3D Memory Staircase Contacts With Stopper Layers Against Shorts
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Solution Overview
Problem
In semiconductor storage devices, such as three-dimensional non-volatile memory, contacts can short circuit with dummy pillars, leading to defects during the manufacturing process, especially when the contact and dummy pillar come into contact with each other.
Innovation Solution
The semiconductor storage device is designed with a stacked body of conductive layers and insulating layers, where contacts are formed in a staircase shape and penetrate through stopper layers to avoid contact with dummy pillars, ensuring electrical connections are made without short circuits by using stopper layers to prevent contact between the contacts and word lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contacts are formed to connect conductive layers in a staircase shape, then electrical connection is achieved, but short circuit defects occur when contacts contact dummy pillars
Solution Approach 1:
A stopper layer is introduced as an intermediary between the contact and the dummy pillar. This stopper layer prevents direct contact between the contact and dummy pillar, thereby eliminating the short circuit defect while maintaining the electrical connection function of the contact to the conductive layer.
Solution Approach 2:
The structure is segmented by introducing a stopper layer that divides the space between the contact and dummy pillar. This segmentation creates distinct functional zones: the contact region for electrical connection and the stopper layer region for isolation, preventing harmful contact while preserving useful connectivity.
2Reliability
If stopper layers are added to prevent contact between contacts and dummy pillars, then short circuit defects are reduced, but device structure becomes more complex
Solution Approach 1:
The stopper layer serves multiple functions simultaneously: it acts as a physical barrier to prevent contact between contacts and dummy pillars, provides structural support in the stacked body, and defines the boundary of the contact region. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The stopper layer is integrated into the existing stacked body structure of conductive and insulating layers, merging the defect prevention function with the structural framework. This integration avoids adding separate complex subsystems while achieving the desired reliability improvement.
Data Source
AI summary
A semiconductor storage device includes a stacked body having a plurality of conductive layers and a plurality of first insulating layers that are alternately stacked, and a staircase portion in which the plurality of conductive layers have been processed into a staircase shape, a contact disposed in the staircase portion and connected to a first conductive layer, which is one of the plurality of conductive layers, and a first pillar that extends in a stacking direction of the stacked body in a portion of the stacked body different from the staircase portion and forms memory cells at each intersection of the first pillar and at least a part of the plurality of conductive layers. The contact penetrates a second conductive layer, which is not one of the plurality of conductive layers and disposed above the first conductive layer, and reaches the first conductive layer to be in contact therewith.