Image Sensor Carrier Transmission via Intermediary Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image sensors have a low transmission efficiency of photo-induced carriers from the photo diode to the floating diffusion region, limiting the conversion of radiation into electric signals.
Innovation Solution
The manufacturing method involves forming a second-conductive-type lightly-doped region that connects with the floating diffusion region, acting as a 'bridge' to shorten the distance and enhance carrier transmission, along with a first-conductive-type isolating layer to prevent signal crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a direct connection between photo diode and floating diffusion region is used, then the transmission path is short, but the transmission efficiency of photo-induced carriers is low
Solution Approach 1:
A lightly-doped region is introduced as an intermediary between the photo diode and the floating diffusion region. This lightly-doped region serves as a bridge that facilitates the transmission of photo-induced carriers by providing a gradual doping profile transition, which reduces carrier scattering and improves transmission efficiency while maintaining a relatively simple overall structure.
2Loss of time
If the distance between photo diode and floating diffusion region is reduced, then transmission time is shortened, but signal crosstalk increases
Solution Approach 1:
The lightly-doped region acts as an intermediary structure that physically separates the photo diode and floating diffusion region while maintaining electrical connectivity for carrier transmission. This intermediate structure reduces direct capacitive coupling between the two regions, thereby minimizing signal crosstalk while keeping the transmission path short and transmission time low.
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 increases the transmission efficiency of photo-induced carriers, allowing them to be transmitted more rapidly and reducing signal delay, thereby improving the overall performance of the image sensor.
Implementation Method 1
An image sensor is a semiconductor device which is configured for capturing radiation and converting the sensed radiation into electric signals. Generally, an image sensor includes a Photo Diode (PD) which is photosensitive
Implementation Method 2
When the image sensor operates, a transfer transistor is opened, and thus, photo-induced carriers in the PD can be transmitted into the FD region through a channel in the transfer transistor
Data Source
AI summary
An image sensor and a manufacturing method thereof are provided. The image sensor includes: a photo diode; a first-conductive-type isolating layer; a second-conductive-type lightly-doped region formed in the first-conductive-type semiconductor substrate; a first-conductive-type lightly-doped region formed under the second-conductive-type lightly-doped region, where the second-conductive-type lightly-doped region is isolated from the second-conductive-type region by the first-conductive-type lightly-doped region; a gate structure of a transfer transistor; and a floating diffusion region which is second-conductive-type heavily-doped. In the image sensor, the second-conductive-type lightly-doped region is formed to be connected with the floating diffusion region, thus, a distance between the floating diffusion region and the photo diode may be reduced which may enable photo-induced carriers to be transmitted from the photo diode to the floating diffusion region more rapidly, and further increase the transmission efficiency of the photo-induced carriers.