Superjunction Power MOSFET with Surrounding LDD Region
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Solution Overview
Problem
Conventional power MOSFETs face challenges in reducing conduction losses (RDSON) and switching losses (Cgd and Qg), with trench MOSFETs exhibiting high switching power loss and lateral double-diffused MOSFETs having higher RDSON, leading to increased energy absorption and heat dissipation issues.
Innovation Solution
The use of a superjunction structure with N-doped and P-doped stripes as the drift region in power MOSFETs, which reduces RDSON without significantly increasing Qg, by calibrating doping concentrations and stripe widths to maintain high BVdss and minimize hot carrier generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If superjunction structure with higher doping concentration is used to reduce RDSON, then conduction loss is improved, but hot carrier generation increases
Solution Approach 1:
The patent introduces the P-type doped stripes as intermediary elements between the N-type conduction paths and the drain region. These P-type stripes act as mediators that facilitate controlled depletion region formation and charge balance, enabling the use of higher N-type doping concentrations (for low RDSON) while the P-type regions prevent excessive hot carrier generation by providing complementary charge compensation and controlling electric field distribution.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the doping concentration ratio and width ratio between N-type and P-type stripes. By optimizing these parameters, the superjunction structure enables high N-type doping (reducing RDSON and conduction loss) while the corresponding P-type doping levels and stripe dimensions are adjusted to maintain electric field control and minimize hot carrier generation through balanced charge distribution.
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 switching losses, reducing energy absorption and heat dissipation while maintaining high voltage handling capabilities, thus improving the overall efficiency and reliability of power MOSFETs.
Implementation Method 1
The use of a superjunction structure with N-doped and P-doped stripes as the drift region in power MOSFETs, which reduces RDSON without significantly increasing Qg, by calibrating doping concentrations and stripe widths to maintain high BVdss
Data Source
AI summary
A semiconductor device has a substrate and a lightly doped drain (LDD) region formed in the substrate. A superjunction is formed in the LDD region.