Dichroic Mirror Optical Inspection for Passivation Layer Thickness
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Solution Overview
Problem
Existing optical inspection systems face challenges in accurately measuring the thickness and uniformity of passivation layers on semiconductor chips due to energy loss and chromatic aberration issues during the inspection process.
Innovation Solution
The optical inspection apparatus employs a dichroic mirror that transmits a first light beam and reflects a second light beam of different wavelengths, allowing for low energy loss and eliminating chromatic aberration by using a first image capturing device to detect the reflected second light beam, which is converted from the first light beam by a wavelength converting layer on the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical inspection system uses a single light source and detector configuration, then the system structure is simple, but energy loss occurs and chromatic aberration affects measurement accuracy
Solution Approach 1:
The optical inspection system is segmented into two independent inspection paths: a first light source with a first detector for inspecting the passivation layer, and a second light source with a second detector for inspecting the semiconductor chip. This segmentation allows each path to be optimized for its specific inspection task, reducing energy loss and eliminating chromatic aberration by using appropriate wavelength ranges for each inspection objective.
Solution Approach 2:
A beam splitter is introduced as an intermediary component to divide the optical paths of the two light sources and direct them to respective detectors. This intermediary enables the system to handle multiple wavelengths and inspection objectives simultaneously without mutual interference, resolving the chromatic aberration issue while maintaining efficient energy utilization in each inspection channel.
2Adaptability or versatility
If the inspection system uses multiple wavelengths of light, then different inspection objectives can be achieved, but chromatic aberration occurs affecting image quality
Solution Approach 1:
The inspection system is divided into separate wavelength channels: a first light source operating at a first wavelength range for passivation layer inspection, and a second light source operating at a second wavelength range for chip inspection. This segmentation eliminates chromatic aberration by preventing multiple wavelengths from overlapping in the same optical path, while maintaining inspection versatility through the dual-channel configuration.
Solution Approach 2:
Each inspection channel is optimized with specific light sources and detectors matched to the local inspection requirements. The first channel uses a first light source and first detector optimized for passivation layer characteristics, while the second channel uses a second light source and second detector optimized for chip inspection, allowing each subsystem to operate at peak performance without chromatic interference.
3Productivity
If a single detector is used to capture reflected light, then the device structure is simple, but energy loss reduces inspection efficiency
Solution Approach 1:
The detection system is segmented into a first detector for capturing reflected light from the passivation layer inspection path and a second detector for capturing reflected light from the chip inspection path. This segmentation ensures that each detector receives optimized light signals without energy loss from competing wavelength channels, thereby improving overall inspection efficiency while maintaining a relatively simple device structure.
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 configuration enables efficient energy utilization and accurate image analysis without the need for image compensation, effectively measuring the thickness and uniformity of passivation layers with high resolution and low energy loss.
Implementation Method 1
The dichroic mirror has a first side and a second side opposite to the first side. The dichroic mirror transmits a first light beam and reflects a second light beam. The wavelength of the second light beam is different from the wavelength of the first light beam.
Implementation Method 2
The first image capturing device is disposed at the second side of the dichroic mirror and is configured to detect the second light beam reflected from the dichroic mirror.
Data Source
AI summary
An optical inspection apparatus includes a dichroic mirror, a first light source, and a first image capturing device. The dichroic mirror has a first side and a second side opposite to the first side. The dichroic mirror transmits a first light beam and reflects a second light beam. The wavelength of the second light beam is different from the wavelength of the first light beam. The first light source is disposed at the first side of the dichroic mirror and is configured to provide the first light beam to pass through the dichroic mirror. The first image capturing device is disposed at the second side of the dichroic mirror and is configured to detect the second light beam reflected from the dichroic mirror.