U-Shaped P-N Junction Fabrication via Single-Angle Implantation
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Solution Overview
Problem
Existing semiconductor manufacturing techniques face challenges in creating complex geometric features like U-shaped P-N junctions due to the need for multiple dopant delivery steps at different angles, which complicates the process, increases time, and results in unsatisfactory doping on curved or angled structures.
Innovation Solution
A method involving single dopant delivery trajectory at a normal angle to fabricate P-N junctions in silicon structures, using multiple dopant delivery steps with varying energies and mask positions to create a U-shaped P-N junction, allowing for the manufacture of complex structures like ring modulators and Mach-Zehnder interferometers without altering the dopant delivery angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple dopant delivery steps at different angles are used to create complex geometric features, then the manufacturing precision of three-dimensional structures is improved, but the device complexity and manufacturing time increase
Solution Approach 1:
The doping process is segmented into multiple sequential implantation steps (first dopant species, then second dopant species at different energies) rather than attempting to create the entire complex structure in one step. This allows precise control over dopant distribution in different regions while maintaining a single delivery angle, resolving the contradiction between precision and complexity.
Solution Approach 2:
Instead of varying the delivery angle in three-dimensional space to achieve complex doping profiles, the patent uses energy dimension variation (different implantation energies for different dopant species) to achieve the same effect. This transforms the problem from a spatial complexity issue to an energy parameter issue, simplifying the manufacturing process.
2Manufacturing precision
If the substrate is tilted to change dopant delivery angle for curved structures, then the doping coverage on curved surfaces is improved, but the manufacturing time and process complexity increase
Solution Approach 1:
The patent performs preliminary masking and alignment steps before dopant implantation to ensure that the dopant delivery trajectory is pre-configured to match the curved or angled structure geometry. By preparing the structure and masks in advance, the actual implantation can proceed at a constant normal angle without time-consuming angle adjustments during the process.
3Manufacturing precision
If acute angle doping is used to deposit dopant about curved structures, then the doping distribution along curved paths is improved, but the manufacturing precision for ring modulators and rotationally symmetric structures deteriorates
Solution Approach 1:
The patent employs a universal normal-angle dopant delivery trajectory that can be applied to various structures including straight waveguides, curved waveguides, ring modulators, and other rotationally symmetric structures. By using masks and multiple implantation steps rather than structure-specific delivery angles, the same doping process can universally manufacture diverse photonic devices, greatly improving ease of manufacture.
4Manufacturing precision
If multiple dopant delivery steps at different angles are used, then the ability to create complex three-dimensional junctions is improved, but the productivity and manufacturing efficiency decrease
Solution Approach 1:
The patent maintains continuous dopant delivery action by using a single fixed delivery trajectory throughout the process. Instead of interrupting the process to reposition or tilt the substrate for angle changes, the doping continues uninterrupted with constant beam parameters, significantly improving manufacturing efficiency while still achieving complex three-dimensional junctions through sequential implantation steps.
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 approach simplifies the manufacturing process by eliminating the need for angle changes, enabling the production of complex structures with rotational symmetry and non-linear layouts, achieving high modulation efficiency and accurate doping profiles.
Implementation Method 1
implanting a first dopant species over a first portion of the Si structure; deep implanting a second dopant species over a second portion of the Si structure; shallow implanting the second dopant species over the second portion
Data Source
AI summary
A method of fabricating a P-N junction in a semiconductor structure, e.g. silicon (Si) structure, is presented. The method may include several implantation steps performed at a single implantation angle with respect to the Si structure. In a first implantation step, a first dopant species is implanted over a first portion of the Si structure including a first edge of the Si structure. In a second implantation step, a second dopant species is implanted over a second portion of the Si structure including a second edge of the Si structure opposed to the first edge but excluding the first edge. The first portion and the second portion may overlap in a central portion of the Si structure between the first edge and the second edge, such that the second dopant species may be implanted below the first dopant species. In a third implantation step, the second dopant species is implanted over the second portion of the Si structure including the second edge of the Si structure opposed to the first edge but excluding the first edge, such that the second dopant species is implanted above the first dopant species.