density in semiconductor circuits leads to higher interconnect RC time constant delays due to capacitance contributions from metal interconnect structures, which are exacerbated by the use of low dielectric constant (low-k) dielectric materials that are susceptible to damage during semiconductor processes.
Innovation Solution
Incorporation of a guard ring structure around through-silicon via (TSV) structures, comprising concentric guard rings and a seal ring, to prevent contaminant diffusion and reduce parasitic capacitance, using materials like copper and barrier layers to protect the interconnect structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-k dielectric material is used to form IMD layers, then capacitance contribution is reduced and signal transport speed is improved, but the material becomes susceptible to damage during semiconductor processes
Solution Approach 1:
A guard ring structure comprising concentric conductive rings is introduced as an intermediary element between the low-k dielectric material and contaminant sources. This guard ring structure prevents contaminant diffusion into the low-k material while maintaining its low capacitance properties, thus protecting the material without compromising signal transport speed.
Solution Approach 2:
The patent converts the potential harm of contaminant diffusion into a benefit by using the guard ring structure to define controlled interfaces. The concentric rings create well-defined boundaries that prevent uncontrolled contaminant ingress while maintaining the electrical performance benefits of low-k materials.
2Productivity
If device density is increased to improve circuit functionality, then RC time constant delay increases due to higher capacitance from metal interconnect structures
Solution Approach 1:
The interconnect structure is segmented into multiple conductive layers with dielectric materials having different dielectric constants. Low-k dielectric material is used in specific regions where capacitance reduction is most critical, while other regions use different materials optimized for their specific functions, allowing high device density without proportional increase in RC delay.
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 guard ring structure effectively reduces parasitic capacitance and protects the interconnect structure from contaminants, enhancing signal transport speed and reliability in semiconductor circuits.
Implementation Method 1
reduce parasitic capacitance between the first guard ring structure and the first TSV structure
Implementation Method 2
prevent contaminant diffusion
Data Source
AI summary
A die includes: a semiconductor substrate; an interconnect structure disposed on the semiconductor substrate and including: inter-metal dielectric (IMD) layers; metal features embedded in the IMD layers; and a guard ring structure including concentric first and second guard rings that extend through at least a subset of the IMD layers; and a through silicon via (TSV) structure extending through the semiconductor substrate and the subset of IMD layers to electrically contact one of the metal features. The first guard ring surrounds the TSV structure; and the second guard ring surrounds the first guard ring and is configured to reduce a parasitic capacitance between the guard ring structure and the TSV structure.