Pixel Isolation Junction Layout for Higher Saturated Charge
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Solution Overview
Problem
The existing imaging element technology experiences degradation of Dark property due to weakened pinning on the silicon substrate, leading to charge flow into photodiodes and the occurrence of voids and dark current, with a limited increase in saturated charge capacity.
Innovation Solution
The imaging element incorporates a substrate with a junction region in the side wall of the pixel isolation section, featuring a P-type and N-type impurity region configuration where the P-type region contacts the back side Si interface, preventing charge flow and enhancing pinning, thereby forming an intense electric field region to increase saturated charge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a P-type diffusion layer and an N-type diffusion layer are formed in a side wall of a trench to increase saturated charge, then the amount of saturated charge Qs increases, but pinning on the light incidence side of the Si substrate is weakened, causing charge to flow into the photodiode and degrading the Dark property
Solution Approach 1:
The patent applies local quality by forming a P-type diffusion layer specifically on the light incidence side of the pixel isolation structure, while forming an N-type diffusion layer on the opposite side. This localized differentiation of impurity types allows the light incidence side to maintain strong pinning (preventing charge leakage that would degrade Dark property) while the other side contributes to increasing saturated charge capacity through the N-type layer configuration.
2Quantity of substance
If the junction region structure is optimized to increase saturated charge capacity, then the amount of saturated charge increases, but the complexity of the device structure increases
Solution Approach 1:
The patent merges multiple functions into the pixel isolation structure. The pixel isolation structure serves both as a physical separator between adjacent pixels and as a carrier for the P-type and N-type diffusion layers that form the junction region. This integration allows the isolation structure to simultaneously achieve charge confinement (increasing saturated charge) and structural organization, without requiring separate independent components for each function.
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 effectively inhibits charge flow into photodiodes, preventing Dark property degradation and increasing the amount of saturated charge, thereby improving the imaging element's performance.
Implementation Method 1
a junction region provided in a side wall of the pixel isolation section, the junction region including a first impurity region including first impurities and a second impurity region including second impurities
Implementation Method 2
to form an intense electric field region in which charge is held
Implementation Method 3
pinning on a light incidence side of an Si (silicon) substrate may be weakened, and charge generated may flow into a photodiode
Data Source
AI summary
The present technology relates to an imaging element and electronic equipment that enable an increase in the amount of saturated charge. The imaging element includes a substrate, a first photoelectric conversion region adjacent a second photoelectric conversion region in the substrate, a pixel isolation section between the first photoelectric conversion region and the second photoelectric conversion region, and a junction region in a side wall of the pixel isolation section, the junction region including a first impurity region including first impurities and a second impurity region including second impurities. The length of a side of the first impurity region, the side perpendicularly intersecting two parallel sides of four sides of the pixel isolation section enclosing the first photoelectric conversion region, is larger than the length between the two parallel sides of the pixel isolation section. The present technology is applicable to, for example, an imaging apparatus.