Gate-All-Around Metal Gate Structure for Short-Channel Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor manufacturing lies in achieving low-cost, high-performance, and low-power integrated circuits with improved gate control and reduced short-channel effects, which existing technologies struggle to address effectively.
Innovation Solution
The development of a semiconductor device featuring a multi-gate transistor with a gate structure that wraps around multiple channel structures, utilizing different metal components for varying threshold voltages and incorporating a metal cap with a mid-gap work function to facilitate gate formation, compatible with CMOS processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-gate transistor structures are used, then manufacturing processes remain simple, but gate control deteriorates and short-channel effects increase
Solution Approach 1:
The patent transitions from a conventional planar single-gate structure to a three-dimensional gate-all-around structure where the gate wraps around the channel region. This dimensional change enables the gate to control the channel from multiple directions (top, bottom, and sidewalls), significantly improving gate control and reducing short-channel effects while maintaining compatibility with scaled manufacturing processes.
Solution Approach 2:
The patent employs a multi-layer gate structure comprising different metal components with distinct work functions. Specifically, it uses a first metal layer with a first work function and a second metal layer with a second work function, allowing independent optimization of threshold voltages for different transistor types (e.g., NFET and PFET) within the same device, thereby improving overall device performance and control.
2Manufacturing precision
If multiple metal components with different work functions are used, then threshold voltage control improves, but manufacturing process complexity increases
Solution Approach 1:
The patent introduces a metal cap structure formed prior to the final gate metal deposition. This metal cap serves as a preliminary structure that facilitates the subsequent formation of the multi-layer gate structure with different work functions. The metal cap is strategically positioned and removed in controlled steps, enabling precise threshold voltage control while managing the complexity of the manufacturing process through pre-planned, sequential operations.
Solution Approach 2:
The gate structure is divided into multiple discrete metal layers, each with a specific work function tailored for different transistor requirements. This segmentation allows independent optimization of threshold voltages for NFET and PFET devices, enabling precise control over device characteristics while maintaining a systematic manufacturing approach through layer-by-layer deposition and selective removal processes.
3Productivity
If transistor dimensions are scaled down, then production efficiency and cost reduction improve, but short-channel effects and gate control deterioration worsen
Solution Approach 1:
The gate-all-around structure provides three-dimensional control over the channel region, with the gate extending around the channel from multiple directions. This dimensional approach maintains effective gate control even as horizontal dimensions are scaled down, allowing continued transistor miniaturization for higher density and productivity without sacrificing the essential gate control needed for reliable operation.
Solution Approach 2:
The multi-metal gate structure with different work functions enables optimized threshold voltage control for scaled transistors. By selecting appropriate metal combinations, the design compensates for short-channel effects that become more pronounced at smaller dimensions, maintaining device reliability and performance as transistors are scaled down to increase production capacity and circuit density.
Data Source
AI summary
Aspects of the disclosure provide a semiconductor device and a method for forming the semiconductor device. The semiconductor device includes a first channel structure, a first gate dielectric layer surrounding the first channel structure, and a first metal gate surrounding first gate dielectric layer. The first metal gate includes a first metal layer in direct contact with the first gate dielectric layer and a first metal cap in direct contact with the first gate dielectric layer, wherein the first metal cap is in direct contact with the first metal layer.