Convex Source/Drain Epitaxy for FinFET Contact Resistance
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Solution Overview
Problem
As semiconductor devices transition to nanometer technology process nodes, forming FinFETs with convex-shaped source/drain regions poses challenges in achieving defect-free structures and reducing contact resistance, leading to performance degradation.
Innovation Solution
An epitaxial scheme is employed using a cyclic deposition-etch process with remote plasma chemical vapor deposition (RPCVD) to form merged, convex-shaped source/drain regions between neighboring fins, increasing volume and landing area for contacts, and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar source/drain regions are used in scaled FinFETs, then fabrication is simpler, but contact resistance increases and device performance degrades
Solution Approach 1:
The patent applies curvature by forming convex-shaped source/drain regions instead of planar regions. The convex shape is achieved through epitaxial growth processes that create rounded, elevated structures. This curvature increases the contact area between the source/drain region and the contact, thereby reducing contact resistance and improving device performance while maintaining fabrication feasibility through controlled epitaxial processes
2Reliability
If source/drain region volume is increased to reduce contact resistance, then contact resistance decreases, but fabrication difficulty increases
Solution Approach 1:
The patent applies preliminary action by first forming recesses in the semiconductor substrate before epitaxial growth. These pre-formed recesses serve as templates that guide the subsequent epitaxial growth process, ensuring that the convex source/drain regions form with the desired shape and volume. This preliminary structuring enables precise control over the final source/drain region geometry, achieving both increased volume for reduced contact resistance and high manufacturing precision
3Reliability
If convex-shaped source/drain regions are formed to increase landing area, then contact resistance reduces, but defect formation increases
Solution Approach 1:
The patent applies parameter changes by carefully controlling epitaxial growth parameters including temperature, pressure, gas flow rates, and precursor ratios. These parameter optimizations ensure that the convex source/drain regions form with the desired shape and volume while maintaining a defect-free crystalline structure. The controlled epitaxial process allows the material to grow in a highly ordered manner, preventing defects even as the structure becomes more complex and convex
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
The approach results in defect-free source/drain regions with reduced contact resistance and improved device performance by enhancing the volume and landing area for contacts, thus addressing the challenges of scaling and fabrication in FinFETs.
Implementation Method 1
epitaxially growing a source/drain region in the recess using a remote plasma chemical vapor deposition (RPCVD) process
Implementation Method 2
epitaxially growing a source/drain region in the recess
Data Source
AI summary
The present disclosure relates generally to an epitaxy scheme for forming source/drain regions in a semiconductor device, such as an n-channel device. In an example, a method of manufacturing a semiconductor device is provided. The method generally includes forming a recess in a fin, the fin being on a substrate. The recess is proximate a gate structure over the fin. The method includes epitaxially growing a source/drain region in the recess using a remote plasma chemical vapor deposition (RPCVD) process. The RPCVD process includes using a silicon source precursor and a hydrogen carrier gas.