Semiconductor Temperature Detection via Optical Fiber Mediator
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Solution Overview
Problem
Conventional semiconductor devices with integrated temperature detecting elements for wide gap semiconductor elements face challenges such as increased device area, cost, and assembly complexity, and the conventional temperature detecting elements like photodiodes become unusable at high temperatures above 200°C.
Innovation Solution
A semiconductor device configuration that includes a wide gap semiconductor element, a current detecting portion, an optical fiber, and a photodiode, where the photodiode receives emitted light through the optical fiber to generate an output current proportional to the light emission intensity and operating current, allowing temperature detection without being integrally formed with the semiconductor element, thus reducing device area and improving assemblability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature detecting element is formed inside the semiconductor device together with a power semiconductor element, then temperature detection function is achieved, but device area increases and cost increases
Solution Approach 1:
An optical fiber is introduced as an intermediary to transmit light signals between the wide gap semiconductor element and the external photodiode. This allows temperature detection without integrating the detecting element inside the device, thereby reducing device area while maintaining the temperature detection function.
2Reliability
If a temperature detecting element is formed inside the semiconductor device together with a power semiconductor element, then temperature detection function is achieved, but wire bonding process complexity increases
Solution Approach 1:
The optical fiber serves as a mediator that eliminates the need for complex wire bonding processes. Light signals can be transmitted through the optical fiber without requiring electrical connections, thereby simplifying the assembly process and reducing device complexity.
3Temperature
If a conventional photodiode is used as temperature detecting element in wide gap semiconductor element operated at 200°C or higher, then temperature detection is attempted, but the photodiode does not operate and becomes unusable
Solution Approach 1:
The optical fiber acts as an intermediary that allows the photodiode to be positioned outside the high-temperature environment. The wide gap semiconductor element emits light at high temperatures, which is transmitted through the optical fiber to the photodiode, enabling temperature detection without exposing the photodiode to temperatures above its operational limit.
Solution Approach 2:
The conventional direct electrical contact method is replaced with an optical detection system. Instead of using a photodiode that directly contacts the high-temperature semiconductor element, the system uses light emission and optical fiber transmission to indirectly detect temperature, thereby protecting the photodiode from high-temperature damage.
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
Enables normal operation of the temperature detecting function for wide gap semiconductor elements, reduces costs, improves assemblability, and allows temperature detection even at high operating temperatures above 200°C by using the photodiode effectively with the optical fiber to measure output current.
Implementation Method 1
The semiconductor device is formed of a wide gap semiconductor material having light-emitting property to emit light during operation
Implementation Method 2
Emitted light during operation of the semiconductor element is incident on the optical fiber. The photodiode receives the emitted light obtained by propagation through the optical fiber
Implementation Method 3
The photodiode generates an output current corresponding to a light emission intensity of the emitted light received through the optical fiber
Data Source
AI summary
An optical fiber is provided between a photodiode and a semiconductor active portion of a wide gap semiconductor element forming portion such that emitted light at the time of light emission of the semiconductor active portion of the wide gap semiconductor element forming portion is incident from an incident surface of the optical fiber, and is received from an emitting surface to the photodiode through the optical fiber. Specifically, the incident surface of the optical fiber is arranged so as to be opposed to a side surface portion of the wide gap semiconductor element forming portion, so that the emitted light at the time of light emission of the wide gap semiconductor element is incident on the incident surface.