Stacked Conductor Structure Using Selective Etching
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Solution Overview
Problem
The complexity and cost of manufacturing integrated circuits with multi-layer conductor structures are increased due to the need for precise registration of masks and the sequential construction of interconnections across multiple layers, which is error-prone and requires expensive machinery.
Innovation Solution
A stacked conductor structure with alternating layers of different materials, where conductor posts are formed using unbalanced etchants to traverse through the structure, allowing for selective electrical connections between layers without the need for precise registration and incremental construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography techniques with masks and etchants are used to manufacture conductors in multi-layer structures, then conductor interconnections can be formed, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent segments the conductor layers into two distinct sets (first set and second set) with different material compositions. This segmentation allows different etchants to selectively remove specific conductor materials, simplifying the formation of conductor posts that connect only to intended layers without requiring complex mask registration across multiple photolithography cycles.
Solution Approach 2:
The patent applies local quality by making different portions of the stacked conductor structure have different material properties. Specifically, the first set of conductor layers contains a first conductor material while the second set contains a second conductor material, enabling spatially selective etching where etchants affect only specific regions based on material composition rather than requiring precise mask alignment.
2Ease of manufacture
If sequential via construction is used to connect multiple metal layers, then interconnections can be established, but the manufacturing process becomes more complex and expensive
Solution Approach 1:
The patent performs preliminary action by pre-differentiating the conductor layers with distinct materials before the via formation process. This preliminary material differentiation enables subsequent bulk etching operations to automatically achieve selective connectivity without requiring sequential via construction at each layer interface, thereby improving manufacturing efficiency.
Solution Approach 2:
The patent replaces the mechanical mask alignment and sequential deposition system with a chemical etching system that uses material composition differences. Instead of mechanically building vias layer by layer with precise mask registration, the process uses chemical etchants that automatically stop or continue etching based on the conductor material being encountered, substituting mechanical precision requirements with chemical selectivity.
3Ease of manufacture
If mechanical drilling is used to create vias in multi-layer stacks, then vertical connections can be formed, but the risk of wafer damage increases and expensive machinery is required
Solution Approach 1:
The patent replaces the mechanical drilling system with a chemical etching system. Instead of using mechanical drills that physically contact and potentially damage the wafer, the process uses chemical etchants that remove conductor materials through chemical reactions. This substitution eliminates mechanical stress and physical contact risks, improving wafer integrity while using standard wafer fabrication equipment rather than expensive specialized drilling machinery.
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 method reduces manufacturing costs and complexity by enabling cost-effective, simple connections between metal layers with substantial overlap regions, using a single wafer fabrication machine and minimizing the need for expensive machinery.
Implementation Method 1
A first hole may be formed through the stacked structure by a first unbalanced etchant. A second hole may be formed through the stacked structure by a second unbalanced etchant.
Data Source
AI summary
A circuit structure that includes a plurality of stacked conductor layers separated from each other by respective dielectric layers. The conductor layers may include a first set of conductor layers made of a first type conductor material and a second set of conductor layers made of a second type conductor material different from the first. A pair of conductor posts may traverse the stacked conductor layers. A first post may be electrically connected to the first set of conductor layers and electrically insulated from the second set of conductor layers. A second post electrically connected to the second set of conductor layers and electrically insulated from the first set of conductor layers.