Cobalt-Capped Through-Substrate Via Structure
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Solution Overview
Problem
The semiconductor industry faces limitations in increasing circuit density due to physical constraints in two-dimensional integration, prompting the need for three-dimensional ICs with through-substrate vias (TSVs) to enhance electrical connections between stacked dies, but existing TSV formation methods require larger carrier substrates and complex designs.
Innovation Solution
A method for forming a through-substrate via structure involving a semiconductor substrate with a metal-oxide semiconductor transistor, where an opening is etched and filled with a conductive layer, surrounded by a diffusion barrier and isolation layer, and capped with a cobalt-based layer to prevent copper diffusion, allowing for efficient electrical connections between dies without the need for a large carrier substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-substrate vias are formed by etching openings and filling with conductive material, then electrical connections between stacked dies are improved, but carrier substrate size increases and design complexity increases
Solution Approach 1:
The patent segments the TSV structure into multiple functional layers: isolation layer (first material), diffusion barrier layer (second material), and capping layer (third material). This segmentation allows each layer to perform its specific function independently, improving electrical connection reliability while maintaining manageable design complexity through modular structure design.
Solution Approach 2:
The patent employs composite material structure with multiple distinct layers having different properties. The isolation layer uses a first material, the diffusion barrier layer uses a second material, and the capping layer uses a third material. This composite approach optimizes each layer's performance for its specific function, achieving reliable electrical connections without requiring oversized carrier substrates or overly complex designs.
2Ease of manufacture
If TSV structure is formed without capping layer, then manufacturing process is simpler, but copper diffusion occurs compromising reliability
Solution Approach 1:
The patent applies preliminary anti-action by forming a diffusion barrier layer and capping layer during the TSV formation process itself, rather than adding them later. The diffusion barrier layer (second material) is formed to prevent copper diffusion into the isolation layer, and the capping layer (third material) is formed to prevent copper diffusion into the overlying dielectric layer. This preliminary protection ensures reliability without significantly complicating the manufacturing process.
3Ease of operation
If carrier substrate is made larger to accommodate wire bonding, then ease of operation improves, but area occupied increases
Solution Approach 1:
The patent transitions from two-dimensional wire bonding to three-dimensional vertical connections through TSVs. By etching openings through the substrate and filling them with conductive material, the invention enables electrical connections in the vertical dimension, eliminating the need for lateral wire bonding and the associated large carrier substrate area.
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 approach enables the formation of a compact and reliable TSV structure that facilitates efficient electrical connections between stacked dies, overcoming the limitations of two-dimensional integration and reducing the complexity of carrier substrate requirements.
Implementation Method 1
forming a capping layer comprising cobalt on the top surface of the conductive layer
Implementation Method 2
forming a conductive layer to fill the opening
Data Source
AI summary
A device including a first dielectric layer on a semiconductor substrate, a gate electrode formed in the first dielectric layer, and a through-substrate via (TSV) structure penetrating the first dielectric layer and extending into the semiconductor substrate. The TSV structure includes a conductive layer, a diffusion barrier layer surrounding the conductive layer and an isolation layer surrounding the diffusion barrier layer. A capping layer including cobalt is formed on the top surface of the conductive layer of the TSV structure.