Vertical Power MOSFET Defect Region Design for Diode Recovery
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Solution Overview
Problem
In vertical power MOSFETs with a superjunction structure, increasing the electron beam radiation to improve recovery speed of the built-in diode leads to increased defect formation throughout the semiconductor wafer, resulting in higher leak current and reduced power efficiency, making it difficult to selectively form defects in the thickness or plane direction and increasing overall power consumption.
Innovation Solution
A semiconductor device design with a cell region and an intermediate region, where p-type and n-type column regions are alternately formed, with a defect region only in the n-type column region of the cell region, allowing for controlled defect density and reduced leak current, thereby improving switching characteristics and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the radiation amount of electron beam is increased to improve recovery speed of built-in diode, then the recovery speed is improved, but the leak current increases
Solution Approach 1:
The patent applies local quality by creating defect regions only in specific n-type column regions (fifth and sixth regions) while leaving other n-type column regions (first through fourth regions) defect-free. This selective defect formation allows the built-in diode to achieve fast recovery speed in localized areas without generating harmful leak current throughout the entire device structure.
Solution Approach 2:
The patent segments the semiconductor wafer into multiple n-type column regions (first through sixth regions) with different defect characteristics. By dividing the structure into distinct regions with controlled defect densities, the patent enables differential functionality: some regions provide fast recovery while others maintain low leak current, resolving the contradiction between speed and harmful effects.
2Speed
If the radiation amount of electron beam is increased to improve recovery speed, then the recovery speed is improved, but the power consumption increases
Solution Approach 1:
The patent implements local quality by applying electron beam radiation selectively to specific n-type column regions (fifth and sixth regions) rather than uniformly across all regions. This localized defect formation achieves the desired fast recovery speed in critical areas while minimizing the generation of leak current in other regions, thereby reducing overall power consumption.
Solution Approach 2:
The patent segments the device into multiple functional regions with different defect densities. By dividing the n-type column regions into those with defects (fifth and sixth regions for fast recovery) and those without defects (first through fourth regions for low leak current), the patent optimizes the balance between recovery speed and power consumption.
3Speed
If defects are formed throughout the entire semiconductor wafer to improve recovery speed, then the recovery speed is improved, but the defects are also present in the pn junction interface causing increased leak current
Solution Approach 1:
The patent applies local quality by creating defect regions only in specific n-type column regions (fifth and sixth regions) while maintaining defect-free conditions in other regions (first through fourth regions). This selective approach ensures that defects are localized away from critical pn junction interfaces, achieving fast recovery speed without compromising manufacturing precision or increasing leak current.
Solution Approach 2:
The patent segments the semiconductor structure into multiple n-type column regions with different defect characteristics. By dividing the regions into those containing defects (for recovery speed improvement) and those remaining defect-free (for maintaining low leak current and high manufacturing precision), the patent resolves the contradiction between achieving fast recovery and maintaining manufacturing precision.
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 selective formation of defects in the n-type column region of the cell region enhances the recovery time of the built-in diode, reduces leak current, and improves breakdown voltage, achieving lower power consumption while maintaining high breakdown voltage and reduced on-state resistance.
Implementation Method 1
an electron beam is radiated to the inside of a semiconductor wafer on which the vertical power MOSFET is formed from a major surface or a back surface of the semiconductor wafer
Data Source
AI summary
Reduction of power consumption of a semiconductor device is aimed. The semiconductor device includes a cell region where a vertical power MOSFET is formed and an intermediate region surrounding the cell region. In each of the cell region and the intermediate region, a plurality of p-type column regions and a plurality of n-type column regions are alternately formed. The n-type column region arranged in the cell region has a defect region formed therein, whereas the n-type column region arranged in the intermediate region does not have the defect region. A defect density in the n-type column region arranged in the cell region is larger than that in the n-type column region arranged in the intermediate region.