Source/Drain Contact Structure With Doped Epitaxy for Low Resistance
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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 as device dimensions shrink and complexity increases.
Innovation Solution
The implementation of improved epitaxial and metal alloy structures, including the use of epitaxial layers with high doping concentrations and self-aligned silicide processes, to enhance contact resistance and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication processes are used, then manufacturing simplicity is maintained, but contact resistance between source/drain structures and contacts increases
Solution Approach 1:
The patent applies preliminary action by forming the epitaxial layer with high doping concentration before the contact formation step. This pre-doped epitaxial layer serves as a low-resistance pathway that is already in place before contacts are formed, eliminating the need for additional heavy doping steps after contact formation and thereby reducing contact resistance without significantly complicating the fabrication process
Solution Approach 2:
The patent changes the doping concentration parameter of the epitaxial layer to achieve high doping levels (e.g., 1E19 to 1E21 atoms/cm³) in the source/drain regions. This parameter change creates a highly conductive region that reduces contact resistance between the metal contacts and the semiconductor, effectively solving the contact resistance problem through material composition modification
2Productivity
If device dimensions are reduced to increase functional density, then production efficiency and cost are improved, but contact resistance increases due to smaller contact areas
Solution Approach 1:
The patent compensates for reduced contact area by dramatically increasing the doping concentration parameter in the epitaxial layer. This creates a highly conductive region that offsets the geometric disadvantage of smaller contact areas, allowing continued scaling while maintaining acceptable contact resistance levels
Solution Approach 2:
The patent creates a composite structure consisting of the highly doped epitaxial layer combined with the source/drain regions. This composite approach uses the epitaxial layer's high carrier concentration to provide a low-resistance pathway that compensates for the reduced dimensions, effectively managing contact resistance in scaled devices
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, maintains high activation and doping concentrations, and improves overall device performance, particularly in FinFETs and other advanced transistor types.
Implementation Method 1
an epitaxial layer is formed above the fin structure
Implementation Method 2
self-aligned silicide 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.