Probe Card Alignment via Dual-Side Illumination Imaging
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Solution Overview
Problem
In semiconductor device testing, probe cards often fail to align properly with wafer stages, leading to inaccurate test results and reduced production yield due to improper contact with conductor pads.
Innovation Solution
A testing system that includes a probe card, a test head, a camera, a light source, and a backlight unit, where the probe needles are illuminated from both sides to enhance image contrast, allowing for precise alignment of the probe card relative to the wafer stage using real-time imaging and automatic adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment methods are used, then the probe card may align with the wafer stage, but the alignment precision is insufficient leading to false test results
Solution Approach 1:
The patent replaces traditional mechanical alignment systems with an optical imaging system. A camera captures images of the probe needles and wafer stage, and a controller processes these images to calculate and execute precise alignment adjustments, substituting mechanical alignment methods with optical-mechanical integration for higher precision.
Solution Approach 2:
The patent uses optical imaging to create a visual copy of the probe needles and wafer stage position. The camera captures images that are processed to determine relative positions, allowing the system to visualize and adjust alignment based on this optical copy rather than direct mechanical contact or less precise methods.
2Measurement precision
If expensive optical components are used for alignment, then alignment precision improves, but manufacturing costs increase
Solution Approach 1:
The patent employs a standard camera and basic optical components rather than expensive specialized alignment optics. The system uses readily available, cost-effective components that can be easily replaced or upgraded, avoiding the need for costly proprietary optical alignment systems while achieving sufficient precision.
Solution Approach 2:
By replacing complex mechanical alignment mechanisms with a simpler optical imaging and image processing system, the patent reduces the need for expensive precision mechanical components. The controller-based image analysis provides a more economical approach to achieving high alignment precision.
3Ease of manufacture
If probe card alignment is not precise, then manufacturing costs are reduced, but production yield decreases due to scratches and false test results
Solution Approach 1:
The patent performs alignment verification and adjustment before actual testing begins. The camera captures images, the controller calculates alignment status, and adjustments are made proactively before the probe card contacts the wafer for testing, preventing scratches and ensuring accurate results from the start.
Solution Approach 2:
The system uses real-time image feedback from the camera to monitor alignment status. The controller processes these images and provides feedback on alignment accuracy, enabling continuous adjustment and verification to ensure proper alignment before and during the testing process, thereby preventing defects.
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
This method ensures accurate and efficient alignment of the probe card, preventing scratches on semiconductor devices and increasing production yield while reducing manufacturing costs by eliminating the need for expensive optical components.
Implementation Method 1
a light source and a backlight unit positioned at two sides of the probe needles. The camera images the probe needles by detecting light provided by the light source and the backlight unit
Data Source
AI summary
A method for probe card alignment is provided. The method includes providing a probe card with a plurality of probe needles having their distal ends on a reference plane. The method further includes providing a light from both the upper side and lower side of the reference plane. The method also includes using a camera to image the probe needles. In addition, the method includes performing a probe card alignment process according to the image generated by the camera.