JoFET Qubit Fabrication Using Laser-Recrystallized Superconducting Silicon
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Solution Overview
Problem
The challenge lies in integrating superconductor qubits, particularly those using Josephson field effect transistors (JoFETs), into semiconductor technologies due to material incompatibilities between superconductor regions and conventional microelectronics.
Innovation Solution
A method involving pulsed laser induced epitaxy (PLIE) is employed to create superconductor qubits by implanting dopants in semiconductor layers, using protective dielectric layers to protect non-melting regions while selectively melting others, forming JoFETs with superconductor properties through controlled laser pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superconductor regions are made from conventional materials, then superconductor properties are achieved, but compatibility with semiconductor technologies is lost
Solution Approach 1:
The patent changes the material parameters by using heavily doped silicon (e.g., boron-doped silicon with concentrations around 10^20 atoms/cm³) instead of conventional superconductor materials like aluminum or niobium. This parameter change allows the semiconductor substrate to exhibit superconductor properties at millikelvin temperatures, achieving both superconductor functionality and compatibility with standard semiconductor manufacturing processes
Solution Approach 2:
The patent uses the same semiconductor material (silicon) for both the semiconductor device components and the superconductor regions. By making the superconductor regions from the same base material as the semiconductor layer, just with different doping concentrations, the patent achieves material homogeneity that enables integration without requiring multiple material systems or complex heterostructure interfaces
2Reliability
If laser pulses are applied to create superconductor regions, then superconductor properties are formed, but damage occurs to adjacent non-superconductor regions
Solution Approach 1:
The patent segments the silicon layer into different functional regions with different doping concentrations: heavily doped regions (10^20 atoms/cm³) that become superconductor regions when irradiated, and lightly doped or intrinsic regions (10^16-10^18 atoms/cm³) that remain as normal semiconductor. This segmentation allows selective laser irradiation to affect only the heavily doped regions without damaging the adjacent non-superconductor regions
Solution Approach 2:
The patent introduces dopant concentration as an intermediary parameter that mediates between the laser irradiation effect and the material response. The heavily doped silicon acts as an intermediary that absorbs laser energy and undergoes phase transformation to become superconductor, while the lightly doped regions serve as a buffer that protects adjacent non-superconductor regions from laser damage
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 allows for the integration of superconductor qubits into semiconductor devices, ensuring compatibility with existing semiconductor technologies and enabling the formation of JoFETs with desired superconductor properties.
Implementation Method 1
exposing the protective dielectric layer to at least one laser pulse
Implementation Method 2
melt the semiconductor of the second regions
Implementation Method 3
implanting dopants in second regions of the semiconductor layer
Implementation Method 4
Cooling of the semiconductor material causes its recrystallisation which confers superconductor properties thereon
Implementation Method 5
recrystallised semiconductor material having superconductor material properties
Implementation Method 6
the superposition of the protective dielectric portion and of the protective dielectric layer over the first region prevents said at least one laser pulse from reaching the first region
Data Source
AI summary
A method for making a device with superconductor qubit(s) including at least one JoFET formed by the following steps of:making, over a semiconductor layer, a protective dielectric portion arranged over a first region of the semiconductor layer;implanting dopants in second regions adjacent to the first region;depositing a protective dielectric layer covering the protective dielectric portion and the second regions;exposing the protective dielectric layer to a laser pulse;and wherein the materials and the thicknesses of the protective dielectric portion and of the protective dielectric layer are selected so as to prevent the laser pulse from reaching the first region, and melting the semiconductor of the second regions which forms, after cooling, a recrystallised semiconductor material having superconductor material properties.