Ferroelectric Data Holding Device with Miniaturized Dummy Elements
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Solution Overview
Problem
The existing data holding devices face challenges in reducing variations in ferroelectric element characteristics due to mask pattern density, leading to increased chip area and manufacturing costs, as dummy elements occupy a large area when ferroelectric elements are small.
Innovation Solution
A data holding device is designed with a loop structure unit, nonvolatile storage unit, and circuit separation unit, where ferroelectric elements are surrounded by a dummy element smaller in width, and the loop structure unit holds data using logic gates connected in a loop shape, with equal inter-element distances to minimize area occupation and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy elements identical in size with ferroelectric elements are provided to suppress etching loading effect, then variations in ferroelectric element characteristics are reduced, but the chip area is significantly enlarged
Solution Approach 1:
The patent applies local quality by making the dummy elements smaller in size than the ferroelectric elements. Specifically, the dummy elements have a width of 0.5 μm while the ferroelectric elements have a width of 1.0 μm. This local differentiation allows the dummy elements to provide sufficient etching loading effect suppression in their local region without occupying excessive chip area, thus resolving the contradiction between reliability improvement and area minimization.
2Area of stationary object
If the size of ferroelectric elements is reduced to minimize chip area, then area is saved, but reliability is lowered due to increased variations from mask pattern density
Solution Approach 1:
The patent applies preliminary anti-action by introducing dummy elements that preemptively counteract the harmful etching loading effect before it can cause variations in ferroelectric element characteristics. These dummy elements are strategically positioned adjacent to the ferroelectric elements to create a balanced mask pattern density, thereby preventing reliability degradation even when ferroelectric elements are miniaturized.
3Manufacturing precision
If dummy elements are provided adjacent to ferroelectric elements, then etching loading effect is suppressed, but the ratio of dummy element area to total device area becomes very large
Solution Approach 1:
The patent applies parameter changes by modifying the size parameter of the dummy elements. Instead of making dummy elements identical in size to ferroelectric elements (1.0 μm width), the dummy elements are designed with a smaller width of 0.5 μm. This parameter change maintains sufficient etching loading effect suppression while reducing the area ratio of dummy elements to total device area, thereby resolving the contradiction between manufacturing precision and area efficiency.
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 configuration effectively reduces variations in ferroelectric element characteristics, minimizes chip area, and maintains reliability, allowing for efficient data storage and operation similar to volatile devices without significant area increase.
Implementation Method 1
The nonvolatile storage unit includes a plurality of ferroelectric elements and is configured to store the data held in the loop structure unit in a nonvolatile manner using hysteresis characteristics of the ferroelectric elements
Data Source
AI summary
A data holding device includes a loop structure unit configured to hold data using a plurality of logic gates connected in a loop shape, a nonvolatile storage unit including a plurality of ferroelectric elements, the nonvolatile storage unit configured to store the data held in the loop structure unit in a nonvolatile manner using hysteresis characteristics of the ferroelectric elements, and a circuit separation unit configured to electrically separate the loop structure unit and the nonvolatile storage unit. The ferroelectric elements of the nonvolatile storage unit are surrounded by a dummy element smaller in width than the ferroelectric elements.