Ion-Beam Assisted Sputtering for Superconducting Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for depositing superconducting films, such as reactive sputtering and CVD, require elevated temperatures, making them incompatible with heat-sensitive substrates and leading to films with granular or columnar void structures, especially when attempting to produce high Tc NbN films at room temperature.
Innovation Solution
An ion-beam assisted sputtering method where a substrate is bombarded with nitrogen ions simultaneously with sputtering from a transition metal target, allowing for the deposition of superconducting transition metal nitride films at ambient temperature without applied heat, using multiple ion beams and targets to achieve desired film compositions and structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reactive sputtering or CVD is used to deposit superconducting films, then high Tc NbN films can be produced, but elevated temperatures (>500°C) are required which makes the process incompatible with heat-sensitive substrates and causes granular or columnar void structures
Solution Approach 1:
The patent changes the fundamental parameters of the deposition process by introducing ion beam assistance to reactive sputtering. This modification enables the deposition to proceed at room temperature instead of requiring elevated temperatures (>500°C), thereby resolving the contradiction between achieving high-quality superconducting films and avoiding substrate heating. The ion beam provides the necessary energy to facilitate the sputtering process at lower temperatures.
Solution Approach 2:
The patent replaces the thermal field-based sputtering process with an ion beam-based physical sputtering process. Instead of relying on thermal energy to drive the deposition, the invention uses ion bombardment to eject atoms from the target, enabling the process to occur at room temperature and eliminating the need for high-temperature processing that causes substrate heating and film degradation.
2Temperature
If room temperature deposition is attempted with conventional methods, then substrate heating is avoided, but films exhibit granular or columnar void structures with normal state resistivity well above 150 μΩ·cm
Solution Approach 1:
The patent replaces conventional thermal sputtering with ion beam-assisted physical sputtering. The ion beam provides direct mechanical bombardment that ejects atoms from the target without requiring high temperatures, enabling room temperature deposition while producing dense, uniform films with low resistivity, thereby eliminating the granular and columnar void structures characteristic of conventional low-temperature methods.
Solution Approach 2:
The patent modifies the sputtering process parameters by introducing ion beam assistance, which fundamentally changes the energy delivery mechanism. This parameter change enables the process to proceed at room temperature while maintaining film density and uniformity, resolving the contradiction between low temperature deposition and high film quality.
3Reliability
If precise control over relative concentrations of sputtering gases and large sputtering powers is used to achieve high Tc NbN films, then superconducting properties are improved, but substrate heating occurs
Solution Approach 1:
The patent substitutes thermal sputtering with ion beam-assisted physical sputtering. This replacement eliminates the need for high sputtering powers and precise gas concentration control that cause substrate heating. The ion beam provides the necessary energy for the sputtering process, allowing high Tc NbN film deposition at room temperature without substrate heating.
Solution Approach 2:
The patent changes the energy delivery parameter from thermal to ion beam-based, fundamentally altering the process. This parameter change enables the deposition to proceed at room temperature with reduced substrate heating, while maintaining the ability to achieve high superconducting Tc through controlled ion bombardment and sputtering.
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 method enables the deposition of high-quality superconducting films with improved uniformity and density on various substrates, including heat-sensitive ones, with reduced temperature increases and increased operating ranges for ion concentrations, achieving superconducting Tc values comparable to single crystals without the need for high-temperature processing.
Implementation Method 1
bombarding a substrate with nitrogen ions supplied from an ion beam
Implementation Method 2
sputtering from a transition metal target substantially simultaneously with the bombardment to deposit a transition metal nitride film onto the substrate
Data Source
AI summary
A method of making a thin film can include bombarding a substrate with first ions supplied from a first ion beam; and sputtering from a metal sputtering target substantially simultaneously with the bombardment to deposit a metal-ion film onto the substrate, wherein the method is performed without applied heat, and the metal sputtering target comprises one or more of a metal, a transition metal, a semi-metal, alloys thereof and combinations thereof.