Solid-State Imaging Device Siloxane Resin Waveguide Crack Prevention
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Solution Overview
Problem
The use of siloxane resin as a material for the core part of an optical waveguide in solid-state imaging devices leads to deterioration in image quality and yield due to brittleness and poor adhesion, causing cracks during the dicing process and resulting in chippings that affect light transmission to photodiodes.
Innovation Solution
A solid-state imaging device configuration where a siloxane resin is used as a first light transmission layer and a second light transmission layer is formed, with the interface between these layers in contact with a guard ring, and the first light transmission layer is either formed with a lower surface height than the guard ring or removed in the dicing area to prevent crack propagation and improve adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If siloxane resin is used as a material for the core part of an optical waveguide, then high refractive index and heat resistance are achieved, but brittleness and poor adhesion cause cracks during dicing process
Solution Approach 1:
The patent divides the optical waveguide structure into separate functional layers: a first light transmission layer (siloxane resin) for heat resistance and a second light transmission layer (adhesive material) for crack prevention. This segmentation allows each layer to specialize in its strength while the adhesive layer bonds them together to prevent crack propagation during dicing.
Solution Approach 2:
The patent creates a composite structure by combining siloxane resin (providing high refractive index and heat resistance) with an adhesive material layer (providing crack resistance and bonding). This composite approach allows the system to simultaneously achieve thermal stability and mechanical integrity during the dicing process.
2Illumination intensity
If siloxane resin is used as a material for the core part of an optical waveguide, then high refractive index is achieved, but poor adhesion causes peeling at interfaces
Solution Approach 1:
The patent introduces an intermediary adhesive material layer between the siloxane resin layer and other structural layers. This intermediary layer serves as a bonding interface that compensates for the poor adhesion properties of siloxane resin, preventing peeling while allowing the siloxane layer to maintain its high refractive index for optimal light transmission.
Solution Approach 2:
The patent combines siloxane resin (high refractive index) with an adhesive material (strong bonding capability) in a layered composite structure. This allows the system to simultaneously achieve both optical performance and mechanical adhesion strength that neither material could provide alone.
3Manufacturing precision
If the area per unit pixel is reduced for higher integration, then higher resolution is achieved, but insufficient light enters the photodiode
Solution Approach 1:
The patent modifies the refractive index parameter of the light transmission layers by using siloxane resin with high refractive index. This parameter change enhances light gathering efficiency and directs oblique light rays more effectively onto the photodiode, compensating for the reduced pixel area and maintaining sufficient light intake for high-resolution imaging.
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 reduces the occurrence of cracks and subsequent image quality and yield deterioration by ensuring that any cracks stop at the guard ring, minimizing peeling and attachment of chippings to on-chip lenses, thereby enhancing the reliability and performance of the imaging device.
Implementation Method 1
an optical waveguide formed by surrounding a core material with a high refractive index using a cladding material with a low refractive index between the photodiode and the on chip lens
Implementation Method 2
an on-chip lenses are formed on the photoelectric conversion part, and incident light is collected to the photoelectric conversion part by the on-chip lenses
Implementation Method 3
a photoelectric conversion part of photodiodes... incident light is collected to the photoelectric conversion part by the on-chip lenses and photoelectrically converted
Data Source
AI summary
A solid-state imaging device includes: a photodiode formed to be segmented with respect to each pixel in a pixel area in which plural pixels are integrated on a light receiving surface of a semiconductor substrate; an insulator film formed on the semiconductor substrate to cover the photodiode; a recessed part formed with respect to each of the pixels in the insulator film in an upper part of the photodiode; a first light transmission layer of a siloxane resin formed to fill the recessed part and configure an optical waveguide in the pixel area; a second light transmission layer formed to configure an on-chip lens with respect to each of the pixels in the pixel area; and a guard ring formed to surround an outer circumference of the pixel area to partition an inner area containing the pixel area and an outer dicing area.