Ferroelectric Capacitor Grain Boundary Gap Filling
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Solution Overview
Problem
Ferroelectric memories, such as FeRAM, face challenges in yield improvement due to deterioration of ferroelectric characteristics caused by exposure to reducing substances like moisture or hydrogen, which leads to the formation of gaps along grain boundaries in the ferroelectric film, resulting in reduced residual polarization charge and contact failures.
Innovation Solution
A method involving the use of a second protective insulating film formed by atomic layer deposition (ALD) to fill gaps generated along the grain boundary of the dielectric film, combined with a first protective insulating film formed by sputtering, to prevent the penetration of reducing substances and maintain the integrity of the ferroelectric capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single protective insulating film is formed by sputtering method, then the formation process is simple and fast, but gaps along grain boundaries of the dielectric film are not properly filled and reducing substances can penetrate through
Solution Approach 1:
The protective insulating film is divided into two separate films: a first protective insulating film formed by sputtering method and a second protective insulating film formed by atomic layer deposition method. Each film serves a specific function - the first film provides rapid coverage while the second film specifically fills the gaps along grain boundaries, together achieving comprehensive protection.
Solution Approach 2:
The patent uses a composite structure of two different insulating films with distinct formation methods and material properties. The first protective insulating film (e.g., silicon oxide) and second protective insulating film (e.g., aluminum oxide) are combined to leverage the advantages of both sputtering (speed) and atomic layer deposition (gap-filling capability).
2Ease of manufacture
If the ferroelectric film is exposed to reducing substances like moisture or hydrogen, then the manufacturing process is simple, but gaps form along grain boundaries and ferroelectric characteristics deteriorate
Solution Approach 1:
The protective insulating films are formed in advance before the ferroelectric film is exposed to reducing substances during subsequent manufacturing processes. This preliminary protection prevents gap formation along grain boundaries and maintains ferroelectric characteristics throughout the manufacturing process.
Solution Approach 2:
The protective insulating films create an inert barrier environment that prevents reducing substances (moisture, hydrogen) from reaching the ferroelectric film. This protective barrier maintains the ferroelectric characteristics by blocking the harmful chemical interactions that would otherwise occur during manufacturing.
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 effectively prevents the deterioration of ferroelectric characteristics by blocking hydrogen and other reducing substances, improving the yield and maintaining the electrical performance of the ferroelectric capacitor by ensuring the gaps are filled and the lower electrode is protected from corrosion.
Implementation Method 1
forming a first protective insulating film on the upper electrodes and the dielectric film by a sputtering method
Implementation Method 2
forming a second protective insulating film on the first protective insulating film by an atomic layer deposition method, thereby filling gaps generated along a grain boundary of the dielectric film with the second protective insulating film
Data Source
AI summary
A method of manufacturing a semiconductor device includes: forming an insulating film above a semiconductor substrate; forming a conductive film on the insulating film; forming a dielectric film on the conductive film; forming a plurality of upper electrodes at intervals on the dielectric film; forming a first protective insulating film on the upper electrodes and the dielectric film by a sputtering method; forming a second protective insulating film on the first protective insulating film by an atomic layer deposition method, thereby filling gaps of a grain boundary of the dielectric film with the second protective insulating film; and patterning the conductive film after the second protective insulating film is formed to provide a lower electrode.