High-Voltage Semiconductor Device Body Effect Isolation
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Solution Overview
Problem
Traditional high-voltage semiconductor devices, such as LDMOSFETs, suffer from reduced performance due to the body effect, which causes a decrease in driving current as the voltage applied to the source region increases, affecting the transistor's performance.
Innovation Solution
A high-voltage semiconductor device design that includes doping regions with a conductivity type different from the body region to isolate the body region from the substrate, reducing or eliminating the body effect, and utilizing an epitaxial layer with field insulating layers to maintain performance across varying voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the source region is electrically connected to the underlying p-type semiconductor substrate via the body region, then the device structure is simple and manufacturing cost is low, but the body effect is induced causing threshold voltage change and reduced driving current
Solution Approach 1:
An n-type isolation layer is introduced between the p-type body region and the p-type semiconductor substrate. This intermediary layer electrically isolates the body region from the substrate, preventing the body effect while maintaining structural simplicity. The isolation layer acts as a mediator that blocks the harmful electrical connection without requiring complex additional structures.
2Adaptability or versatility
If the source region is coupled to internal circuit or resistor, then the device functionality is enhanced, but the body effect causes driving current to decrease with increasing source region voltage
Solution Approach 1:
The n-type isolation layer serves as an electrical barrier between the source region and the substrate, preventing the body effect from occurring. This allows the source region to be coupled to internal circuits or resistors for enhanced functionality while maintaining stable threshold voltage and consistent driving current across varying source region voltages.
3Reliability
If additional isolation structures are added to eliminate the body effect, then the threshold voltage stability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The n-type isolation layer is merged with the existing device structure during the epitaxial growth process. Rather than adding a separate complex isolation structure, the isolation function is integrated into the semiconductor layer formation process, achieving body effect elimination without significantly increasing device complexity or manufacturing steps.
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
The solution effectively reduces or eliminates the body effect, maintaining or improving the performance of high-voltage semiconductor devices by isolating the body region from the substrate, and allows for stable peak electric fields without additional manufacturing costs for isolation structures.
Implementation Method 1
doping regions with a conductivity type different from the body region to isolate the body region from the substrate, reducing or eliminating the body effect
Implementation Method 2
field insulating layers to maintain performance across varying voltages
Data Source
AI summary
A high-voltage semiconductor device is provided. The device includes a semiconductor substrate having a first conductivity type, and a first doping region having a second conductivity type therein. An epitaxial layer is on the semiconductor substrate. A body region having the first conductivity type is in the epitaxial layer on the first doping region. A second doping region and a third doping region that have the second conductivity type are respectively in the epitaxial layer on both opposite sides of the body region, so as to adjoin the body region. Source and drain regions are respectively in the body region and the second doping region. A field insulating layer is in the second doping region between the source and drain regions. A gate structure is on the epitaxial layer to cover a portion of the field insulating layer.