Semiconductor Quantum Structures Minimizing Parasitic Capacitance
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Solution Overview
Problem
Current semiconductor quantum computers face challenges in isolating microscopic particles, preserving quantum interactions, and scaling due to high noise levels and parasitic capacitances in traditional FET transistor structures, which degrade performance and require costly, difficult-to-maintain superconducting structures operating at low temperatures.
Innovation Solution
A modified semiconductor process that minimizes capacitance between the control gate and quantum well by eliminating metal, contact, and raised diffusion, allowing for larger Coulomb blockade voltages and easier electronic control, enabling the creation of reliable semiconductor quantum structures with tunneling through oxide layers or local depleted regions in both planar and 3D processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional FET transistor structures are used in quantum computers, then quantum interactions can be implemented, but parasitic capacitances increase and noise levels rise, degrading performance
Solution Approach 1:
The patent removes metal layers, contact structures, and raised diffusion regions from the quantum well area to eliminate parasitic capacitances. This extraction of harmful elements directly reduces noise and improves quantum interaction preservation while maintaining the essential transistor functionality through alternative gate control mechanisms.
Solution Approach 2:
The invention applies different structural qualities to different regions: the quantum well region is kept free of metal and contacts to minimize capacitance, while other regions of the transistor maintain standard structures for electrical control. This localized differentiation allows quantum operations to proceed with minimal interference while preserving overall device functionality.
2Reliability
If superconducting structures are used to reduce noise, then quantum performance improves, but operational temperature requirements become extremely low and maintenance complexity increases
Solution Approach 1:
The patent employs standard semiconductor materials and processes rather than expensive superconducting materials. By using conventional silicon-based structures with modified geometries to reduce parasitic capacitance, the invention achieves quantum operations at higher, more practical temperatures without requiring costly superconducting infrastructure or extreme cryogenic maintenance.
3Ease of manufacture
If conventional semiconductor processes are used, then manufacturing is easier, but quantum structure performance degrades due to high capacitance
Solution Approach 1:
The manufacturing process is segmented into distinct stages: standard CMOS fabrication steps are performed first, then additional steps are added to remove metal and contact structures from the quantum well region and to create aperture tunneling paths. This segmentation allows the use of conventional manufacturing for the bulk of the device while adding specialized features only where quantum performance is critical.
Solution Approach 2:
The patent introduces oxide layers and depleted regions as intermediary structures between the gate and quantum well. These intermediary elements provide the necessary electrical control while maintaining low capacitance, serving as mediators that reconcile the conflicting requirements of manufacturability and quantum performance.
4Ease of operation
If metal and contact structures are present in quantum wells, then electrical connections are established, but Coulomb blockade voltages are reduced and control precision decreases
Solution Approach 1:
Metal layers and contact structures are completely removed from the quantum well region. Electrical control is achieved through the gate electrode acting directly on the semiconductor channel, eliminating the need for side contacts that would introduce parasitic capacitance and reduce Coulomb blockade effects. This extraction preserves large voltage control while maintaining electrical operability.
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 results in reduced noise, relaxed analog resolution, and improved scalability of semiconductor quantum structures, enabling more efficient quantum computing at higher temperatures with reduced operational costs and complexity.
Implementation Method 1
quantum structures with tunneling through oxide layers or local depleted regions
Data Source
AI summary
A novel and useful modified semiconductor fabrication technique for realizing reliable semiconductor quantum structures. Quantum structures require a minimization of the parasitic capacitance of the control gate and the quantum well. The modified semiconductor process eliminates the fabrication of the metal, contact, and optionally the raised diffusion layers from the quantum wells, thereby resulting in much lower well and gate capacitances and therefore larger Coulomb blockade voltages. This allows easier implementation of the electronic control circuits in that they can have larger intrinsic noise and relaxed analog resolution. Several processes are disclosed including implementations of semiconductor quantum structures with tunneling through an oxide layer as well as tunneling through a local well depleted region. These techniques can be used in both planar semiconductor processes and 3D, e.g., FinFET, semiconductor processes. A dedicated process masking step is used for realizing the raised diffusions. In addition, the edge of the raised diffusion layer may be placed either in the gate region or the active layer region.