Dual-Work Function Gate Electrode for Semiconductor Reliability
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Solution Overview
Problem
Semiconductor devices face challenges in balancing increased operation speed, reliability, and reproducibility as line widths and spacing between patterns decrease, leading to difficulties in retaining high reliability and reproducibility while enhancing performance.
Innovation Solution
A semiconductor device design featuring a gate electrode with two portions having different work functions, where the first gate portion with a lower work function reduces threshold voltage and the second gate portion with a higher work function relieves hot carrier effects, improving durability and switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If line widths of semiconductor patterns and space between patterns are reduced to increase integration, then device miniaturization is achieved, but operation speed and reliability deteriorate
Solution Approach 1:
The gate electrode is divided into two portions with different work functions: a first gate portion adjacent to the source region and a second gate portion adjacent to the drain region. This local differentiation allows optimization of electrical characteristics in different regions, improving operation speed without requiring further miniaturization of the overall device structure.
Solution Approach 2:
The gate electrode is segmented into multiple portions with different work functions rather than using a uniform gate structure. This segmentation enables independent optimization of threshold voltage and hot carrier effects in different regions of the transistor, resolving the tradeoff between speed and reliability.
2Area of stationary object
If line widths of semiconductor patterns and space between patterns are reduced to increase integration, then device miniaturization is achieved, but reliability and reproducibility deteriorate
Solution Approach 1:
Different portions of the gate electrode are assigned different work functions to address specific reliability issues in different regions. The first gate portion optimizes threshold voltage for reliable switching, while the second gate portion mitigates hot carrier effects that degrade reliability, allowing the device to maintain high reliability without increasing line widths.
3Device complexity
If a uniform gate electrode is used, then device structure is simple, but threshold voltage control and hot carrier effect mitigation cannot be optimized simultaneously
Solution Approach 1:
The gate electrode structure is differentiated into portions with different work functions to achieve local optimization. The first gate portion provides threshold voltage control adjacent to the source region, while the second gate portion provides hot carrier effect mitigation adjacent to the drain region, allowing simultaneous optimization of both parameters.
Solution Approach 2:
The gate electrode is segmented into functional portions with different work functions, enabling independent control of threshold voltage and hot carrier effects. This segmentation resolves the contradiction between structural simplicity and performance optimization by introducing minimal complexity only where needed.
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 design effectively reduces hot carrier effects and improves switching speed, maintaining reliability and reproducibility while enhancing performance, thereby addressing the tradeoff between device characteristics.
Implementation Method 1
The first and second gate portions have different work functions from each other. The first gate portion with a lower work function reduces threshold voltage
Implementation Method 2
the second gate portion with a higher work function relieves hot carrier effects, improving durability and switching speed
Data Source
AI summary
A source region and a drain region are disposed in a substrate. A gate insulating film is disposed on the substrate. A gate electrode is disposed on the gate insulating film. The gate electrode may include a first gate portion adjacent to the source region and a second gate portion adjacent to the drain region. The first and second gate portions have different work functions from each other.