CMOS Image Sensor Pixel Separation Structure for Higher Signal Charge
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Solution Overview
Problem
Conventional solid-state imaging elements can suppress color mixture and increase light receiving sensitivity between pixels, but they fail to easily enhance the signal charge amount that each pixel can accumulate.
Innovation Solution
A solid-state imaging element with a photoelectric conversion section and an inter-pixel separation section that includes a protruding section, where the inter-pixel separation section is formed in a grid pattern and varies in shape, material, and conductivity type to increase the surface area of PN joint portions and optical path length, allowing for improved light reflection and charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an insulative and/or reflective wall is formed between pixels to suppress color mixture, then color mixture is suppressed, but the signal charge amount that each pixel can accumulate cannot be easily increased
Solution Approach 1:
The inter-pixel separation section extends in the depth direction (third dimension) with a protruding shape toward the photoelectric conversion section. This vertical extension increases the separation effectiveness against color mixture while the increased surface area of the separation section also provides additional space for charge accumulation, resolving the contradiction between suppressing color mixture and increasing signal charge amount
Solution Approach 2:
The protruding section of the inter-pixel separation section is nested within the pixel structure, extending into the space above the photoelectric conversion section. This nested configuration allows the separation section to effectively suppress color mixture from adjacent pixels while simultaneously increasing the available volume and surface area within the pixel for accumulating signal charges
2Use of energy by moving object
If an anti-reflection film with moth-eye structure is formed to confine incident light and increase optical path length, then light receiving sensitivity is increased, but the signal charge amount that each pixel can accumulate cannot be easily increased
Solution Approach 1:
The patent combines the anti-reflection film with moth-eye structure and the inter-pixel separation section with protruding shape into a unified structure. The protruding separation section serves dual functions: it maintains the light confinement effect of the moth-eye structure for increased light receiving sensitivity, and simultaneously provides additional surface area and volume for charge accumulation, thereby increasing the signal charge amount
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 solution effectively increases the signal charge amount and light receiving sensitivity of each pixel while suppressing color mixture, enhancing the imaging performance.
Implementation Method 1
The inter-pixel separation section can include at least one of a material having a refractive index lower than the photoelectric conversion section or a light reflection material
Implementation Method 2
A solid-state imaging element includes a photoelectric conversion section formed in each pixel
Data Source
AI summary
The present technology relates to a solid-state imaging element and electronic equipment that allow an increase in the signal charge amount Qs that each pixel can accumulate. A solid-state imaging element according to the first aspect of the present technology includes: a photoelectric conversion section formed in each pixel; and an inter-pixel separation section separating the photoelectric conversion section of each pixel, in which the inter-pixel separation section includes a protruding section having a shape protruding toward the photoelectric conversion section. The present technology can be applied to a back-illuminated CMOS image sensor, for example.