IR Sensor Absorption Liner Layer for Dopant Diffusion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated chip image sensors with photonic devices face reduced quantum efficiency and reliability due to dopant diffusion from the absorption structure to the vertical well region, especially under high temperatures, which impede current flow and depth sensing performance.
Innovation Solution
Incorporating a liner layer made of undoped semiconductor material or with a low doping concentration between the absorption structure and the vertical well region, which mitigates dopant diffusion and enhances the separation between the two, thereby improving quantum efficiency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liner layer is added between the absorption structure and vertical well region, then quantum efficiency and reliability are improved by preventing dopant diffusion, but device complexity increases due to additional manufacturing steps
Solution Approach 1:
An undoped semiconductor liner layer is introduced as an intermediary barrier between the absorption structure and vertical well region. This liner layer physically blocks dopant diffusion while maintaining electrical functionality, thereby improving reliability without requiring fundamental changes to the sensor architecture
Solution Approach 2:
The liner layer is designed with specific parameter constraints: undoped or low doping concentration, thickness between 1-100 nm, and matching semiconductor material properties. These parameter optimizations ensure the liner layer prevents dopant diffusion while minimizing impact on quantum efficiency and maintaining compatibility with existing manufacturing processes
2Reliability
If the liner layer thickness is increased to better block dopant diffusion, then reliability improves, but quantum efficiency decreases due to increased recombination losses
Solution Approach 1:
The liner layer thickness is precisely controlled within the range of 1-100 nm. This optimized thickness range provides sufficient barrier properties to prevent dopant diffusion while remaining thin enough to minimize carrier recombination losses, thereby balancing reliability improvement with quantum efficiency maintenance
Solution Approach 2:
The liner layer is applied selectively only in regions where dopant diffusion is problematic, specifically at the interface between the absorption structure and vertical well region. This localized application prevents dopant contamination where needed while minimizing the overall impact on light absorption and carrier generation in the bulk absorption region
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 liner layer effectively reduces dark current and increases quantum efficiency, enhancing the overall performance and reliability of the image sensor by preventing dopant diffusion and maintaining efficient conversion of incident electromagnetic radiation into electrical signals.
Implementation Method 1
mitigates dopant diffusion from the absorption structure to the vertical well region
Implementation Method 2
maintaining efficient conversion of incident electromagnetic radiation into electrical signals
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an integrated chip including a substrate comprising a first semiconductor material and a recess in a top surface of the substrate. An absorption structure is disposed within the recess and comprising a second semiconductor material different from the first semiconductor material. The absorption structure has a first doping type. A vertical well region is disposed within the substrate and underlies the absorption structure. The vertical well region has a second doping type different from the first doping type. A liner layer is disposed between the absorption structure and the substrate. The liner layer comprises the second semiconductor material and separates the vertical well region from the absorption structure.