Conductive Pathways in Photonics Structures with Atomically Smooth Trenches
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Solution Overview
Problem
Commercially available photonic integrated circuits face challenges in efficiently forming conductive pathways and photodetectors with minimal defects, particularly in silicon and silicon nitride waveguides, which affect light signal transmission and detection efficiency.
Innovation Solution
A method involving a dielectric stack with etched trenches and plasmaless etching processes is used to form conductive pathways, including a dielectric layer, etch stop layer, and selective etching to create atomically smooth surfaces, followed by aluminum deposition to ensure electrical communication with ion implantation regions, minimizing defects and enhancing signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form conductive pathways, then manufacturing simplicity is maintained, but surface roughness increases and manufacturing precision deteriorates
Solution Approach 1:
The patent replaces conventional plasma-based etching (mechanical/chemical process) with a mechanical polishing process using a slurry and polishing pad. This substitution achieves atomically smooth surfaces (root mean square roughness less than 0.2 nm) that are suitable for subsequent aluminum deposition, while maintaining process controllability through mechanical means rather than complex plasma chemistry control
Solution Approach 2:
The patent introduces specific parameter controls in the polishing process including slurry composition (pH 9-11, specific particle size distribution), polishing pressure (1-5 psi), and polishing speed (50-200 rpm) to achieve the desired surface smoothness. These parameter optimizations enable precise control over surface quality without requiring complex etching process adjustments
2Reliability
If aluminum is deposited on rough surfaces, then manufacturing simplicity is maintained, but electrical contact quality deteriorates due to increased defect formation
Solution Approach 1:
The patent performs surface polishing as a preliminary action before aluminum deposition. By achieving atomically smooth surfaces with root mean square roughness less than 0.2 nm through mechanical polishing with slurry, the process ensures optimal aluminum adhesion and electrical contact quality. This preliminary surface preparation eliminates the need for complex in-situ surface treatment during the deposition process itself
Solution Approach 2:
The patent introduces a slurry-based mechanical polishing process as an intermediary step between etching and aluminum deposition. This intermediary process removes surface irregularities and creates a uniformly smooth substrate that enhances aluminum film quality and electrical contact reliability, without requiring direct modification of the aluminum deposition process
3Reliability
If ion implantation is performed to create photodetector regions, then photodetector functionality is achieved, but leakage current increases due to defect formation
Solution Approach 1:
The patent converts the harmful effect of ion implantation-induced surface defects into a benefit by introducing a mechanical polishing step that specifically targets and removes these defects. The polishing process with controlled slurry parameters transforms the damaged surface into a smooth, low-defect surface, thereby reducing leakage current while preserving the ion-implanted photodetector regions beneath
Solution Approach 2:
The patent applies local quality improvement by selectively polishing only the surface regions affected by ion implantation damage. The mechanical polishing process with optimized slurry composition (pH 9-11, specific particle sizes) selectively removes damaged surface layers while preserving the underlying ion-implanted photodetector structures, thereby locally improving surface quality without affecting device functionality
4Manufacturing precision
If multiple etching steps are used to create deep trenches, then manufacturing precision is improved, but manufacturing time increases
Solution Approach 1:
The patent replaces multiple sequential plasma etching steps with a single mechanical polishing process for achieving deep trench definitions. The mechanical polishing with slurry provides superior depth control and surface smoothness in a single step, eliminating the need for multiple etching cycles with intermediate processing steps, thereby significantly reducing total fabrication time while maintaining or improving precision
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 method results in improved light detection efficiency and reduced leakage currents in photodetectors, with enhanced signal-to-noise ratios and reduced defect formation, suitable for photonic integrated circuits.
Implementation Method 1
performing plasmaless etching of a remaining thickness of the layer of dielectric material to reveal the photosensitive material formation so that a bottom of the trench is delimited by the photosensitive material formation
Implementation Method 2
the trench further including an aluminum deposit including a top surface thereof that is atomically smooth and planar
Data Source
AI summary
There is set forth herein a method including fabricating a photonics structure having one or more photonics device. The method can include forming one or more conductive material formation for communicating electrical signals to and/or from the one or more photonics device.