LDMOS RESURF Layer Layout for Low On-Resistance and High Breakdown
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Solution Overview
Problem
Lateral double-diffused metal oxide semiconductor (LDMOS) transistors face a trade-off between specific on-resistance (Rdson) and drain-to-source breakdown voltage (BVd_s), where reducing on-resistance increases breakdown voltage, but increasing thickness of the oxide layer and distance between regions increases on-resistance, limiting overall performance.
Innovation Solution
Incorporating a reduced surface field effect layer of a first doping type formed by ion implantation in a predetermined region of the well region, with a body region and drain portion of different doping types, and an insulating structure between them, allowing for a spacing that adjusts based on doping concentration to balance on-resistance and breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the oxide layer thickness and distance between regions are increased to improve breakdown voltage, then breakdown voltage is improved, but on-resistance increases
Solution Approach 1:
The patent applies local quality by creating a reduced surface field effect layer in a specific predetermined region of the well region, rather than uniformly modifying the entire structure. This localized doping approach allows the surface field to be reduced only where necessary (near the drain region) while maintaining optimal characteristics in other areas, thus improving breakdown voltage without unnecessarily increasing on-resistance across the entire device.
Solution Approach 2:
The patent changes the doping concentration parameter by forming a reduced surface field effect layer with a first doping type in a predetermined region. This parameter change modifies the electrical characteristics locally, enabling the surface field to be reduced in the critical region near the drain, which improves breakdown voltage without requiring increased oxide thickness that would otherwise increase on-resistance.
2Strength
If the oxide layer thickness is increased to improve breakdown voltage, then breakdown voltage is improved, but specific on-resistance increases
Solution Approach 1:
The reduced surface field effect layer is formed in a predetermined region of the well region, applying local quality modification only where the surface field needs reduction. This localized approach improves breakdown voltage without requiring a uniform increase in oxide thickness across the entire device, thereby avoiding the penalty of increased specific on-resistance.
Solution Approach 2:
By changing the doping concentration in the predetermined region through ion implantation, the patent modifies the electrical parameters locally. This parameter change allows the surface field to be reduced in the critical region, improving breakdown voltage without the need to increase oxide thickness, thus maintaining low specific on-resistance.
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 configuration enables both low on-resistance and high breakdown voltage by optimizing the doping concentration and spacing between layers, improving the voltage withstanding performance and reducing surface electric fields.
Implementation Method 1
a reduced surface field effect layer of a first doping type formed by an implantation process in a predetermined region of the well region
Data Source
AI summary
A laterally diffused metal oxide semiconductor device can include: a well region having a second doping type; a reduced surface field effect layer of a first doping type formed by an implantation process in a predetermined region of the well region, where a length of the reduced surface field effect layer is less than a length of the well region; a body region of the first doping type extending from a top surface of the well region into the well region; a drain portion of the second doping type extending from the top surface of the well region into the well region; and an insulating structure located between the body region and the drain portion, at least a portion of the insulating structure is located on the top surface of the well region.