Oblique Deposition for Quantum Dot Gate Electrode Fabrication
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Solution Overview
Problem
Conventional methods for fabricating quantum dot devices are limited by semiconductor manufacturing processes, leading to increased complexity, expense, and risk of damage due to the number of steps involved, and struggle to achieve optimal scaling and precision in the size and density of quantum dot devices.
Innovation Solution
The process involves oblique deposition of gate electrodes over a nanowire using a temporary masking structure with oblique angles to control the size and location of the electrodes, reducing the number of fabrication steps and improving precision, while using a sacrificial layer and photoresist layer to form overhang structures and isotropically etch the sacrificial layer to create curved sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional semiconductor manufacturing processes are used to fabricate quantum dot devices, then the fabrication can be performed using standard processes, but the complexity and expense increase due to the large number of steps involved
Solution Approach 1:
The patent combines multiple fabrication operations into a single oblique deposition step. By depositing gate electrodes at an oblique angle through a mask structure, the process simultaneously defines electrode patterns, creates sidewalls, and forms quantum dot structures, eliminating the need for separate etching and deposition steps required in conventional approaches
Solution Approach 2:
The mask structure is pre-formed with openings positioned to define both the gate electrode locations and the quantum dot regions. This preliminary structuring allows subsequent oblique deposition to automatically create the desired complex geometry without requiring additional intermediate steps
2Ease of manufacture
If conventional semiconductor manufacturing processes are used to fabricate quantum dot devices, then standard fabrication tools can be utilized, but the risk of damage increases due to the number of fabrication steps
Solution Approach 1:
By merging multiple fabrication steps into a single oblique deposition operation, the patent reduces the number of times the nanowire structure must be handled and processed, thereby minimizing cumulative damage risk from repeated fabrication interventions
3Productivity
If conventional semiconductor manufacturing processes are used, then existing fabrication capabilities can be leveraged, but optimal scaling and precision in the size and density of quantum dot devices cannot be achieved
Solution Approach 1:
The patent utilizes the deposition angle as a critical parameter to control the geometry of formed structures. By adjusting the oblique angle, the process precisely controls sidewall angles, electrode dimensions, and quantum dot sizes, enabling optimal scaling and density that cannot be achieved with conventional vertical deposition and separate etching processes
4Device complexity
If oblique deposition is used to deposit gate electrodes, then the number of fabrication steps is reduced and precision is improved, but the fabrication process becomes more specialized
Solution Approach 1:
The oblique deposition process serves multiple functions simultaneously: it deposits conductive material, defines electrode patterns through mask alignment, creates sidewall structures, and forms quantum dot regions. This multi-functionality reduces overall process complexity while maintaining ease of manufacture by using a single specialized technique to accomplish what would otherwise require multiple separate 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 minimizes the complexity and expense of the fabrication process, reduces the risk of damage, and allows for the precise control of electron flow in and out of the quantum dot region, enabling improved scaling and density of quantum dot devices.
Implementation Method 1
depositing a first gate electrode on the substrate and overlapping a third region of the nanowire, wherein the depositing of the first gate electrode includes depositing conductive material through the at least one opening from a first oblique angle from a surface of the substrate
Implementation Method 2
depositing a second gate electrode on the substrate and overlapping a fourth region of the nanowire, wherein the depositing of the second gate electrode includes depositing conductive material through the at least one opening from a second oblique angle from the surface of the substrate
Data Source
AI summary
In an embodiment, a fabrication method comprises forming first and second electrodes over a substrate that includes a nanowire that extends between, and beneath portions of, the first and second electrodes. The method also includes forming a mask structure that defines at least one opening over a portion of the nanowire and defines at least one overhang portion over a gap between the substrate and the mask. The method further includes depositing a first gate electrode on the substrate and overlapping a third region of the nanowire, and depositing a second gate electrode on the substrate and overlapping a fourth region of the nanowire. The depositing of the first gate electrode includes depositing conductive material through the at least one opening from a first oblique angle, and the depositing of the second gate electrode includes depositing conductive material through the at least one opening from a second oblique angle.