Graded Refractive Index Dielectric Layer for Image Sensor Light Focusing

The patent changes the refractive index parameter of the dielectric layer by implanting ions (such as nitrogen or fluorine) into the material. This modification creates a graded refractive index profile that varies continuously through the layer thickness, enabling effective light focusing without adding complex structural elements. The parameter change approach resolves the contradiction by achieving improved light detection through material property modification rather than structural complexity increase.

The patent implements local quality by creating a refractive index gradient within the dielectric layer, where different regions have different refractive indices. The refractive index is highest at the interface with the pixel layer and decreases toward the top surface, with the gradient optimized for each wavelength range (blue, green, red channels). This local variation in material property enables precise light focusing at different depths and wavelengths, improving detection effectiveness without requiring multiple separate lens structures.

The patent replaces the mechanical approach of forming physical microlens structures with a field-based approach using ion implantation. Instead of mechanically shaping the dielectric layer into lens forms, the patent uses ion bombardment to modify the refractive index profile. This substitution achieves precise light focusing control through material property modification rather than mechanical shaping, improving manufacturing precision while maintaining relative ease of manufacture through established semiconductor processing techniques.

The patent achieves precise light focusing by controlling the refractive index parameter through ion implantation dose and energy. By varying the implantation conditions, the refractive index gradient can be precisely tuned for different wavelength channels and focal depths. This parameter control approach enables high manufacturing precision in light focusing while using standard semiconductor fabrication processes, avoiding the need for complex mechanical lens fabrication equipment.

The patent achieves multi-functionality by using a single dielectric layer that serves both as a protective passivation layer and as a light-focusing element with graded refractive index. The ion implantation process modifies the same dielectric material to create the refractive index gradient, eliminating the need for separate focusing structures. This universal approach increases light intensity at the photodetector while avoiding the complexity of adding multiple functional layers or components.

The dielectric layer performs self-service by simultaneously providing electrical passivation and optical focusing functions. The ion implantation process modifies the dielectric layer's own properties to enable light focusing, rather than requiring a separate component. The dielectric layer essentially serves itself by having its refractive index profile optimized to focus light onto the photodetector, reducing the need for additional fabrication steps and structures.