Low-Temperature Ferroelectric Film Sputtering for Flexible Substrates
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Solution Overview
Problem
Conventional methods for producing ferroelectric films require high temperatures of 300°C or higher, limiting the use of substrates to those with heat resistance and preventing the use of organic materials, and the hydrothermal synthesis method is not suitable for all applications due to its wet process nature.
Innovation Solution
A production process using a sputtering method at substrate temperatures below 300°C, followed by a thermal history or electric field application, to form a ferroelectric film with a fluorite-type orthorhombic crystal phase, allowing the use of substrates with lower heat resistance, including organic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (sputtering, CVD, PLD, ALD) are used to form ferroelectric films, then ferroelectric films can be obtained, but high temperature deposition or annealing (300°C or higher) is required, limiting substrate choices and reducing productivity
Solution Approach 1:
The invention changes the key parameter of deposition temperature from conventional high temperatures (300°C or higher) to low temperatures (below 300°C). This is achieved by optimizing sputtering conditions including using specific target materials (HfO2-based solid solution), controlling oxygen partial pressure, and adjusting deposition power to enable ferroelectric film formation at low temperatures without requiring high-temperature annealing, thereby expanding substrate material selection to include organic substrates
Solution Approach 2:
The invention uses HfO2-based solid solution materials as composite materials with specific compositions (containing Hf, Zr, and other elements in controlled ratios). These composite materials possess inherent properties that enable low-temperature ferroelectric film formation, eliminating the need for high-temperature processing and allowing use of temperature-sensitive substrates
2Reliability
If high temperature deposition or annealing (300°C or higher) is used, then ferroelectric films can be formed, but productivity decreases and cost increases due to limited substrate options and required heat resistance
Solution Approach 1:
The invention fundamentally changes the temperature parameter from 300°C or higher to below 300°C during deposition and subsequent thermal history. This parameter change enables use of low-cost, low-heat-resistance substrates, eliminates the need for expensive high-temperature equipment, and improves production efficiency by allowing continuous processing without complex thermal management
3Temperature
If hydrothermal synthesis method is used, then low temperature (below 300°C) ferroelectric films can be obtained, but the wet process nature limits applicability for certain uses
Solution Approach 1:
The invention replaces the hydrothermal synthesis method's wet chemical process with a dry sputtering process. This substitution maintains the low temperature advantage (below 300°C) while eliminating the wet process limitations, enabling broader application range including uses where wet processes are incompatible, such as integration with certain electronic devices and fabrication of multi-layer structures
Solution Approach 2:
The invention changes the process type parameter from wet (hydrothermal) to dry (sputtering) while maintaining low temperature operation. This parameter change preserves the low-temperature benefit for substrate compatibility while expanding application versatility by removing wet process constraints
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
Enables the production of ferroelectric films at lower temperatures, improving productivity and cost-effectiveness, and enabling the use of organic substrates, while maintaining ferroelectric properties.
Implementation Method 1
using a sputtering method comprising sputtering a target at a temperature of a substrate of lower than 300° C., to deposit on the substrate a film of a metal oxide
Implementation Method 2
or applying an electric field to said film after said deposition or after said thermal history of lower than 300° C.
Data Source
AI summary
Provided is a method for forming a ferroelectric film of a metal oxide having a fluorite-type structure at a low temperature of lower than 300° C., and a ferroelectric film obtained at a low temperature. The present invention provides a production method of a ferroelectric film comprising a crystalline metal oxide having a fluorite-type structure of an orthorhombic crystal phase, which comprises using a film sputtering method comprising sputtering a target at a substrate temperature of lower than 300° C., to deposit on the substrate a film of a metal oxide which is capable of having a fluorite-type structure of an orthorhombic crystal phase, and having a subsequent thermal history of said film of lower than 300° C.; or applying an electric field to said film after said deposition or after said thermal history of lower than 300° C. Also provided are the ferroelectric film, which is formed on an organic substrate, glass, or metal substrate, which can be used only at low temperatures, and a ferroelectric element and a ferroelectric functional element or device using the ferroelectric film.