Probe Tip Distance Compensation via Reflected Image Measurement
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Solution Overview
Problem
Existing wafer probe stations face challenges in accurately determining and compensating for the distance between a probe tip and a device under test after a temperature change, affecting the operational accuracy of semiconductor component testing.
Innovation Solution
A method involving a reflective surface on the device under test, capturing images at different temperatures, measuring distances, and calculating a relative position adjustment by dividing the difference in distances between the probe and its reflected image to compensate for temperature-induced changes, allowing for precise alignment of the probe tip with the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature of the device under test is changed, then the operational accuracy of the wafer probe station is improved through compensation, but the complexity of the measurement and compensation process increases
Solution Approach 1:
A reflective surface is introduced as an intermediary element on the device under test to enable optical measurement of distance changes. This mediator allows the image taking device to capture reflected images of the probe, facilitating non-contact measurement of thermal expansion/contraction without direct mechanical intervention
Solution Approach 2:
The patent replaces direct mechanical measurement methods with an optical measurement system consisting of an image taking device and reflective surface. This substitution enables precise measurement of distance changes due to temperature variations without mechanical contact, simplifying the compensation process while maintaining high accuracy
2Measurement precision
If direct measurement of probe tip distance is performed, then the measurement process is simple, but the measurement precision is insufficient after temperature changes
Solution Approach 1:
The reflective surface creates an optical copy (reflected image) of the probe and its reference point. By measuring the distance between the reference point and its reflected image, the system indirectly determines the probe-to-device distance with high precision, avoiding direct measurement difficulties
Solution Approach 2:
The measurement is transformed from direct vertical distance measurement to horizontal distance measurement in the image plane. By measuring the distance between the reference point and its reflected image in the 2D image space, the system accurately determines the 3D spatial relationship without direct vertical measurement
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 method enables accurate and efficient compensation of the probe tip position after temperature changes, reducing measurement errors and maintaining testing accuracy, making the process convenient and efficient for users.
Implementation Method 1
providing a reflective surface on the device under test; capturing by an image taking device a first image having the probe and a reflected image of the probe on the reflective surface
Data Source
AI summary
A method for compensating to a first distance between a probe tip and a device under test (DUT) after a temperature change of the DUT includes: capturing a first image having the probe and its reflected image on a reflective surface of the DUT at a first temperature; measuring a second distance between a reference point of the probe and its reflected image; changing the first temperature of the DUT to a second temperature; capturing a second image having the probe and its reflected image on the reflective surface at the second temperature; measuring a third distance between the reference point of the probe and its reflected image; dividing the difference between the third and the second distances by two to obtain a fourth distance; and determining a relative position between the probe and the DUT by the fourth distance to compensate to the first distance.