Radiation-Resistant Image Sensor Package with Local Passivation
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Solution Overview
Problem
Silicon semiconductor image sensor chips used in high radiation environments, such as satellites or nuclear power plants, experience degradation due to radiation exposure, particularly affecting the transistor regions within the CMOS structure, leading to increased leakage currents and circuit damage.
Innovation Solution
A radiation-resistant image sensor package design incorporating a radiation-resistant passivation layer on the optical cover, specifically targeting the peripheral circuit region vulnerable to radiation while maintaining transparency and protection for the light receiving pixel region, utilizing materials like tungsten or tungsten compounds to minimize radiation impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional image sensor package is used in a high radiation environment, then the package structure provides basic protection and light transmission, but the transistor regions experience radiation-induced degradation and increased leakage currents
Solution Approach 1:
The patent applies a radiation-resistant passivation layer selectively to the peripheral circuit region where transistors are located, while leaving the pixel region without this layer to maintain light transmission. This local differentiation protects vulnerable transistor regions from radiation-induced leakage currents while preserving the optical functionality of the pixel regions.
Solution Approach 2:
The radiation-resistant passivation layer acts as an intermediary substance between the radiation environment and the sensitive transistor regions. Materials such as tungsten or tungsten compounds are used to create this protective barrier that filters harmful radiation before it reaches the transistor gates, thereby preventing radiation-induced degradation.
2Reliability
If a radiation-resistant passivation layer is added to protect transistor regions, then radiation resistance is improved, but the device structure and manufacturing complexity increase
Solution Approach 1:
The radiation-resistant passivation layer is applied only to the peripheral circuit region rather than the entire sensor surface. This selective application reduces the overall material usage and manufacturing complexity while providing targeted protection where it is most needed - in the transistor-dense peripheral regions.
Solution Approach 2:
The patent employs composite material structures by combining conventional passivation layers with radiation-resistant materials such as tungsten or tungsten compounds. This composite approach enhances radiation resistance while managing the complexity through the use of well-established material combinations in semiconductor manufacturing.
3Reliability
If the entire optical cover is made of radiation-resistant material, then complete radiation protection is achieved, but light transmission and image quality are compromised
Solution Approach 1:
The patent implements spatial differentiation by applying radiation-resistant passivation material only to the peripheral circuit region and omitting it from the pixel region. This ensures that the pixel region maintains optimal light transmission characteristics for high-quality imaging, while the peripheral region receives necessary radiation protection for the transistors.
Solution Approach 2:
The optical cover is functionally segmented into two distinct zones: a pixel region optimized for light transmission and a peripheral circuit region protected by radiation-resistant passivation. This segmentation allows each zone to be optimized for its specific function without compromising the other.
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
The solution effectively protects the transistor regions from radiation-induced damage, maintaining image sensor performance and extending its operational lifetime in high radiation environments without compromising image quality.
Implementation Method 1
a radiation-resistant passivation layer coupled to the optical cover
Data Source
AI summary
A radiation-resistant image sensor package may include: a substrate; an image sensor disposed over the substrate; and an optical cover disposed over the image sensor, wherein a radiation-resistant passivation layer is coupled to the optical cover.