Chamber Temperature Control via Self-Refresh Current Measurement
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Solution Overview
Problem
Existing semiconductor test handlers face challenges in precisely controlling the temperature distribution within a chamber due to heat generated by devices under test, leading to issues with yield and reliability, especially when testing multiple devices simultaneously.
Innovation Solution
A method that measures self-refresh currents of semiconductor memory devices with linear temperature compensated self-refresh (Li-TCSR) functionality to generate local temperature values, which are displayed in a two-dimensional map, allowing for real-time temperature monitoring and adjustment of offset values to maintain precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to monitor chamber temperature, then temperature control is achieved, but temperature distribution precision deteriorates due to heat generated by devices under test
Solution Approach 1:
The patent uses self-refresh current as an intermediary parameter to indirectly measure device temperature. Instead of placing temperature sensors near devices (which would be affected by device-generated heat), the system measures the self-refresh current drawn by each device, which correlates to its temperature. This current measurement serves as a mediator that provides accurate temperature information without being influenced by the thermal environment near the device.
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensing system with an electrical measurement system. Instead of using temperature sensors that physically contact or proximity-measure thermal conditions (which are affected by device heat), the system substitutes electrical current measurement (self-refresh current) to infer temperature. This substitution eliminates the measurement interference caused by device-generated heat.
2Measurement precision
If independent temperature control for each device is implemented, then temperature precision is improved, but system complexity and testing costs increase
Solution Approach 1:
The patent makes the existing temperature control system universal by enabling it to perform both chamber-level temperature control and device-level temperature monitoring using the same infrastructure. The self-refresh current measurement capability is integrated into the existing temperature control loop, allowing the system to simultaneously manage overall chamber temperature and individual device temperatures without adding separate complex control systems for each device.
Solution Approach 2:
The patent enables each device to effectively monitor its own temperature through its self-refresh current characteristics. Each device's self-refresh operation serves dual purposes: maintaining memory data retention and providing temperature information. The device's own operational current becomes the measurement signal, eliminating the need for external sensing hardware at each device location.
3Productivity
If multiple devices are tested simultaneously in a chamber, then productivity increases, but temperature distribution control deteriorates due to heat from respective devices
Solution Approach 1:
The patent segments the temperature monitoring function to the individual device level by measuring self-refresh current for each device separately. Instead of using a single chamber-wide temperature sensor that averages thermal conditions, the system divides temperature measurement into discrete device-specific measurements through individual current sensing. This segmentation allows identification and control of temperature variations among multiple devices tested simultaneously.
Solution Approach 2:
The patent implements feedback control by continuously measuring self-refresh current of each device and using this information to adjust heating or cooling. The measured current provides real-time temperature feedback for each device, enabling the control system to compensate for temperature variations caused by device-generated heat and maintain uniform temperature distribution across all devices in the chamber.
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 approach enables precise and efficient temperature control within the test handler, improving yield and reliability by allowing for real-time monitoring and adjustment of temperature distribution across multiple devices, reducing testing costs and enhancing product reliability.
Implementation Method 1
the heat caused by the respective semiconductor memory devices under test
Implementation Method 2
Using a heater and a fan included in the chamber, the inner air of the chamber may be set to a given (or, alternatively predetermined) test temperature
Implementation Method 3
Using a heater and a fan included in the chamber, the inner air of the chamber may be set to a given (or, alternatively predetermined) test temperature
Data Source
AI summary
To measure an inner temperature of a chamber included in a test handler, self-refresh currents of semiconductor memory devices under test are measured. The semiconductor memory devices are disposed in the chamber and have a function of linear temperature compensated self-refresh (Li-TCSR). Local temperature values are generated based on the self-refresh currents, where each local temperature value indicates a temperature near the corresponding semiconductor memory device of the semiconductor memory devices under test.