Pixel Trench-Notch Layout for Manufacturable NIR Absorption
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Solution Overview
Problem
Existing pixel designs with trenches for increasing light path in silicon photodetectors face manufacturing challenges and inefficiencies in light absorption, particularly for near-infrared wavelengths, due to optimized trench dimensions that are difficult to produce using standard microelectronic fabrication processes.
Innovation Solution
The design incorporates trenches with notches in a central region, forming a grid-like pattern that mimics the absorption efficiency of previous designs but is manufacturable using standard processes, with trenches and notches aligned in a specific pattern to enhance light absorption without crossing each other, and V-shaped patterns in corners for improved symmetry and light dispersal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optimized trench dimensions are used to improve light absorption efficiency, then quantum efficiency is improved, but manufacturing difficulty increases due to incompatibility with standard microelectronic fabrication processes
Solution Approach 1:
The patent modifies the geometric parameters of the trench structure by adding notches at specific positions and orientations. These parameter changes enable the structure to achieve enhanced light absorption efficiency while remaining compatible with standard microelectronic fabrication processes, thus resolving the contradiction between improved quantum efficiency and manufacturing ease
Solution Approach 2:
The continuous trench structure is segmented by introducing notches that divide the trench into multiple sections. This segmentation increases the effective light path length and improves light absorption efficiency while maintaining manufacturability through standard fabrication techniques
2Ease of manufacture
If standard microelectronic fabrication processes are used to simplify manufacturing, then ease of manufacture is improved, but light absorption efficiency decreases due to inability to achieve optimized trench dimensions
Solution Approach 1:
By changing the geometric parameters of the trench structure through the addition of notches, the patent achieves enhanced light absorption efficiency using standard fabrication processes, thus resolving the contradiction between ease of manufacture and light absorption efficiency
3Reliability
If light path length in silicon is increased to improve absorption of near-infrared light, then quantum efficiency is improved, but device complexity increases due to need for specialized structures
Solution Approach 1:
The trench structure is segmented with notches to increase the effective light path length, improving quantum efficiency while maintaining a relatively simple overall structure that does not require specialized fabrication processes
Solution Approach 2:
The notches are positioned at specific orientations (e.g., 45 degrees) to create a three-dimensional light scattering effect that increases the effective light path length without significantly increasing the physical footprint or structural complexity of the device
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 quantum efficiency by dispersing light and increasing the light path in the photodetector, improving absorption by up to 3.8% compared to similar pixels, while being manufacturable with standard microelectronic processes, thus overcoming previous manufacturing limitations.
Implementation Method 1
This design enhances quantum efficiency by dispersing light and increasing the light path in the photodetector
Implementation Method 2
it is known to add diffractive structures on a face of the pixel which is intended to receive light
Data Source
AI summary
A pixel includes, on a first face, first trenches extending parallel to a first direction and regularly spaced in a second direction (orthogonal to the first direction) and second trenches extending parallel to the second direction and regularly spaced in the first direction. The first trenches include first notches, each first notch extending from a first trench and being aligned with a corresponding second trench. The second trenches include second notches, each second notch extending from a second trench and being aligned with a corresponding first trench.