Superjunction Lateral Power MOSFET with Surrounding LDD
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Solution Overview
Problem
Conventional power MOSFETs face challenges in achieving low switching and conduction losses, high breakdown voltage, and efficient manufacturability due to trade-offs between trench and lateral double-diffused MOSFET structures, which result in high gate-to-drain capacitance and resistance, leading to increased energy consumption and heat dissipation.
Innovation Solution
The development of a semiconductor device with a superjunction structure surrounded by a lightly doped drain (LDD) region, which reduces resistance (RDSON) and maintains high breakdown voltage (BVdss) by forming a superjunction in the LDD region, utilizing N-doped and P-doped stripes that fully deplete prior to breakdown, thereby reducing switching and conduction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration of LDD region is reduced to support higher breakdown voltage, then BVdss increases, but RDSON increases leading to higher conduction losses
Solution Approach 1:
Different regions of the drift region are doped with different concentrations and types (N-type and P-type stripes with alternating doping), creating localized properties where each stripe can be optimized independently - N-stripes provide conduction paths while P-stripes provide depletion regions, achieving both low RDSON and high BVdss
2Loss of energy
If superjunction structure is implemented to reduce RDSON, then conduction losses are reduced, but manufacturing complexity increases due to high-energy ion implants and complex trench etches
Solution Approach 1:
The formation of N-type and P-type superjunction stripes is merged into a single ion implantation process using a patterned mask, combining multiple doping steps into one operation. The self-aligned nature of the process further merges alignment steps, significantly reducing manufacturing complexity while achieving the superjunction structure
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 superjunction structure effectively lowers RDSON and maintains high BVdss, reducing total power loss and heat dissipation while simplifying manufacturing processes by eliminating the need for high-energy ion implants and complex trench etches.
Implementation Method 1
utilizing N-doped and P-doped stripes that fully deplete prior to breakdown
Implementation Method 2
forming a superjunction in the LDD region
Data Source
AI summary
A semiconductor device has a substrate and a gate formed over the substrate. An LDD region is formed in the substrate adjacent to the gate. A superjunction is formed in the LDD region while a portion of the LDD region remains between the superjunction and gate. A mask is formed over the substrate. A first region is doped with a first type of dopant using the mask. A stripe is doped with a second type of dopant using a portion of the mask. A drain contact region is formed in the substrate. The first region extends to the drain contact region. The first region and stripe are formed using chain implants. A source field plate and drain field plate are formed over the substrate. A trench is formed in the substrate. A source contact region is formed in the trench.