Semiconductor Gate Extending Portion Reduces Drain-to-Gate Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor structures face challenges in reducing drain-to-gate capacitance, which leads to unwanted current flow and power loss in high-speed switching components due to the coupling effect, despite attempts to minimize it through field plate structures and oxide layer thickness modifications.
Innovation Solution
A semiconductor structure is designed with a polysilicon gate having regions of opposite doping types, where the gate extending portion acts as both a field plate and a capacitor series connection to reduce drain-to-gate capacitance, fabricated using implantation processes without altering existing MOS process specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field plate structure is electrically connected to the gate to disperse electric field strength, then component damage is avoided, but drain-to-gate capacitance increases causing power loss
Solution Approach 1:
The gate structure is segmented into two distinct parts: the main gate electrode and the gate extending portion. These segments have different doping types (first doping type for main gate, second doping type for extending portion), allowing them to perform different functions. The main gate controls the channel while the extending portion disperses the electric field, thereby reducing the harmful capacitance effect while maintaining the field dispersion benefit.
Solution Approach 2:
Different regions of the gate structure are assigned different doping types to optimize local functions. The main gate region has one doping type optimized for channel control, while the gate extending portion has an opposite doping type optimized for electric field dispersion. This local differentiation allows each region to excel at its specific function without compromising the other.
2Loss of energy
If oxide layer thickness is increased underneath the field plate to reduce capacitance, then drain-to-gate capacitance decreases, but manufacturing complexity increases
Solution Approach 1:
Instead of changing the physical dimension (oxide thickness) to reduce capacitance, the invention changes the electrical parameter (doping type) of the gate extending portion. This parameter change achieves capacitance reduction through the electrical characteristics of the oppositely doped region, avoiding the need to modify oxide layer thickness and the associated manufacturing complexity.
3Loss of energy
If dopant implantation is performed to reduce capacitance, then drain-to-gate capacitance decreases, but resistance increases
Solution Approach 1:
The gate is segmented into a main gate electrode and a gate extending portion with opposite doping types. The gate extending portion with the second doping type (opposite to the main gate) provides capacitance reduction while the main gate maintains low resistance for current conduction. This segmentation allows the system to achieve capacitance reduction without sacrificing resistance characteristics.
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
This design effectively reduces drain-to-gate capacitance, preventing component damage in high-voltage environments, avoiding undesired current flow, and improving switching frequency and power conversion efficiency.
Implementation Method 1
Due to the effect of capacitor series connection, the drain-to-gate capacitance is reduced
Implementation Method 2
the gate extending portion has the function of field plate, which can effectively disperse the electric field strength of the drain region
Implementation Method 3
two regions with opposite doping types are formed in the polysilicon gate of a MOS transistor using implantation processes
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate, a gate disposed on the substrate, a source disposed in the substrate and located on one side of the gate, a drain disposed in the substrate and located on another side of the gate, and a gate extending portion disposed on the substrate and located between the gate and the drain. The doping type of the gate is the opposite of that of the gate extending portion.