3D Memory Cell Stack Layout With Dummy Support Structures
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Solution Overview
Problem
Existing integrated circuit fabrication techniques struggle to produce smaller and denser memory cells due to the lack of effective methods for forming vertically overlapping and horizontally extending features in semiconductor substrates.
Innovation Solution
The method involves forming a stack of alternating sacrificial and dielectric materials over a semiconductor substrate, creating openings in the stack, and depositing conductive or programmable materials into these openings to form operative and dummy structures. These structures are then extended horizontally and vertically to create overlapping features that support the formation of smaller and denser memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication techniques are used, then manufacturing process is simple, but memory cell size and density cannot be reduced
Solution Approach 1:
The patent transitions from planar 2D memory cell layouts to 3D vertically overlapping structures. Multiple memory cells are stacked vertically with horizontally extending features at different elevation levels, enabling density multiplication without increasing footprint area. The vertically overlapping conductive and insulating layers create multiple functional planes within a single vertical column space.
Solution Approach 2:
The memory array is segmented into multiple vertically stacked layers, each containing horizontally extending features. Individual memory cells are divided across these layers, with conductive elements at different elevations forming separate but interconnected functional units. This segmentation allows parallel processing and independent formation of each layer's features.
2Quantity of substance
If vertically overlapping and horizontally extending features are formed, then memory cell density increases, but fabrication process complexity increases
Solution Approach 1:
Alternating conductive and insulating layers are formed in a predetermined stacked sequence before any patterning or opening formation occurs. This preliminary layering establishes the vertical framework that guides subsequent horizontal feature formation, ensuring proper alignment and electrical isolation between layers without requiring complex post-formation adjustments.
Solution Approach 2:
Horizontally extending features are formed within openings that penetrate through multiple vertically stacked layers. The features are nested within the vertical structure, with conductive elements positioned within insulating matrices at different elevations. This nesting allows multiple functional elements to occupy the same horizontal footprint while maintaining vertical separation.
3Manufacturing precision
If smaller memory cells are fabricated, then integrated circuit density improves, but structural support becomes insufficient
Solution Approach 1:
The structure combines conductive materials (such as metal layers) with insulating materials (such as dielectric layers) in alternating vertical stacks. This composite arrangement provides both electrical functionality and mechanical support, with the insulating layers acting as structural matrices that hold and isolate the thinner conductive features while contributing to overall structural integrity.
Solution Approach 2:
By extending features horizontally through multiple vertical layers rather than confining them to a single plane, the patent distributes mechanical loads across a larger three-dimensional volume. The horizontally extending conductive traces spanning multiple elevations provide reinforcement similar to rebar in concrete, preventing structural failure despite reduced feature dimensions.
Data Source
AI summary
A method of forming circuitry components includes forming a stack of horizontally extending and vertically overlapping features. The features extend horizontally though a primary portion of the stack with at least some of the features extending extend farther in the horizontal direction in an end portion. Operative structures are formed vertically through the features in the primary portion and dummy structures are formed vertically through the features in the end portion. Openings are formed through the features to form horizontally elongated and vertically overlapping lines from material of the features. The lines individually extend laterally about sides of vertically extending portions of both the operative structures and the dummy structures. Sacrificial material that is elevationally between the lines is at least partially removed in the primary and end portions laterally between the openings. Other aspects and implementations are disclosed.