Guard Ring Structure for Backside Illuminated Sensor Crosstalk
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Solution Overview
Problem
Backside-illuminated sensors in semiconductor technologies experience crosstalk due to light being directed towards one pixel also reaching adjacent pixels, leading to inefficiencies in light sensing and signal interference.
Innovation Solution
Incorporation of sensor isolation features, such as doped regions and plug structures filled with dielectric or metal materials, disposed between sensor elements to minimize light and electrical crosstalk, with dimensions optimized for effective isolation and configured to reduce interference between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If backside-illuminated sensors are used to sense light from the backside surface, then light sensing capability is improved, but crosstalk among sensor pixels increases
Solution Approach 1:
The patent divides the sensor array into isolated pixel regions by introducing guard rings between adjacent pixels. These guard rings segment the continuous substrate into discrete sensing zones, preventing light and electrical signals from one pixel from interfering with adjacent pixels, thus reducing crosstalk while maintaining backside illumination capability.
Solution Approach 2:
The guard rings act as intermediary structures between adjacent sensor pixels. They serve as electrical isolation barriers and optical shields, mediating the interaction between neighboring pixels by blocking unwanted light paths and electrical signal leakage, thereby reducing crosstalk without compromising the overall light sensing performance.
2Reliability
If guard ring structures are added to reduce crosstalk, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the guard ring structure: electrical isolation, optical shielding, and pixel definition are all achieved through the same guard ring feature. This merging of functions reduces the need for separate isolation structures, thereby improving signal integrity while limiting the increase in device complexity.
Solution Approach 2:
The guard rings serve multiple purposes simultaneously: they provide electrical isolation between pixels, block stray light from reaching adjacent pixels, and define the boundaries of each pixel region. This multi-functionality allows the structure to improve signal integrity across multiple parameters without proportionally increasing device complexity.
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 implementation of sensor isolation features significantly reduces crosstalk among sensor pixels, enhancing the efficiency of light exposure and signal integrity by minimizing light spreading and electrical interference, thereby improving the overall performance of backside-illuminated semiconductor devices.
Implementation Method 1
sensor isolation features, such as doped regions and plug structures filled with dielectric or metal materials, disposed between sensor elements to minimize light and electrical crosstalk
Implementation Method 2
sensor isolation features, such as doped regions and plug structures filled with dielectric or metal materials, disposed between sensor elements to minimize light and electrical crosstalk
Data Source
AI summary
The present disclosure provides a backside illuminated semiconductor device. The device includes a substrate having a front surface and a back surface; a plurality of sensor elements formed in the substrate, each of the plurality of sensor elements is designed and configured to receive light directed towards the back surface; and a sensor isolation feature formed in the substrate, and disposed horizontally between two adjacent elements of the plurality of sensor elements, and vertically between the back surface and the front surface.