Wafer Acceptance Test Structure for Probecard Needle Anomaly Detection
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Solution Overview
Problem
Wafer acceptance tests face challenges due to probecard needle deformation, deviation, or blunting during mechanical contact, which can damage wafer components during subsequent tests, necessitating a method to assess needle normality effectively.
Innovation Solution
A test structure and process involving a row of pads with specific electrical connections and disconnections, allowing probecard needles to be tested by contacting different pads and portions to determine anomalies through electrical conductivity and resistance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If probecard needles are used repeatedly for wafer testing, then testing productivity is improved, but needle reliability deteriorates due to deformation, deviation, or blunting from mechanical impact
Solution Approach 1:
The patent implements preliminary testing of probecard needles before they are used for actual wafer acceptance testing. A test structure with multiple pads is provided on the wafer, allowing needles to be tested in advance to identify anomalies such as deformation, deviation, or blunting. This preliminary action prevents defective needles from damaging wafer components during subsequent tests.
Solution Approach 2:
The patent establishes a feedback mechanism where the electrical test results from the test structure are used to determine needle normality. By measuring electrical conductivity and resistance between pads through the needles, the system provides feedback information about needle condition. This feedback allows for real-time identification of anomalous needles and prevents their use in damaging wafer components.
2Reliability
If comprehensive needle testing is implemented, then needle reliability is improved, but device complexity increases due to additional test structures and procedures
Solution Approach 1:
The test structure provided on the wafer serves multiple functions: it tests the electrical integrity of probecard needles, identifies anomalies such as deformation or blunting, and prevents damage to wafer components. By making the test structure multi-functional, the patent reduces the need for separate testing mechanisms and minimizes overall system complexity while maintaining comprehensive needle reliability.
Solution Approach 2:
The patent merges the needle testing function with the existing wafer test structure by integrating test pads and metal lines into the wafer design. This combination allows needle testing to be performed as part of the standard wafer acceptance test process, eliminating the need for separate testing equipment or procedures and thereby reducing device complexity.
3Object-affected harmful factors
If anomalous needles are identified and removed, then wafer component protection is improved, but testing time is increased due to additional inspection steps
Solution Approach 1:
The patent performs needle anomaly identification as a preliminary action before actual wafer testing begins. By testing needles in advance using the test structure and determining their normality beforehand, the process prevents damage to wafer components while minimizing time loss. The preliminary testing is integrated into the existing workflow, allowing for efficient identification and removal of anomalous needles without significant delays.
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 solution enables timely identification of anomalous probecard needles, reducing the risk of damaging wafer components and enhancing the reliability of the wafer acceptance test process by confirming needle integrity before subsequent tests.
Implementation Method 1
The first peripheral metal line is disposed at a first side of the row and electrically connected to the second pad and the third pad. The second peripheral metal line is disposed at a second side of the row and electrically connected to the second pad and the third pad.
Data Source
AI summary
Provided is a test structure for wafer acceptance test (WAT). The test structure includes a row of a plurality of first pads electrically connecting to each other, a second pad, a third pad, a first peripheral metal line, and a second peripheral metal line. The second pad is disposed in the vicinity of a first end of the row, wherein the second pad is electrically disconnected to the first pads. The third pad is disposed in the vicinity of a second end of the row, wherein the third pad is electrically disconnected to the first pads. The first peripheral metal line is disposed at a first side of the row and electrically connected to the second pad. The second peripheral metal line is disposed at a second side of the row and electrically connected to the third pad.