Low-Stress TiN Superconducting Resonators for Quantum Circuits
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Solution Overview
Problem
Current superconducting integrated circuits face challenges in achieving high intrinsic quality factors, reproducibility across wafers, and stability over a milli-Kelvin temperature range, particularly for quantum computing applications, due to the lack of suitable high-performance materials.
Innovation Solution
The development of low-stress polycrystalline Titanium Nitride (TiN) superconducting resonators with internal stress between 50 MPa and 250 MPa, used in coplanar waveguide resonators, which are fabricated using techniques such as plasma etching and annealing to enhance quality factors, and integrated into circuits for quantum bits and interconnect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional superconducting materials are used, then the intrinsic quality factor Qi is insufficient, but using high-performance materials lacks scalability and reproducibility
Solution Approach 1:
The patent applies parameter changes by precisely controlling the internal stress parameter of TiN material within 50-250 MPa, and optimizing deposition parameters including temperature (150-450°C), power (6-12 kW), and gas flow rates (Ar: 15-33 sccm, N2: 90-100 sccm) to achieve high Qi values exceeding 10^7 while maintaining scalability
Solution Approach 2:
The patent uses composite material structure with TiN superconducting layer deposited on silicon substrate with specific surface treatments (oxide, hydroxyl, nitride, or fluoride terminations), creating a composite system that achieves both high performance and manufacturability
2Reliability
If high-performance TiN materials are used, then quality factor improves, but stress control and compositional uniformity across wafer become challenging
Solution Approach 1:
The patent controls stress parameter within 50-250 MPa range and maintains stoichiometric composition uniformity across the wafer by optimizing deposition parameters including temperature gradient control, gas flow distribution, and power density, achieving both high Qi and manufacturing precision
Solution Approach 2:
The patent implements process feedback by monitoring and adjusting deposition parameters in real-time to maintain compositional uniformity and stress control across the wafer surface, ensuring reproducible high-quality resonators
3Duration of action of moving object
If superconducting resonators are designed for high-Q operation, then coherence time increases, but device complexity and fabrication difficulty increase
Solution Approach 1:
The patent achieves high coherence time by optimizing the resonator geometric parameters (length, width, gap) alongside material parameters, designing distributed resonators with specific dimensions that resonate at target frequencies while maintaining simple fabricable structures
Solution Approach 2:
The patent creates universal resonator designs that can be fabricated using standard semiconductor processing techniques, making the high-Q resonators compatible with existing manufacturing infrastructure and reducing fabrication complexity
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
These TiN resonators achieve high quality factors exceeding 10^7 at high powers and 10^6 at low power single photon regimes, enabling improved coherence times for quantum computing and facilitating scalable, low-loss superconducting integrated circuits and interconnect structures.
Implementation Method 1
Superconductor materials have substantially no electrical resistance below a certain critical temperature
Implementation Method 2
fabricated using techniques such as plasma etching and annealing to enhance quality factors
Data Source
AI summary
A superconducting integrated circuit includes at least one superconducting resonator, including a substrate, a conductive layer disposed over a surface of the substrate with the conductive layer including at least one conductive material including a substantially low stress polycrystalline Titanium Nitride (TiN) material having an internal stress less than about two hundred fifty MPa (magnitude) such that the at least one superconducting resonator and/or qubit (hereafter called “device”) is provided as a substantially high quality factor, low loss superconducting device.