LDMOS Field Plate Doping Layout for Breakdown and On-Resistance
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Solution Overview
Problem
In semiconductor devices, particularly LDMOSFETs, there is a trade-off between achieving high breakdown voltage and reducing on-resistance, as increasing impurity concentration in the drift layer to lower on-resistance can lead to reduced breakdown voltage, and vice versa, making it challenging to simultaneously improve both performance metrics.
Innovation Solution
The introduction of a field plate portion with a specific semiconductor region structure, including high and low concentration regions, allows for a uniform equipotential line distribution, which helps maintain breakdown voltage even with slightly increased impurity concentration in the drift layer, thereby reducing on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the impurity concentration of the drift layer is lowered to improve breakdown voltage, then the on-resistance increases
Solution Approach 1:
The patent applies local quality by creating a field plate portion with non-uniform impurity concentration distribution. The field plate includes a first semiconductor region with first impurity concentration and a second semiconductor region with second impurity concentration different from the first. This localized variation in impurity concentration allows the structure to simultaneously achieve high breakdown voltage in the drift layer region and low on-resistance in the field plate region, resolving the trade-off between these two parameters.
2Object-generated harmful factors
If the impurity concentration of the drift layer is increased to reduce on-resistance, then the breakdown voltage is reduced
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through the field plate portion structure. The drift layer maintains low impurity concentration for high breakdown voltage, while the field plate portion introduces regions with different impurity concentrations to provide low on-resistance pathways. This spatial separation of functional requirements allows both high breakdown voltage and low on-resistance to be achieved simultaneously.
3Reliability
If thick insulating films are used to improve breakdown voltage, then manufacturing costs increase
Solution Approach 1:
The patent applies parameter changes by transitioning from using thick insulating films to using a semiconductor-based field plate portion with controlled impurity concentrations. This parameter change in the material composition and doping profile allows the achievement of high breakdown voltage through electrical field control rather than physical insulation thickness, thereby reducing manufacturing costs and process 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 enhances both breakdown voltage and reduces on-resistance, achieving a balance between the two previously conflicting performance metrics, while also reducing manufacturing costs by eliminating the need for thick insulating films.
Implementation Method 1
The introduction of a field plate portion with a specific semiconductor region structure, including high and low concentration regions, allows for a uniform equipotential line distribution, which helps maintain breakdown voltage
Implementation Method 2
the first semiconductor region is electrically connected to the source region, and the second semiconductor region is electrically connected to the drain region
Data Source
AI summary
In semiconductor device, a field plate portion having a high concentration p-type semiconductor region, a low concentration p-type semiconductor region having a lower impurity concentration than the high concentration p-type semiconductor region and a high concentration n-type semiconductor region is provided. Then, the high concentration p-type semiconductor region is electrically connected to the source region while the high concentration n-type semiconductor region is electrically connected to the drain region.