TSV Composite Ring Structure for Electric Coupling Reduction
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Solution Overview
Problem
The existing through-silicon via (TSV) structures face adverse electric coupling effects between the conductive substrate and the conductive material, which affects the performance of 3D stack ICs, particularly in high-temperature processes and copper filling challenges.
Innovation Solution
A novel TSV structure with a composite ring structure is proposed, comprising a wafer, through via, conductive layer, through via dielectric ring, first conductive ring, and first dielectric ring, where the rings are designed to reduce or eliminate electric coupling by forming a composite annular structure and filling the through via with a conductive material, optionally with a serpent-like conductive layer extension to shield interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple through-silicon via structure is used, then the manufacturing process is simple, but adverse electric coupling effects occur between the conductive substrate and conductive material
Solution Approach 1:
The patent implements a nested ring structure where an inner conductive ring is surrounded by an outer dielectric ring, which is in turn surrounded by an outer conductive ring. This nested configuration creates multiple shielding layers that progressively reduce electric coupling effects while maintaining a compact via structure, resolving the contradiction between manufacturing simplicity and electric coupling reduction.
Solution Approach 2:
The outer dielectric ring serves as an intermediary layer between the inner and outer conductive rings. This dielectric material acts as a mediator that electrically isolates the two conductive rings, preventing direct electric coupling and reducing interference between signal lines, thus addressing the harmful electric coupling effect.
2Reliability
If copper is used as conductive material, then electrical resistance is low, but copper filling is difficult and voids are formed
Solution Approach 1:
The patent applies different materials with different properties to different regions of the via structure. The inner conductive ring uses copper for low resistance where signal transmission is critical, while the outer conductive ring and barrier layers use materials better suited for filling processes. This local differentiation allows optimization of both electrical performance and manufacturability.
Solution Approach 2:
The via structure employs composite material construction with multiple conductive rings made of different materials (copper, tungsten, or tungsten silicide) combined with dielectric barriers. This composite approach leverages the advantages of each material: copper's low resistance, tungsten's fillability, and dielectric's isolation properties, thereby resolving the contradiction between low resistance and easy filling.
3Adaptability or versatility
If via-first-before-CMOS process is used, then compatibility with conventional CMOS is good, but conductive material must bear high temperatures
Solution Approach 1:
The via structure is formed preliminarily before the CMOS process, with the nested ring configuration already in place. The robust multi-layer structure is designed to withstand the subsequent high-temperature CMOS processing steps. The dielectric barriers and multiple conductive layers are pre-configured to maintain structural integrity during thermal processing, enabling compatibility with conventional CMOS workflows.
Solution Approach 2:
The nested ring structure with dielectric barriers provides beforehand cushioning against thermal stress during CMOS processing. The multiple layers act as a protective cushion that absorbs and distributes thermal expansion stresses, preventing deformation or failure of the conductive material during high-temperature exposure in subsequent CMOS steps.
4Speed
If wafer is thinned to reduce connection distance, then transmission speed increases, but structural stability decreases
Solution Approach 1:
The thinned wafer structure incorporates composite material construction with multiple conductive rings and dielectric layers that provide structural reinforcement. These composite layers compensate for the reduced bulk material, maintaining structural stability despite wafer thinning, while the shortened connection distance achieves faster transmission speeds.
Solution Approach 2:
The nested ring structure within the thinned wafer provides internal structural support. The concentric arrangement of conductive and dielectric rings creates a mechanically robust configuration that distributes stress evenly, maintaining structural integrity even when the overall wafer thickness is reduced to enable faster signal transmission.
Data Source
AI summary
A TSV structure includes a through via connecting a first side and a second side of a wafer, a conductive layer which fills up the through via, a through via dielectric ring surrounding and directly contacting the conductive layer, a first conductive ring surrounding and directly contacting the through via dielectric ring as well as a first dielectric ring surrounding and directly contacting the first conductive ring and surrounded by the wafer.