Solid-State Image Sensor Pillars for Pixel Light Leakage Control
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Solution Overview
Problem
Conventional solid-state imaging elements face issues with color reproducibility due to light leakage between pixels, especially in high-image-height regions, leading to mixed colors and decreased image quality.
Innovation Solution
Incorporation of columnar structures, such as pillars made of materials like silicon or gallium phosphide, between the light incident surfaces to block oblique light entry and reduce light leakage between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pixel height is increased to improve light collection, then the photoelectric conversion efficiency is improved, but light leakage to adjacent pixels increases due to oblique light entry and internal reflections
Solution Approach 1:
The patent introduces a light shielding film as an intermediary layer between pixels. This film is positioned at the light incident surface and extends in the depth direction, acting as a mediator that blocks oblique light and internal reflections before they can leak into adjacent pixels, while allowing vertical light to pass through to the photodiode for photoelectric conversion.
Solution Approach 2:
The light shielding film is designed with a specific spatial configuration that extends in both the horizontal direction (to cover the region between pixels) and the depth direction (from the light incident surface toward the photodiode). This multi-dimensional structure effectively blocks light leakage paths without interfering with the vertical light path needed for photoelectric conversion.
2Adaptability 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:
The light shielding film serves as an additional intermediary layer that works in conjunction with the color filter. While the color filter selectively transmits certain wavelengths, the light shielding film blocks the spatial leakage of light (both transmitted and reflected) to adjacent pixels, thereby preserving color imaging capability while eliminating the harmful light leakage effect.
3Ease of operation
If wiring inside the element is present to conduct electrical signals, then electrical connectivity is improved, but light reflection occurs that causes light to enter adjacent pixels
Solution Approach 1:
The light shielding film is positioned to block light paths that would otherwise be reflected by the wiring structures. By placing this shielding layer strategically, the patent prevents reflected light from reaching adjacent pixels while maintaining the electrical connectivity function of the wiring.
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 use of columnar structures effectively suppresses light leakage, enhancing color reproducibility and improving image quality by preventing light from entering adjacent pixels.
Implementation Method 1
light entering a CMOS image sensor is photoelectrically converted by a photodiode as a photoelectric conversion element in a pixel
Implementation Method 2
the columnar structure includes at least one of silicon, germanium, gallium phosphide... the pillars effectively suppress light leakage
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.