Recessed Transistor with Strained Channel for Drive Current
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Solution Overview
Problem
The challenge in integrated circuit fabrication is to reduce the size of transistors while maintaining or improving performance metrics such as drive current, which is hindered by small channel effects and lattice mismatch complications.
Innovation Solution
Transistors with channel regions extending within strained semiconductor material are developed, utilizing a combination of different semiconductor materials with lattice mismatch to induce strain, enhancing electron mobility and drive current. This is achieved by forming a recessed transistor structure with a gate dielectric material and source/drain regions, where the channel region is partially or entirely within the strained semiconductor material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If transistor size is reduced to achieve higher integration levels, then integration density is improved, but small channel effects and performance degradation worsen
Solution Approach 1:
The patent applies parameter changes by introducing strain into the semiconductor material through lattice mismatch between different material layers. This strain modifies the physical parameters of the channel material, enhancing carrier mobility and compensating for performance degradation caused by reduced channel dimensions, thereby maintaining transistor reliability at smaller sizes
Solution Approach 2:
The patent employs composite materials by combining different semiconductor materials with mismatched lattice constants (e.g., SiGe source/drain regions with silicon channel). This composite structure generates mechanical strain in the channel region, improving electron or hole mobility and offsetting the negative effects of small channel dimensions, thus resolving the contradiction between size reduction and performance maintenance
2Device complexity
If conventional transistor structures are used to maintain simplicity, then device complexity is reduced, but drive current and performance are limited
Solution Approach 1:
The patent modifies the physical state and properties of the semiconductor material by introducing strain through lattice mismatch. This parameter change significantly enhances carrier mobility in the channel, leading to improved drive current without requiring complex device architectures, thus achieving high performance with relatively simple structural modifications
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 strained semiconductor material significantly enhances electron mobility, leading to improved drive current in transistors, potentially surpassing conventional transistor performance, and can be applied in memory arrays like RRAM and DRAM.
Implementation Method 1
The strained semiconductor material may improve electron mobility within the channel regions and thereby improve drive current
Data Source
AI summary
Some embodiments include a construction having a second semiconductor material over a first semiconductor material. A region of the second semiconductor material proximate the first semiconductor material has strain due to different lattice characteristics of the first and second semiconductor materials. A transistor gate extends downwardly into the second semiconductor material. Gate dielectric material is along sidewalls and a bottom of the transistor gate. Source/drain regions are along the sidewalls of the transistor gate, and the gate dielectric material is between the source/drain regions and the transistor gate. A channel region extends between the source/drain regions and is under the bottom of the transistor gate. At least some of the channel region is within the strained region.