Trench Double Layer Heterostructure Light Sensor
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Solution Overview
Problem
Conventional light sensors face challenges in achieving high accuracy and durability due to the need for a thin cap layer, which can be damaged during the doping process, and result in increased leakage current and latency.
Innovation Solution
A light sensor with a trench double layer heterostructure is developed, featuring a thick cap layer and a trench that reduces the risk of damage during doping, while also minimizing leakage current and improving parameters like inter-pixel capacitance and accumulative latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thin cap layer is used to achieve narrow bandgap properties, then the bandgap accuracy is improved, but the light sensor becomes damaged during the doping process
Solution Approach 1:
The cap layer is segmented into two distinct layers: a first cap layer with a first thickness and a second cap layer with a second thickness greater than the first thickness. The second cap layer extends over a trench, providing mechanical support and preventing damage during doping while the first cap layer maintains the required narrow bandgap properties for accurate light detection.
Solution Approach 2:
Different regions of the cap layer structure are assigned different thicknesses and materials to serve different functions. The first cap layer region provides narrow bandgap properties for detection accuracy, while the second cap layer region provides enhanced mechanical strength and protection during doping. The trench region provides structural support where the cap layer is thinnest.
2Measurement precision
If a thin cap layer is used to achieve narrow bandgap properties, then the bandgap accuracy is improved, but the yield of light sensors decreases due to damage
Solution Approach 1:
The cap layer is segmented into two distinct layers: a first cap layer with a first thickness and a second cap layer with a second thickness greater than the first thickness. The second cap layer extends over a trench, providing mechanical support and preventing damage during doping while the first cap layer maintains the required narrow bandgap properties for accurate light detection.
Solution Approach 2:
The second cap layer is formed beforehand to provide protective cushioning over the trench region during the doping process. This pre-formed protective layer prevents damage to the underlying first cap layer and substrate during subsequent doping operations, thereby improving manufacturing yield.
3Reliability
If a thick cap layer is used to prevent damage during doping, then the durability is improved, but the bandgap becomes too wide reducing detection accuracy
Solution Approach 1:
The cap layer is segmented into two distinct layers: a first cap layer with a first thickness and a second cap layer with a second thickness greater than the first thickness. The second cap layer extends over a trench, providing mechanical support and preventing damage during doping while the first cap layer maintains the required narrow bandgap properties for accurate light detection.
Solution Approach 2:
Different regions of the cap layer structure are assigned different thicknesses and materials to serve different functions. The first cap layer region provides narrow bandgap properties for detection accuracy, while the second cap layer region provides enhanced mechanical strength and protection during doping. The trench region provides structural support where the cap layer is thinnest.
4Measurement precision
If conventional light sensor design is used with thin cap layer, then the bandgap properties are achieved, but leakage current increases
Solution Approach 1:
The cap layer is segmented into two distinct layers: a first cap layer with a first thickness and a second cap layer with a second thickness greater than the first thickness. The second cap layer extends over a trench, providing mechanical support and preventing damage during doping while the first cap layer maintains the required narrow bandgap properties for accurate light detection.
Solution Approach 2:
A trench is formed extending into the substrate beneath the cap layer, removing material that would otherwise create leakage paths. This extracted region isolates the detection area and reduces parasitic leakage current while allowing the cap layer to maintain its narrow bandgap properties.
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 trench double layer heterostructure design enhances the accuracy and durability of light sensors by reducing the risk of damage during doping, minimizing leakage current, and improving performance metrics such as accumulative latency and quantum efficiency.
Implementation Method 1
photons received by the N-type semiconductor generate photocurrent resulting in a voltage at the electrical contact
Data Source
AI summary
A light sensor includes an N-type semiconductor. The light sensor further includes a P-type semiconductor stacked on at least a portion of the N-type semiconductor, partially defining a trench extending into the P-type semiconductor, and having a trench portion aligned with the trench and extending farther into the N-type semiconductor than other portions of the P-type semiconductor. The light sensor also includes a passivation layer stacked on and contacting the P-type semiconductor and partially defining the trench that extends through the passivation layer and into the P-type semiconductor. The light sensor further includes an electrical contact stacked on the passivation layer, positioned within the trench, and extending through the passivation layer into the P-type semiconductor such that photons received by the N-type semiconductor generate photocurrent resulting in a voltage at the electrical contact.