Epitaxial PMOS Channel Layout for Leakage and Threshold Control
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Solution Overview
Problem
Miniaturization of CMOS devices poses challenges in fabricating and maintaining performance due to issues with PMOS and NMOS transistors, affecting operational parameters.
Innovation Solution
The integration of an epitaxial channel material, such as silicon germanium, in PMOS transistors, along with specific gate dielectric and electrode materials, enhances threshold voltage and electron mobility, improving drive current and reducing current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If miniaturization is implemented to increase device density, then productivity and integration are improved, but manufacturing precision and performance reliability deteriorate due to fabricating challenges
Solution Approach 1:
The patent applies local quality by introducing epitaxial channel material specifically in the channel region of PMOS transistors, where it is most needed for performance optimization. This localized modification allows the channel material to be tailored for PMOS devices without affecting NMOS transistors, enabling precise control over carrier mobility and threshold voltage in the critical channel region while maintaining overall device miniaturization benefits
Solution Approach 2:
The patent employs composite materials by combining epitaxial silicon germanium channel material with traditional silicon substrate and gate dielectric materials. This composite structure leverages the superior hole mobility of silicon germanium in the channel region while maintaining compatibility with existing CMOS fabrication processes, thereby improving PMOS performance without compromising manufacturing precision during miniaturization
2Productivity
If miniaturization is implemented to increase device density, then productivity is improved, but performance reliability deteriorates due to performance challenges
Solution Approach 1:
The patent applies parameter changes by modifying the channel material composition to silicon germanium, which fundamentally alters the electrical parameters including hole mobility and effective mass. This parameter transformation enables PMOS transistors to maintain high performance with reduced threshold voltage and improved drive current even at miniaturized dimensions, thereby preserving performance reliability while achieving increased device density
3Ease of manufacture
If conventional CMOS structures are used, then ease of manufacture is maintained, but performance parameters deteriorate due to miniaturization effects
Solution Approach 1:
The patent applies segmentation by dividing the channel structure into distinct regions: a silicon germanium epitaxial channel layer and an underlying silicon substrate. This segmentation allows independent optimization of the channel material properties for enhanced carrier mobility while maintaining compatibility with standard CMOS fabrication processes, thus improving operational performance without sacrificing ease of manufacture
Solution Approach 2:
The patent employs preliminary action by pre-forming the epitaxial silicon germanium channel layer before subsequent CMOS processing steps. This preliminary structuring of the channel region with optimized material properties enables improved performance from the outset, allowing standard fabrication processes to proceed while achieving superior transistor characteristics that overcome miniaturization limitations
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 solution effectively addresses performance challenges by increasing threshold voltage and reducing leakage current in CMOS devices, enhancing overall device performance.
Implementation Method 1
The integration of an epitaxial channel material, such as silicon germanium, in PMOS transistors
Data Source
AI summary
A microelectronic device, comprises a base structure comprising: active regions individually comprising semiconductor material; and isolation regions horizontally alternating with the active regions and individually comprising insulative material; epitaxial semiconductor material on the semiconductor material of one of the active regions, the epitaxial semiconductor material substantially confined within a horizontal area of the one of the active regions and offset from horizontal boundaries of two of the isolation regions horizontally neighboring the one of the active regions; gate dielectric material on the epitaxial semiconductor material, portions of the semiconductor material of the one of the active regions not covered by the epitaxial semiconductor material, and portions of the two of the isolation regions; and a gate electrode stack on the gate dielectric material.