Hetero-junction Semiconductor Device Stress Management
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Solution Overview
Problem
The miniaturization of transistors in semiconductor devices leads to decreased turn-on current, affecting operation speed and yield due to variations in trench depths and thin film sizes, which complicates the application of stress for improved carrier mobility.
Innovation Solution
A semiconductor device with a hetero-junction structure comprising a buffer layer, a first semiconductor layer, and a second semiconductor layer, where the buffer layer reduces stress and misfit dislocations, and a gate electrode is formed on the second semiconductor layer to enhance carrier mobility and operation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistors are miniaturized to increase integration density, then device integration is improved, but turn-on current decreases and operation speed deteriorates
Solution Approach 1:
The patent applies different stress conditions to different regions of the transistor channel. Tensile stress is applied to n-channel regions while compressive stress is applied to p-channel regions, optimizing carrier mobility locally for each transistor type without affecting the entire device structure uniformly.
Solution Approach 2:
The patent changes the physical state of the channel region by introducing stress through heteroepitaxial layers with different lattice constants. This modifies the band structure and carrier mobility parameters, enabling high-speed operation in miniaturized transistors despite reduced dimensions.
2Speed
If stress is applied to channel regions to increase carrier mobility, then operation speed is improved, but manufacturing complexity increases due to trench formation and lattice matching requirements
Solution Approach 1:
The patent segments the channel region into distinct n-channel and p-channel portions, applying appropriate stress to each segment independently. This allows optimized carrier mobility for each transistor type while maintaining a unified device structure that simplifies overall fabrication.
Solution Approach 2:
The patent uses heteroepitaxial composite structures combining semiconductor layers with different lattice constants. These composite materials provide built-in stress without requiring separate trench formation and stress application steps, reducing fabrication complexity while achieving the desired stress effects.
3Reliability
If trench regions are formed and thin films are deposited to apply stress, then carrier mobility is improved, but yield decreases due to variations in trench depths and film sizes
Solution Approach 1:
The patent extracts the stress application mechanism from the traditional trench-based approach and integrates it directly into the channel region through heteroepitaxial growth. This eliminates the need for separate trench formation and film deposition steps, reducing variability in stress application and improving manufacturing precision.
Solution Approach 2:
The patent incorporates stress-inducing layers during the initial heteroepitaxial growth stage, before subsequent fabrication steps. This preliminary integration of stress application ensures consistent stress distribution throughout the channel region, reducing yield variations caused by later process variations.
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 proposed solution improves carrier mobility and operation characteristics by reducing stress and misfit dislocations, leading to increased electron mobility and high power efficiency with a normally off property, thus addressing the challenges of miniaturization and yield in semiconductor devices.
Implementation Method 1
a buffer layer, a first semiconductor layer, and a second semiconductor layer, where the buffer layer reduces stress and misfit dislocations
Implementation Method 2
a material having a less or greater lattice constant than that of silicon (Si) should be formed to enable application of stress
Implementation Method 3
application of tensile stress or compressive stress to channel regions of transistors to improve driving current characteristics and operation speed
Data Source
AI summary
A semiconductor may include a semiconductor substrate including a first region and a second region disposed at opposite sides of the first region, a first trench formed in the first region, a buffer layer filling a portion of the first trench, a first semiconductor layer formed on the buffer layer, a second semiconductor layer forming a hetero-junction with the first semiconductor layer on the first semiconductor layer of the first region and a gate electrode formed on the second semiconductor layer of the first region.