Wafer Probe Station Thermal Expansion Alignment
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Solution Overview
Problem
Wafer probe stations face challenges in accurately maintaining the operational distance between probes and the device under test after thermal changes, leading to potential misalignment and ineffective testing due to thermal expansions or contractions.
Innovation Solution
A wafer probe station design incorporating a thermal chuck, chuck stage, platen, first and second focusing devices, and a thermal plate, where the first focusing device uses a mirror and optical element to adjust for changes in the device under test's position, and the second focusing device adjusts for probe tip focus, with a thermal plate maintaining the operational temperature to ensure accurate alignment and contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermal chuck is heated to operational temperature, then the device can operate at the required temperature, but thermal expansion causes misalignment between probes and the device under test
Solution Approach 1:
The patent applies preliminary action by performing focus adjustments at room temperature before heating to operational temperature. The first focusing device adjusts the device under test position and the second focusing device adjusts probe tip focus while the system is cool, establishing baseline alignment that compensates for anticipated thermal expansion effects.
Solution Approach 2:
The patent utilizes parameter changes by measuring the actual change in operation distance after thermal heating occurs. The system monitors how the operation distance changes with temperature and uses this information to adjust focusing parameters, thereby compensating for thermal expansion effects on alignment precision.
2Stability of the object's composition
If the operation distance changes due to thermal expansion, then the structural integrity is maintained, but the probe contact accuracy deteriorates
Solution Approach 1:
The patent implements feedback by measuring the actual change in operation distance between probes and device under test after thermal heating. This measurement feedback is used to adjust the focusing devices, creating a closed-loop system that compensates for thermal expansion effects and maintains probe contact accuracy despite structural changes.
3Manufacturing precision
If focusing adjustments are made after heating, then alignment can be corrected, but the complexity of the procedure increases
Solution Approach 1:
The patent reduces procedure complexity by performing both focusing adjustments (first focusing device for device under test, second focusing device for probe tips) at room temperature before heating. This preliminary action eliminates the need for complex post-heating adjustments, simplifying the overall procedure while maintaining high alignment precision.
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 accurate and easy determination of the actual change in operation distance between probes and the device under test at operational temperature, ensuring proper contact and testing even with thermal expansions, and provides an even light distribution for precise probe tip placement.
Implementation Method 1
the wafer probe station experiences thermal expansions at the operational temperature
Implementation Method 2
The optical element is movable relative to the mirror along an extension direction of the platen. The mirror is configured to reflect an image from the device under test to the optical element.
Implementation Method 3
The optical element is configured to focus the image.
Implementation Method 4
The thermal plate is located between the second focusing device and the platen. The thermal plate is configured to heat up to the operational temperature.
Data Source
AI summary
A wafer probe station includes a thermal chuck, a chuck stage, a platen, some probes, a first focusing device, a second focusing device and a thermal plate. The thermal chuck heats up to an operational temperature and holds a device under test (DUT). The chuck stage connects with the thermal chuck and moves the thermal chuck. The thermal chuck locates between the chuck stage and the platen. The probes are disposed on the platen and configured to contact with the DUT. The first focusing device is disposed on the platen to focus on the DUT. The second focusing device is disposed on the chuck stage to focus on the probes. The thermal plate locates between the second focusing device and the platen and is configured to heat up to the operational temperature. The thermal plate has a through hole aligning with the second focusing device.