Nonvolatile Memory Dummy Patterns for Warpage Control
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Solution Overview
Problem
Nonvolatile memory devices face warpage issues due to the limitations in integration density and structural integrity, particularly in three-dimensional memory devices where unit memory cells are vertically arranged, leading to challenges in maintaining compactness and performance.
Innovation Solution
Incorporating a dummy pattern composed of dummy material in trenches formed on the substrates where the upper and lower insulating layers meet, which helps in stabilizing the structure and preventing warpage by distributing stress and maintaining the thickness of the substrates effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If three-dimensional memory device structure with vertically arranged unit memory cells is adopted to increase integration density, then integration density is improved, but structural integrity deteriorates leading to warpage
Solution Approach 1:
The patent introduces dummy patterns specifically at the substrate regions where insulating layers are formed, creating local structural reinforcement zones. These dummy patterns are strategically placed only where needed to prevent warpage during bonding processes, rather than uniformly across the entire device structure, thus maintaining high integration density while providing targeted structural support.
Solution Approach 2:
The patent employs composite structure by combining the active memory cell regions with dummy pattern regions. The dummy patterns are formed using the same material layers as the functional regions (including semiconductor layers and insulating layers), creating a composite structure that provides mechanical stability without interfering with the electrical functionality of the memory device.
2Productivity
If substrate thickness is reduced to enable higher integration density, then integration density is improved, but mechanical strength deteriorates causing warpage during bonding
Solution Approach 1:
The patent forms dummy patterns in advance before the bonding process, creating preliminary structural reinforcement elements within the substrate. These dummy patterns are prepared as part of the substrate fabrication process, ensuring that the mechanical strength is sufficient during subsequent bonding operations without requiring thicker substrates or post-fabrication reinforcement.
Solution Approach 2:
The dummy patterns provide localized mechanical strength enhancement only in the regions where insulating layers will be formed and bonded. This local reinforcement approach allows the majority of the substrate to remain thin for high integration density, while specific critical regions gain the necessary mechanical strength to prevent warpage during bonding processes.
Data Source
AI summary
A nonvolatile memory device includes an upper insulating layer. A first substrate is on the upper insulating layer. An upper interlayer insulating layer is on the first substrate. A plurality of word lines is stacked on the first substrate in a first direction and extends through a partial portion of the upper interlayer insulating layer. A lower interlayer insulating layer is on the upper interlayer insulating layer. A second substrate is on the lower interlayer insulating layer. A lower insulating layer is on the second substrate. A dummy pattern is composed of dummy material. The dummy pattern is disposed in a trench formed in at least one of the first and second substrates. The trench is formed on at least one of a surface where the upper insulating layer meets the first substrate, and a surface where the lower insulating layer meets the second substrate.