Ultra-thin SOI CMOS for Cryogenic Quantum Control
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Solution Overview
Problem
Conventional CMOS technology is not suitable for operating at low temperatures, particularly cryogenic temperatures, due to issues like MOSFET channels freezing out, making it unsuitable for controlling quantum circuits, and the impracticality of producing complex CMOS circuits in a research laboratory setting.
Innovation Solution
The development of ultra-thin silicon-on-insulator (SOI) CMOS technology for fabricating controller and observer circuits, which utilize SOI-CMOSFETs to achieve high unity-gain frequency, rapid pulse edge transition times, high bandwidth, and low power operation, enabling effective control and measurement of quantum bits at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMOS technology is used at low temperatures, then device simplicity is maintained, but MOSFET channels freeze out rendering them unsuitable for controlling quantum circuits
Solution Approach 1:
The patent changes the physical parameters of the MOSFET structure by transitioning to ultra-thin body SOI technology with specific dimensional constraints (body thickness ≤ 50 nm, channel length ≤ 100 nm). These parameter changes prevent channel freeze-out by maintaining sufficient carrier density through quantum confinement effects in the ultra-thin body, enabling reliable operation at cryogenic temperatures down to 4.2 K and below.
2Ease of manufacture
If complex CMOS circuits are produced in a research laboratory, then research flexibility is improved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent segments the quantum computing system into distinct functional modules: quantum bit devices fabricated using standard semiconductor processes, and controller/observer circuits implemented separately using ultra-thin SOI CMOS technology. This segmentation allows each subsystem to be optimized and manufactured independently using appropriate processes, then integrated through standardized interfaces, thereby reducing overall manufacturing complexity while maintaining research flexibility.
3Adaptability or versatility
If standard CMOS technology is used at room temperature, then manufacturing simplicity is maintained, but application scope is limited to room temperature operations
Solution Approach 1:
The patent applies parameter changes by specifying ultra-thin body dimensions (thickness ≤ 50 nm) and optimized doping profiles that fundamentally alter the temperature-dependent electrical characteristics of the MOSFET. These parameter changes enable the devices to maintain acceptable performance across an extended temperature range from room temperature down to cryogenic temperatures (4.2 K and below), thereby expanding the operating temperature range without requiring entirely different device physics.
Data Source
AI summary
This invention concerns interfacing to electronic circuits or systems operating at low temperature or ultra-low temperature using complementary metal-oxide semiconductor (CMOS) technology. Low temperature in this case refers to cryogenic temperatures in particular, but not exclusively, to the 4.2 K region. Ultra-low temperatures here refers to the sub-1 K range, usually accessed using dilution refrigerator systems. The electronic circuits comprise a controller (for writing and manipulation), an observer (for readout and measurement) circuits, or both, fabricated from ultra-thin silicon-on-insulator (SOI) CMOS technology.