Segmented Through-Substrate Via Structure for Thick Silicon
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Solution Overview
Problem
Current tungsten-filled through-silicon vias (TSVs) are limited in depth and thickness, making them unsuitable for thicker semiconductor substrates and larger interposer die sizes, which are required for advanced electronics and heat sinking applications.
Innovation Solution
A through-substrate via structure with a conductive via extending from one major surface to a shallow depth and a recessed region from the opposing surface, allowing for a wider conductive region along the sidewall, enabling the use of tungsten as a cost-effective conductive material and supporting thicker substrates and larger die sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tungsten-filled TSVs are used for cost-effectiveness, then manufacturing cost is reduced, but substrate thickness is limited to less than 100 microns
Solution Approach 1:
The via structure is divided into two segments: a first via extending from the first substrate surface to a first depth, and a second via extending from the second substrate surface to a second depth. This segmentation allows each via to be formed independently within the capability limits of existing etch and deposition tools (less than 100 microns depth), while collectively achieving through-vias in thicker substrates (200-250 microns). The conductive material is deposited in corresponding segments within each via, enabling cost-effective tungsten usage throughout the entire via structure.
2Ease of manufacture
If etch tools are used to form vias, then via formation is achieved, but via depth is limited to 100 microns
Solution Approach 1:
The via formation process is segmented into two independent via formation operations. The first via is formed from the first substrate surface using standard etch tools to a depth within tool capabilities. The second via is formed from the second substrate surface using the same standard etch tools. This segmentation enables the overall substrate thickness to exceed 100 microns while each individual via formation step remains within the 100-micron depth capability of existing etch tools.
3Ease of manufacture
If deposition tools are used to deposit tungsten, then tungsten deposition is achieved, but via depth is limited to 100 microns
Solution Approach 1:
The tungsten deposition process is segmented into two independent deposition operations. Tungsten is deposited within the first via from the first substrate surface using standard deposition tools. Tungsten is also deposited within the second via from the second substrate surface using the same standard deposition tools. This segmentation enables cost-effective tungsten deposition throughout the entire via structure while each individual deposition step remains within the 100-micron depth capability of existing deposition tools.
4Ease of operation
If substrate thickness is increased to 200-250 microns for handling and larger bumps, then handling capability and bump size are improved, but via formation and tungsten deposition become infeasible with existing tools
Solution Approach 1:
The via formation and tungsten deposition processes are segmented into two independent operations performed from opposite substrate surfaces. This segmentation allows the substrate thickness to be increased to 200-250 microns for improved handling capability and larger bump support, while each individual via formation and deposition step remains within the 100-micron depth capability of existing tools. The two segments work together to achieve the desired thick-substrate performance.
5Area of stationary object
If interposer die size is increased to greater than 15 mm per side, then application requirements are met, but via formation through the entire substrate becomes infeasible
Solution Approach 1:
The via formation process is segmented into two independent via formation operations performed from opposite substrate surfaces. This segmentation enables the interposer die size to be increased to greater than 15 mm per side to meet application requirements, while each individual via formation step remains within the processing capabilities of existing tools. The segmented approach allows larger die sizes without compromising via formation feasibility.
Data Source
AI summary
A through-substrate via structure includes a conductive via structure including trench portions at a first major surface of a substrate and extending to a first distance. A first insulating structure is over sidewalls of the trench portions, and a conductive material is over the first insulating structure. A recessed region extends from a second major surface of the substrate to a second distance greater than the first distance and laterally overlaps and interfaces both trench portions. A second insulating structure includes a first portion within the recessed region and a second portion adjacent to the second major surface outside of the recessed region, which includes an outer surface overlapping the second major surface outside of the recessed region. A first conductive region includes a proximate end coupled to the conductive material through openings in the first portion, and an opposite distal that is outward from the second portion.