Lateral Double-Diffused Transistor Field Plate for Breakdown Voltage
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Solution Overview
Problem
Conventional techniques for achieving high breakdown voltage in lateral double-diffused transistors result in increased drain-to-source on-resistance, which undesirably decreases switching speed.
Innovation Solution
A method involving a substrate with a device region including a source, gate, and drain region, where a field structure is formed around the drain and coupled to a potential that distributes the electric field across the substrate between the gate and drain, reducing impact ionization and improving breakdown voltage without increasing the distance between the gate and drain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the drain and the gate is increased to achieve high breakdown voltage, then the breakdown voltage increases, but the drain-to-source on-resistance increases which decreases switching speed
Solution Approach 1:
The patent segments the electric field distribution by introducing a field structure (such as a field oxide region or field plate) between the drain and gate. This field structure divides the electric field into multiple regions, allowing the drain-to-source distance to remain short for fast switching while still achieving high breakdown voltage through the distributed field segments.
Solution Approach 2:
The field structure acts as an intermediary element between the drain and gate. It mediates the electric field distribution, preventing direct high-field stress between the drain and gate that would require large spacing, while still providing the necessary voltage blocking capability through its own field distribution properties.
2Reliability
If conventional techniques are used to achieve high breakdown voltage, then the breakdown voltage increases, but the device complexity increases due to additional structures
Solution Approach 1:
The field structure is merged with existing device components such as the gate electrode or drain region. For example, the field plate may be formed as an extension of the gate electrode, or the field oxide region may be integrated with the existing isolation structures, thereby achieving high breakdown voltage without adding significant structural complexity.
Solution Approach 2:
The field structure serves multiple functions simultaneously: it provides voltage blocking for high breakdown voltage, distributes the electric field to reduce peak stress, and can also serve as part of the gate control structure or isolation region. This multi-functionality reduces the need for separate dedicated structures.
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 approach enhances gate dielectric breakdown voltage while maintaining fast switching speed by dispersing the electric field, thereby improving the performance of high power devices like transistors.
Implementation Method 1
An interconnection to the field structure is formed. The interconnection is coupled to a potential which distributes the electric field across the substrate between the second side of the gate and the drain.
Data Source
AI summary
A method of forming a device is disclosed. The method includes providing a substrate having a device region. The device region includes a source region, a gate region and a drain region defined thereon. The substrate is prepared with gate layers on the substrate. The gate layers are patterned to form a gate in the gate region and a field structure surrounding the drain region. A source and a drain are formed in the source region and drain region respectively. The drain is separated from the gate on a second side of the gate and the source is adjacent to a first side of the gate. An interconnection to the field structure is formed. The interconnection is coupled to a potential which distributes the electric field across the substrate between the second side of the gate and the drain.