SiC MPS Diode JTE Doping for Stable Breakdown Control
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Solution Overview
Problem
The design of junction termination extensions (JTE) in SiC semiconductor power devices leads to unstable and difficult-to-control breakdown behavior between the termination and active areas, as typical process parameters affect both regions simultaneously, making it challenging to optimize avalanche ruggedness and unclamped-inductive switching performance.
Innovation Solution
A method involving ion implantation to form inner wells and JTE structures of a second charge type, with multiple ion implantation steps to control dopant concentration, allowing for precise formation of JTE borders and rings to separate the termination and active areas, thereby optimizing breakdown behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a JTE structure is formed using typical process parameters, then the breakdown in the termination area is controlled, but the breakdown behavior becomes unstable and difficult to control because the same parameters affect both the termination area and the active area simultaneously
Solution Approach 1:
The patent segments the doping process into distinct ion implantation steps: a first ion implantation step for forming the JTE structure and a second ion implantation step for adjusting the dopant concentration in the active area. This segmentation allows independent control of termination area breakdown and active area breakdown, resolving the coupling effect that caused unstable breakdown behavior.
Solution Approach 2:
The JTE structure is formed in advance through a preliminary ion implantation step before the active area doping is finalized. This preliminary action establishes the termination area breakdown characteristics first, allowing subsequent adjustments to the active area without affecting the already-optimized JTE structure, thereby stabilizing the overall breakdown behavior.
2Ease of manufacture
If the same ion implantation parameters are used for both JTE formation and active area doping, then the process is simple, but it is difficult to steer the breakdown at the termination area and the active area individually
Solution Approach 1:
The doping process is divided into separate ion implantation steps with distinct parameters: a first step with parameters optimized for JTE formation and a second step with parameters optimized for active area doping. This segmentation enables precise independent control of breakdown characteristics at different locations while maintaining a relatively simple overall process structure.
Solution Approach 2:
Different ion implantation parameters are applied to different regions: the first ion implantation uses parameters (dose, energy, tilt angle) specifically tailored for JTE structure formation, while the second ion implantation uses different parameters for active area doping. This local quality approach allows precise control of breakdown at each location without compromising process simplicity.
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 enhances the dopant concentration control, leading to improved avalanche ruggedness and unclamped-inductive switching performance by independently managing breakdown in the termination and active areas, stabilizing the breakdown behavior.
Implementation Method 1
forming, by ion implantation, one or more inner wells of a second charge type different from the first charge type in an active area of the semiconductor power device
Implementation Method 2
the breakdown behavior of the semiconductor power device is predominantly determined by the dopant concentration in the various parts of the device
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Aspects of the present disclosure relate to a semiconductor power device and to a method for manufacturing the same. Aspects of the present disclosure particularly relate to a merged P-i-N Schottky, MPS, diode, more in particular a Silicon Carbine, SiC, MPS diode. The semiconductor power device comprises a semiconductor body comprising a conductive substrate and an epitaxial layer of a first charge type grown on the conductive substrate, and one or more inner wells of a second charge type different from the first charge type in an active area of the semiconductor power device. At least some of the one or more inner wells of the second charge type are formed using at least two ion implantation steps. One step is dedicated to forming the inner wells of the second type whereas one or more further ion implantation steps are simultaneously used for forming a respective JTE structure and for increasing a dopant concentration of at least one well of the second charge type.