3D Nonvolatile Memory Separation Trenches for Mold Lift Prevention
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Solution Overview
Problem
Current nonvolatile memory devices face challenges in increasing storage capacity and reliability due to limitations in their design, particularly in the formation of separation trenches which can lead to faults like mold lifting and reduced integration density.
Innovation Solution
A three-dimensional nonvolatile memory device with a vertical channel structure is developed, featuring a staircase extension area, alternate stacking of electrode layers and interlayer insulating layers, and varying depths of separation trenches to prevent faults and enhance integration, along with a method of fabrication that includes forming insulating and support layers, creating a mold structure, and substituting sacrificial layers with conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separation trenches are formed in conventional nonvolatile memory devices, then cell separation is achieved, but mold lifting faults occur and integration density decreases
Solution Approach 1:
The separation insulating layer is divided into multiple segments with different depths: a first separation insulating layer at a first depth and a second separation insulating layer at a second depth greater than the first depth. This segmentation allows different regions of the memory device to have optimized separation structures, preventing mold lifting in critical areas while maintaining integration density overall.
Solution Approach 2:
Different depths of separation insulating layers are applied to different regions of the device. The first separation insulating layer provides separation in general areas, while the second separation insulating layer provides deeper separation in specific regions where mold lifting is a concern. This local differentiation of quality resolves the contradiction by providing enhanced separation only where needed.
2Productivity
If storage capacity is increased through vertical stacking, then integration density improves, but manufacturing precision requirements increase
Solution Approach 1:
The electrode layers are divided into multiple stacks: a first stack of electrode layers and a second stack of electrode layers separated by the separation insulating layers. This segmentation of the vertical structure allows for more manageable manufacturing processes compared to forming a single tall stack, as each sub-stack can be formed and separated independently, reducing the cumulative precision requirements.
Solution Approach 2:
The separation insulating layers are formed between the electrode layer stacks during the stacking process itself, rather than requiring post-formation separation. This preliminary action of creating separation structures during assembly reduces the need for high-precision post-processing steps and simplifies the overall manufacturing sequence.
Data Source
AI summary
A three-dimensional nonvolatile memory device includes: a substrate including a cell area and an extension area having a staircase structure; a vertical structure on the substrate; a stacking structure having electrode layers and interlayer insulating layers on the substrate; a separation insulating layer on the substrate and separating the electrode layers; and a through-via wiring area adjacent to the cell or extension area and having through-vias passing through the substrate, wherein the cell area includes a main cell area in which normal cells are arranged and an edge cell area, the separation insulating layer includes a main separation insulating layer in the main cell area and an edge separation insulating layer in the edge cell area, and a lower surface of the main separation insulating layer is higher than the upper surface of the substrate and has a different depth than a lower surface of the edge separation insulating layer.