FinFET Source/Drain Epitaxy for Higher Faceted Junction Volume
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to form source/drain regions with increased height and volume to reduce stress relaxation and improve device performance.
Innovation Solution
The process involves growing layers of material using different epitaxial processes that promote growth along various facets, with specific process parameters controlled to enhance facet formation and increase the height of the source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional epitaxial processes are used to form source/drain regions, then the manufacturing process is simple, but the source/drain region height and volume are insufficient leading to stress relaxation
Solution Approach 1:
The epitaxial growth process is divided into multiple sequential stages, each with different process parameters. The first stage grows initial source/drain regions with standard parameters, while the second stage continues growth with modified parameters (different temperature, pressure, or gas flow rates) to achieve enhanced height and volume. This segmentation allows the system to achieve complex geometric outcomes through controlled sequential steps rather than a single complex process.
Solution Approach 2:
The patent applies parameter changes by modifying epitaxial growth conditions between stages. Specific parameters such as temperature, pressure, gas flow rates, or composition ratios are adjusted to promote preferential growth in certain directions during the second stage, thereby increasing the vertical height and overall volume of the source/drain regions without requiring fundamentally new process equipment or methods.
2Reliability
If source/drain region height is increased to reduce stress relaxation, then device performance improves, but the manufacturing precision requirements increase
Solution Approach 1:
The epitaxial growth is performed in periodic stages with distinct parameter sets. The first stage establishes a foundation with standard parameters, then the second stage applies different parameters to promote facet formation and height increase. This periodic application of different growth conditions allows precise control over the final geometry, reducing the need for post-growth trimming or correction while achieving the desired height and facet structure.
Solution Approach 2:
Instead of using mechanical means such as physical deposition or layer-by-layer assembly to build height, the patent substitutes a chemical growth mechanism through epitaxial processes. The controlled chemical reactions during epitaxial growth naturally form facets and achieve height increases through crystal structure development, which is inherently more precise and controllable than mechanical assembly methods.
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 results in source/drain regions with a larger volume, which reduces stress relaxation and improves the contact between the source/drain regions and the contacts, leading to enhanced device performance.
Implementation Method 1
performing a first epitaxial process to grow a first semiconductor material in the recess, wherein the first epitaxial process preferentially forms facet planes of a first crystalline orientation
Data Source
AI summary
A method includes forming a fin protruding from a substrate; forming an isolation region surrounding the fin; forming a gate structure extending over the fin and the isolation region; etching the fin adjacent the gate structure to form a recess; forming a source/drain region in the recess, including performing a first epitaxial process to grow a first semiconductor material in the recess, wherein the first epitaxial process preferentially forms facet planes of a first crystalline orientation; and performing a second epitaxial process to grow a second semiconductor material on the first semiconductor material, wherein the second epitaxial process preferentially forms facet planes of a second crystalline orientation, wherein a top surface of the second semiconductor material is above a top surface of the fin; and forming a source/drain contact on the source/drain region.