Depletion MOS Device Breakdown Voltage via Protection Region
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Depletion MOS devices suffer from low breakdown voltage due to band-to-band breakdown, limiting their applications, as existing methods struggle to adjust impurity densities without affecting both enhancement and depletion MOS devices in a circuit.
Innovation Solution
A method of manufacturing a depletion MOS device that includes forming a breakdown protection region between the drain and threshold voltage adjustment region, using impurities of a different conductive type to increase breakdown voltage, while maintaining compatibility with existing manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impurity density in drift region is increased to improve breakdown voltage, then breakdown voltage increases, but performance of enhancement MOS devices deteriorates
Solution Approach 1:
The patent divides the device structure into distinct regions with different impurity concentrations: the drift region maintains standard impurity density for enhancement device compatibility, while a newly introduced breakdown protection region adjacent to the drain is doped with higher impurity concentration to specifically enhance breakdown voltage. This segmentation allows independent optimization of each region's function.
Solution Approach 2:
The patent applies local quality by creating a breakdown protection region with specifically tailored impurity concentration that differs from the drift region. This localized high-doping region is positioned precisely where breakdown occurs (near the drain edge under the gate), providing breakdown enhancement only where needed without affecting the overall device performance or enhancement MOS compatibility.
2Reliability
If threshold voltage adjustment region impurity density is increased to improve breakdown protection, then breakdown voltage increases, but conversion of enhancement devices to depletion devices fails
Solution Approach 1:
The patent separates the threshold voltage adjustment function from the breakdown protection function by introducing a dedicated breakdown protection region. The threshold voltage adjustment region maintains its original impurity density for proper device conversion, while the breakdown protection region provides enhanced breakdown voltage through separate high-doping.
Solution Approach 2:
The breakdown protection region acts as an intermediary structure between the drain and the threshold voltage adjustment region. It provides the necessary breakdown protection without interfering with the threshold voltage conversion process, effectively mediating between the two functions that previously conflicted.
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 method effectively increases the breakdown voltage of depletion MOS devices, broadening their applications without impacting the performance of enhancement MOS devices.
Implementation Method 1
implanting second conductive type impurities to form the drift region, the source, the drain, and the threshold voltage adjustment region, respectively; defining a breakdown protection region between the drain and the threshold voltage adjustment region, and implanting first conductive type impurities to form the breakdown protection region
Data Source
AI summary
The present invention discloses a method of manufacturing a depletion metal oxide semiconductor (MOS) device. The method includes: providing a substrate; forming a first conductive type well and an isolation region in the substrate to define a device area; defining a drift region, a source, a drain, and a threshold voltage adjustment region, and implanting second conductive type impurities to form the drift region, the source, the drain, and the threshold voltage adjustment region, respectively; defining a breakdown protection region between the drain and the threshold voltage adjustment region, and implanting first conductive type impurities to form the breakdown protection region; and forming a gate in the device area; wherein a part of the breakdown protection region is below the gate, and the breakdown protection region covers an edge of the threshold voltage adjustment region.