Band Gap Reference Circuit Testing Under Wafer Chuck Temperature Drift
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Solution Overview
Problem
The measurement of temperature characteristics in semiconductor devices with band gap reference circuits is inaccurate due to variations in measuring temperature, which deviate from the set temperature of the wafer chuck by up to 10°C, making it difficult to accurately test the temperature characteristics of the BGR circuit.
Innovation Solution
Measure the temperature dependencies of the reference voltage and absolute temperature proportional voltage for a plurality of samples, calculate the differences between median values, and use these differences to accurately test the temperature characteristics of the band gap reference circuit even when the measuring temperature is not accurately known.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the temperature of the wafer chuck is set to a specific value for testing, then the testing process can be standardized and automated, but the actual measuring temperature of the semiconductor device deviates from the set temperature due to heat transfer instability through the probe
Solution Approach 1:
The patent replaces the mechanical thermal contact measurement system with an electrical measurement system. Instead of measuring temperature directly through thermal contact between the probe and semiconductor device, the invention measures electrical parameters (voltage, current) that can be correlated to temperature characteristics, thereby avoiding the temperature deviation caused by unstable thermal contact.
Solution Approach 2:
The patent introduces electrical parameters as an intermediary to indirectly measure temperature characteristics. Rather than directly measuring the problematic temperature parameter through unstable thermal contact, the invention uses electrical measurements as a mediator that can be accurately obtained through the probe while still providing information about the semiconductor device's temperature behavior.
2Measurement precision
If the probe contacts the semiconductor device to transfer heat for temperature measurement, then temperature can be measured, but the heat transfer amount becomes unstable causing temperature deviation up to 10°C
Solution Approach 1:
The patent replaces the unstable mechanical thermal contact system with an electrical measurement system. The probe maintains physical contact for electrical measurement purposes but does not rely on this contact for heat transfer, thereby eliminating the reliability issue of unstable heat transfer while preserving the ability to measure temperature characteristics through electrical parameters.
Solution Approach 2:
The patent extracts the temperature measurement function from the thermal contact mechanism. Instead of using heat transfer through the probe contact as the measurement mechanism, the invention separates the measurement function to use electrical parameters, leaving the thermal contact issue resolved by not depending on it for measurement.
3Ease of manufacture
If temperature characteristics are tested using direct thermal contact method, then the testing process is simple, but the measurement accuracy is insufficient for high safety standards in vehicle-mounted electronic systems
Solution Approach 1:
The patent replaces the simple but inaccurate direct thermal contact measurement method with an electrical parameter-based measurement method. While the new method requires additional measurement steps, it maintains ease of implementation through standard electrical testing equipment while achieving the measurement accuracy required for vehicle-mounted electronic systems with high safety standards.
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 more accurate testing of the temperature characteristics of the band gap reference circuit by correcting the absolute temperature proportional voltage, ensuring precise temperature measurement despite variations in measuring temperature.
Implementation Method 1
a band gap reference circuit BGR1 that generates a reference voltage Vref1
Implementation Method 2
an absolute temperature proportional voltage Vptat1 that has a relationship in which an absolute temperature proportional voltage Vptat1 is proportional to an absolute temperature
Data Source
AI summary
Before a temperature characteristic of a band gap reference circuit is tested, temperature dependencies of a reference voltage and an absolute temperature proportional voltage for a plurality of samples are measured. When the temperature characteristic is tested, based on a difference ΔVref between the reference voltage of the band gap reference circuit at a predetermined temperature and a median value of the reference voltages of the plurality of samples, a difference ΔVptat between the absolute temperature proportional voltage of the band gap reference circuit at a predetermined temperature and a median value of the absolute temperature proportional voltages of the plurality of samples is calculated.