Reverse-Conducting Semiconductor Structure for Lower Recovery Loss
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Solution Overview
Problem
Existing semiconductor devices face challenges in reducing reverse recovery losses and preventing hole injection during reverse recovery, especially without the use of a lifetime control region.
Innovation Solution
The semiconductor device incorporates trench contact portions and plug regions to reduce resistance and improve minority carrier extraction, while maintaining a low doping concentration in the anode region to prevent hole injection during reverse recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a lifetime control region is used to extract minority carriers, then reverse recovery losses are reduced, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The patent extracts the minority carrier extraction function from a dedicated lifetime control region and relocates it to the trench contact portion. By forming the trench contact portion to extend through the emitter region to the base region, the contact portion itself performs the minority carrier extraction function, eliminating the need for a separate lifetime control region and reducing device complexity.
Solution Approach 2:
The trench contact portion is designed to serve multiple functions simultaneously: it provides electrical contact between the emitter and base regions while also functioning as a minority carrier extraction region. This multi-functionality eliminates the need for separate dedicated regions for each function, thereby reducing overall device complexity.
2Reliability
If the anode region doping concentration is increased to reduce resistance, then conductivity improves, but hole injection during reverse recovery increases
Solution Approach 1:
The patent applies different doping concentrations to different regions: the anode region maintains low doping concentration to prevent hole injection, while the trench contact portion uses high doping concentration (n+ type) to ensure low contact resistance. This localized differentiation of doping quality allows each region to optimize its specific function without compromising the other.
Solution Approach 2:
The trench contact portion acts as an intermediary structure that provides a low-resistance path for carrier extraction without requiring high doping in the anode region. By introducing this intermediate high-doped contact region, the system achieves good conductivity where needed while maintaining low doping in regions where hole injection must be prevented.
3Reliability
If the trench contact portion extends deeper to improve contact, then resistance decreases, but breakage at the trench contact portion ends increases
Solution Approach 1:
The patent performs preliminary doping of the trench contact portion with high concentration n+ type impurities before final structure formation. This preliminary action creates a robust, highly conductive contact region that can extend deeper without becoming brittle, thereby reducing resistance while maintaining strength and preventing breakage at the trench ends.
Solution Approach 2:
The patent changes the doping concentration parameter within the trench contact portion to n+ type (high concentration), which fundamentally alters the mechanical and electrical properties of the contact region. This parameter change enables the trench contact to extend deeper into the substrate while maintaining both low resistance and high mechanical strength, preventing breakage.
Data Source
AI summary
A semiconductor device, including a semiconductor substrate having a diode portion, wherein the diode portion includes: an anode region which is provided on a front surface of the semiconductor substrate and is of a second conductivity type; a trench portion provided so as to extend in a predetermined extending direction on the front surface of the semiconductor substrate; a trench contact portion provided on the front surface of the semiconductor substrate; and a plug region which is provided at a lower end of the trench contact portion and is of a second conductivity type, and which has a doping concentration higher than that of the anode region, wherein a plurality of plug regions, each of which being the plug region, is provided separately from each other along the extending direction, is provided.