Imaging Device Dummy Pattern Prevents Passivation Film Peeling
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Solution Overview
Problem
The peeling of passivation films during the removal of protective tapes in imaging devices reduces the package yield, as the contact area between the tape and the passivation film is not effectively managed.
Innovation Solution
A dummy pattern structure with protruding elements, such as convex, cylindrical, conical, or pyramidal shapes, is introduced in the peripheral area of the imaging device, reducing the contact area between the tape and the passivation film while increasing the contact area with the microlens material layer, thereby preventing film peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective tape is attached on the passivation film to protect the imaging device during substrate thinning, then the imaging device is protected during processing, but the passivation film peels off when the tape is removed
Solution Approach 1:
The dummy pattern acts as an intermediary structure between the tape and the passivation film. The tape adheres to the dummy pattern instead of directly to the passivation film, preventing direct contact and subsequent peeling of the passivation film when the tape is removed
Solution Approach 2:
The peripheral area is segmented into dummy pattern regions and non-dummy pattern regions. The dummy patterns are distributed throughout the peripheral area, creating discrete contact points for the tape rather than continuous contact with the passivation film
2Stability of the object's composition
If the tape contact area with the passivation film is reduced, then passivation film peeling is prevented, but the protective effect during processing is reduced
Solution Approach 1:
The peripheral area is divided into multiple dummy pattern elements distributed throughout the region. This segmentation provides sufficient tape contact area for protection while ensuring the tape does not contact the passivation film directly on the microlens structure
Solution Approach 2:
The dummy patterns serve as intermediary contact points that provide adequate adhesion area for the tape while physically separating the tape from the passivation film on the microlens structure, maintaining both protection and film integrity
3Stability of the object's composition
If the dummy pattern surface area is too large, then tape contact is sufficiently reduced, but the manufacturing complexity increases
Solution Approach 1:
The dummy patterns are localized to the peripheral area surrounding the active area, with different surface area ratios in different regions. The dummy pattern surface area is optimized locally to provide sufficient protection while minimizing overall complexity
Solution Approach 2:
The surface area of the dummy patterns is controlled to be within a specific range (50-80% of the peripheral area outside the microlens structure). This parameter optimization ensures adequate tape contact reduction while maintaining manufacturability
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 dummy pattern design effectively prevents passivation film peeling by reducing the contact area with the tape and enhancing adhesion with the microlens material, thereby improving the package yield and reducing fabrication costs.
Implementation Method 1
a passivation film is conformally formed on the microlens structure and the dummy pattern
Data Source
AI summary
An imaging device is provided. The imaging device includes a plurality of photoelectric conversion elements formed on a substrate in an active area. A microlens structure is disposed above the photoelectric conversion elements. A dummy pattern having a plurality of protruding elements is disposed above the substrate in a peripheral area surrounding the active area. Furthermore, a passivation film is conformally formed on the microlens structure and the dummy pattern. The passivation film on the tops of the protruding elements of the dummy pattern has a surface area smaller than a surface area of the peripheral area outside of the microlens structure.