Trench Transfer Gate Layout for Global Shutter Charge Capacity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In CMOS solid-state imaging devices capable of global shutter functionality, increasing the charge holding capacity reduces the photodiode area, leading to lower light reception sensitivity and saturated charge amounts compared to non-global shutter types.
Innovation Solution
A solid-state imaging device with a trench gate structure in the first transfer gate and a semiconductor region between adjacent trench gate sections for charge holding, allowing for increased saturated charge capacity without reducing the photodiode area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charge holding region area is increased to increase holding capacity, then the charge holding capacity is improved, but the photodiode area is reduced
Solution Approach 1:
The invention transitions from a planar charge holding region to a three-dimensional structure by forming the charge holding region vertically between different depth levels (between the first transfer gate electrode and the second transfer gate electrode). This vertical extension increases the charge holding capacity without requiring additional horizontal area, thereby preserving the photodiode area while achieving higher charge storage capability.
Solution Approach 2:
The charge holding region is nested within the vertical space between the first and second transfer gate electrodes, utilizing the depth dimension of the device structure. This nested configuration allows the charge holding region to occupy the vertical space that would otherwise be unused, increasing storage capacity without expanding the device footprint or reducing photodiode area.
2Quantity of substance
If the charge holding region area is increased to increase holding capacity, then the charge holding capacity is improved, but the light reception sensitivity is reduced
Solution Approach 1:
By extending the charge holding region vertically between different depth levels rather than expanding it horizontally, the invention increases charge holding capacity without encroaching on the photodiode's light-receiving area. This dimensional transition ensures that light reception sensitivity is maintained while achieving higher charge storage capability.
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 enhances the amount of saturated charges that can be held in the charge holding region, maintaining or improving light reception sensitivity while enabling global shutter functionality.
Implementation Method 1
a photoelectric conversion element configured to generate a charge in response to incident light
Data Source
AI summary
A solid-state imaging device includes a pixel having a photoelectric conversion element which generates a charge in response to incident light, a first transfer gate which transfers the charge from the photoelectric conversion element to a charge holding section, and a second transfer gate which transfers the charge from the charge holding section to a floating diffusion. The first transfer gate includes a trench gate structure having at least two trench gate sections embedded in a depth direction of a semiconductor substrate, and the charge holding section includes a semiconductor region positioned between adjacent trench gate sections.