JTE Border Structure for Surface Charge Robust SiC Termination
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Solution Overview
Problem
High voltage semiconductor devices, particularly Silicon Carbide (SiC) products, face challenges in designing robust termination areas due to unoptimized dimensions, process variations, and passivation charges, leading to reduced reverse blocking capability, unstable performance, and limited application fields.
Innovation Solution
The semiconductor device incorporates a junction termination extension (JTE) border with a first layer of one conductivity type and a second layer of a different conductivity type, allowing for controlled depletion regions and reduced surface charge impact, along with floating JTE rings and a passivation layer to enhance ruggedness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitride-based passivation is used in the termination area, then the semiconductor device is protected from environmental factors, but positive interface charges accumulate in the semiconductor body causing depletion regions that reduce reverse blocking capability and stability
Solution Approach 1:
An intermediary layer of second conductivity type is introduced between the passivation layer and the semiconductor body of first conductivity type. This intermediary layer acts as a buffer that prevents direct charge transfer and reduces the formation of depletion regions caused by passivation charges, thereby maintaining reverse blocking capability while preserving the protective function of the passivation.
Solution Approach 2:
The conductivity type parameter is changed in the termination area by introducing a layer of second conductivity type, which is opposite to the semiconductor body's first conductivity type. This parameter change fundamentally alters the electrical behavior at the passivation-semiconductor interface, preventing charge accumulation and depletion region formation that would otherwise occur with direct passivation contact.
2Stability of the object's composition
If a large, lowly doped p-type JTE border is used to spread equipotential lines, then the electric field is distributed more evenly, but the impact of passivation charges becomes more visible and reverse blocking capability decreases
Solution Approach 1:
The termination area is divided into regions with different conductivity types. The JTE border maintains its p-type (first conductivity type) characteristics for field distribution, while a specific layer adjacent to the passivation is made of n-type (second conductivity type). This local quality differentiation allows the JTE to perform its field-spreading function while the n-type layer locally counteracts passivation charge effects.
Solution Approach 2:
The termination area employs a composite structure combining p-type JTE border material with an n-type layer adjacent to the passivation. This composite configuration leverages the field-spreading capability of the p-type JTE while the n-type component provides charge compensation, achieving both electric field distribution and maintained reverse blocking capability.
3Stability of the object's composition
If floating guard rings with low P-type doping are used to spread the field, then field crowding is reduced, but process variations in lithography and ion implantation create weak spots that reduce device ruggedness
Solution Approach 1:
The conductivity type parameter is changed from uniform P-type doping to a combination of P-type (first conductivity type) and N-type (second conductivity type) layers. This parameter change creates a more robust structure where the N-type layer provides charge compensation that is less sensitive to variations in lithography alignment and ion implantation dosing, reducing the formation of weak spots.
Solution Approach 2:
A composite doping structure is implemented where lowly doped P-type JTE border is combined with an N-type layer adjacent to the passivation. This composite approach creates mutual compensation effects that reduce sensitivity to process variations, as errors in one doping process can be compensated by the other layer's charge characteristics.
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 configuration improves the semiconductor device's performance by minimizing the effect of passivation charges, enhancing ruggedness, and providing stable working conditions, thereby increasing the reliability and effectiveness of the termination area.
Implementation Method 1
a controlled depletion region allowing for further process variation
Data Source
Figure 1~2
Figure 2A~2B
Figure 2C~2D
AI summary
The present disclosure relates to a semiconductor device that comprises a semiconductor body including a semiconductor substrate and an epitaxial layer formed on the semiconductor substrate. An active area and a termination area adjacent the active area are arranged in the epitaxial layer. The termination area comprises a junction termination extension, JTE, border of a first conductivity type. The JTE border comprises a first layer of the first conductivity type, and a second layer of a second conductivity type different from the first conductivity type. The second layer is located on top of the first layer. The semiconductor substrate and the epitaxial layer have the second conductivity type.