Micro Lens Etching via Spacer Layer for Solid State Imaging
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Solution Overview
Problem
Existing methods for forming micro lenses in solid state imaging devices, particularly those using inorganic materials, are insufficient in reducing the distance between adjacent lenses, hindering sensitivity improvement and material flexibility.
Innovation Solution
A method involving a three-layer structure, with a lens material layer of inorganic material, an intermediate layer of organic material, and a mask layer, using specific etching gases like SF6 and CHF3 to reduce the distance between micro lenses and control lens shapes, allowing for closer packing and increased surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the distance between adjacent micro lenses is reduced to increase light collection area, then the sensitivity of the solid state imaging device is improved, but the lens shapes deform due to adhesion during heat treatment
Solution Approach 1:
A spacer layer is introduced as an intermediary substance between adjacent micro lenses during the heat treatment process. This spacer layer prevents direct contact and adhesion between the lens resin layers, allowing the lenses to be positioned closer together without deformation. The spacer layer acts as a physical barrier that maintains lens shape precision while enabling reduced spacing for increased light collection area.
Solution Approach 2:
The spacer layer is applied to the micro lenses before the heat treatment process occurs. This preliminary action ensures that when the lenses are heated and softened, they are already protected from adhesion, preventing deformation before it can occur. The spacer layer is positioned in advance to anticipate and prevent the adhesion problem during subsequent heating.
2Reliability
If the distance between micro lenses is reduced to improve sensitivity, then more light can be collected, but the etching process cannot achieve sufficient precision to maintain lens shape
Solution Approach 1:
The spacer layer serves as a mediator that enables precise lens positioning during etching. By providing a physical reference and separation structure, it allows the etching process to create closer-spaced lenses while maintaining shape precision. The spacer layer ensures that even at reduced distances, the lenses retain their intended geometry throughout the manufacturing process.
Solution Approach 2:
The invention changes the physical state and properties of the lens material by introducing the spacer layer, which alters the effective spacing parameters during manufacturing. This allows the etching process to work with modified geometric parameters that enable closer lens spacing while maintaining the necessary shape precision for reliable optical performance and high sensitivity.
3Adaptability or versatility
If inorganic material is used for lens material layer to provide flexibility in wavelength selection, then material flexibility is improved, but the distance between micro lenses cannot be reduced sufficiently
Solution Approach 1:
The spacer layer acts as a mediator that decouples the relationship between lens material type and achievable spacing. By providing physical separation and support, it enables the use of inorganic lens materials while still achieving reduced distances between lenses. The spacer layer makes it possible to combine material flexibility with compact lens spacing that would otherwise be unattainable with inorganic materials alone.
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 enables the formation of micro lenses with reduced distances between adjacent lenses, enhancing light collection efficiency and providing flexibility in material choice based on wavelength requirements, thereby improving sensitivity and practicality.
Implementation Method 1
transcribing the lens shapes of the intermediate layer to the lens material layer to form micro lenses by etching the intermediate layer and the lens material layer while using a processing gas containing SF6 gas and CHF3 gas
Data Source
AI summary
In a method for forming micro lenses, a lens material layer made of an inorganic material is formed on a substrate, and an intermediate layer made of an organic material is formed on the lens material layer. Then, a mask layer made of an organic material is formed on the intermediate layer, and lens shapes are formed in the mask layer. The lens shapes of the mask layer are transcribed to the intermediate layer by etching the mask layer and the intermediate layer. Thereafter, the lens shapes of the intermediate layer are transcribed to the lens material layer to form micro lenses by etching the intermediate layer and the lens material layer using a processing gas containing SF6 gas and CHF3 gas.