Fin Active Region Epitaxial Growth with Inflection Points
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Solution Overview
Problem
The existing semiconductor devices with fin active regions and epitaxially grown source/drain regions often have uneven sidewalls due to wet and anisotropic etching processes, which can lead to performance issues in metal oxide semiconductor (MOS) transistors.
Innovation Solution
The semiconductor devices incorporate fin active regions with epitaxial regions having inflection points, where the upper width is greater than the lower width, and source/drain regions with vertically flat sidewalls or inflection points, along with specific gate and spacer structures, to enhance performance and manufacturing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching and anisotropic etching processes are used to form recess regions, then the recess regions can be formed, but the sidewalls become uneven and spherical in shape
Solution Approach 1:
A mandrel structure is formed in the recess region before epitaxial growth to guide the formation of source/drain regions. This preliminary structure ensures that the epitaxial growth proceeds uniformly and produces vertically flat sidewalls, preventing the spherical shape that would otherwise result from wet and anisotropic etching processes alone.
Solution Approach 2:
The mandrel acts as an intermediary structure between the recess region and the final source/drain regions. It provides a template that controls the epitaxial growth process, ensuring uniform sidewall formation while still allowing the recess regions to be formed using conventional wet and anisotropic etching processes.
2Device complexity
If epitaxial growth is performed without a mandrel, then the process is simpler, but the sidewalls of source/drain regions become uneven
Solution Approach 1:
The mandrel is formed as a preliminary structure before epitaxial growth to provide a template for uniform source/drain region formation. This approach maintains relatively simple epitaxial growth processes while ensuring vertically flat sidewalls, avoiding the need for complex multi-step etching and growth sequences.
3Reliability
If uniformly shaped source/drain regions are formed, then MOS transistor performance is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The mandrel structure is formed in advance to template the uniform source/drain regions, ensuring consistent MOS transistor performance. This approach achieves reliable device performance while keeping the overall process relatively simple by using a single mandrel-based epitaxial growth step rather than multiple complex etching and deposition cycles.
Solution Approach 2:
The mandrel structure serves multiple functions: it defines the recess region boundaries, templates the source/drain region formation, and ensures uniform sidewall profiles. This self-service capability of the mandrel reduces the need for additional process steps to achieve uniform source/drain regions, thereby maintaining manufacturing simplicity while improving device reliability.
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 configuration improves the performance of MOS transistors by ensuring uniformity and efficiency in the epitaxial growth, leading to better electrical characteristics and manufacturing consistency.
Implementation Method 1
a first epitaxial region in the first fin active region between the first gate patterns
Data Source
AI summary
Semiconductor devices are providing including a first isolation region configured to define a first fin active region protruding from a substrate, first gate patterns on the first fin active region, and a first epitaxial region in the first fin active region between the first gate patterns. Sidewalls of the first epitaxial region have first inflection points so that an upper width of the first epitaxial region is greater than a lower width of the first epitaxial region.