HEMT Source/Drain Multi-Layer Cap for Leakage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High Electron Mobility Transistors (HEMTs) face challenges in reducing leakage current and improving conductance and on-state current characteristics due to the proximity of source/drain regions to the gate, which affects the resistance and performance of the device.
Innovation Solution
A multi-layer semiconductor cap is used in the source/drain regions of HEMTs, comprising a delta-doped layer and a high etch selectivity layer, where the etching process increases the distance between the delta-doped layer and the conductive gate, reducing leakage current and allowing the high selectivity layer to be closer to the gate, thereby reducing resistance and enhancing conductance and on-state current characteristics without increasing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source/drain regions are placed close to the gate, then the resistance is reduced and conductance is improved, but the leakage current increases
Solution Approach 1:
The source/drain region is segmented into multiple semiconductor layers with different doping characteristics. The first semiconductor layer has higher doping concentration to reduce resistance, while the second semiconductor layer has lower doping concentration to reduce leakage current. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between conductance and leakage current.
Solution Approach 2:
Different regions of the source/drain structure are assigned different doping concentrations tailored to their specific functional requirements. The region closer to the gate (second semiconductor layer) has lower doping to minimize leakage, while the region farther from the gate (first semiconductor layer) has higher doping to minimize resistance. This local quality differentiation resolves the contradiction by optimizing each location for its primary function.
2Reliability
If the delta-doped layer is placed close to the gate, then the on-state current is improved, but the leakage current increases
Solution Approach 1:
The doped region is segmented into two separate semiconductor layers with different doping concentrations. The first layer provides high doping for low resistance, while the second layer provides low doping for low leakage. This segmentation allows the structure to achieve both low on-resistance and low leakage current, resolving the contradiction.
Solution Approach 2:
The source/drain region uses a composite structure of two semiconductor layers with different doping characteristics. This composite material approach combines the advantages of both high-doping (low resistance) and low-doping (low leakage) regions in a single integrated structure, resolving the contradiction between on-state current and leakage current.
3Ease of manufacture
If a single-layer semiconductor cap is used, then the manufacturing is simpler, but the ability to reduce leakage current while maintaining low resistance is limited
Solution Approach 1:
The semiconductor cap is segmented into multiple layers with different doping concentrations, allowing independent optimization of resistance and leakage current characteristics for each layer. This segmentation enables sophisticated electrical performance tuning while maintaining compatibility with standard semiconductor manufacturing processes.
Solution Approach 2:
The invention changes the doping concentration parameter across different semiconductor layers. By varying the doping concentration from high in the first layer to low in the second layer, the structure achieves both low resistance and low leakage current, demonstrating how parameter changes can resolve performance contradictions.
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 solution effectively reduces resistance and improves the conductance and on-state current characteristics of HEMTs by spacing the delta-doped layer away from the gate, while maintaining low leakage current, thus enhancing the transistor's performance.
Implementation Method 1
an etching process is applied to a sidewall the semiconductor cap to increase a distance between the delta-doped layer and the conductive gate
Data Source
AI summary
An embodiment high electron mobility transistor (HEMT) includes a gate electrode over a semiconductor substrate and a multi-layer semiconductor cap over the semiconductor substrate and adjacent the gate electrode. The multi-layer semiconductor cap includes a first semiconductor layer and a second semiconductor layer comprising a different material than the first semiconductor layer. The first semiconductor layer is laterally spaced apart from the gate electrode by a first spacing, and the second semiconductor layer is spaced apart from the gate electrode by a second spacing greater than the first spacing.