CMOS Image Sensor Columnar Filters for Pixel Light Leakage
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Solution Overview
Problem
Conventional solid-state imaging elements suffer from light leakage between pixels due to oblique light entry and internal reflections, leading to decreased color reproducibility in images.
Innovation Solution
Incorporation of columnar structures, such as pillars made of materials like silicon or gallium phosphide, between the light incident surfaces to block unwanted light wavelengths and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a color filter is disposed on each pixel to acquire color images, then color imaging capability is improved, but light leakage to adjacent pixels occurs due to oblique light entry and internal reflections
Solution Approach 1:
A wavelength selective structure is introduced as an intermediary component between the color filter and the photodiode. This structure selectively transmits specific wavelength bands while blocking others, thereby preventing oblique light and reflected light from reaching adjacent pixels while maintaining the color filtering function.
Solution Approach 2:
The patent adds a vertical dimension to light control by stacking multiple functional layers (color filter, wavelength selective structure, photodiode) in the depth direction. This multi-layer configuration enables wavelength-selective blocking of oblique light paths without affecting the primary light reception function.
2Device complexity
If conventional structures are used, then device simplicity is maintained, but color reproducibility decreases due to light leakage and color mixing among pixels
Solution Approach 1:
The wavelength selective structure utilizes changes in optical parameters (refractive index, thickness, material composition) to achieve wavelength-selective transmission. By adjusting these parameters, the structure can be optimized to block specific wavelength bands that cause color mixing while maintaining transmission of desired wavelengths.
Solution Approach 2:
The patent employs composite material structures combining different materials with complementary optical properties. The wavelength selective structure may use combinations of dielectric materials, metals, or semiconductors to achieve enhanced wavelength selectivity and blocking performance while maintaining manufacturing feasibility.
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
Enhances color reproducibility by minimizing light leakage and improving image quality in high-angle light conditions.
Implementation Method 1
the columnar structure includes at least one of silicon, germanium, gallium phosphide, aluminum oxide, cerium oxide, hafnium oxide, indium oxide, tin oxide, niobium pentoxide, magnesium oxide, tantalum pentoxide, titanium pentoxide, titanium oxide, tungsten oxide, yttrium oxide, zinc oxide, zirconia, cerium fluoride, gadolinium fluoride, lanthanum fluoride, and neodymium fluoride
Implementation Method 2
there is another possibility that light that has been transmitted through the color filter is reflected by wiring inside the element to enter an adjacent pixel
Implementation Method 3
light entering a CMOS image sensor is photoelectrically converted by a photodiode as a photoelectric conversion element in a pixel
Data Source
AI summary
A solid-state imaging device according to an embodiment includes: a semiconductor substrate including a photoelectric conversion element; a lens disposed above a first light incident surface of the photoelectric conversion element; and a plurality of columnar structures disposed on a surface parallel to the first light incident surface that is located between a second light incident surface of the lens and the first light incident surface of the photoelectric conversion element. The columnar structure includes at least one of silicon, germanium, gallium phosphide, aluminum oxide, cerium oxide, hafnium oxide, indium oxide, tin oxide, niobium pentoxide, magnesium oxide, tantalum pentoxide, titanium pentoxide, titanium oxide, tungsten oxide, yttrium oxide, zinc oxide, zirconia, cerium fluoride, gadolinium fluoride, lanthanum fluoride, and neodymium fluoride.