3D Memory Word Lines With Conductive Caps Against Molybdenum Oxidation
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in effectively forming capped molybdenum word lines and achieving efficient memory opening fill structures within the memory openings, particularly in integrating conductive capping materials that maintain electrical conductivity while preventing oxidation of molybdenum layers.
Innovation Solution
The method involves forming an alternating stack of insulating and molybdenum layers, selectively depositing conductive capping materials like ruthenium or tungsten within memory openings, and replacing sacrificial silicon nitride layers with molybdenum layers, ensuring the capping materials are in contact with the molybdenum layers to form electrically conductive layers that protect against oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive capping materials are deposited on molybdenum layers to prevent oxidation, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies composite materials by creating electrically conductive layers that combine molybdenum layers with conductive capping materials (such as ruthenium, tungsten, or their nitrides/oxides). This composite structure prevents oxidation of the molybdenum while maintaining electrical conductivity, directly resolving the contradiction between reliability improvement and device complexity increase.
Solution Approach 2:
The conductive capping materials serve as intermediary layers between the molybdenum word lines and the surrounding environment. These capping materials protect the molybdenum from oxidation while maintaining electrical conductivity, effectively mediating between the need for oxidation protection and the requirement for electrical functionality.
2Productivity
If sacrificial silicon nitride layers are replaced with molybdenum layers, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by first forming sacrificial silicon nitride layers in the alternating stack before replacing them with molybdenum layers. This preliminary structure guides the subsequent selective deposition of conductive capping materials, ensuring precise formation of the memory opening fill structures while maintaining manufacturing efficiency.
Solution Approach 2:
The conductive capping materials are selectively deposited only in specific locations where the sacrificial silicon nitride layers were previously positioned. This local quality approach ensures that capping materials are formed with high precision only where needed, rather than uniformly across the entire structure, thereby balancing manufacturing precision requirements with productivity.
3Reliability
If alternating stacks of insulating and molybdenum layers are formed, then electrical conductivity is improved, but loss of substance increases
Solution Approach 1:
The patent applies thin films by using thin molybdenum layers in the alternating stack structure. The molybdenum layers are sufficiently thin to reduce material usage while still providing the necessary electrical conductivity when combined with the conductive capping materials. This thin film approach minimizes loss of molybdenum substance while maintaining electrical performance.
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 enables the creation of robust three-dimensional memory devices with effective memory opening fill structures, ensuring reliable electrical conductivity and preventing molybdenum oxidation, thereby enhancing the performance and durability of the memory devices.
Implementation Method 1
selectively depositing conductive capping materials like ruthenium or tungsten within memory openings
Implementation Method 2
selectively depositing conductive capping materials like ruthenium or tungsten within memory openings
Implementation Method 3
conductive capping material portions which comprise a material other than molybdenum and which are in contact with an outer sidewall of a respective one of the memory opening fill structures
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers, memory openings vertically extending through the alternating stack, and memory opening fill structures located within the memory openings. Each of the memory opening fill structures includes a respective vertical semiconductor channel and a respective vertical stack of memory elements. Each of the electrically conductive layers include a molybdenum layer and a plurality of conductive capping material portions in contact with an outer sidewall of a respective one of the memory opening fill structures.