Drift Layer Defective Structure for High-Voltage Diodes
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Solution Overview
Problem
In high-breakdown-voltage lateral diodes using bonded SOI wafers, increasing the thickness of the silicon active layer enhances breakdown voltage but leads to higher carrier concentrations and reverse recovery charge, creating a trade-off that hinders performance.
Innovation Solution
The introduction of a defective layer with higher hydrogen or helium concentration in the bottom part of the drift layer, formed by ion irradiation, reduces resistivity and carrier lifetime, thereby increasing breakdown voltage and reducing reverse recovery charge without thickening the drift layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the silicon active layer is increased, then the breakdown voltage is improved, but the reverse recovery charge increases
Solution Approach 1:
The patent introduces a defective layer with non-uniform hydrogen concentration distribution within the drift layer. The hydrogen concentration is higher in the bottom part (near the insulating layer interface) and lower in the upper part, creating local quality variations that affect carrier behavior differently at different depths, thereby resolving the trade-off between breakdown voltage and reverse recovery charge
Solution Approach 2:
The patent changes the physical and chemical parameters of the drift layer by introducing a defective layer with controlled hydrogen concentration. This defective layer modifies the electrical characteristics (resistivity, carrier lifetime) of the drift layer without changing its thickness, enabling improved breakdown voltage and reduced reverse recovery charge simultaneously
2Strength
If the thickness of the silicon active layer is increased, then the breakdown voltage is improved, but the carrier concentration increases
Solution Approach 1:
The defective layer creates local quality differences in carrier concentration and lifetime. By having higher hydrogen concentration in the bottom part of the drift layer, carriers in that region have shorter lifetimes and different concentrations compared to the upper part, allowing the structure to achieve high breakdown voltage without uniformly high carrier concentration throughout the entire drift layer
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 delays complete depletion of the drift layer, raising breakdown voltage and shortening carrier lifetime to decrease reverse recovery charge, enhancing turnoff speed and efficiency in semiconductor devices like FRD, IGBT, and MOSFET.
Implementation Method 1
The introduction of a defective layer with higher hydrogen or helium concentration in the bottom part of the drift layer, formed by ion irradiation
Data Source
AI summary
According to one embodiment, a hydrogen concentration of a bottom part in a vicinity of a boundary with the insulating layer in the first silicon layer is higher than a hydrogen concentration of a part above the bottom part in the first silicon layer. And a resistivity of the bottom part in the first silicon layer is lower than a resistivity of the part above the bottom part in the first silicon layer.