Two-Stage Storage Electrode Landing Pad Alignment
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Solution Overview
Problem
As semiconductor devices miniaturize, the challenge of maintaining capacitor capacity while preventing defects and instability in cylindrical lower electrodes during dry etching becomes significant, leading to potential collapse and increased leakage current due to high aspect ratios and lithography-related superposition displacement.
Innovation Solution
A semiconductor device with a first pillar-shaped storage electrode and a second crown-shaped storage electrode connected via a landing pad with a larger landing surface, which enhances mechanical strength and reduces positional displacement, thereby stabilizing the electrode structure and minimizing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the lower electrode is heightened to increase surface area and capacitor capacity, then capacitor capacity is improved, but dry etching defects occur due to high aspect ratio
Solution Approach 1:
The lower electrode is divided into two separate electrodes (first storage electrode and second storage electrode) positioned at different heights, rather than forming a single tall cylindrical electrode. This segmentation allows each electrode to have a manageable aspect ratio while collectively providing sufficient surface area for capacitor capacity.
Solution Approach 2:
Instead of increasing capacitor capacity solely by increasing the height of a single electrode in one dimension, the invention utilizes the vertical dimension by creating a two-stage structure with electrodes at different levels, effectively distributing the capacity across multiple dimensional planes.
2Quantity of substance
If the height of the lower electrode is increased to ensure capacitor capacity, then capacitor capacity is improved, but the lower electrode becomes unstable and may collapse
Solution Approach 1:
The single tall electrode is segmented into two shorter electrodes at different heights, reducing the aspect ratio of each individual electrode. This segmentation enhances the structural stability of each electrode while maintaining the required total surface area for capacitor capacity.
Solution Approach 2:
A landing pad structure is introduced as an intermediary element between the first and second storage electrodes. This landing pad provides mechanical support and stabilizes the upper electrode, preventing collapse while allowing the electrodes to maintain their respective positions for optimal capacity.
3Reliability
If a two-stage structure is used in the lower electrode to reduce dry etching defects, then dry etching reliability is improved, but lithography superposition displacement causes positional misalignment
Solution Approach 1:
The landing pad serves as a reference intermediary structure that facilitates precise alignment between the first and second storage electrodes. By using the landing pad as a common reference feature, the invention compensates for lithography superposition displacement and ensures accurate positional alignment.
Solution Approach 2:
The landing pad structure enables self-alignment of the two-stage electrode system. The electrodes are positioned relative to the landing pad rather than requiring precise direct alignment between themselves, allowing the structure to self-correct for lithography variations.
4Device complexity
If the contact area between first and second storage electrodes is reduced due to positional displacement, then manufacturing complexity is reduced, but mechanical strength decreases and collapse occurs
Solution Approach 1:
The landing pad acts as a mechanical intermediary that distributes and transfers load between the first and second storage electrodes. This intermediary structure enhances the overall mechanical strength of the two-stage electrode system, preventing collapse even when direct contact area between electrodes is limited.
Data Source
AI summary
A semiconductor device includes a first storage electrode, a second storage electrode that is arranged above the first storage electrode, a first landing pad that is arranged between a top surface of the first storage electrode and a bottom surface of the second storage electrode, the first landing pad connecting the first storage electrode and the second storage electrode, the first landing pad having a first landing surface, the first landing surface being larger than the bottom surface of the second storage electrode, and the second storage electrode being placed on the first landing surface, a capacitive insulating film that is laminated on the first and second storage electrodes and on an outer circumferential surface of the first landing pad, and a plate electrode that contacts the capacitive insulating film.