FinFET Source/Drain Buffer Layer for Lattice Mismatch Control
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving high integration density and operation speed due to limitations in strain application and lattice mismatch between fin-shaped active regions and source/drain regions, leading to potential cracks and crystal defects.
Innovation Solution
A semiconductor device design incorporating a fin-shaped active region with a gate insulating film, gate electrode, insulating spacers, source/drain regions made of compound semiconductor materials, and a buffer layer to reduce lattice mismatch and apply compressive stress, thereby enhancing carrier mobility and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If compound semiconductor materials with different lattice constants are used in source/drain regions, then carrier mobility is improved, but lattice mismatch and stress accumulation occur
Solution Approach 1:
A buffer layer comprising a first buffer region and a second buffer region is introduced between the group IV semiconductor material and the group III-V or group II-VI compound semiconductor materials. The first buffer region has a lattice constant intermediate between the group IV semiconductor and the compound semiconductor, and the second buffer region has a lattice constant closer to the compound semiconductor. This gradient structure gradually transitions the lattice constant, reducing mismatch and stress accumulation while enabling the use of high-mobility compound semiconductor materials in the source/drain regions.
2Productivity
If fin-shaped active region is used to increase integration density, then device integration is improved, but stress management and crystal defect prevention become more difficult
Solution Approach 1:
The buffer layer with gradient lattice constants acts as an intermediary structure between the group IV semiconductor substrate and the compound semiconductor source/drain regions. This gradual transition reduces stress concentration and prevents crystal defects in the fin-shaped active region, enabling high integration density while maintaining device reliability.
Solution Approach 2:
The lattice constant parameter is gradually changed through the buffer layer structure, transitioning from the group IV semiconductor lattice constant to the compound semiconductor lattice constant. This parameter gradient reduces stress accumulation and prevents crystal defects in the fin-shaped active region, allowing for higher integration density without compromising reliability.
3Speed
If group III-V or group II-VI compound semiconductor materials are used in source/drain regions, then operation speed is increased, but manufacturing complexity increases
Solution Approach 1:
The buffer layer is segmented into a first buffer region and a second buffer region with different lattice constants. This segmentation allows for gradual lattice constant transition, reducing manufacturing complexity by breaking down the challenging interface into manageable intermediate layers that can be grown sequentially.
Solution Approach 2:
The lattice constant parameter is systematically changed through the buffer layer structure, providing a controlled transition that simplifies the manufacturing process. By gradually adjusting the lattice constant rather than making abrupt changes, the epitaxial growth process becomes more manageable while still achieving the high operation speed benefits of compound semiconductor materials.
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 design increases the operation speed of transistors by applying compressive stress to the fin-shaped active region and reduces lattice mismatch, minimizing cracks and improving the reliability of the semiconductor device.
Implementation Method 1
a buffer layer between the fin-shaped active region and the source/drain regions, the one pair of source/drain region are located on both sides of the gate electrode. The one pair of source/drain regions include a compound semiconductor material including atoms from different groups. The lower buffer layer includes a compound semiconductor material that is amorphous and includes atoms from different groups
Implementation Method 2
The one pair of source/drain regions include a compound semiconductor material including atoms from different groups. The lower buffer layer includes a compound semiconductor material that is amorphous and includes atoms from different groups
Data Source
AI summary
A semiconductor device includes a substrate including a fin-shaped active region that protrudes from the substrate, a gate insulating film covering a top surface and both side walls of the fin-shaped active region, a gate electrode on the top surface and the both side walls of the fin-shaped active region and covering the gate insulating film, one pair of insulating spacers on both side walls of the gate electrode, one pair of source/drain region on the fin-shaped active region and located on both sides of the gate electrode, and a lower buffer layer between the fin-shaped active region the source/drain region. The source/drain regions include a compound semiconductor material including atoms from different groups. The lower buffer layer includes a compound semiconductor material that is amorphous and includes atoms from different groups.