Multilayer Electrode Planarization for Ferroelectric Film Reliability
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Solution Overview
Problem
Existing ferroelectric memory technologies face challenges in reducing the thickness of ferroelectric films while maintaining crystallinity and preventing defective coverage of hydrogen barrier and barrier metal films, which leads to characteristic deterioration and reliability issues.
Innovation Solution
A semiconductor device with a multilayer electrode structure where the upper electrode layer is made of a conductive material with etching selectivity, allowing for planarization and use as an etching mask, combined with a hydrogen barrier film and barrier metal film to prevent defective coverage and ensure uniform film thickness, thereby enhancing the reliability of the ferroelectric film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the ferroelectric film is reduced to not more than 100 nm, then the voltage and size of the ferroelectric memory are reduced, but the film cannot attain crystallinity capable of exhibiting excellent ferroelectricity
Solution Approach 1:
The patent changes the deposition parameters and post-processing conditions to achieve crystallinity in thin ferroelectric films. Specifically, it uses pulsed laser deposition with controlled laser energy, substrate temperature, and oxygen partial pressure to form crystalline structures at thicknesses of 100 nm or less, which traditionally cannot achieve proper crystallinity.
Solution Approach 2:
The patent replaces conventional sputtering or sol-gel processes with pulsed laser deposition technology. This substitution enables precise control over film formation dynamics, allowing atoms to arrange into crystalline structures even in extremely thin films where thermal energy is insufficient for crystallization in traditional methods.
2Manufacturing precision
If films (hydrogen barrier film and barrier metal film) are formed on the electrode with irregular surface morphology, then the films cannot be formed with uniform thickness, but defective coverage occurs leading to characteristic deterioration
Solution Approach 1:
The patent introduces a planarization step before forming the hydrogen barrier film and barrier metal film. By planarizing the electrode surface in advance, subsequent films can be deposited uniformly without defects, preventing characteristic deterioration of the ferroelectric film.
Solution Approach 2:
The patent introduces a planarization layer as an intermediary between the irregular electrode surface and the films that require uniform deposition. This intermediate layer provides a flat substrate for film formation, ensuring both uniform thickness and complete coverage while isolating the film deposition process from the underlying surface irregularities.
3Reliability
If the hydrogen barrier film and barrier metal film are formed on an irregular electrode surface, then the films exhibit defective coverage, but this leads to hydrogen reduction and characteristic deterioration of the ferroelectric film
Solution Approach 1:
The patent performs planarization of the electrode surface before depositing the hydrogen barrier film and barrier metal film. This preliminary action ensures that the barrier films are formed with uniform thickness and complete coverage, effectively preventing hydrogen reduction of the ferroelectric film without sacrificing manufacturing precision.
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 solution prevents defective coverage of films on the electrode, maintains the crystallinity of the ferroelectric film, and improves the reliability and lifespan of the semiconductor device by ensuring uniform film thickness and hydrogen barrier properties.
Implementation Method 1
When a film is formed on the electrode upper layer, the film can be formed with a generally uniform thickness on the electrode
Implementation Method 2
the ferroelectric film 105 can be prevented from characteristic deterioration resulting from hydrogen reduction
Data Source
AI summary
The semiconductor device according to the present invention includes a ferroelectric film and an electrode stacked on the ferroelectric film. The electrode has a multilayer structure of an electrode lower layer in contact with the ferroelectric film and an electrode upper layer stacked on the electrode lower layer. The electrode upper layer is made of a conductive material having an etching selection ratio with respect to the materials for the ferroelectric film and the electrode lower layer. The upper surface of the electrode upper layer is planarized.