Vacancy-Oxygen Defect Region in Power Diodes
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Solution Overview
Problem
Conventional power diodes face a tradeoff in reducing switching loss and achieving soft recovery characteristics, with methods either increasing switching loss or compromising on noise reduction, due to conflicting requirements in controlling carrier lifetime and current decrease rates during reverse recovery.
Innovation Solution
A semiconductor device with a vacancy-oxygen complex defect region formed by ion implantation of oxygen and electron beam irradiation, which acts as recombination centers to control carrier lifetime and reduce switching loss while maintaining soft recovery characteristics, is introduced. This region is strategically placed to shorten the carrier lifetime of residual holes, thereby reducing the reverse recovery current peak and increasing its decrease rate without increasing the forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If carrier lifetime is reduced to decrease reverse recovery current peak, then switching loss is reduced, but current decrease rate increases causing hard recovery characteristics and electromagnetic noise
Solution Approach 1:
The patent applies local quality by creating a carrier lifetime control region with specific depth range (0.3-0.7 times drift layer thickness) and controlled oxygen concentration (1×10^16 to 1×10^18 atoms/cm³). This localized region provides selective carrier recombination without uniformly affecting the entire drift layer, enabling soft recovery characteristics while reducing switching loss.
Solution Approach 2:
The patent changes physical parameters by controlling oxygen concentration and depth position to create vacancy-oxygen complex defects. By adjusting oxygen concentration within specific ranges and positioning the control region at optimal depth, the patent achieves both reduced switching loss and soft recovery characteristics through parameter optimization.
2Object-generated harmful factors
If carrier lifetime is reduced to achieve soft recovery characteristics, then electromagnetic noise is suppressed, but switching loss increases
Solution Approach 1:
The patent creates a localized carrier lifetime control region rather than uniformly modifying the entire drift layer. This regional approach allows selective carrier control where needed while preserving low-resistance properties in other areas, achieving both soft recovery and low switching loss.
Solution Approach 2:
The patent creates a composite structure by introducing vacancy-oxygen complex defects into the semiconductor crystal lattice. This composite defect structure provides carrier recombination centers while maintaining the overall semiconductor properties, enabling dual benefits of soft recovery and low conduction loss.
3Duration of action of moving object
If oxygen concentration is increased to form recombination centers, then carrier lifetime is controlled, but forward voltage increases due to higher operating resistance
Solution Approach 1:
The patent confines high oxygen concentration to a specific depth range (0.3-0.7 times drift layer thickness) rather than distributing it uniformly. This localization ensures carrier lifetime control where needed while minimizing impact on overall forward voltage and operating resistance.
Solution Approach 2:
The patent optimizes oxygen concentration within a specific range (1×10^16 to 1×10^18 atoms/cm³) to achieve effective carrier recombination without excessive resistance increase. By controlling oxygen concentration parameters within optimal bounds, the patent balances carrier lifetime control with low forward voltage.
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 semiconductor device effectively reduces switching loss and achieves soft recovery characteristics by strategically controlling the carrier lifetime and current decrease rate, suppressing surge voltage and maintaining low operating resistivity, thus addressing the tradeoff in conventional technologies.
Implementation Method 1
a high-concentration oxygen region is formed by introducing oxygen into the semiconductor substrate by ion implantation
Implementation Method 2
the vacancy-oxygen complex defect region is formed of complex defects of vacancies and oxygen
Data Source
AI summary
A semiconductor device that includes a p-type region formed selectively along one principle surfaces of an n-type drift layer and having a resistance that is lower than that of the drift layer, and in which, when a depth R at which a vacancy-oxygen complex defect region is provided in the drift layer with a thickness t from a surface of a pn junction being a boundary of the p-type region in a thickness direction of the drift layer from a back surface of a semiconductor substrate, resistivity of the drift layer is ρ, and width W of a depletion layer extending in the drift layer from the pn junction with a reverse bias voltage V to the pn junction is represented as W=0.54×√/(ρ×V), the vacancy-oxygen complex defect region is provided at the depth R represented by 0<R≦t−W.