Image Sensor Passivation Layer Segmentation for Blue Light Transmittance
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Solution Overview
Problem
Existing image sensors suffer from reduced color reproducibility, particularly for blue light, due to light transmittance characteristics of the passivation layer and p-type impurity ion implantation, which affects electron generation and output.
Innovation Solution
The image sensor design includes a substrate with photodiodes, a dielectric layer, a passivation layer partially removed to expose the dielectric layer under specific color filters, and an ion implantation region to optimize the depth and position of the photodiode region, enhancing light transmittance and color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed in the image sensor manufacturing process, then the surface is protected and dark current is reduced, but light transmittance decreases causing loss of light signal
Solution Approach 1:
The passivation layer is segmented into different regions: a first passivation layer covering the photodiode surface for dark current reduction, and a second passivation layer with openings for color filters to transmit light. This segmentation allows simultaneous achievement of surface protection and light transmittance.
Solution Approach 2:
Different regions of the passivation layer have different properties: the first passivation layer maintains continuous coverage for protection, while the second passivation layer has localized openings aligned with color filters to maximize light transmission in those specific areas.
2Reliability
If p-type impurity ion implantation is performed to prevent dark current, then surface dark current is reduced, but color reproducibility of blue light deteriorates due to electron capture in the p-type region
Solution Approach 1:
The ion implantation is segmented into two regions: a first ion implantation region at the surface for dark current prevention, and a second ion implantation region deeper in the substrate for blue light electron generation. This segmentation allows the p-type region to serve dual functions without compromising color reproducibility.
Solution Approach 2:
The solution moves from a two-dimensional surface implantation to a three-dimensional structure with implantation at different depths. The second ion implantation region is positioned at a depth where blue light electrons are generated, separating the dark current prevention function from the blue light reception function in the vertical dimension.
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 improves color reproducibility by increasing the transmittance of blue light and enhancing the output for colors with lower ratios, such as blue, thereby improving overall image sensor performance.
Implementation Method 1
an image sensor is a semiconductor device for converting optical images into electric signals
Implementation Method 2
p-type impurity ion implantation is performed in order to reduce or prevent dark current from being generated
Data Source
AI summary
Disclosed is an image sensor. The image sensor includes a substrate having photodiodes therein; a dielectric layer on the substrate; a passivation layer on the dielectric layer exposing the dielectric layer in a region corresponding to a first color filter; and a color filter layer on the exposed dielectric layer and the passivation layer.