Dual Workfunction Gate Electrodes for III-V Semiconductor Leakage Control
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Solution Overview
Problem
Conventional semiconductor fabrication processes face challenges in scaling to sub-10 nm feature sizes due to variability and trade-offs between critical dimension and spacing, leading to elevated off-state leakage issues in group III-V semiconductor devices caused by band-to-band tunneling (BTBT) and floating body barrier lowering (BIBL).
Innovation Solution
Implementing dual workfunction gate electrodes with distinct metal workfunctions on the source and drain sides to reduce band bending and the BTBT window, using N-type and P-type metals in the gate electrode to control thermionic leakage and electric field, without altering channel or source/drain materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional single workfunction gate electrode is used, then device structure is simple, but leakage current increases due to band-to-band tunneling and floating body effects
Solution Approach 1:
The gate electrode is segmented into two distinct workfunction materials (first workfunction material and second workfunction material) with different workfunctions, allowing independent optimization of source and drain side band bending to reduce leakage current while maintaining manageable structural complexity
Solution Approach 2:
Different regions of the gate electrode are assigned different workfunction materials tailored to local requirements: the first workfunction material optimizes the source side for reduced thermionic emission, while the second workfunction material optimizes the drain side for reduced band-to-band tunneling, achieving local quality optimization
2Productivity
If feature size is scaled down to sub-10 nm, then device density increases, but manufacturing precision becomes difficult to maintain
Solution Approach 1:
The invention changes the workfunction parameter of the gate electrode by using multiple materials with different workfunctions, allowing optimization of electrical characteristics without further scaling physical dimensions, thus maintaining manufacturing precision while achieving performance improvement
3Productivity
If channel width is reduced to increase density, then device capacity increases, but off-state leakage worsens due to enhanced band-to-band tunneling
Solution Approach 1:
The dual workfunction gate electrode applies different workfunction materials at different locations along the channel, with the first material addressing source side leakage and the second material addressing drain side leakage, enabling localized optimization that maintains effectiveness even as channel dimensions are reduced for increased density
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
Significantly reduces leakage current and power in high mobility transistors, enhancing the performance of III-V and Ge-based semiconductor devices by minimizing band-to-band tunneling and floating body effects.
Implementation Method 1
dual workfunction gate electrodes with distinct metal workfunctions on the source and drain sides to reduce band bending and the BTBT window, using N-type and P-type metals in the gate electrode to control thermionic leakage and electric field
Implementation Method 2
using N-type and P-type metals in the gate electrode to control thermionic leakage and electric field
Data Source
AI summary
Group III-V semiconductor devices having dual workfunction gate electrodes and their methods of fabrication are described. In an example, an integrated circuit structure includes a gallium arsenide layer on a substrate. A channel structure is on the gallium arsenide layer. The channel structure includes indium, gallium and arsenic. A source structure is at a first end of the channel structure and a drain structure is at a second end of the channel structure. A gate structure is over the channel structure, the gate structure having a first workfunction material laterally adjacent a second workfunction material. The second workfunction material has a different workfunction than the first workfunction material.