Semiconductor Gate Structure Aluminum Nitride Work Function Film
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Solution Overview
Problem
Existing multi-gate transistors face challenges in reducing or modulating threshold voltages due to limitations in the thickness of work function films and the available space for thick metal film deposition.
Innovation Solution
A semiconductor device is designed with a first and second active pattern on a substrate, separated by a field insulating film, and each active pattern is intersected by a gate structure. The gate structure includes a gate insulating film, an aluminum nitride film, and an upper conductive film, allowing for the modulation of threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the thickness of work function films is reduced to modulate threshold voltages, then threshold voltage modulation capability is improved, but the film thickness reaches its limit and further reduction is difficult
Solution Approach 1:
The patent transitions from controlling threshold voltage through film thickness (one dimension) to controlling it through film area/size (another dimension). The work function film is formed with varying areas over different regions of the active pattern, allowing threshold voltage modulation without relying on thickness variation. This resolves the contradiction by providing an additional degree of freedom for threshold voltage control.
Solution Approach 2:
The patent changes the controlling parameter from film thickness to film area. By adjusting the area of the work function film rather than its thickness, the patent achieves threshold voltage modulation while avoiding the manufacturing precision limits associated with thin film control. This parameter substitution resolves the technical contradiction.
2Adaptability or versatility
If thick metal film is deposited to reduce threshold voltage, then threshold voltage reduction is achieved, but the available space for metal film deposition is limited
Solution Approach 1:
The patent applies local quality by forming work function films with different areas at different locations on the active pattern. Instead of uniformly depositing thick metal film across the entire structure (which would require excessive space), the work function film is localized to specific regions with optimized areas. This allows threshold voltage reduction capability while minimizing the space required for metal film deposition.
3Ease of operation
If multi-gate transistor structure is used to enhance current control capability, then current control capability is improved, but threshold voltage modulation becomes more difficult due to structural constraints
Solution Approach 1:
The patent segments the gate structure into multiple gates (first gate and second gate) that can independently control different aspects of transistor operation. The first gate controls current flow through the channel, while the second gate (with work function film) specifically controls threshold voltage. This segmentation allows both current control capability and threshold voltage modulation to be achieved simultaneously without mutual interference.
Solution Approach 2:
The multi-gate structure is designed to perform multiple functions: the first gate provides current control while the second gate provides threshold voltage modulation. By assigning different functions to different gates, the patent achieves both current control capability and threshold voltage modulation capability within the same device structure, resolving the contradiction between these two requirements.
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 semiconductor device effectively reduces or modulates threshold voltages, enhancing the control capability of current and suppressing short channel effects, while maintaining the benefits of three-dimensional channel transistors.
Implementation Method 1
each of the first upper insertion film and the second upper insertion film includes an aluminum nitride film... effectively reduces or modulates threshold voltages
Data Source
AI summary
A semiconductor device includes first and second active patterns disposed on a substrate, a field insulating film disposed between the first and second active patterns, a first gate structure intersecting the first active pattern, and a second gate structure intersecting the second active pattern, in which the first gate structure includes a first gate insulating film on the first active pattern, a first upper insertion film on the first gate insulating film, and a first upper conductive film on the first upper insertion film, and the second gate structure includes a second gate insulating film on the second active pattern, a second upper insertion film on the second gate insulating film, and a second upper conductive film on the second upper insertion film. Each of the first and second upper insertion films may include an aluminum nitride film. Each of the first and second upper conductive films may include aluminum.