Floating-Gate LDMOS Structure for Breakdown Voltage Control
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Solution Overview
Problem
Conventional high voltage semiconductor devices face challenges in maintaining breakdown voltage and specific on-resistance characteristics during turn-on and turn-off, leading to increased impact ionization and reduced device performance due to electric field concentration near the drain edge.
Innovation Solution
Incorporating a floating gate and/or connection structure between the gate electrode and drain, allowing for improved breakdown voltage characteristics and electric field distribution control, while simplifying the manufacturing process by forming these structures simultaneously with the gate electrode or field plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LDMOS structure with field plate and gate electrode is used, then the device achieves high input impedance and fast switching response, but breakdown voltage deteriorates during turn-off due to electric field concentration at drift region edges
Solution Approach 1:
A floating gate is introduced as an intermediary structure between the gate electrode and drain. This floating gate redistributes the electric field in the drift region, preventing field concentration at the edges while maintaining the high input impedance and fast switching characteristics of the conventional LDMOS structure.
Solution Approach 2:
The floating gate extends in the vertical dimension below the gate electrode, creating a three-dimensional electric field distribution. This additional dimensional control allows for optimized field distribution in the drift region, reducing breakdown voltage deterioration during turn-off.
2Reliability
If the device is turned on with conventional structure, then charge carriers increase in the drift region, but breakdown voltage deteriorates due to impact ionization near drain edge
Solution Approach 1:
The floating gate acts as a mediator that redistributes charge carriers in the drift region during turn-on. By controlling the electric field distribution, it reduces the intensity of field concentration near the drain edge, thereby suppressing impact ionization while maintaining necessary charge carrier flow.
3Reliability
If additional floating gate structures are formed to improve breakdown voltage, then device performance enhances, but manufacturing process complexity increases
Solution Approach 1:
The floating gate is formed simultaneously with the gate electrode in the same deposition and patterning processes. This merging of formation steps eliminates the need for separate floating gate fabrication steps, reducing manufacturing process complexity while maintaining the breakdown voltage improvement benefits.
Solution Approach 2:
The same deposition and patterning processes serve dual purposes: forming both the gate electrode and the floating gate structure. This multi-functionality approach reduces the total number of manufacturing steps and simplifies the overall fabrication process.
Data Source
AI summary
Disclosed is a high voltage semiconductor device and a method of manufacturing the same and, more particularly, a high voltage semiconductor device and a method of manufacturing the same enabling more effective integration through improvement of breakdown voltage (BV) characteristics during device turn-on and/or turn-off and consequent improvement of specific on-resistance (Rsp) characteristics by forming or including a floating gate and/or a connection structure on a substrate, between a gate electrode and a drain.