Semiconductor Contact Plug Fabrication via Sacrificial Layer Segmentation
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Solution Overview
Problem
In highly integrated semiconductor devices, securing an overlap margin is challenging due to insufficient space, and existing methods for modifying contact shapes often compromise process efficiency and precision.
Innovation Solution
A method for fabricating semiconductor devices with asymmetric contacts involves forming contact plugs and metal patterns using a sacrificial layer and spacer, with etching techniques to create trenches and ensure overlap margins, utilizing materials like oxide-based sacrificial layers and nitride-based spacers, and electroless plating for metal deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contact shape is modified to secure overlap margin, then overlap margin is improved, but process complexity and difficulty increase
Solution Approach 1:
The contact formation process is segmented into multiple stages: initial contact hole formation, sacrificial layer deposition, spacer formation, and selective sacrificial layer removal. This segmentation allows precise control of the contact shape and overlap margin while maintaining manageable process complexity through modular fabrication steps
Solution Approach 2:
A sacrificial layer is deposited and spacers are formed in advance before final contact hole definition. This preliminary action enables precise control of the contact shape and overlap margin, as the spacers pre-define the lateral boundaries of the contacts before metal filling occurs
2Manufacturing precision
If contact shape is modified to secure overlap margin, then overlap margin is improved, but process efficiency deteriorates
Solution Approach 1:
The formation of spacers and the definition of contact shapes are merged into a single conformal deposition and etch sequence. The sacrificial layer removal and contact hole exposure are combined in one process flow, improving efficiency while maintaining the precise overlap margin control enabled by the spacer structure
Solution Approach 2:
The spacers self-align to the sacrificial layer pattern, automatically defining the contact lateral boundaries without requiring additional alignment steps. This self-service mechanism maintains manufacturing precision while reducing process complexity and improving overall fabrication efficiency
3Manufacturing precision
If asymmetric contacts are formed, then overlap margin is secured, but etching precision requirements increase
Solution Approach 1:
The sacrificial layer acts as an intermediary structure that simplifies the etching process. Instead of directly etching asymmetric contact holes with high precision requirements, the process uses the sacrificial layer as a template, and spacers as boundary definers, converting a difficult direct etching problem into a more manageable conformal deposition and selective removal sequence
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 enhances the overlap margin in semiconductor devices while maintaining process efficiency and precision, reducing the complexity of metal etching and ensuring reliable contact formation.
Implementation Method 1
The sacrificial layer may include a material having an etching selection ratio higher than an etching selection ratio of the spacer, and the removal of the first and second portions of the sacrificial layer may be performed by wet etching using the etching selection ratio of the material
Implementation Method 2
forming a contact plug filling the first and second contact holes and forming a metal pattern filling the second and third trenches
Data Source
AI summary
Semiconductor devices, and methods for fabricating a semiconductor device, include forming a contact hole penetrating an interlayer insulating layer and exposing a conductor defining a bottom surface of the contact hole, forming a sacrificial layer filling the contact hole, forming a first trench overlapping a part of the contact hole by removing at least a part of the sacrificial layer, forming a spacer filling the first trench, forming a second trench by removing a remainder of the sacrificial layer, and forming a metal electrode filling the contact hole and the second trench using electroless plating.