Semiconductor Contact Plug Void-Free Connection via Segmented Structure
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Solution Overview
Problem
Existing semiconductor devices face challenges in forming contact plugs that are well-connected to conductive lines without voids, leading to potential electrical discontinuities and copper elution issues, especially when using different materials like copper and tungsten.
Innovation Solution
A contact plug is formed using a positive patterning process instead of a damascene process, with a multi-layered structure including a capping pattern, a conductive pattern, and an amorphous metal pattern, which covers the upper surface of the conductive structure, ensuring a void-free connection and reducing copper elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damascene process is used to form contact plugs, then the manufacturing process is simpler, but voids form at the interface between the contact plug and conductive line leading to poor electrical connection
Solution Approach 1:
The contact plug is divided into multiple segments: a lower contact plug portion made of tungsten and an upper contact plug portion made of copper, with distinct material compositions for each segment. This segmentation allows each portion to be optimized for its specific function while eliminating voids at the interface through controlled formation processes
Solution Approach 2:
The contact plug uses a composite structure combining tungsten and copper materials. The tungsten provides mechanical strength and void-free adhesion to the conductive line, while the copper portion provides excellent electrical conductivity. This composite material approach resolves the contradiction by achieving both reliable connection and good electrical performance
2Reliability
If copper and tungsten are used together in the contact plug, then electrical characteristics improve, but copper elution occurs at the interface
Solution Approach 1:
A barrier layer is introduced as an intermediary between the tungsten lower contact plug portion and the copper upper contact plug portion. This barrier layer prevents direct contact between copper and tungsten, thereby stopping copper elution while maintaining excellent electrical characteristics through the multi-layer structure
3Productivity
If the contact plug area is reduced, then device density increases, but void formation becomes more likely
Solution Approach 1:
The formation parameters of the contact plug are precisely controlled, including the etch depth, deposition thickness, and annealing conditions. By optimizing these parameters, the contact plug achieves adequate adhesion to the conductive line with minimal area, preventing void formation while maintaining high device density
Data Source
AI summary
A semiconductor device may include a conductive structure on a substrate, a contact plug on the conductive structure, and a magnetic tunnel junction structure on the contact plug. A lower surface of the contact plug may have an area greater than that of an upper surface thereof, and the contact plug may include a capping pattern at least partially covering an upper surface of the conductive structure, a conductive pattern on the capping pattern, and an amorphous metal pattern on the conductive pattern.