SiC Current Sensor Trench Isolation for Breakdown Voltage
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Solution Overview
Problem
The breakdown voltage of current sensing parts in semiconductor devices decreases when they are integrated on the same semiconductor substrate as the main semiconductor element, leading to reliability issues, especially under high-voltage and high-temperature conditions.
Innovation Solution
A semiconductor device design that includes a trench isolating part with an insulating film and a conductive layer embedded in the trench, isolating the current sensing part from the main semiconductor element, thereby suppressing overvoltage and blocking current flow from the intrinsic diode, enhancing the surge and breakdown capabilities of the current sensing part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current sensing part is integrated on the same semiconductor substrate as the main semiconductor element, then device complexity is reduced and productivity is improved, but the breakdown voltage of the current sensing part decreases leading to reduced reliability
Solution Approach 1:
The semiconductor substrate is divided into a first region containing the main semiconductor element and a second region containing the current sensing part, with a trench physically separating them. This segmentation allows both components to coexist on the same substrate while maintaining electrical isolation, thus reducing device complexity while preserving the breakdown voltage of the current sensing part.
Solution Approach 2:
A trench filled with insulating material is introduced as an intermediary structure between the main semiconductor element and the current sensing part. This intermediary provides electrical isolation and prevents voltage breakdown while allowing both components to be integrated on the same substrate, resolving the contradiction between integration benefits and reliability concerns.
2Reliability
If the current sensing part is isolated from the main semiconductor element using a trench, then the breakdown voltage and reliability are improved, but the manufacturing process complexity increases
Solution Approach 1:
The substrate is segmented into distinct regions for the main semiconductor element and current sensing part, with the trench providing both isolation and a structured framework for subsequent manufacturing steps. This segmentation simplifies the overall manufacturing process by providing clear spatial boundaries for material deposition and processing.
Solution Approach 2:
The trench is formed and filled with insulating material before completing the fabrication of both the main semiconductor element and the current sensing part. This preliminary action establishes the isolation structure early in the manufacturing process, simplifying subsequent steps and reducing overall manufacturing complexity while ensuring reliable electrical isolation.
3Reliability
If a deep trench is used to isolate the current sensing part, then the surge capability and breakdown voltage are significantly improved, but the manufacturing precision requirements increase
Solution Approach 1:
The trench depth and insulating material properties are optimized specifically for the isolation function between the main semiconductor element and the current sensing part, without requiring uniform high precision throughout the entire device structure. This localized optimization achieves the necessary surge capability and breakdown voltage while maintaining reasonable manufacturing precision requirements.
Solution Approach 2:
The trench is filled with insulating material to create a composite structure combining the semiconductor substrate with the insulating layer. This composite structure provides the necessary electrical isolation and surge capability while the insulating material compensates for any variations in trench depth, reducing the stringency of manufacturing precision requirements.
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 design improves the surge and breakdown capabilities of the current sensing part, preventing decreases in breakdown voltage and allowing for more reliable operation under high-voltage conditions, potentially reducing the need for separate diodes and minimizing chip size in applications like inverters.
Implementation Method 1
an insulating film provided in the trench, the insulating film isolating the current sensing part and the main semiconductor element from each other
Implementation Method 2
a semiconductor element arranged on a semiconductor substrate containing a semiconductor material having a bandgap wider than that of silicon
Data Source
AI summary
A current sensing part that detects overcurrent of a main semiconductor element is arranged on a same silicon carbide base as the main semiconductor element. An isolating part is arranged between the main semiconductor element and the current sensing part. The isolating part has a function of suppressing interference of the main semiconductor element and the current sensing part at the silicon carbide base. The isolating part is constituted by a trench provided a predetermined depth from a front surface of the silicon carbide base. An insulating film is provided in the trench, along inner walls of the trench. A poly-silicon layer is provided on the insulating film. With such a configuration, decreases in breakdown voltage of the current sensing part may be prevented.