Pixel Sensor Vertical Transfer Gates for Reduced Photodiode Saturation
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Solution Overview
Problem
Digital camera image sensors face inefficiencies in electron transmission, leading to lag times and photodiode saturation issues due to the lack of conductive protrusions in transistor structures, which affect the conversion of electromagnetic radiation into digital data.
Innovation Solution
Incorporating a plurality of conductive protrusions into the gate conductor of transistor structures within image sensors, which increases the channel volume and enhances electron transmission efficiency between regions, thereby reducing lag times and occurrences of photodiode saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistor structures without conductive protrusions are used, then device complexity is reduced, but electron transmission efficiency deteriorates leading to lag times and photodiode saturation
Solution Approach 1:
The gate conductor is segmented into multiple conductive protrusions (first, second, and third conductive protrusions) that extend into the substrate at different locations. This segmentation increases the channel volume and provides multiple pathways for electron transmission, thereby improving electron transmission efficiency and reducing lag times without significantly increasing overall device complexity
Solution Approach 2:
The invention transitions from a planar gate conductor configuration to a three-dimensional structure with conductive protrusions extending vertically into the substrate. This dimensional change increases the channel volume and enhances electron transmission efficiency by providing additional transmission pathways through the substrate
2Reliability
If conventional transistor structures without conductive protrusions are used, then manufacturing process is simpler, but photodiode saturation occurs more frequently
Solution Approach 1:
The gate conductor is divided into multiple segmented conductive protrusions that can be formed using standard semiconductor fabrication techniques such as selective epitaxial growth or selective deposition. This segmentation approach to prevent photodiode saturation is compatible with existing manufacturing processes
Solution Approach 2:
Conductive protrusions are strategically positioned at specific locations within the substrate to create localized regions of enhanced electron transmission. This local quality enhancement addresses photodiode saturation issues at critical points without requiring complete restructuring of the entire device
3Speed
If conventional transistor structures are used, then device structure is simpler, but lag times increase due to inefficient electron transmission
Solution Approach 1:
The gate conductor is transformed from a two-dimensional planar structure to a three-dimensional configuration with conductive protrusions extending into the substrate. This dimensional enhancement increases channel volume and provides multiple electron transmission pathways, thereby increasing electron transmission speed and reducing lag times
Solution Approach 2:
Multiple conductive protrusions are merged with the gate conductor to form an integrated structure that combines the gate control function with enhanced electron transmission pathways. This merging approach increases transmission speed while consolidating functions within a unified structure
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
The improved electron transmission efficiency in pixel transfer gate applications results in faster charge transfer and reduced photodiode saturation, enhancing the overall performance of digital image sensors.
Implementation Method 1
Each of which generates an electrical signal based on electromagnetic illumination of a given area over a given time period
Data Source
AI summary
A method of detecting electromagnetic radiation includes illuminating a photodiode of a pixel sensor with electromagnetic radiation, using vertical gate structures of a transfer transistor to couple a cathode of the photodiode to an internal node of the pixel sensor, thereby generating an internal node voltage level, and generating an output voltage level of the pixel sensor based on the internal node voltage level.