Wafer Inspection Temperature Correction for Infrared Measurement Drift
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Solution Overview
Problem
Conventional methods for measuring the surface temperature of semiconductor wafers using infrared sensors face challenges such as heat generation during testing, temperature stabilization issues, optical path transmittance deterioration, and infrared radiation emission from optical components, leading to measurement errors.
Innovation Solution
An inspection apparatus that includes an electrical contactor to stabilize the semiconductor device, a wafer support with integrated black bodies for calibration, and a temperature measurement system with correction units to account for distance, ambient, fiber, and ferrule temperature changes, ensuring precise non-contact temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If non-contact temperature measurement using infrared sensor is employed, then measurement speed and responsiveness are improved, but measurement precision deteriorates due to various error factors
Solution Approach 1:
The patent implements feedback by measuring the actual temperature of the wafer using the infrared sensor, comparing it with the set temperature, and generating correction values to adjust for deviations. This closed-loop feedback mechanism continuously refines the measurement accuracy while maintaining high-speed non-contact measurement capability.
Solution Approach 2:
The patent introduces intermediate correction values as mediators between the raw infrared measurement and the final temperature result. These correction values, derived from measurements of reference regions and optical path components, serve as intermediate steps to eliminate systematic errors and achieve precise temperature measurement.
2Measurement precision
If conventional calibration methods using black body furnace are used, then measurement precision is improved, but productivity deteriorates due to time-consuming calibration process
Solution Approach 1:
The patent performs preliminary calibration actions by pre-measuring the infrared radiation characteristics of reference regions with known temperatures and pre-calculating correction values. This preliminary action stores calibration data that can be quickly applied during actual measurements, eliminating the need for time-consuming recalibration while maintaining high precision.
Solution Approach 2:
The patent creates copies of calibration reference regions directly on the wafer surface, allowing the measurement system to calibrate using these embedded references during normal operation. This copying approach eliminates the need for separate calibration procedures using external black body furnaces, significantly improving productivity while maintaining measurement precision.
3Adaptability or versatility
If optical path components are added for infrared transmission, then measurement capability is improved, but measurement precision deteriorates due to transmittance deterioration and infrared radiation from components
Solution Approach 1:
The patent applies feedback by measuring the temperature of optical path components themselves using the infrared sensor, detecting the infrared radiation they emit, and generating correction values to compensate for this interference. This feedback mechanism continuously adjusts for optical path effects, maintaining measurement precision despite the presence of necessary optical components.
Solution Approach 2:
The patent converts the harmful infrared radiation emitted by optical path components into a measurable signal that can be used for correction. By detecting and quantifying the radiation from these components, the system transforms them from sources of error into reference points that enable systematic compensation and improved measurement accuracy.
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 apparatus corrects for measurement errors, enabling accurate and precise surface temperature measurement of semiconductor wafers under varying conditions.
Implementation Method 1
an infrared-light receiving unit configured to receive infrared radiation emitted from the wafer
Implementation Method 2
a temperature measurement control unit configured to control temperature measurement of the measurement target based on an infrared radiation amount of the infrared radiation received
Data Source
AI summary
An inspection apparatus that brings an electrical contactor into contact with an electrode terminal of a device under test on a wafer, electrically connects a tester and the device under test via the electrical contactor, and performs testing of the device under test. The inspection apparatus includes a wafer support portion for supporting the wafer, an infrared-light receiving unit for receiving infrared radiation emitted from the wafer with at least the wafer as a measurement target, and a temperature measurement control unit for controlling temperature measurement of the measurement target based on an infrared radiation amount of the infrared radiation received by the infrared-light receiving unit. The temperature measurement control unit includes a temperature correction unit that corrects the measurement temperature based on the infrared radiation amount from the wafer.