Silicon Nitride Ring for Uniform Vertical Channel in 3D Memory
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in achieving uniform-thickness vertical semiconductor channels, which are crucial for efficient memory operations, due to limitations in the formation of silicon nitride rings and tunneling dielectric layers.
Innovation Solution
A three-dimensional memory device is designed with a silicon nitride ring formed around an opening in a memory film, using a method that selectively grows silicon nitride material on sidewalls while suppressing deposition on tunneling dielectric layers and chemical oxide surfaces, enabling a continuous semiconductor channel to be deposited for uniform thickness and improved channel integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form silicon nitride rings and tunneling dielectric layers, then the memory device can be manufactured, but uniform-thickness vertical semiconductor channels cannot be achieved
Solution Approach 1:
The patent performs preliminary actions by forming the memory film with the opening and preparing the sidewall surface before depositing the silicon nitride ring. This preliminary preparation ensures that subsequent semiconductor channel deposition occurs on a properly prepared surface, enabling uniform thickness. The tunneling dielectric layer is also formed in advance with controlled thickness, setting the stage for achieving uniform vertical channels.
Solution Approach 2:
The patent applies local quality by forming the silicon nitride ring specifically around the opening in the memory film, creating a localized structure with distinct properties. The ring has a specific thickness and position that differs from surrounding areas, allowing precise control over the semiconductor channel formation in that local region. This localized approach enables uniform channel thickness where needed while maintaining flexibility in other areas.
2Reliability
If silicon nitride material is deposited on all surfaces, then complete coverage is achieved, but deposition on tunneling dielectric layers and chemical oxide surfaces cannot be suppressed
Solution Approach 1:
The patent uses the opening structure in the memory film as an intermediary element that enables selective deposition. The opening provides a defined space where silicon nitride ring material can be deposited on sidewalls while preventing deposition on tunneling dielectric layers and chemical oxide surfaces. This intermediary structure acts as a physical barrier and deposition template, ensuring material is placed only where needed for channel integrity.
Solution Approach 2:
The patent implements local quality by controlling deposition to occur only on specific surfaces - the sidewalls of the opening - while suppressing deposition on other surfaces like tunneling dielectric layers and chemical oxide surfaces. This spatially selective deposition ensures that silicon nitride material is deposited only where it contributes to channel integrity, maintaining reliability while simplifying the manufacturing process through natural deposition selectivity.
3Reliability
If the semiconductor channel is deposited without a silicon nitride ring, then the manufacturing process is simpler, but channel discontinuity is more likely to occur
Solution Approach 1:
The patent performs preliminary action by forming the silicon nitride ring structure before depositing the semiconductor channel material. This pre-formed ring provides a reliable template and support structure that ensures continuous channel formation. The ring is prepared in advance with proper thickness and positioning, eliminating the risk of channel discontinuity during subsequent deposition steps.
Solution Approach 2:
The silicon nitride ring acts as an intermediary structure between the substrate and the semiconductor channel. It provides a stable foundation and confinement structure that guides the semiconductor material deposition, ensuring continuous and uniform channel formation. This intermediary element simplifies the overall process by providing a reliable framework that prevents channel discontinuity without requiring complex in-situ control mechanisms.
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 ensures a uniform-thickness vertical semiconductor channel, enhancing the operational efficiency and reliability of the memory device by reducing the likelihood of channel discontinuity and increasing on-current in NAND strings.
Implementation Method 1
forming a silicon nitride ring by selectively growing a silicon nitride material from a physically exposed sidewall of an annular silicon nitride layer portion of the silicon nitride layer while suppressing deposition of the silicon nitride material on a physically exposed surface of the tunneling dielectric layer and on the chemical oxide layer
Implementation Method 2
forming a chemical oxide layer on the physically exposed surface of the underlying semiconductor material portion
Data Source
AI summary
An alternating stack of insulating layers and sacrificial material layers is formed over a substrate. A memory opening is formed through the alternating stack. A memory film including a silicon nitride layer and a tunneling dielectric layer is formed in the memory opening, and an opening is formed through the memory film. A chemical oxide layer is formed on a physically exposed surface of an underlying semiconductor material portion. A silicon nitride ring can be formed by selectively growing a silicon nitride material from an annular silicon nitride layer portion of the silicon nitride layer while suppressing deposition of the silicon nitride material on the tunneling dielectric layer and on the chemical oxide layer. A vertical semiconductor channel can be formed by depositing a continuous semiconductor material layer on the underlying semiconductor material portion and the tunneling dielectric layer and on the silicon nitride ring.