Variable Geometry Wafer Test Probes for Uniform Contact
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Solution Overview
Problem
Current wafer testing methods result in varying contact forces and areas across a probe array due to deflection of the support structure, leading to inconsistent electrical contact with C4 bumps, as each probe must apply sufficient force to overcome deflection, causing uneven contact pressure.
Innovation Solution
The configuration of each probe in the array is tailored based on the expected deflection at its position, allowing for varying probe geometries such as height, feature size, and shape to maintain uniform engagement and force distribution across the array, compensating for substrate deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid probe array with uniform probe configuration is used, then the probe support structure provides stable support, but the support structure deflects under test load causing varying contact forces across the array
Solution Approach 1:
The patent applies local quality by varying the probe configuration (length, stiffness, or pre-load) based on the local position within the array. Probes at different locations are customized to compensate for the specific deflection characteristics of the support structure at each position, ensuring uniform contact force across all probes despite the rigid support structure's deflection under load.
2Force
If probe displacement is increased to overcome support structure deflection, then contact force is sufficient to penetrate oxide layers, but contact area varies across the array leading to inconsistent electrical contact
Solution Approach 1:
The patent implements local quality by tailoring each probe's configuration to its specific position in the array. This customization ensures that each probe achieves the necessary contact force for oxide layer penetration while maintaining consistent contact area, thereby ensuring uniform electrical contact quality across all probes in the array.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the probes with varying lengths, stiffness, or pre-loads before testing. This pre-adjustment compensates for the support structure's deflection characteristics, allowing each probe to maintain optimal contact conditions without requiring real-time adjustment during the testing process.
3Force
If overdrive is increased to compensate for support structure deflection, then probe contact force is sufficient, but the resulting forces cause significant deflection of the probe support structure
Solution Approach 1:
The patent resolves this contradiction by applying local quality through position-dependent probe configuration. Instead of uniformly increasing overdrive across all probes, each probe is customized with appropriate length, stiffness, or pre-load settings that generate sufficient contact force locally without requiring excessive overall overdrive, thereby minimizing support structure deflection.
Data Source
AI summary
A system for testing functionality of die on a wafer including a plurality of contacts includes a support structure and a plurality of probes mounted to the support structure in an array. A configuration of each of the plurality of probes varies based on a position of the probe within the array to maintain uniform engagement between the plurality of probes and a corresponding plurality of contacts across the array.