Multi-Protrusion Transfer Gate for Faster Pixel Sensor Charge Transfer
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Solution Overview
Problem
Existing pixel sensor technologies face challenges with electron transmission efficiency, leading to increased lag times and occurrences of photodiode saturation, particularly in deep photodiode applications.
Innovation Solution
The introduction of a transistor structure with a gate conductor featuring a plurality of conductive protrusions extending into the substrate between regions, enhancing the channel area and improving electron transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transfer gate structure is used, then the device complexity is low, but the electron transmission efficiency is insufficient leading to increased lag times and photodiode saturation
Solution Approach 1:
The gate conductor is segmented into multiple protrusions extending into the substrate, creating multiple discrete conductive regions. This segmentation increases the effective channel area for electron transmission while maintaining a relatively simple overall structure that can be integrated into existing pixel sensor designs
Solution Approach 2:
The gate conductor transitions from a planar two-dimensional structure to a three-dimensional structure with protrusions extending into the substrate. This dimensional change increases the channel area and improves electron transmission efficiency by providing multiple pathways for electron flow between the photodiode and floating diffusion region
2Loss of time
If the channel area is increased to improve electron transmission, then the lag time and photodiode saturation are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The protrusions are formed as part of the gate conductor fabrication process, integrating the channel area enhancement into existing manufacturing steps. This preliminary action ensures that the increased channel area is achieved without requiring additional precision-critical steps, as the protrusion formation is coupled with standard gate patterning and deposition processes
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 reduces lag times and occurrences of photodiode saturation by improving electron transmission efficiency between regions, effectively addressing the limitations of existing technologies.
Implementation Method 1
a gate conductor including an array of conductive protrusions extending into the substrate between the source region and the floating diffusion region
Data Source
AI summary
A pixel sensor includes a photodiode including an anode overlying a cathode positioned in a substrate and a transfer transistor structure including a source region extending along a surface of the substrate adjacent to the anode and overlying the cathode, a floating diffusion region extending along the surface of the substrate parallel to the source region, and a gate conductor including an array of conductive protrusions extending into the substrate between the source region and the floating diffusion region.