MIM Capacitor Lower Electrode Amorphous Layer Leakage
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Solution Overview
Problem
Conventional MIM capacitors with multilayered AlOx and HfOx dielectric films face challenges in securing a desired capacitance value while minimizing the capacitor area, as reducing the thickness leads to increased leakage current due to crystallization of the lower electrode and subsequent dielectric film, making it difficult to maintain a high dielectric constant and prevent dielectric breakdown.
Innovation Solution
The solution involves forming a lower electrode with a multilayer structure where the upper portion, in contact with the capacitor dielectric film, remains amorphous to prevent crystallization of the dielectric film, while the rest of the electrode is partially crystallized to maintain low resistance, using materials like titanium nitride or tantalum nitride, and depositing a high dielectric constant film like HfOx in an amorphous state to suppress leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the thickness of the capacitor dielectric film is reduced to minimize capacitor area, then the capacitance density is improved, but the leakage current increases due to crystallization of the lower electrode and dielectric film
Solution Approach 1:
The lower electrode is designed with different crystalline states in different regions: the first lower electrode portion (in contact with dielectric film) is maintained in amorphous state to prevent leakage, while the second lower electrode portion (not in contact) is allowed to be partially crystallized for low resistance. This local differentiation resolves the contradiction between area reduction and leakage prevention.
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 effectively reduces leakage current and maintains a high dielectric constant, allowing for a thinner capacitor dielectric film while ensuring a sufficient capacitance value, thereby enhancing the reliability and performance of the MIM capacitor.
Implementation Method 1
the upper portion of the lower electrode in contact with a capacitor dielectric film is not subjected to the plasma processing, so as to keep the upper portion of the lower electrode amorphous. Thus, in the formation of a capacitor dielectric film, the capacitor dielectric film can be prevented from succeeding to the crystallinity of the underlying film.
Implementation Method 2
the first conducting layer and having been subjected to plasma processing for reducing resistance thereof
Implementation Method 3
forming, on the first conducting layer, a second conducting layer corresponding to another part of the lower electrode
Data Source
AI summary
A semiconductor device includes a capacitor formed by successively stacking a lower electrode, a capacitor dielectric film and an upper electrode on a substrate. The lower electrode includes a first conducting layer and a second conducting layer formed on the first conducting layer and having higher resistivity than the first conducting layer, and the capacitor dielectric film is formed so as to be in contact with the second conducting layer of the lower electrode.