3D NAND Cell Contact Structure for Dense Reliable Gate Connection
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Solution Overview
Problem
The integration of two-dimensional non-volatile memory devices is limited by the need for expensive equipment to form fine patterns, hindering cost-effective performance improvements.
Innovation Solution
A non-volatile memory device with a mold structure featuring a step-shaped arrangement of gate electrodes and insulating layers, along with a channel and cell contact structure that enhances contact area with gate electrodes, improving integration and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If two-dimensional non-volatile memory devices use fine pattern formation to increase integration, then integration density improves, but manufacturing cost increases due to expensive equipment requirements
Solution Approach 1:
The patent transitions from two-dimensional planar memory cells to three-dimensional vertically-stacked memory cells. Multiple gate electrodes and channel structures are stacked in the vertical direction, allowing integration density to increase without requiring proportionally smaller lateral feature sizes. This dimensional change enables higher integration while avoiding the need for extremely expensive fine-patterning equipment.
2Quantity of substance
If three-dimensional memory structures are implemented to increase integration, then integration density improves, but device complexity increases
Solution Approach 1:
The three-dimensional memory structure is segmented into repeating units, each comprising a channel structure and associated gate electrodes stacked vertically. This modular segmentation allows the complex 3D structure to be built from standardized building blocks, simplifying manufacturing and reducing overall device complexity while maintaining high integration density.
Solution Approach 2:
Multiple gate electrodes are nested around the channel structure in a vertical stack, with each gate electrode positioned at different heights. This nesting arrangement allows multiple control elements to be integrated in a compact vertical space, achieving high integration density without proportionally increasing lateral footprint or manufacturing complexity.
3Quantity of substance
If contact structure width is reduced to increase integration, then integration density improves, but contact reliability deteriorates
Solution Approach 1:
The contact structure transitions from a lateral width-based contact to a vertical-height-based contact. By extending the contact structure vertically to make contact with the uppermost gate electrode, the effective contact area is increased without requiring larger lateral dimensions. This maintains integration density while improving contact reliability through increased contact area.
Data Source
AI summary
A non-volatile memory device includes a substrate having a cell array region and an extension region. A mold structure includes a plurality of gate electrodes and a plurality of mold insulating layers alternately stacked on the substrate such that the mold structure has a step shape that steps downwardly in the extension region in a direction away from the cell array region. A channel structure penetrates through the mold structure in the cell array region, and a cell contact structure penetrates through the mold structure in the extension region. A portion of the cell contact structure is in contact with a portion of an uppermost one of the gate electrodes. The cell contact structure includes a first portion in contact with a side surface of the uppermost one of the gate electrodes and a second portion in contact with a top surface of the uppermost one of the gate electrodes. A width of the first portion is smaller than a width of the second portion.