Ferroelectric Memory Cell Oxygen Vacancy Profile for Low Leakage
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Solution Overview
Problem
The integration of non-volatile memory technologies in semiconductor industry faces challenges in controlling oxygen vacancies, which affect the ferroelectric properties and data retention capabilities of memory cells due to uncontrolled variations in oxygen vacancy concentrations and distributions, leading to increased leakage current and reduced endurance.
Innovation Solution
A memory cell design that incorporates a controlled distribution and concentration of oxygen vacancies in the memory layer, using techniques such as varying oxygen precursor gases, pulse times, and anneal steps during deposition to tailor the oxygen vacancy profile, enhancing ferroelectric properties and data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen vacancies are introduced in the memory layer, then ferroelectric properties are enhanced, but leakage current increases and endurance deteriorates
Solution Approach 1:
The patent applies local quality by creating distinct regions within the memory layer with different oxygen vacancy concentrations. The method introduces oxygen vacancies selectively in specific zones rather than uniformly throughout the entire layer, allowing the ferroelectric region to benefit from enhanced polarization while maintaining low-leakage regions with controlled vacancy concentrations. This spatial differentiation resolves the contradiction by localizing the harmful effect to specific areas while preserving beneficial properties in other regions.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the concentration and distribution of oxygen vacancies through pulsed laser deposition parameters. By adjusting laser pulse duration, oxygen partial pressure, and substrate temperature during deposition, the method optimizes the oxygen vacancy concentration to enhance ferroelectric properties while maintaining it below the threshold that would cause excessive leakage current. This parameter optimization resolves the contradiction between enhancing ferroelectricity and controlling leakage.
2Speed
If oxygen vacancy concentration is increased to improve switching speed, then polarization properties are enhanced, but data retention stability decreases
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of oxygen vacancies within the memory layer. Regions closer to the electrode interfaces have higher oxygen vacancy concentrations to enhance switching speed and polarization, while the central region maintains lower vacancy concentrations to ensure data retention stability. This spatial variation in oxygen vacancy quality allows simultaneous optimization of both switching speed and data retention without compromising either property.
3Ease of manufacture
If uniform oxygen vacancy distribution is used, then manufacturing is simplified, but ferroelectric properties and data retention are compromised
Solution Approach 1:
The patent applies periodic action by using pulsed laser deposition with controlled oxygen exposure during the deposition process. The method alternates between depositing material with oxygen vacancies and exposing to oxygen to create the desired vacancy distribution pattern. This periodic cycling of deposition and oxygen exposure enables precise control over oxygen vacancy distribution while maintaining a relatively simple manufacturing process, resolving the contradiction between manufacturing simplicity and performance requirements.
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
The controlled oxygen vacancy profile improves the memory cell's polarization properties, leading to faster switching, more stable data retention, and reduced leakage current, thereby enhancing the overall performance and endurance of the memory cell.
Implementation Method 1
controlling oxygen vacancies in a memory layer... enhancing ferroelectric properties and data retention
Data Source
AI summary
According to various aspects a memory cell is provided, the memory cell including: a first electrode; a second electrode; and a memory layer disposed between the first electrode and the second electrode, wherein the memory layer includes a first memory portion having a first concentration of oxygen vacancies and a second memory portion having a second concentration of oxygen vacancies different from the first concentration of oxygen vacancies.