Photodetector Pixel Trench Layout for Manufacturable IR Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pixel designs with trenches for increasing light path in silicon photodetectors face challenges in manufacturing due to optimized trench dimensions and pitches for infrared light, leading to defects in the pattern formation during microelectronic fabrication processes.
Innovation Solution
The proposed pixel design incorporates first and second trenches with notches in the central region, forming a pattern similar to a grid with rotational symmetry, allowing for improved light absorption while being manufacturable using standard microelectronic processes by avoiding complete grid formation in the central region and using notches to mimic the desired pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If first and second trenches are added to increase light path, then quantum efficiency is improved, but manufacturability with standard fabrication processes deteriorates
Solution Approach 1:
The trench structure is segmented into first trenches extending in a first direction and second trenches extending in a second direction perpendicular to the first direction. This segmentation allows each trench set to be formed using separate fabrication steps, making the overall structure compatible with standard microelectronic fabrication processes while maintaining the light-path enhancement effect.
Solution Approach 2:
The patent introduces a third dimension by adding notches that extend vertically from the trench bottoms toward the surface. These notches create additional light scattering paths without requiring the trenches to cross each other, thus maintaining manufacturability while improving quantum efficiency.
2Reliability
If trenches are made to cross each other to maximize light absorption, then light path is increased, but fabrication complexity increases
Solution Approach 1:
The trench system is divided into two independent sets: first trenches extending in one direction and second trenches extending perpendicular to them. Neither set crosses the other, allowing each to be formed in separate fabrication steps without requiring complex alignment or additional processing for intersections.
Solution Approach 2:
Instead of having trenches cross in the horizontal plane, the patent uses vertical notches extending from the trench bottoms to create additional light scattering paths. This vertical dimensionality avoids the fabrication complexity of crossing trenches while maintaining effective light absorption.
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 design enhances the quantum efficiency of the photodetector by dispersing light at normal incident angles, increasing the light pathlength, and improves manufacturability by ensuring adequate photoresist mask adherence during etching.
Implementation Method 1
The trenches 112 and 114... allow to increase the light path in the silicon of the photodetector
Implementation Method 2
increase the light path in the silicon of the photodetector, thus increasing the quantum efficiency
Implementation Method 3
a silicon portion forming a photodetector... configured to received light, for example infra-red light
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present disclosure relates to a pixel (Pix3) comprising, on a first face, first trenches (302) parallel to a first direction (Y) and regularly spaced in a second direction (X) and second trenches (304) parallel to the second direction (X) and regularly spaced in the first direction (Y). The first trenches (302) comprise first notches (320) each extending from a first trench (320) and being aligned with a corresponding second trench (304). The second trenches (304) comprise second notches (322) each extending from a second trench (304) and being aligned with a corresponding first trench (302).