LDMOS Drift Region Doping Layout for Breakdown and On-Resistance
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Solution Overview
Problem
Optimizing the breakdown voltage and on-resistance of LDMOS transistors is challenging due to the need for a trade-off in doping concentration, which complicates their design and manufacturing process.
Innovation Solution
Incorporating a first deep well region with a specific doping type and a buried layer to optimize the doping concentration distribution, allowing for improved breakdown voltage and on-resistance, while maintaining normal operation without affecting the device's voltage and resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If doping concentration is increased to reduce on-resistance, then on-resistance decreases, but breakdown voltage decreases
Solution Approach 1:
The patent applies local quality by creating different doping concentration regions within the drift region. A first doping region with higher concentration is formed adjacent to the body region, while a second doping region with lower concentration is formed adjacent to the drain region. This spatial variation in doping quality allows the device to achieve low on-resistance near the body region while maintaining high breakdown voltage near the drain region, effectively resolving the trade-off between these two parameters.
Solution Approach 2:
The drift region is segmented into multiple doping regions with different concentration levels. Rather than using a uniform doping concentration throughout the drift region, the patent divides it into at least two distinct regions: a first doping region closer to the body region and a second doping region closer to the drain region. This segmentation allows each region to be optimized for its specific functional requirement, enabling simultaneous optimization of on-resistance and breakdown voltage.
2Reliability
If doping concentration is decreased to increase breakdown voltage, then breakdown voltage increases, but on-resistance increases
Solution Approach 1:
The patent applies local quality by creating different doping concentration regions within the drift region. A first doping region with higher concentration is formed adjacent to the body region, while a second doping region with lower concentration is formed adjacent to the drain region. This spatial variation in doping quality allows the device to achieve low on-resistance near the body region while maintaining high breakdown voltage near the drain region, effectively resolving the trade-off between these two parameters.
Solution Approach 2:
The drift region is segmented into multiple doping regions with different concentration levels. Rather than using a uniform doping concentration throughout the drift region, the patent divides it into at least two distinct regions: a first doping region closer to the body region and a second doping region closer to the drain region. This segmentation allows each region to be optimized for its specific functional requirement, enabling simultaneous optimization of on-resistance and breakdown voltage.
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 effectively optimizes the compromise between breakdown voltage and on-resistance, enhancing the performance of LDMOS transistors in switching regulators by adjusting the doping concentration and introducing a buried layer to ensure normal operation and improved performance.
Implementation Method 1
a drift region (312) in the first deep well region (221) and having a second doping type
Data Source
AI summary
A semiconductor device having an LDMOS transistor can include: a first deep well region having a first doping type; a drift region located in the first deep well region and having a second doping type; and a drain region located in the drift region and having the second doping type, where the second doping type is opposite to the first doping type, and where a doping concentration peak of the first deep well region is located below the drift region to optimize the breakdown voltage and the on-resistance of the LDMOS transistor.