Integrated Support and Contact Structures in 3D Memory
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in achieving efficient structural support and contact formation for vertical NAND strings, leading to limitations in device density and reliability.
Innovation Solution
The proposed solution involves forming an alternating stack of insulating and sacrificial material layers over a substrate, creating memory and support openings, and replacing the sacrificial layers with electrically conductive layers while using fin-containing dielectric pillars and tubular dielectric liners to provide structural support and contact structures, enabling the formation of integrated support and contact structures within the memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional separate support structures and contact structures are used in three-dimensional memory devices, then structural support is provided, but device density is limited and fabrication complexity increases
Solution Approach 1:
The patent combines the support structure and contact structure into a single integrated support and contact structure. The fin-containing dielectric pillar serves dual functions: providing structural support during fabrication and serving as the contact structure after sacrificial material removal. This merging eliminates the need for separate support structures and subsequent removal processes, thereby increasing device density and simplifying fabrication.
Solution Approach 2:
The integrated support and contact structure performs multiple functions: it provides structural support during the fabrication process, defines the contact region, and becomes the final contact structure. The fin-containing dielectric pillar universally serves both as a support element and as a contact conduit, reducing the number of required structures and fabrication steps.
2Quantity of substance
If larger terrace regions are used to accommodate separate support structures, then structural support is ensured, but device density decreases
Solution Approach 1:
By merging the support function and contact function into a single structure, the patent eliminates the need for large terrace regions. The integrated support and contact structure can be formed in smaller openings, allowing closer spacing of memory stack structures and thereby increasing device density while maintaining adequate structural support.
Solution Approach 2:
The patent uses vertical fins extending from the dielectric pillar to provide structural support in the vertical dimension, allowing the horizontal footprint to be minimized. This dimensional approach enables sufficient support strength with reduced terrace region area, increasing overall device density.
3Reliability
If conventional contact formation processes are used, then contact structures are formed, but the risk of punch-through and short circuits increases
Solution Approach 1:
The integrated support and contact structure is formed before the sacrificial material is removed. This preliminary formation ensures that the contact structure is in place and properly positioned before critical subsequent processing steps, reducing the risk of misalignment, punch-through, or short circuits that could occur with later contact formation.
Solution Approach 2:
The dielectric material surrounding the fin-containing structure provides beforehand cushioning and protection during fabrication. This dielectric cushion prevents damage to the contact structure during processing and reduces the risk of punch-through and short circuits by providing electrical isolation and mechanical protection.
Data Source
AI summary
Memory openings and support openings are formed through an alternating stack of insulating layers and sacrificial material layers over a substrate. The support openings are laterally expanded by laterally recessing the insulating layers with respect to the sacrificial material layers. The laterally expanded support openings are filled with a combination of a dielectric material and a sacrificial fill material to form support pillar structures. After forming memory films and channels in the memory openings, the sacrificial material layers are replaced with electrically conductive layers while the support pillar structures provide structural support to the insulating layers. The sacrificial fill material is replaced with contact via structures to form integrated support and contact structures.