CMOS Image Sensor Encapsulation Using Transparent Substrate Support
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Solution Overview
Problem
Conventional CMOS image sensors have thick encapsulation structures, which hinder the manufacturing of thinner versions with improved mechanical support and cleanliness during the process.
Innovation Solution
A method involving the formation of a blind hole in a combined layer with a micro convex lens, filling with conductive material, and using a transparent substrate for mechanical support during grinding to achieve a thin CMOS image sensor encapsulation structure, where the transparent substrate material is fixed with a high-light-transmittance adhesive and a dummy wafer is used to facilitate wafer thinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional encapsulation structures are used, then the structure provides sufficient mechanical support, but the thickness is relatively large
Solution Approach 1:
The encapsulation structure is divided into multiple functional layers: a first insulating layer with blind holes for electrical connections, a transparent substrate layer for mechanical support and light transmission, and a second insulating layer for protection. This segmentation allows each layer to be optimized independently, achieving thin overall thickness while maintaining mechanical strength through the transparent substrate.
Solution Approach 2:
The transparent substrate material is selectively positioned to cover specific regions where mechanical support is most needed, while allowing other regions to be thinner. The blind holes are strategically located to provide electrical connections only where required, enabling local optimization of both thickness and mechanical support properties.
2Length of moving object
If wafer thinning is performed, then the encapsulation structure thickness is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The blind holes are formed in the first insulating layer before the wafer thinning process. This preliminary action allows the electrical connection structure to be established while the wafer is still thick and easier to handle, simplifying the overall manufacturing process by avoiding the complexity of forming blind holes in a already-thinned structure.
Solution Approach 2:
Instead of thinning the wafer first and then forming the encapsulation structure, the invention forms the encapsulation structure components (blind holes, insulating layers) on the thick wafer first, then performs thinning. This inverted sequence simplifies the manufacturing process by avoiding delicate operations on thin structures.
3Illumination intensity
If the encapsulation structure is made thinner, then the light transmittance is improved, but the mechanical support is reduced
Solution Approach 1:
The encapsulation structure uses composite materials, particularly the transparent substrate material that combines high light transmittance properties with adequate mechanical strength. This composite approach allows the structure to be thin for good light transmission while the transparent substrate provides the necessary mechanical support.
Solution Approach 2:
The transparent substrate is positioned strategically to provide mechanical support only in regions where it is most needed for structural integrity, while allowing other regions to be thinner to maximize light transmittance. This local optimization resolves the contradiction between thickness and mechanical support.
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 method results in a thin CMOS image sensor encapsulation structure with enhanced mechanical support and higher cleanliness, allowing the wafer to be thinned to 20-100µm thickness while maintaining reliability and light transmittance.
Implementation Method 1
the transparent substrate material provides more mechanical support forces for the wafer, such that the wafer can become thinner by grinding
Implementation Method 2
The transparent substrate material is fixed on surfaces of the first insulating layer and the micro convex lenses by a high-light-transmittance adhesive glue
Implementation Method 3
A surface of the first insulating layer facing away from the wafer has a micro convex lens
Implementation Method 4
filling an electrically conductive material in the blind hole having the second insulating layer, and making a conductor (wire) in the combined layer extend to a surface of the first insulating layer to be electrically connected to the electrically conductive material
Data Source
Figure 1~2B
Figure 3A~4B
Figure 4C~5B
AI summary
The present disclosure provides a CMOS image sensor encapsulation structure and a method for manufacturing the same, belonging to the technical field of image sensors. In steps of the method for manufacturing a CMOS image sensor encapsulation structure of the present disclosure, firstly, a transparent substrate material is fixed to a surface of a first insulating layer having a micro convex lens, a dummy wafer is fixed on a surface of the transparent substrate material, and then a wafer is thinned by grinding, and in this process, the transparent substrate material provides more mechanical support force for the wafer, therefore, the wafer can become thinner by grinding, thus the CMOS image sensor encapsulation structure is characterized by being formed in a thin shape. Besides, a second installation area has a protection glue layer which can prevent oxygen and moisture from entering internal elements and absorb scattered light, thus the whole CMOS image sensor encapsulation structure has a longer service life and better use effects. Moreover, in the manufacture process, the transparent substrate material is manufactured in a semiconductor factory, thus the cleanliness is higher, and pollution to the CMOS image sensor encapsulation structure can be avoided.