Wafer Prober Forcer Misalignment Detection
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Solution Overview
Problem
Conventional wafer probers lack the ability to detect misalignment of the forcer relative to the platen, leading to testing errors and damage to probing needles, probe cards, and wafers, with existing protective measures only effective during wafer profiling and cleaning processes.
Innovation Solution
An optical sensor system with a transmitter, receiver, and reflector is integrated into the wafer prober to automatically detect forcer misalignment by monitoring radiation reflections, triggering an alert or suspending operations to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional wafer prober operation continues without misalignment detection, then productivity is maintained, but damage to probe cards and wafers occurs leading to increased loss of substance
Solution Approach 1:
The optical sensor system performs preliminary detection of forcer misalignment by monitoring the position of the forcer relative to the platen before electrical testing occurs. The transmitter emits radiation that reflects off the forcer to the receiver, continuously monitoring forcer position. When misalignment is detected before testing, the system can take preventive action to avoid damage to probe cards and wafers, thus reducing loss of substance while maintaining productivity.
Solution Approach 2:
The optical sensor system establishes a feedback loop by continuously monitoring forcer position through radiation reflection and providing real-time information about forcer alignment. This feedback enables the system to detect misalignment conditions and respond appropriately, preventing damage to expensive components while maintaining operational continuity through timely intervention.
2Reliability
If optical sensor system is added to detect forcer misalignment, then reliability of testing is improved, but device complexity increases
Solution Approach 1:
The optical sensor system uses an intermediary approach by introducing a non-contact radiation-based monitoring system between the forcer and the control system. The transmitter and receiver act as intermediaries that monitor forcer position without physically contacting or interfering with the forcer's movement, thus improving testing reliability while adding minimal complexity compared to direct mechanical sensing methods.
Solution Approach 2:
The patent replaces potential mechanical contact-based alignment detection with an optical system that uses radiation emission and detection. This substitution eliminates the need for mechanical sensors that would require physical contact with the forcer, reducing friction and wear while improving reliability. The optical system adds complexity only in terms of electronic components rather than mechanical assemblies.
3Object-affected harmful factors
If forcer misalignment is not detected, then ease of operation is maintained, but harmful factors increase due to undetected misalignment
Solution Approach 1:
The optical sensor system enables the wafer prober to self-monitor and self-diagnose forcer misalignment conditions. The system automatically detects misalignment through radiation reflection monitoring and can trigger alerts or stop operations without requiring external inspection. This self-service capability reduces harmful factors by continuously monitoring for errors while maintaining ease of operation through automated detection rather than requiring operator intervention.
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 system effectively reduces operational costs and improves performance by preventing damage to expensive probe cards and wafers by detecting and responding to forcer misalignment during electrical testing.
Implementation Method 1
a transmitter configured to transmit radiation toward a reflector
Implementation Method 2
the reflector reflects the radiation toward a receiver
Data Source
AI summary
A system is provided for detecting a forcer misalignment, e.g., due to forcer loss of registration (FLR), in a wafer prober used for electrical testing of a semiconductor wafer. The system includes an optical sensor system including a transmitter and receiver affixed to the forcer or to a reference structure (e.g., the prober platen), and a reflector affixed to the other one of the forcer or reference structure. The transmitter emits radiation toward the reflector, which reflects the radiation toward the receiver. The receiver detects the reflected radiation, and generates an output signal indicating the quantity of received radiation. Alignment monitoring circuitry is configured to identify a misalignment of the forcer relative to the reference structure (e.g., platen) based on the output signal generated by the receiver, and in response, output an alert signal, e.g., to suspend operations of the prober and/or display an error notification to an operator.