Wafer Inspection Probe Elastic Contact Signal Transmission
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Solution Overview
Problem
Existing wafer inspection systems face challenges in transmitting short-pulse test signals due to signal distortion caused by cable materials and length, and temperature-induced thermal expansion affects the stability of conducting units, leading to unstable signal transmission and increased complexity and cost.
Innovation Solution
A wafer inspection system with a probe device and supporting device where elastic contact members are located on the probe device, eliminating the need for signal cables and reducing temperature effects, allowing for more stable and flexible signal transmission by adjusting the height and horizontal distance of contact members to prevent collisions and ensure reliable contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cables are used to transmit test signals between the supporting unit and driver IC, then the system configuration is simple, but the test signal suffers from distortion and deformation due to cable material effects and long transmission path length
Solution Approach 1:
The patent extracts and eliminates the cable from the signal transmission path. By providing conducting units directly on the supporting unit that can make direct electrical contact with the driver IC, the cable is removed entirely. This extraction resolves the contradiction by eliminating the source of signal distortion (cable material effects and long path length) while simplifying the overall configuration.
2Reliability
If conducting units are disposed on the supporting unit to eliminate cables, then the transmission path length is reduced, but the conducting units are affected by thermal expansion and contraction due to temperature control, causing unstable contact performance
Solution Approach 1:
Instead of placing the conducting units on the temperature-controlled supporting unit, the patent inverts the arrangement by placing elastic contact members on the probe device (which is not subject to temperature control). These elastic contact members then contact the electrically conductive portion of the probe device, which serves as the stable reference point. This inversion resolves the thermal expansion issue while maintaining short transmission path length.
3Reliability
If elastic contact members are provided on the probe device with adjustable height and horizontal distance, then collision with wafer is prevented and contact stability is improved, but the device configuration becomes more complex
Solution Approach 1:
The patent employs dynamic design by making the elastic contact members height-adjustable and horizontally positionable. This allows the system to adapt to different wafer positions and test requirements dynamically. The adjustability provides collision prevention and stable contact while maintaining reasonable configuration complexity through standardized adjustment mechanisms.
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 transmits short-pulse test signals with improved stability and reduced complexity, preventing temperature-induced instability and collision issues, while maintaining a simple configuration and lowering costs.
Implementation Method 1
The positive electrode of the die is contacted by a probe of a probe device, and the negative electrode of the die is contacted by an electrically conductive portion provided on a bottom surface of the probe device... a test loop is thus formed and the test signal outputted from the driver IC is able to be transmitted to the positive electrode of the die via the cable and the probe device and then transmitted back to the driver IC from the negative electrode of the die via the supporting unit and the cable
Implementation Method 2
The conducting unit is usually an elastic contact member (pogo pin) provided with a spring and a contact head. In order for the spring to bear the weight of the contact head and to elastically push the contact head to cause good contact between the contact head and the electrically conductive portion of the probe device
Implementation Method 3
the temperature of the supporting unit may be raised or lowered. Therefore, the conducting units disposed on the supporting unit are liable to be affected by the temperature of the supporting unit, e.g. thermal expansion and contraction caused by temperature changes
Data Source
AI summary
A wafer inspection system includes a supporting device having electrically connected supporting and contact portions for supporting a wafer's back, and a probe device having a probe and elastic contact members. When a probe tip of the probe contacts the wafer's front, a contact tip of the elastic contact member is abutted against a contact surface of the contact portion. The contact tip is higher than the probe tip. The contact surface is higher than the wafer's front. Alternatively, the contact surface having a radius larger than or equal to twice the wafer's radius. The horizontal distance between the probe tip and the contact tip is larger than or equal to twice the wafer's radius. This satisfies the test requirement of short-pulse test signal and prevents the structural design and transmitting stability of the elastic contact members from being affected by the inspection temperature.