Capacitor Lower Electrode Support via Silicon Nitride Layers
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Solution Overview
Problem
The conventional method for manufacturing capacitor lower electrodes in semiconductor memory faces challenges in increasing supporting stress and preventing deformation as dimensions decrease, making it difficult to fabricate dielectric layers and upper electrodes outside the lower electrodes.
Innovation Solution
A method involving the formation of a stacked structure with conductive plugs, partial etching of layers to create concave portions and trenches, followed by depositing a second silicon nitride layer to enhance the contact area and supporting stress of the capacitor lower electrodes, thereby reducing the difficulty in placing dielectric and upper electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dimensions are decreased to increase memory cell density, then storage capacity is improved, but supporting stress of capacitor lower electrodes decreases making fabrication difficult
Solution Approach 1:
A support structure comprising a first silicon nitride layer and a second silicon nitride layer is formed around the capacitor lower electrode before the upper electrode and dielectric layer are fabricated. This preliminary support structure provides mechanical reinforcement to the capacitor lower electrode, preventing collapse or deformation during subsequent fabrication processes despite reduced dimensions.
Solution Approach 2:
The support structure acts as an intermediary element between the capacitor lower electrode and the surrounding environment. It provides mechanical support and stability to the capacitor lower electrode during the fabrication process, enabling precise formation of upper electrodes and dielectric layers without causing collapse or deformation.
2Quantity of substance
If surface area of capacitor lower electrodes is increased to improve storage capacity, then data storage capacity is improved, but supporting stress decreases making it difficult to prevent collapsing
Solution Approach 1:
The support structure is formed in advance around the capacitor lower electrode to provide mechanical reinforcement. This allows the capacitor lower electrode to achieve larger surface area for increased storage capacity while maintaining sufficient supporting stress through the surrounding support structure.
3Ease of manufacture
If conventional manufacturing method is used, then process simplicity is maintained, but capacitor lower electrodes collapse or deform making subsequent layer fabrication difficult
Solution Approach 1:
The support structure is formed as a preliminary step in the manufacturing process, providing mechanical stability to the capacitor lower electrode before subsequent fabrication steps. This ensures manufacturing precision is maintained without significantly complicating the overall process.
Solution Approach 2:
The support structure is segmented into two distinct silicon nitride layers (first and second silicon nitride layers) with different etching rates. This segmentation allows each layer to serve specific functions: the first layer provides initial support and the second layer provides additional support and pattern definition, together ensuring electrode stability.
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 enhanced contact area between the second silicon nitride layer and the capacitor lower electrodes increases supporting stress, simplifies the placement of dielectric and upper electrodes, and prevents the lower electrodes from collapsing or deforming.
Implementation Method 1
depositing a second silicon nitride layer onto the hard mask layer and into the concave portions
Implementation Method 2
partially etching a hard mask layer, a first silicon nitride layer and a dielectric layer in the stacked structure to form a plurality of concave portions
Data Source
AI summary
A method for manufacturing capacitor lower electrodes includes a dielectric layer, a first silicon nitride layer and a hard mask layer; partially etching the hard mask layer, the first silicon nitride layer and the dielectric layer to form a plurality of concave portions; depositing a second silicon nitride layer onto the hard mask layer and into the concave portions; partially etching the second silicon nitride layer, the hard mask layer and the dielectric layer to form a plurality of trenches; forming a capacitor lower electrode within each trench and partially etching the first silicon nitride layer, the second silicon nitride layer, the dielectric layer and the capacitor lower electrodes to form an etching area; and etching and removing the dielectric layer from the etching area, thereby a periphery of each capacitor lower electrode is surrounded and attached to by the second silicon nitride layer.