Ferroelectric Memory HfZrO ALD for Direct Orthorhombic Phase Formation
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Solution Overview
Problem
Forming a ferroelectric material in the orthorhombic phase (O-phase) is challenging, as existing methods require additional energy-intensive annealing steps to achieve the desired crystal structure, which complicates the fabrication process and increases costs.
Innovation Solution
Employing an atomic layer deposition (ALD) process using a mixed precursor or co-pulsing precursors for hafnium zirconium oxide (HfZrO) to directly form the ferroelectric layer with an orthorhombic crystal structure, eliminating the need for annealing and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to form ferroelectric material, then the material can be deposited, but it cannot achieve the orthorhombic phase with high ferroelectric polarization
Solution Approach 1:
The patent changes the deposition parameters by using a mixed precursor containing both hafnium and zirconium in specific ratios, along with controlling oxygen partial pressure and deposition temperature, to directly form the orthorhombic phase with high ferroelectric polarization without requiring post-deposition annealing
Solution Approach 2:
The patent employs a composite hafnium-zirconium oxide system where the combination of Hf and Zr in a mixed precursor creates synergistic effects that stabilize the orthorhombic phase and enhance ferroelectric properties, achieving better performance than single-element oxides
2Reliability
If additional annealing steps are added to form orthorhombic phase, then ferroelectric properties can be improved, but fabrication complexity and cost increase
Solution Approach 1:
The patent performs the crystal phase formation during the deposition process itself by using a mixed precursor and controlling deposition conditions, rather than requiring a separate post-deposition annealing step. This preliminary action integrates phase formation into the deposition process, simplifying the overall fabrication
Solution Approach 2:
The patent merges the deposition and crystal phase formation steps into a single process by using a mixed precursor that self-organizes into the orthorhombic structure during deposition, eliminating the need for separate annealing operations and reducing process complexity
3Manufacturing precision
If mixed precursor is used in ALD process, then orthorhombic phase can be directly formed, but precursor delivery complexity increases
Solution Approach 1:
The patent uses a mixed precursor as an intermediary that contains both hafnium and zirconium in controlled ratios, which simplifies the delivery mechanism by providing both elements in a single precursor stream rather than requiring separate delivery systems for each element
Solution Approach 2:
The patent optimizes the mixed precursor composition and delivery parameters to achieve the desired orthorhombic phase while maintaining ease of manufacture, by adjusting precursor ratios, pulse timings, and reaction conditions to balance phase control with process simplicity
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 results in a more uniform domain crystal orientation, improved ferroelectric properties, and reduced fabrication costs by directly forming the O-phase without additional energy-intensive steps, enhancing the ferroelectric memory device's performance.
Implementation Method 1
forming a ferroelectric layer between a gate electrode and a channel layer by a first atomic layer deposition (ALD) process
Implementation Method 2
providing a first mixed precursor during a second section, wherein the first mixed precursor comprises two precursors that are different from each other
Data Source
AI summary
Provided is a method of forming a ferroelectric memory device including: forming a ferroelectric layer between a gate electrode and a channel layer by a first atomic layer deposition (ALD) process. The first ALD process includes: providing a first precursor during a first section; and providing a first mixed precursor during a second section, wherein the first mixed precursor includes a hafnium-containing precursor and a zirconium-containing precursor. In this case, the ferroelectric layer is directly formed as Hf0.5Zr0.5O2 with an orthorhombic phase (O-phase) to enhance the ferroelectric polarization and property.