SiC Circuit Layout Using Parasitic Capacitance for Radiation Stability
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Solution Overview
Problem
Semiconductor elements in radiation environments, such as nuclear plants, face instability due to radiation-induced charge accumulation and noise, particularly in silicon carbide (SiC) integrated circuits, which are prone to characteristic fluctuations and noise due to their n-type substrate and high radiation sensitivity.
Innovation Solution
A radiation-resistant circuit device is designed with a SiC integrated circuit, a printed board, conductive wiring, and insulating material to form a large parasitic capacitance between the substrate electrode and the conductive wiring, stabilizing the substrate potential and reducing noise and drift effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an n-type substrate is used in SiC integrated circuits to achieve radiation resistance, then radiation resistance is improved, but substrate potential stability deteriorates because the substrate cannot be connected to GND potential
Solution Approach 1:
An insulating layer is introduced as an intermediary between the n-type SiC substrate and the underlying structure. This insulating layer enables the substrate to be electrically isolated, allowing it to maintain a stable positive potential without direct connection to GND, thus resolving the contradiction between radiation resistance and potential stability
Solution Approach 2:
The substrate potential parameter is changed from GND (0V) to a fixed positive potential. By applying and maintaining this positive potential through the insulating layer structure, the substrate operates in a stable state that prevents parasitic diode conduction while ensuring radiation resistance
2Reliability
If SiC material is used instead of Si to improve radiation resistance, then radiation resistance is improved, but integrated circuit formation difficulty increases due to lack of p-type substrates
Solution Approach 1:
The substrate type parameter is changed from p-type (standard for Si) to n-type (available for SiC). This parameter change enables the use of SiC material for radiation-resistant applications while accommodating the manufacturing constraints by designing the circuit architecture for n-type substrates
Solution Approach 2:
Instead of trying to create p-type SiC substrates (the conventional approach for integrated circuits), the invention inverts the approach by designing the entire circuit architecture to work with n-type substrates, which are readily available for SiC manufacturing
3Ease of operation
If the substrate is set to GND potential in SiC integrated circuits, then ease of operation is improved, but parasitic current flow occurs due to forward-biased PN junction diodes
Solution Approach 1:
A positive potential is applied to the substrate in advance to prevent the parasitic PN junction diodes from becoming forward-biased. This preliminary anti-action counteracts the tendency toward parasitic current flow before it can occur, ensuring stable operation
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
The solution enables stable operation of SiC integrated circuits in radiation environments by reducing noise and characteristic fluctuations, ensuring accurate measurements even under high radiation doses, thereby enhancing the reliability of measuring instruments.
Implementation Method 1
forming a large parasitic capacitance between a substrate electrode and the conductive wiring
Implementation Method 2
SiC that is used in a power semiconductor in recent years is a typical semiconductor material that has a wide band gap and is resistant to radiation
Data Source
AI summary
Provided is a SiC semiconductor element equipped with a SiC integrated circuit having a stable characteristic, which operates normally even in a radiation environment. A radiation resistant circuit device includes: a SiC semiconductor element equipped with a SiC integrated circuit, a printed board on which the SiC semiconductor element is provided, a conductive wiring that is arranged inside the printed board and has a predetermined surface facing a bottom surface of a substrate electrode of the SiC integrated circuit, and an insulating material arranged between the bottom surface of the substrate electrode of the SiC integrated circuit and the predetermined surface of the conductive wiring.