Ferroelectric Capacitor Array with Maskless Etching for Read Stability
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Solution Overview
Problem
Existing memory technologies face challenges in forming arrays of capacitors and memory cells that efficiently store data without volatility and data loss during read operations, particularly with ferroelectric capacitors where reading memory states can reverse the polarization, necessitating immediate rewriting.
Innovation Solution
The method involves forming arrays of capacitors and memory cells by creating elevationally-extending capacitor electrode lines, forming a capacitor insulator over these lines, and using maskless anisotropic etching to create spaced capacitor electrodes, allowing for non-volatile data storage and minimizing data loss during read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If ferroelectric capacitors are used for non-volatile memory storage, then data retention capability is improved, but reading memory states causes polarization reversal requiring immediate rewriting
Solution Approach 1:
The patent segments the capacitor structure into distinct components including a substrate, a tunnel barrier layer, a ferroelectric layer, and an electrode. This segmentation allows the read operation to affect only the polarization state without destroying the stored data, as the structured layers protect the information integrity during reading.
Solution Approach 2:
The patent implements a preliminary write operation before the read operation to restore the polarization state. This preliminary action ensures that any polarization reversal during reading is immediately corrected, preventing data loss while maintaining the non-volatile storage capability.
2Ease of manufacture
If conventional capacitor structures are used, then manufacturing process is simpler, but data storage stability and non-volatility are insufficient
Solution Approach 1:
The patent employs a composite capacitor structure consisting of a tunnel barrier layer (e.g., oxide material), a ferroelectric layer (e.g., lead zirconate titanate), and electrode materials. This composite structure combines the advantages of each material to achieve both non-volatile data storage and improved reliability while maintaining compatibility with existing semiconductor manufacturing processes.
Solution Approach 2:
The patent transitions from planar capacitor structures to vertically-stacked three-dimensional capacitor structures. This dimensional change increases the effective storage area without proportionally increasing the footprint, thereby improving data storage stability and density while remaining manufacturable using standard semiconductor fabrication techniques.
3Speed
If polarization reversal is allowed during read operations, then reading speed is faster, but immediate rewriting is required increasing time overhead
Solution Approach 1:
The patent schedules a preliminary write operation to occur before the read operation in the memory cell cycle. This preliminary action proactively restores the polarization state before any potential reversal occurs during reading, thereby enabling fast read operations without the need for corrective rewriting afterward, thus reducing overall time overhead.
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 enables efficient, non-volatile data storage and retrieval in memory cells, reducing the need for immediate rewriting after reading and enhancing the stability of memory states.
Implementation Method 1
A capacitor has two electrical conductors separated by electrically insulating material. Energy as an electric field may be electrostatically stored within such material.
Implementation Method 2
One type of non-volatile capacitor is a ferroelectric capacitor which has ferroelectric material as at least part of the insulating material. Ferroelectric materials are characterized by having two stable polarized states
Implementation Method 3
using maskless anisotropic etching to create spaced capacitor electrodes
Data Source
AI summary
A method of forming an array of capacitors comprises forming elevationally-extending and longitudinally-elongated capacitor electrode lines over a substrate. Individual of the capacitor electrode lines are common to and a shared one of two capacitor electrodes of individual capacitors longitudinally along a line of capacitors being formed. A capacitor insulator is formed over a pair of laterally-opposing sides of and longitudinally along individual of the capacitor electrode lines. An elevationally-extending conductive line is formed over the capacitor insulator longitudinally along one of the laterally-opposing sides of the individual capacitor electrode lines. The conductive line is cut laterally through to form spaced individual other of the two capacitor electrodes of the individual capacitors. Other methods are disclosed, including structures independent of method of manufacture.