Image Sensor Blocking Region Layout Against Particle Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensors experience performance degradation due to leakage currents caused by fine particles generated during the manufacturing process, which affect the photodiode's performance.
Innovation Solution
The image sensor design includes a substrate with deep trenches and a blocking region doped with a specific element, such as boron-11, on the second surface, which prevents the influence of leakage currents from fine particles by forming a high-concentration blocking region using a high-energy implant method, separating the photoelectric conversion regions from potential contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-energy implant method is used to form blocking region, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The blocking region is formed before the photoelectric conversion regions through preliminary high-energy ion implantation. This preliminary action creates a protected zone that prevents metal particles from reaching the photodiodes during subsequent manufacturing processes, thereby improving manufacturing precision while managing complexity through structured process sequencing
Solution Approach 2:
The blocking region is created with specific local properties (high concentration of first element, different conductivity type) in the region adjacent to the second surface, while the photoelectric conversion regions maintain their original properties. This local differentiation allows the blocking region to specifically counteract particle contamination without affecting the overall device functionality
2Reliability
If blocking region with high element concentration is formed, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The blocking region is formed by changing the concentration parameter of the first element to a high level (1E16/cm³ to 1E18/cm³) through high-energy ion implantation. This parameter change creates a region with sufficient charge carriers to block leakage currents from metal particles, improving reliability while the implantation process inherently controls the concentration distribution
Solution Approach 2:
The blocking region acts as an intermediary layer between potential metal particle contaminants and the photoelectric conversion regions. By introducing this intermediate structure with controlled element concentration, the patent protects the sensitive photodiodes from particle-induced leakage currents without requiring direct modification of the photodiode structure itself
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 approach effectively reduces the impact of leakage currents on the photodiode performance, enhancing the overall reliability and efficiency of the image sensor by isolating the photoelectric conversion regions from contaminants.
Implementation Method 1
implanting a first element of a first type from a first surface of the substrate by using a first high-energy implant method to form a blocking region
Data Source
AI summary
An image sensor according to an embodiment includes a substrate having first and second surfaces facing each other, separated by a deep trench, and including a plurality of pixel regions; a plurality of photoelectric conversion regions disposed in the plurality of pixel regions; a blocking region disposed in the plurality of pixel regions; and a plurality of color filters and a plurality of micro lenses disposed on the second surface of the substrate. The blocking region is disposed adjacent to the second surface of the substrate, the blocking region includes a first element of a first type, and the plurality of photoelectric conversion regions include a second element of a second type different from the first type. The concentration of the first element on the second surface of the substrate in the blocking region is about 1E16/cm3 to about 1E18/cm3.