Photocoupler Vf Voltage for Substrate Temperature Monitoring

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Solution Overview

Problem

Monitoring substrate temperature in semiconductor devices typically requires additional components like thermocouples or thermistors, increasing costs and component variations due to temperature characteristics of electronic components.

Innovation Solution

A semiconductor device that utilizes a photocoupler with a light emitting diode and a substrate temperature monitor circuit to read the Vf voltage value of the light emitting diode for temperature monitoring, eliminating the need for additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a thermocouple or thermistor is used to monitor substrate temperature, then temperature monitoring capability is achieved, but the number of components and costs increase

Engineering Contradiction:

Improvesubstrate temperature monitoring capabilityVSAvoidnumber of components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The light emitting diode in the photocoupler is made to serve dual functions: signal transmission and temperature monitoring. By reading the Vf voltage value of the light emitting diode, the system can monitor substrate temperature without requiring separate temperature sensing components, thus reducing component count while maintaining monitoring capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The temperature sensing function is merged with the existing light emitting diode component of the photocoupler. The Vf voltage characteristic of the light emitting diode is utilized for temperature measurement, combining signal transmission and temperature monitoring into a single component rather than using separate thermocouple or thermistor elements

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If a thermocouple or thermistor is used to monitor substrate temperature, then temperature monitoring capability is achieved, but costs increase

Engineering Contradiction:

Improvesubstrate temperature monitoring capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The light emitting diode serves itself by providing both its primary function of signal transmission and an additional temperature sensing function. The Vf voltage characteristic inherent to the light emitting diode is exploited for temperature measurement, eliminating the need for separate temperature sensing components and reducing overall system cost

Inventive Principle:

Principle #25Self-service

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 precise monitoring and feedback of substrate temperature, improving sensing function precision and reducing component and cost variations without adding extra components.

Implementation Method 1

a light emitting diode that converts an electric signal received from the first circuit into an optical signal

Methodology Applied

Scientific EffectLight emitting diode effect: Light Emitting Diode

Implementation Method 2

a light receiving device that converts the optical signal into an electric signal

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 3

a substrate temperature monitor circuit reading a Vf voltage value of the light emitting diode of the photocoupler to monitor temperature of the substrate

Methodology Applied

Scientific EffectTemperature dependence of forward voltage:

Data Source

PatentUS10505518B2Semiconductor device with substrate temperature monitor circuit

Publication Date: 2019.12.10 MITSUBISHI ELECTRIC CORP

AI summary

First and second circuits, a photocoupler and a substrate temperature monitor circuit are formed on a substrate. A photocoupler includes a primary-side light emitting diode that converts an electric signal received from the first circuit into an optical signal, and a light receiving device that converts the optical signal into an electric signal and outputs the electric signal to the second circuit. The substrate temperature monitor circuit reads a Vf voltage value of the primary-side light emitting diode of the photocoupler to monitor temperature of the substrate.