Solid-State Imaging Pixel With Light-Reflection Conductive Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solid-state imaging devices face challenges in achieving higher pixel density, resolution, and sensitivity while minimizing color mixture and light leakage, due to the difficulty in reducing the height of the photodiode region without compromising sensitivity and the inefficiency of light collection, especially with diagonally incident light.
Innovation Solution
The proposed solid-state imaging device incorporates a specific pixel structure with a photodiode region, signal charge storing, reading, and discharging units, along with a light-reflection conductive layer and a microlens system that enhances light absorption and reduces light leakage by optimizing the light propagation length and using a light-transmission intermediate layer to improve sensitivity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the photodiode region is reduced to increase pixel density, then the pixel density increases, but the sensitivity deteriorates
Solution Approach 1:
The patent introduces a light reflection conductive layer that redirects diagonally incident light back into the photodiode region, effectively utilizing the lateral dimension to compensate for the reduced vertical depth. This allows the photodiode region to maintain high pixel density while recovering light absorption capability through a different spatial dimension (light path redirection).
Solution Approach 2:
The light reflection conductive layer acts as an intermediary element between the microlens and the photodiode region. It mediates the interaction by capturing diagonally incident light that would otherwise be lost and redirecting it into the photodiode region, thereby maintaining sensitivity despite the reduced photodiode height.
2Quantity of substance
If the pixel size is reduced to increase pixel density, then the pixel density increases, but the light collection efficiency deteriorates
Solution Approach 1:
By introducing the light reflection conductive layer, the patent extends the light collection path from a single vertical pass to include lateral reflection and secondary passage through the photodiode region. This dimensional change in light path allows smaller pixels to maintain effective light collection by utilizing reflected light paths.
Solution Approach 2:
The light reflection conductive layer enables continuous light interaction with the photodiode region by reflecting diagonally incident light back into the active region. This creates a continuous useful action where light that would have been lost on a single pass is instead redirected for additional absorption opportunities, maintaining efficiency in reduced-size pixels.
3Quantity of substance
If the photodiode region height is reduced to achieve higher pixel density, then the pixel density increases, but the light absorption capability deteriorates
Solution Approach 1:
The patent converts the harmful effect of diagonally incident light (which would cause color mixture and light leakage to adjacent pixels) into a beneficial effect by using the light reflection conductive layer to redirect this light back into the photodiode region. The previously wasted diagonal light paths are now utilized to enhance light absorption in the reduced-height photodiode region.
Solution Approach 2:
The light reflection conductive layer introduces a lateral reflection dimension to the light absorption process. Instead of relying solely on vertical light passage through the photodiode region, the system now utilizes lateral reflection to create additional light paths, compensating for the reduced vertical absorption path length.
4Quantity of substance
If pixel density is increased by reducing pixel size, then the pixel density increases, but color mixture increases
Solution Approach 1:
The light reflection conductive layer is selectively positioned around each pixel's photodiode region, creating localized light management. This local quality approach ensures that reflected light is redirected specifically into the intended pixel region, preventing color mixture while maintaining high pixel density through targeted light path control.
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 allows for increased pixel density, improved resolution, reduced color mixture, and enhanced sensitivity by effectively absorbing and directing light within the photodiode region, preventing light leakage to adjacent pixels and maintaining sensitivity.
Implementation Method 1
a microlens formed over the fifth semiconductor region
Implementation Method 2
a photodiode region including the semiconductor P-region 32 and the semiconductor N-regions 35a and 35b is formed. Due to this light exposure, signal charges (here, free electrons) are generated in a photoelectric conversion region in the photodiode region
Implementation Method 3
a reflection conductive layer formed on an outer periphery of the third semiconductor region, the fourth semiconductor region, and the insulating layer and reflecting an electromagnetic energy wave
Data Source
AI summary
An island-shaped semiconductor constituting a pixel includes a first semiconductor N+-region formed on a substrate, a second semiconductor P-region formed on the region, third semiconductor N-regions formed on upper lateral sides of the region, insulating layers formed on the outer periphery of the regions and lower lateral sides of the region, gate conductive layers formed on the outer periphery of the insulating layers and functioning as gate electrodes forming a channel in a lower area of the region, light-reflection conductive layers formed on the outer periphery of the N regions and a portion of the insulating layers where the gate conductive layers are not formed, a fifth semiconductor P+-region formed on the region and the regions, and a microlens formed on the region and whose focal point is located near the upper surface of the region.