Diffusing Plate Illumination for Thin Semiconductor Chip Recognition
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Solution Overview
Problem
In the thin chip die bonding process, the difference in thermal expansion coefficients between the silicon substrate and thin films causes deformation, leading to uneven light distribution and unclear images when using coaxial spot or ring lighting units, making it difficult to accurately recognize and pick up semiconductor chips.
Innovation Solution
A method involving a surface-emitting light source with a diffusing plate to ensure uniform light distribution across the chip surface, and optionally using multiple light sources at a low angle to sandwich the chip, enhancing image clarity and feature visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coaxial spot lighting unit or ring lighting unit is used to radiate light to thin chips, then chip pickup work can be carried out with image recognition, but the light is not uniformly radiated due to chip deformation, resulting in unclear chip images and inability to accurately judge chip status
Solution Approach 1:
A transparent or translucent plate is introduced as an intermediary between the light source and the chip. This plate diffuses the light to achieve uniform illumination across the chip surface, while still allowing the imaging device to capture clear images through the plate for chip recognition and status judgment.
Solution Approach 2:
The lighting approach is changed from direct coaxial spot or ring lighting to diffuse lighting through a transparent plate. This parameter change in lighting method enables uniform light distribution even when chips are deformed, resolving the contradiction between maintaining measurement precision and achieving illumination uniformity.
2Productivity
If light is radiated to deformed thin chips using conventional lighting methods, then the imaging device can attempt to capture images, but the deformed chips cause non-uniform light distribution making it impossible to obtain clear images
Solution Approach 1:
The transparent or translucent plate serves as a mediator that ensures uniform light distribution to deformed chips, enabling clear image capture. This allows the chip pickup process to maintain both high productivity through automated imaging and high reliability through clear, accurate images for defect detection.
Solution Approach 2:
The transparent plate is positioned beforehand to compensate for the expected non-uniform light distribution caused by chip deformation. This prior cushioning approach ensures that even when chips are deformed during handling, clear images can still be obtained, maintaining both productivity and reliability.
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 approach allows for clear image acquisition and accurate chip recognition, even with thin chips, reducing errors in the chip picking process and improving productivity by ensuring proper chip placement and identification.
Implementation Method 1
A method involving a surface-emitting light source with a diffusing plate to ensure uniform light distribution across the chip surface
Implementation Method 2
radiating first irradiation light emitted from a first light source, from above, to an upper surface of a first semiconductor chip to be peeled off from the pressure-sensitive adhesive tape out of the plural semiconductor chips held with the pressure-sensitive adhesive tape, receiving first reflected light from the upper surface of the first semiconductor chip by image pickup means, and acquiring a first image of the upper surface of the first semiconductor chip
Data Source
AI summary
A technique is provided which can exactly recognize a chip to be picked up when picking up the chip from a wafer sheet in a process of die bonding a thin chip. A camera is coupled to one end of a lens barrel, an objective lens is attached to an opposite end of the lens barrel, and an image of a main surface of a chip is photographed through the objective lens. A surface-emitting lighting unit, a diffusing plate and a half mirror are internally provided between the lens barrel and the chip. Further, another lens barrel having a coaxial drop lighting function of radiating light to the main surface of the chip along the same optical axis as that of the camera is disposed.