Wafer ID Reader Optical Path Merging
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Solution Overview
Problem
Conventional systems require two cameras and illumination systems to read both sides of a semiconductor wafer simultaneously, leading to space, obstruction, and cost issues.
Innovation Solution
An optical ID reader system with a single camera and illumination assembly that uses optical elements like mirrors or prisms to guide light from both sides of the wafer, allowing for simultaneous top and bottom image reading with improved contrast and reduced interference, and can rotate to locate ID marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two cameras and illumination systems are used to read both sides of the wafer simultaneously, then reading accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two separate imaging systems into a single camera system by using beam splitters and mirrors to direct light from both the top and bottom surfaces of the wafer to a single camera sensor. This merging approach maintains the capability to read both sides simultaneously while reducing device complexity and cost associated with having two complete camera and illumination systems.
Solution Approach 2:
The patent introduces optical intermediaries (beam splitters and mirrors) that mediate between the two wafer surfaces and the single camera. These intermediary optical elements enable the single camera to receive and process light from both surfaces simultaneously, achieving dual-side reading capability without requiring two separate camera systems.
2Measurement precision
If two cameras and illumination systems are used to read both sides of the wafer simultaneously, then reading accuracy is improved, but space requirement increases
Solution Approach 1:
By merging the optical paths from both wafer surfaces into a single camera system using beam splitters and mirrors, the patent significantly reduces the spatial footprint required for dual-side reading. Instead of accommodating two separate camera assemblies with their respective illumination systems, the single integrated system requires substantially less space while maintaining simultaneous reading capability.
3Adaptability or versatility
If conventional systems are used to read both sides of the wafer, then reading capability is achieved, but obstruction issues occur
Solution Approach 1:
The patent uses beam splitters and mirrors as optical intermediaries to create separate optical paths for light from the top and bottom surfaces of the wafer. These intermediaries direct the light paths around potential obstructions and converge them at the single camera sensor, enabling reading capability while avoiding obstruction issues that would occur with direct dual-camera approaches.
4Device complexity
If a single camera system is used to read both sides of the wafer, then space and cost are reduced, but image contrast may deteriorate due to stray light
Solution Approach 1:
The patent employs beam splitters and mirrors as optical intermediaries that can be designed with appropriate coatings and angles to minimize stray light and interference. These intermediary elements help maintain image contrast by directing light efficiently while blocking or redirecting stray light paths that would otherwise degrade image quality in a single-camera dual-side reading system.
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
Enables efficient and accurate reading of ID marks on both sides of wafers with a compact design, reducing space requirements and costs while maintaining high throughput and accuracy.
Implementation Method 1
The optical element can be disposed to receive images from a high angle with respect to the surface of the workpiece
Implementation Method 2
optical elements to guide the light from the workpiece images to a camera
Implementation Method 3
The ID reader can enclose the workpiece edge from a side or from a back side to allow workpiece forward movement. With the enclosure, the image contrast can be significantly improved by reducing stray light or interference light from ambient
Implementation Method 4
The ID reader comprises a light source assembly to illuminate the image
Implementation Method 5
A beam splitter can be disposed on the light path for providing the coaxial light path, for example, a straight path for the image directly to the camera, and a reflected path for the light source
Implementation Method 6
The light source assembly can further comprise filter to control the wavelengths of sending and receiving images, thus further improving the signal to noise contrast ratio
Data Source
AI summary
The present invention discloses apparatuses and methods for simultaneous viewing and reading top and bottom images from a workpiece. The present ID reader can comprise an enclosure covering a top and bottom section of the workpiece with optical elements to guide the light from the workpiece images to a camera. The optical element can be disposed to receive images from a high angle with respect to the surface of the workpiece. The present ID reader can further comprise a light source assembly to illuminate the image. The light source assembly can utilize a coaxial light path with the images, preferably for bright field illumination. The light source assembly can also utilize a non-coaxial light path, preferably for dark field illumination.