Semiconductor Device Gate Electrode Segmentation for Miller Factor Reduction
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges in reducing the Miller factor, which affects the operation performance due to limited gate-source capacitance and parasitic capacitance, leading to increased electric interference between the gate and drain electrodes.
Innovation Solution
The semiconductor device incorporates a specific metal layer configuration with overlapping portions between the gate electrode and the source electrode, increasing gate-source capacitance by positioning the first and second metal layers closer to the drain electrode, and using a p-type doped layer to suppress two-dimensional electron gas under the gate, thereby reducing the Miller ratio and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate electrode is positioned closer to the drain electrode to improve device performance, then the operation performance improves, but the parasitic capacitance between gate and drain increases leading to higher Miller factor
Solution Approach 1:
The gate electrode is segmented into a main body portion and an extending portion that protrudes toward the drain electrode. This segmentation allows the extending portion to be positioned closer to the drain to improve performance while the main body portion maintains appropriate spacing to control parasitic capacitance. The segmented structure enables independent optimization of different gate regions for conflicting performance requirements.
Solution Approach 2:
Different portions of the gate electrode have different spatial relationships with the drain electrode. The extending portion is locally positioned closer to the drain to enhance performance, while the main body portion maintains greater distance to minimize parasitic effects. This local quality differentiation resolves the contradiction by applying different positioning strategies to different parts of the same component.
2Reliability
If the gate-source capacitance is increased to reduce the Miller factor, then the Miller ratio decreases, but the device complexity increases due to additional metal layers and structures
Solution Approach 1:
The first and second metal layers are merged to form a unified gate structure that integrates multiple functions. The gate electrode combines the controlling function with the capacitance enhancement function through its extending portion, eliminating the need for separate components. This merging reduces device complexity while achieving the desired increase in gate-source capacitance for Miller factor reduction.
Solution Approach 2:
The gate electrode serves multiple functions simultaneously: it controls the channel current, provides capacitance to reduce the Miller factor, and the extending portion additionally provides performance enhancement by being positioned closer to the drain. This multi-functionality reduces the need for separate components, thereby reducing device complexity while achieving reliability improvement.
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 configuration enhances the gate-source capacitance, decreases the Miller ratio, and reduces electric interference, leading to improved operational performance and reduced parasitic capacitance, making the semiconductor device more efficient.
Implementation Method 1
increasing gate-source capacitance by positioning the first and second metal layers closer to the drain electrode
Implementation Method 2
using a p-type doped layer to suppress two-dimensional electron gas under the gate
Data Source
AI summary
A semiconductor device includes a substrate, an active layer, a source electrode, a drain electrode, a gate electrode, a first metal layer, and a second metal layer. The active layer is disposed on the substrate. The source electrode and the drain electrode are electrically connected to the active layer. The gate electrode is disposed on the active layer and between the source electrode and the drain electrode. The gate electrode has a first extending portion extending toward the drain electrode. The first metal layer is partially disposed between the first extending portion and the active layer, and extends toward the drain electrode. The second metal layer is disposed above the first extending portion and extends toward the drain electrode. Another portions of the first and second metal layers protrude from the first extending portion. The first metal layer and the second metal layer are electrically connected to the source electrode.