Movable Aperture Elements for Uniform Illumination in Image Sensor Testing
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Solution Overview
Problem
The challenge in testing integrated image sensors on wafers is the nonuniformity of illumination due to the distance between the light source and the wafer, which is constrained by system components, leading to inconsistent testing results.
Innovation Solution
A control ring member with movable aperture elements is positioned between the light source and the probe card, allowing for adjustment of the light path to ensure uniform illumination across multiple image sensor test sites by varying the distance and diameter of the apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between the light source and the wafer is increased to accommodate system components, then the space for components is sufficient, but the uniformity of illumination at the multiple image sensing elements deteriorates
Solution Approach 1:
A diffuser is introduced as an intermediary component between the light source and the wafer. The diffuser scatters and redistributes the light rays, transforming the nonuniform illumination pattern into a more uniform distribution across the wafer surface, thereby resolving the contradiction between maintaining component spacing and achieving uniform illumination
Solution Approach 2:
The optical parameters of the system are modified by changing the distance between the light source and diffuser, and between the diffuser and wafer. By optimizing these distances, the system achieves uniform illumination while maintaining sufficient space for other components
2Manufacturing precision
If the probe card is made thinner to reduce distance between light source and wafer, then the uniformity of illumination improves, but the structural integrity and space for electrical connections deteriorates
Solution Approach 1:
The probe card is divided into multiple layers or sections, allowing the optical path section to be thin for uniform illumination while other sections provide structural support and electrical connection pathways, thus resolving the contradiction between thinness for optical performance and thickness for structural integrity
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 solution achieves uniform illumination across all test sites, improving the accuracy of image sensor testing by compensating for the nonuniformity caused by system component constraints.
Implementation Method 1
each aperture element defining an aperture through which the light passes from the light source to an associated one of the plurality of targets
Data Source
AI summary
A method of increasing uniformity in light from a light source at a plurality of targets of the light includes locating a plurality of movable aperture elements between the light source and the targets. Each aperture element defines an aperture through which the light passes from the light source to an associated one of the plurality of targets associated with the aperture element along a longitudinal axis of the aperture element. The method also includes moving at least one of the aperture elements along its longitudinal axis to change a feature of light incident on the target associated with the aperture element.