Wafer Probe Temperature Monitoring via IR Sensor Aperture
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Solution Overview
Problem
Wafer probe testing systems face challenges in accurately trimming device circuits due to temperature variations in the chuck, leading to incorrect trimming and low yield, as existing systems only calibrate temperature before testing and do not account for drifts during the process.
Innovation Solution
Incorporating infra-red (IR) thermal sensors into the wafer probe test system to monitor the wafer temperature in real-time, allowing for continuous temperature monitoring and recalibration if the temperature falls outside an acceptable range, ensuring accurate trimming and improved yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is only done before wafer testing, then the calibration process is simple and quick, but temperature drifts during testing are not detected leading to incorrect trimming
Solution Approach 1:
The patent replaces mechanical contact-based temperature sensing with non-contact infrared (IR) thermal sensing. The IR sensor detects temperature through radiation without physical contact with the wafer or chuck, eliminating the need for complex mechanical integration while enabling continuous real-time temperature monitoring during the entire testing process
Solution Approach 2:
The patent introduces an intermediary aperture in the probe card that allows IR thermal sensors to sense the wafer temperature without direct contact. This aperture serves as a mediator that enables thermal radiation passage from the wafer to the sensor while maintaining the structural integrity of the probe card and allowing electrical probes to function simultaneously
2Reliability
If chuck temperature is set between wafer lots, then calibration is straightforward, but temperature varies during lot testing causing trimming errors
Solution Approach 1:
The patent implements a feedback mechanism where IR thermal sensors continuously monitor wafer temperature during testing, and the system automatically triggers recalibration when temperature drifts exceed a predetermined threshold. This closed-loop feedback ensures trimming accuracy is maintained throughout the testing process without manually stopping production for frequent recalibrations
Solution Approach 2:
The patent transitions from static temperature calibration (performed once before testing) to dynamic temperature monitoring (continuous during testing). The system adaptively adjusts by triggering recalibration events based on real-time temperature conditions, allowing the calibration state to evolve dynamically with changing thermal conditions during the testing process
3Measurement precision
If temperature monitoring is added to detect drifts, then trimming accuracy improves, but the system complexity and cost increase
Solution Approach 1:
The probe card is designed with multi-functionality: it simultaneously serves as the support structure for electrical probes, provides structural alignment features, and incorporates apertures for thermal sensing. This universal design integrates multiple functions into a single component, reducing overall system complexity despite adding temperature monitoring capability
Solution Approach 2:
The patent applies local quality by placing apertures only in specific locations on the probe card where temperature sensing is needed, rather than making the entire probe card complex. The apertures are strategically positioned to allow IR sensing of the wafer or chuck temperature at critical measurement points while maintaining the integrity of other probe card regions
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 implementation of IR thermal sensors enables real-time temperature monitoring, reducing the chances of incorrect trimming, improving product yield, and enhancing overall equipment effectiveness by allowing for immediate recalibration during testing.
Implementation Method 1
one or more infra-red (IR) thermal sensors. The probe card has an aperture spaced from the probe head, and the IR thermal sensor faces the aperture of the probe card to sense the temperature of the wafer
Data Source
AI summary
A wafer probe test system includes a chuck to support a wafer, and a probe card having a first side to face the chuck, an opposite second side, and an aperture that extends between the first and second sides. The system also includes a probe head mounted to the first side of the probe card and having probe pins to contact a device under test of the wafer, and an infra-red thermal sensor facing the aperture of the probe card to sense a temperature of the wafer.