RC-IGBT Doping Zones for RBSOA and Static Loss Trade-off
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Solution Overview
Problem
There is a need for an improved Reverse-Conducting Insulated Gate Bipolar Transistor (RC-IGBT) that balances robustness, particularly in terms of Safe Operating Area (SOA) capability, with reduced static losses, and an efficient method for producing such devices.
Innovation Solution
The RC-IGBT incorporates a semiconductor body with a pilot region and mixed regions of different conductivity types and doping concentrations, allowing for increased RBSOA capability without significant increases in static losses, achieved through adjustments in doping concentrations and additional photolithography steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration in the pilot region is reduced, then the RBSOA capability is increased, but the static losses may increase
Solution Approach 1:
The patent applies local quality by creating distinct doping concentration zones within the collector layer: the pilot region has a first doping concentration optimized for RBSOA performance, while the mixed region contains first subregions with a second doping concentration optimized for low static losses. This spatial differentiation of doping concentrations allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The collector layer is segmented into functionally distinct regions: a pilot region and a mixed region with first subregions and second subregions. This segmentation allows independent optimization of doping concentrations in each region, enabling the device to achieve both high RBSOA capability and low static losses simultaneously.
2Reliability
If the doping concentration in the pilot region is reduced to improve RBSOA, then the robustness is increased, but the device complexity increases
Solution Approach 1:
The invention introduces local quality variations through differentiated doping concentrations in specific regions (pilot region vs. mixed region with first and second subregions). This allows robustness improvement in the pilot region without requiring complete redesign of the entire device structure, thereby limiting the increase in device complexity.
3Manufacturing precision
If additional photolithography steps are added to achieve different doping concentrations, then the manufacturing precision is improved, but the ease of manufacture decreases
Solution Approach 1:
The patent utilizes parameter changes in the photolithography process (such as exposure time, photoresist thickness, or patterning conditions) to define regions with different doping concentrations. By adjusting these process parameters, precise control over doping concentration distribution is achieved while using standard semiconductor manufacturing techniques.
Data Source
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AI summary
According to an embodiment, the RC-IGBT (1000) comprises a semiconductor body (100) with an emitter side (101) and a collector side (102), a collector layer (1) at the collector side with at least one pilot region (10) and at least one mixed region (11) and a collector electrode (2) on the collector side and in electrical contact with the collector layer. The pilot, IGTB, region is of a first conductivity type. The mixed region has first subregions (111) that are also of the first conductivity type and second, diode, subregions (112) that are of a second, opposite, conductivity type. The doping concentration in the first subregions is different from the doping concentration in the pilot region.