Source/Drain Epitaxial Contact Structure for Low-Resistance Semiconductors
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing contact resistance between source/drain structures and contacts in semiconductor devices, particularly due to high-temperature processes that lower doping concentrations and increase resistance.
Innovation Solution
The implementation of epitaxial layers with high activations and doping concentrations, formed after high-temperature processes, to improve contact resistance, combined with self-aligned silicide processes and specific mask layer configurations to enhance contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature processes are used during semiconductor manufacturing, then certain fabrication steps can be completed, but doping concentrations decrease and contact resistance increases
Solution Approach 1:
The patent applies preliminary action by forming the epitaxial layer with high doping concentration before the high-temperature contact formation process. This ensures that the doping concentration is established at a level that can withstand subsequent thermal processing, preventing the contact resistance increase that would otherwise occur due to doping loss during high-temperature steps.
Solution Approach 2:
The patent utilizes parameter changes by carefully controlling the doping concentration parameter in the epitaxial layer formation process. By optimizing the doping concentration to be sufficiently high initially, the layer can maintain adequate carrier concentration even after high-temperature processing reduces it, thereby maintaining low contact resistance throughout the manufacturing process.
2Reliability
If epitaxial layers with high doping concentrations are formed, then contact resistance is reduced, but process complexity increases
Solution Approach 1:
The patent merges the formation of the epitaxial layer with the source/drain structure creation into a single integrated process step. By forming the epitaxial layer to directly replace or form the source/drain regions, the patent eliminates the need for separate doping and deposition steps, thereby reducing overall process complexity while maintaining the beneficial high doping concentration for low contact resistance.
3Productivity
If geometry size is reduced to increase functional density, then production efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies self-service through self-aligned processes where the epitaxial layer formation is automatically positioned relative to the gate structure. The layer forms conformally on exposed semiconductor surfaces, ensuring precise alignment without requiring additional alignment steps or complex lithography processes, thereby maintaining manufacturing precision while enabling scaled geometry dimensions for higher productivity.
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 effectively reduces contact resistance and maintains high doping concentrations, improving the efficiency of semiconductor devices by ensuring better contact formation and reduced resistance.
Implementation Method 1
The implementation of epitaxial layers with high activations and doping concentrations, formed after high-temperature processes
Data Source
AI summary
A device includes an active region, a gate structure, a source/drain epitaxial structure, an epitaxial layer, a metal alloy layer, a contact, and a contact etch stop layer. The gate structure is across the active region. The source/drain epitaxial structure is over the active region and adjacent the gate structure. The epitaxial layer is over the source/drain epitaxial structure. The metal alloy layer is over the epitaxial layer. The contact is over the metal alloy layer. The contact etch stop layer lines sidewalls of the source/drain epitaxial structure. The metal alloy layer is spaced apart from the contact etch stop layer.