3D Memory Through-Stack Contact Vias With Nested Bulged Connections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing three-dimensional memory devices face challenges in efficiently forming through-stack contact via structures, which are crucial for enhancing connectivity and performance in vertical NAND strings.
Innovation Solution
The formation of a device structure involving alternating stacks of insulating and conductive layers with stepped surfaces, retro-stepped dielectric material portions, and contact via structures that include laterally bulging and vertically extending components, along with annular dielectric spacers, to create stable and efficient connections through the stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional through-stack contact via structures are formed in three-dimensional memory devices, then connectivity is provided through alternating stacks, but the manufacturing complexity and difficulty of forming precise contact structures increase
Solution Approach 1:
The contact via structure is divided into multiple distinct portions: a first portion extending through first alternating stacks, a second portion extending through second alternating stacks, and a third portion coupling these portions. This segmentation allows each portion to be formed and optimized independently, reducing manufacturing complexity while ensuring reliable connectivity through the device.
2Reliability
If through-stack contact via structures are formed to enhance connectivity, then performance improves, but the structural complexity and precision requirements increase
Solution Approach 1:
A dielectric material is introduced as an intermediary substance filling the contact via structure. This dielectric material facilitates the formation process by providing a manageable medium that can be deposited and patterned with standard manufacturing techniques, thereby reducing precision requirements while maintaining performance through proper electrical isolation and structural support.
3Reliability
If contact via structures extend through multiple alternating stacks, then connectivity is enhanced, but the manufacturing process difficulty increases
Solution Approach 1:
The contact via structure employs a nested configuration where the first, second, and third portions are hierarchically arranged and coupled. The first portion is nested within the first alternating stacks, the second portion within the second alternating stacks, and the third portion couples them together. This nesting allows sequential formation processes where each portion can be created in its own manufacturing step, significantly easing the overall manufacturing difficulty while achieving enhanced connectivity through multiple stacks.
Data Source
AI summary
A device structure includes at least one alternating stack of respective insulating layers and respective electrically conductive layers, the at least one alternating stack includes respective stepped surfaces located in a staircase region, at least one retro-stepped dielectric material portion overlying portions of the at least one alternating stack located in the staircase region, a memory opening vertically extending through each layer within the at least one alternating stack, a memory opening fill structure located in the memory opening, a first contact via structure including a first laterally bulging portion in contact with a first electrically conductive layer of the electrically conductive layers within the at least one alternating stack, and a second contact via structure including a plurality of second laterally bulging portions in contact with a plurality of second electrically conductive layers of the electrically conductive layers within the at least one alternating stack.