Capacitor Lower Electrode Liner Structure for BT Ratio Stability
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Solution Overview
Problem
In highly scaled semiconductor memory devices, the miniaturization of circuit patterns leads to complex capacitor formation, where the benzothiophene (BT) ratio degradation issue causes current leakage due to uneven deposition of SiCN, resulting in lower electrode bending and blockage of openings.
Innovation Solution
A semiconductor device design featuring a lower electrode with a first metal nitride, a liner film with a second metal nitride, and a dielectric layer, where the first metal nitride has a higher metal ratio and lower nitrogen ratio compared to the second metal nitride, and the liner film is deposited only on the upper portion of the lower electrode to improve step coverage and prevent seam formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SiCN is deposited onto the hole of the opening through CVD process with poor step coverage, then the BT ratio is enhanced, but the opening is blocked or narrowed causing lower electrode bending
Solution Approach 1:
The patent applies a liner film with specific material composition (higher metal ratio, lower nitrogen ratio) only to the upper portion of the lower electrode where it is needed to prevent bending, while maintaining different properties in other regions. This localized application of specific material properties resolves the contradiction by enhancing BT ratio control precisely where required without causing opening blockage.
Solution Approach 2:
The patent changes the material composition parameters of the liner film by controlling the metal to nitrogen ratio differently from conventional approaches. By using a liner film with higher metal ratio and lower nitrogen ratio, the patent achieves improved BT ratio enhancement while preventing the opening blockage and electrode bending issues that occur with conventional SiCN deposition.
2Device complexity
If the aspect ratio increases, then the capacitor structure is formed, but the BT ratio degradation problem occurs where upper holes become large and lower holes become small
Solution Approach 1:
The liner film is applied specifically to the upper portion of the lower electrode with tailored material properties (higher metal ratio, lower nitrogen ratio) to compensate for the BT ratio degradation that occurs in high aspect ratio structures. This localized intervention addresses the non-uniform hole size issue without requiring changes to the overall capacitor structure.
Solution Approach 2:
The liner film is deposited beforehand to the lower electrode before the opening formation process, preparing the surface with appropriate material properties that prevent subsequent BT ratio degradation. This preliminary action ensures that the upper holes maintain proper size and shape throughout the fabrication process.
3Area of stationary object
If the separation distance between lower electrodes decreases, then the device area is reduced, but current leakage occurs
Solution Approach 1:
The liner film acts as an intermediary layer between the lower electrode and the surrounding structures, providing electrical isolation that prevents current leakage even when the separation distance between lower electrodes is reduced. This intermediary layer enables miniaturization while maintaining electrical integrity.
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 design enhances the BT ratio, reduces current leakage, and prevents lower electrode bending by ensuring uniform deposition and maintaining the integrity of the capacitor structure, thereby improving the reliability and performance of semiconductor devices.
Implementation Method 1
the liner film includes a second metal nitride including a second metal... a third ratio of nitrogen atoms in the first metal nitride is lower than a fourth ratio of nitrogen atoms in the second metal nitride
Implementation Method 2
a supporter surrounding at least a portion of sidewalls of the lower electrode and supporting the lower electrode
Implementation Method 3
a dielectric layer on the lower electrode and the supporter... the dielectric layer is between the upper electrode and the lower electrode
Data Source
AI summary
A semiconductor device includes a substrate, a lower electrode on the substrate and extending in a vertical direction, a supporter surrounding at least a portion of sidewalls of the lower electrode and supporting the lower electrode, a dielectric layer on the lower electrode and the supporter, an upper electrode on the lower electrode and at least a portion of the dielectric layer, wherein the dielectric layer is between the upper electrode and the lower electrode, and a liner film between the lower electrode and the supporter, the liner film surrounding an upper portion of the lower electrode, where the lower electrode includes a first metal nitride including a first metal, the liner film includes a second metal nitride including a second metal, a first ratio of the first metal in the first metal nitride is higher than a second ratio of the second metal in the second metal nitride, and a third ratio of nitrogen atoms in the first metal nitride is lower than a fourth ratio of nitrogen atoms in the second metal nitride.