3D Memory Device Channel Density via Curvature Etching
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Solution Overview
Problem
Current three-dimensional NAND memory devices have limitations in device density due to the presence of dummy rows of inactive semiconductor channels under drain-select-level dielectric isolation structures, which occupy space and reduce efficiency.
Innovation Solution
The formation of plural vertical semiconductor channels in each memory opening, along with the elimination of dummy rows by using a curvature-dependent lateral etch process, increases device density and optimizes the arrangement of memory stack structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dummy rows of inactive semiconductor channels are present under drain-select-level dielectric isolation structures, then device layout is simplified, but device density is reduced
Solution Approach 1:
The patent removes the dummy rows of inactive semiconductor channels from the device structure. By extracting these non-functional elements, the invention increases device density without complicating the manufacturing process, as the removal is achieved through standard etching techniques that eliminate unnecessary structures while preserving the functional memory channels.
Solution Approach 2:
The invention changes the physical parameters of the semiconductor channels by controlling the etch process to create crescent-shaped cross-sections with specific curvature characteristics. This parameter change allows the etch to selectively remove material in certain regions while preserving channels in others, enabling the elimination of dummy rows while maintaining functional structures.
2Quantity of substance
If curvature-dependent lateral etch process is used, then device density is increased, but manufacturing complexity increases
Solution Approach 1:
The patent employs a curvature-dependent lateral etch process that utilizes the curvature of surfaces as a parameter to control etching rates. Surfaces with lower curvature are etched at higher rates while surfaces with higher curvature are etched at lower rates. This parameter-based approach increases device density by selectively removing material while following natural geometric variations, rather than requiring complex patterning steps.
Solution Approach 2:
The etch process is designed to be self-directed by the geometry of the structures themselves. The curvature of the semiconductor channel surfaces automatically determines the etch rate distribution, with the process naturally conforming to the desired crescent-shaped profiles without requiring additional masking or patterning steps. This self-service mechanism simplifies manufacturing while achieving the density improvements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances device density by eliminating unnecessary semiconductor channels and optimizing the layout, leading to more efficient use of space and improved performance in three-dimensional memory devices.
Implementation Method 1
performing a curvature-dependent lateral etch process that etches surfaces of the semiconductor channel layer having a lower curvature at a higher etch rate than surfaces of the semiconductor channel layer having a higher curvature
Data Source
AI summary
A three-dimensional memory device includes an alternating stacks of insulating layers and electrically conductive layers. Memory opening fill structures located in memory openings include a memory film and plural vertical semiconductor channels.