Optimized Field Stop Layers for High-Performance Semiconductors
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Summary
Problems
Conventional semiconductor devices with field stop layers face challenges in maintaining breakdown voltage and reducing on-voltage deviation when the thickness of the drift layer is reduced, particularly in achieving a balanced carrier concentration distribution for efficient hole injection and switching speed.
Innovation solutions
A method involving multiple hydrogen ion implantation processes with varying accelerating voltages to form a broad n-type field stop layer, followed by heat treatment and laser annealing to optimize carrier concentration distribution, reduces the carrier concentration at the interface and enhances the slope of the carrier concentration profile, thereby controlling the carrier concentration ratio and improving switching speed.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If the thickness of the drift layer is reduced to lower the on-voltage, then the on-voltage decreases, but the breakdown voltage cannot be maintained
Why choose this principle:
The patent applies local quality by creating a field stop layer with a specific carrier concentration peak at a defined depth from the back surface. This localized high-concentration region (1E16 to 1E18 atoms/cm³) differs from both the drift layer and collector layer, enabling the thin drift layer structure to maintain breakdown voltage while keeping on-voltage low. The field stop layer's specific position and concentration profile provide localized electrical field control that resolves the contradiction between thin drift layer and high breakdown voltage.
Principle concept:
If the thickness of the drift layer is reduced to lower the on-voltage, then the on-voltage decreases, but the breakdown voltage cannot be maintained
Why choose this principle:
The patent utilizes parameter changes by controlling the carrier concentration distribution through proton irradiation dose and accelerating voltage. By adjusting these parameters, the field stop layer's carrier concentration peak is formed at the optimal depth and magnitude. This parameter control enables the drift layer thickness to be reduced while maintaining the necessary electrical characteristics for both low on-voltage and high breakdown voltage, effectively resolving the contradiction.
Application Domain
Data Source
AI summary:
A method involving multiple hydrogen ion implantation processes with varying accelerating voltages to form a broad n-type field stop layer, followed by heat treatment and laser annealing to optimize carrier concentration distribution, reduces the carrier concentration at the interface and enhances the slope of the carrier concentration profile, thereby controlling the carrier concentration ratio and improving switching speed.
Abstract
A method of manufacturing a semiconductor device, including implanting hydrogen atoms from a second principal surface of a semiconductor substrate, forming a plurality of second semiconductor layers that each have a carrier concentration higher than that of the first semiconductor layer and that have carrier concentration peak values at different depths from the second principal surface of the semiconductor substrate, applying a heat treatment process to promote generation of donors from the hydrogen atoms, implanting an impurity from the second principal surface of the semiconductor substrate, forming a third semiconductor layer in the semiconductor substrate at the second principal surface thereof, and applying another heat treatment process to locally heat the semiconductor substrate, so as to reduce the carrier concentration at an interface between the third semiconductor layer and the second semiconductor layer adjacent to the third semiconductor layer.