Solid State Imaging Device Recesses for Spectral Ripple Suppression
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Solution Overview
Problem
Solid state imaging devices experience image unevenness due to ripples in spectral characteristics caused by interference between directly incident light and light reflected by protective films, which existing methods have not adequately addressed.
Innovation Solution
The implementation of a solid state imaging device with a substrate, pixel, interconnect layers, and an insulating film featuring recesses in the region opposing the second opening, where the edge of the second opening is recessed further than the first, and the recesses have a circular configuration with a concave surface, effectively diffusing and redirecting reflected light away from the pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed over the pixel and interconnect layers, then the device is protected and light shielding is maintained, but ripples occur in spectral characteristics due to interference between directly incident light and reflected light, causing image unevenness
Solution Approach 1:
The patent introduces recesses with curved concave surfaces in the insulating film. These curved surfaces scatter reflected light in multiple directions, preventing the formation of coherent interference patterns that cause spectral ripples. The curvature transforms the flat reflective surface into a scattering surface, effectively eliminating the harmful interference while preserving the protective function of the film.
Solution Approach 2:
The patent applies recesses selectively in specific regions of the insulating film, particularly in areas where interference patterns are most problematic. By locally modifying the surface topology only where needed, the solution maintains the overall protective function while targeting the specific harmful effect of spectral ripples without compromising light shielding reliability.
2Reliability
If the insulating film is made thicker to improve light shielding, then protection is enhanced, but the interference effect between direct and reflected light increases, worsening the spectral ripple
Solution Approach 1:
By incorporating curved recesses in the insulating film, the patent enables the use of thicker film materials without exacerbating interference effects. The curved surfaces scatter reflected light before it can form coherent interference patterns, allowing the film thickness to be increased for better protection and light shielding while maintaining spectral uniformity.
3Object-affected harmful factors
If recesses are added to the insulating film to reduce spectral ripple, then image uniformity is improved, but the device structure and manufacturing process become more complex
Solution Approach 1:
The patent introduces a microstructured recess pattern in the insulating film that creates a controlled porous or textured surface. This approach reduces spectral ripple by scattering light while maintaining a relatively simple overall device structure. The recesses can be formed using standard semiconductor fabrication techniques, minimizing the increase in manufacturing complexity.
Solution Approach 2:
The curved concave surfaces of the recesses are designed to achieve the desired light scattering effect with minimal structural complexity. By optimizing the curvature radius and recess dimensions, the patent achieves effective ripple suppression without requiring overly complex multi-layer or asymmetric structures, thus limiting the increase in device complexity.
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 suppresses the ripple in spectral characteristics, enhancing image uniformity by increasing the surface area of the recesses while maintaining reliable light shielding and protecting the interconnect layers, thereby improving the imaging device's performance.
Implementation Method 1
the recesses have a circular configuration with a concave surface, effectively diffusing and redirecting reflected light away from the pixel
Implementation Method 2
a phenomenon is known in which a ripple occurs in the spectral characteristics due to interference between light directly entering a photoelectric conversion element (a pixel) and light reflected by a protective film
Data Source
AI summary
According to one embodiment, an edge of the second opening is recessed further than an edge of the first opening away from a center of the first opening. The recess has an opening and a concave surface and is disposed in a region inward from the edge of the second opening. The opening has a circular configuration. The concave surface has a curvature.