Pixel Light Guide Wall Layout for Higher-Sensitivity Imaging
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Solution Overview
Problem
Conventional imaging elements suffer from insufficient sensitivity due to the light blocking film interrupting light guiding by the low refractive index film, as the thick light blocking film absorbs incident light at the lower layer of the color filter, hindering improved sensitivity.
Innovation Solution
An imaging element with a light guide wall formed around the color filter, having a refractive index different from the color filter, guides incident light from the color filter to the semiconductor region, and includes a light guide wall bottom film to prevent light absorption and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick light blocking film is arranged at the bottom of the first wall adjacent to the lower layer portion of the color filter, then color mixing is prevented, but the sensitivity is not sufficiently improved because the light blocking film absorbs incident light and interrupts light guiding
Solution Approach 1:
The invention extracts the light blocking function from the thick light blocking film at the bottom of the first wall and relocates it to a light blocking film arranged at the bottom surface of the semiconductor substrate. This allows the first wall to be formed with a low refractive index material that can guide light without interruption, while still preventing color mixing through the separated light blocking structure at the substrate level.
Solution Approach 2:
The invention introduces a light guide wall formed of a low refractive index material as an intermediary structure between the color filter and the semiconductor substrate. This light guide wall mediates the conflicting requirements by guiding light effectively while a separate light blocking film at the substrate level handles the color mixing prevention, allowing both functions to coexist without interference.
2Loss of energy
If a low refractive index film is arranged to guide incident light to the semiconductor region, then sensitivity improvement is expected, but the light guiding is interrupted by the thick light blocking film at the lower layer portion of the color filter
Solution Approach 1:
The invention segments the light blocking function from the light guiding structure by placing the light blocking film at the bottom surface of the semiconductor substrate rather than within the first wall. This segmentation allows the first wall to be continuously formed with low refractive index material for uninterrupted light guiding, while the substrate-level light blocking film handles color mixing prevention separately.
Solution Approach 2:
The invention moves the light blocking function to a different spatial dimension - from within the first wall structure to the bottom surface of the semiconductor substrate. This dimensional relocation allows the first wall to maintain continuous light guiding capability while the substrate-level light blocking film prevents color mixing from a different spatial position.
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 light guide wall enhances light guiding efficiency, improving sensitivity by reflecting obliquely incident light to the photoelectric conversion unit while preventing color mixing and contamination, thus enhancing image quality.
Implementation Method 1
the light guide wall having an end portion disposed in a recess surrounding the pixel formed in the interlayer film at the boundary of the pixels to guide the incident light
Implementation Method 2
an on-chip lens that concentrates the incident light on the photoelectric conversion unit
Implementation Method 3
a color filter that transmits incident light having a predetermined wavelength within the concentrated incident light
Implementation Method 4
a photoelectric conversion unit arranged in a semiconductor substrate to perform photoelectric conversion on incident light
Data Source
AI summary
To improve the sensitivity of the imaging element. An imaging element includes pixels and a light guide wall. The pixels each include: a photoelectric conversion unit arranged in a semiconductor substrate to perform photoelectric conversion on incident light, an on-chip lens that concentrates the incident light on the photoelectric conversion unit, a color filter that transmits incident light having a predetermined wavelength within the concentrated incident light, and an interlayer film disposed between the semiconductor substrate and the color filter. The light guide wall is disposed at a boundary of the pixels and formed in a shape of surrounding the color filter, the light guide wall having an end portion disposed in a recess surrounding the pixel formed in the interlayer film at the boundary of the pixels to guide the incident light.