LDMOS Breakdown Voltage via Vertical Field Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to increase the breakdown voltage of semiconductor devices while minimizing transistor size or on-resistance, as reducing transistor size lowers the breakdown voltage and reduces the margin between the rated and breakdown voltages, making it difficult to accommodate manufacturing variations and transient voltage fluctuations.
Innovation Solution
The solution involves distributing the drain voltage vertically by using a laterally diffused metal oxide semiconductor (LDMOS) field-effect transistor structure on a silicon-on-insulator substrate with buried doped regions that underlie a lateral drift region, reducing the percentage of drain voltage supported by active semiconductor material and increasing the vertical breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If transistor size is decreased to minimize device footprint, then device area is reduced, but breakdown voltage decreases
Solution Approach 1:
The patent transitions from lateral voltage distribution to vertical voltage distribution by introducing buried doped regions beneath the drift region. This dimensional change allows the electric field to be distributed through the vertical depth of the device rather than solely laterally, enabling smaller device footprints while maintaining high breakdown voltage through the vertical extension of the depletion region into the buried doped regions.
2Area of moving object
If transistor size is decreased to minimize on-resistance, then device area is reduced, but margin between rated and breakdown voltage decreases
Solution Approach 1:
By distributing the voltage block in the vertical dimension through buried doped regions, the patent achieves both reduced on-resistance (due to shorter lateral current paths) and increased voltage margin (due to extended vertical depletion region). This allows the device to operate at higher voltages with sufficient margin while occupying minimal area.
3Reliability
If lateral distribution of drain voltage is minimized, then vertical breakdown voltage increases, but device complexity increases
Solution Approach 1:
The patent segments the doped regions into distinct functional zones: buried doped regions for vertical voltage distribution, drift regions for lateral current flow, and contact regions for external connections. This segmentation allows each region to be optimized for its specific function while working together to achieve high breakdown voltage with controlled complexity.
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 increases the vertical breakdown voltage, enhancing the rated drain-to-source breakdown voltage and relaxing design and manufacturing requirements by minimizing lateral distribution of drain voltage and increasing the margin between rated and breakdown voltages.
Implementation Method 1
the voltage applied to a semiconductor device is constrained by the breakdown voltage of the device, which is the minimum applied voltage that causes avalanche breakdown in the device
Data Source
AI summary
Semiconductor device structures and related fabrication methods are provided. An exemplary semiconductor device structure includes a first region of semiconductor material having a first conductivity type and a first dopant concentration, a second region of semiconductor material having a second conductivity type overlying the first region, a drift region of semiconductor material having the first conductivity type overlying the second region, and a drain region of semiconductor material having the first conductivity type. The drift region and the drain region are electrically connected, with at least a portion of the drift region residing between the drain region and the second region, and at least a portion of the second region residing between that drift region and the first region. In one or more exemplary embodiments, the first region abuts an underlying insulating layer of dielectric material.