Symmetric Sensor Probe Assembly for Wafer Testing
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Solution Overview
Problem
In micro-fabrication processes, especially during wafer-level optical testing of integrated circuits, geometric offsets caused by angular adjustments of probes relative to the wafer surface lead to inaccurate measurements and potential collisions due to varying separation distances between the probe and sensor, which are not symmetrically aligned.
Innovation Solution
A sensor probe assembly where the probe and sensor are symmetrically disposed around a common center axis, minimizing geometric offsets and maintaining consistent distance measurements during angular adjustments and surface irregularities, such as waviness or wedging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the probe and sensor are positioned at different locations, then the sensor can measure distance from a fixed position, but angular adjustments cause geometric offsets leading to measurement inaccuracies at the probe
Solution Approach 1:
The patent merges the probe and sensor onto the same center axis, creating a co-aligned configuration where both components share a common reference axis. This integration eliminates the geometric offset problem by ensuring that angular adjustments affect both the probe and sensor equally, maintaining accurate distance measurements despite probe-sensor separation for functional reasons.
2Measurement precision
If the probe is angularly adjusted to optimize readings, then probe measurement accuracy improves, but the sensor measurements become inaccurate due to varying separation distances
Solution Approach 1:
The patent creates an equipotential geometric relationship by positioning both the probe and sensor on the same center axis. This configuration ensures that angular adjustments maintain equal geometric conditions for both components, allowing the system to tolerate angular changes without creating differential measurement errors between the probe and sensor.
3Measurement precision
If distance control is maintained at the sensor location, then sensor measurements remain consistent, but the probe may collide with the wafer surface
Solution Approach 1:
The patent implements a feedback mechanism where the sensor continuously monitors the distance to the wafer surface and provides real-time information about separation changes. This feedback allows the control system to adjust the probe position dynamically, maintaining safe separation distances even when angular adjustments are made, thereby preventing collisions while preserving measurement accuracy.
Data Source
AI summary
A sensor probe assembly includes a probe, and a sensor assembly coupled to the probe. The sensor assembly measures a physical or electrical characteristic of a surface that the probe is near to or in contact with. The sensor assembly is symmetrically disposed around a center axis of the probe.