Multilayer Gate Contact Structure for Semiconductor Isolation
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Solution Overview
Problem
The existing semiconductor gate contact structure fabrication methods often result in shorts between adjacent gates due to improper formation of the gate contact tie down structure, especially when a single layer contact extends from the conductive work function material to the dielectric layer, making it difficult to avoid misalignment and electrical shorts.
Innovation Solution
A gate contact structure comprising a first and second contact layer, where the second contact layer is formed on top of the first, providing a wider 'fat' contact that spans a vertical spacing and includes a dielectric capping layer to prevent shorts, and is electrically connected to the source-drain, allowing for proper electrical isolation and reduced scaling and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single layer contact is used to extend from the conductive work function material to the dielectric layer, then the fabrication process is simpler, but electrical shorts between adjacent gates occur due to misalignment
Solution Approach 1:
The gate contact structure is divided into multiple segments: a first contact layer extending from the conductive gate work function material to a first elevation, and a second contact layer extending from the first contact layer to the dielectric layer. This segmentation allows each layer to be independently formed and aligned, preventing shorts between adjacent gates while maintaining fabrication feasibility through sequential deposition processes.
Solution Approach 2:
The invention transitions from a single-layer horizontal contact to a multilayer vertical structure. The first contact layer provides horizontal electrical connection, while the second contact layer extends vertically to the dielectric layer, creating a three-dimensional contact architecture that improves alignment tolerance and prevents electrical shorts between adjacent gates.
2Power
If the gate contact layer is made wider to provide better electrical connection, then current carrying capacity increases, but the risk of shorts between adjacent gates increases
Solution Approach 1:
The contact structure is segmented into vertical layers rather than a single wide horizontal layer. Each contact layer can be optimized for its specific function: the first contact layer provides broad electrical connection to the gate, while the second contact layer provides vertical connection to the dielectric layer, allowing current to flow through multiple pathways without requiring excessive lateral width that would cause shorts.
Solution Approach 2:
The contact structure utilizes the vertical dimension by stacking contact layers, transforming the current path from purely lateral to a combination of lateral and vertical flow. This dimensional transition allows the contact to achieve high current carrying capacity through increased cross-sectional area in the vertical direction without increasing lateral width, thereby maintaining electrical isolation between adjacent gates.
3Reliability
If a multilayer contact structure is used to prevent shorts, then electrical isolation between gates is improved, but fabrication complexity increases
Solution Approach 1:
The contact structure is segmented into distinct functional layers that can be formed using standard semiconductor deposition and patterning processes. The first contact layer is formed to connect to the gate, and the second contact layer is formed subsequently to connect to the dielectric layer, allowing each layer to be optimized independently while using conventional fabrication techniques.
Solution Approach 2:
The first contact layer is formed in advance before the second contact layer, establishing a foundation that simplifies subsequent processing. The preliminary formation of the first contact layer provides a stable base for the second layer, reducing alignment complexity and allowing the multilayer structure to be built incrementally using standard sequential fabrication processes.
Data Source
AI summary
There is set forth herein a gate contact structure for a gate. The gate contact structure can include a first contact layer and a second contact layer. In one embodiment, a gate contact layer can define a contact that provides a gate tie down. In one embodiment, a gate contact layer can have a minimum width larger than a gate length.