FinFET Carrier Mobility via Segmented Recessed Epitaxial Structures
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Solution Overview
Problem
Current semiconductor devices with finFET structures face challenges in enhancing carrier mobility in the channel region, particularly due to limitations in the design and structure of epitaxial layers and recessed areas.
Innovation Solution
The semiconductor device incorporates a unique structure with active regions featuring protruding portions and recessed areas of varying depths and widths, where epitaxial semiconductor structures with different conductivity types are formed in these recessed areas, creating air gaps and specific patterns to improve carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial layers are formed on both sides of the channel region to increase carrier mobility, then carrier mobility is improved, but device complexity increases due to the need for multiple recessed areas of different depths
Solution Approach 1:
The active region is segmented into multiple protruding portions and recessed areas of different depths (first recessed areas and second recessed areas). Epitaxial layers are selectively formed in specific recessed areas, dividing the carrier mobility enhancement function across multiple segmented regions rather than requiring a uniform complex structure throughout.
Solution Approach 2:
Different regions of the active region are given different properties: first recessed areas receive epitaxial layers for carrier mobility enhancement, while second recessed areas remain without epitaxial layers. This local differentiation allows carrier mobility improvement in specific channel regions without unnecessarily complicating the entire device structure.
2Reliability
If multiple patterns with different widths are formed to create air gaps, then carrier mobility is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
Instead of requiring all patterns to have precisely controlled different widths, the invention forms patterns with substantially the same width and achieves the desired air gap formation through selective etching and epitaxial layer growth in specific recessed areas. This partial action approach reduces manufacturing precision requirements while still achieving carrier mobility enhancement.
Solution Approach 2:
The active region is pre-formed with protruding portions and recessed areas of different depths before pattern formation. This preliminary structuring allows subsequent patterns to be formed with uniform widths while still creating the necessary air gaps through selective material removal and epitaxial growth, rather than requiring precise width control of all patterns from the outset.
3Reliability
If asymmetric semiconductor structures with different widths are formed, then carrier mobility improves, but ease of manufacture decreases
Solution Approach 1:
The semiconductor structure is segmented into first and second recessed areas with different depths, where only the first recessed areas receive epitaxial layers. This segmentation creates the necessary asymmetric carrier mobility enhancement while maintaining manufacturing simplicity through standardized fabrication processes applied to different regions.
Solution Approach 2:
Asymmetric properties (epitaxial layers in first recessed areas, no epitaxial layers in second recessed areas) are applied locally rather than uniformly across all semiconductor structures. This allows carrier mobility improvement in specific regions while using simple, standardized fabrication processes for the entire device, maintaining ease of manufacture.
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 design enhances carrier mobility characteristics in the transistor channel regions, leading to improved performance and efficiency in semiconductor devices with finFET structures.
Implementation Method 1
The plurality of semiconductor structures may be epitaxial layers having a conductivity type different from the active regions
Data Source
AI summary
A semiconductor device includes a first pattern on a first active region, a second pattern on a second active region, and a third pattern on a third active region. The first pattern is spaced from the second pattern by a first interval corresponding to the width of a first recess between the first and second active regions. The second pattern is spaced from the third pattern by a second interval corresponding to the width of a second recess between the second and third active regions. The first, second, and third patterns includes gate patterns, and the first and second recesses include semiconductor material with a conductivity type different from the active regions. The semiconductor material in one recess extends higher than the semiconductor material in the other recess. The first, second, and third patterns have the same width, and the first and second recesses have different depths.