Vertical Memory Channel Protection Against Etching Damage
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Solution Overview
Problem
The complexity of the selective epitaxial growth process increases with the number of stacked memory cells, leading to challenges in forming uniform openings in the side surfaces of channel structures and preventing over-etching of information storage patterns in vertical nonvolatile memory devices.
Innovation Solution
A memory device design that includes a channel protective film between the protrusion of the second source film and the information storage pattern, which helps control the etching process and prevent over-etching, ensuring uniformity and reducing channel resistance by increasing the contact area between the channel pattern and the second source film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective epitaxial growth process is used to electrically connect channel pattern to substrate, then electrical connection is achieved, but process complexity increases with number of stacked memory cells
Solution Approach 1:
The patent extracts the SEG process from the manufacturing flow by directly forming the second source film through deposition after etching the channel structure opening. This eliminates the need for selective epitaxial growth while maintaining electrical connection between the channel pattern and substrate, thereby reducing process complexity.
2Reliability
If opening is formed in side surface of channel structure, then electrical connection is achieved, but etching uniformity of information storage pattern becomes difficult to control
Solution Approach 1:
The patent introduces a channel protective film as an intermediary layer between the information storage pattern and the etching process. This film is formed on the information storage pattern before etching, allowing uniform etching to proceed while protecting the underlying structure. The protective film serves as a mediator that enables precise control of etching depth and uniformity.
3Reliability
If opening is formed in side surface of channel structure, then electrical connection is achieved, but over-etching of information storage pattern occurs
Solution Approach 1:
The patent applies preliminary action by forming the channel protective film on the information storage pattern before the etching process begins. This pre-formed protective layer prevents over-etching by serving as a barrier that limits the etching depth. The protective film is removed after etching is complete, having fulfilled its protective function and prevented damage to the information storage pattern.
4Manufacturing precision
If channel protective film is disposed between protrusion and information storage pattern, then etching uniformity is improved, but device structure becomes more complex
Solution Approach 1:
The channel protective film is a temporary structure formed during manufacturing that is discarded (removed) after serving its protective function. The film is deposited on the information storage pattern, enables uniform etching, and then is completely removed to reveal the uniformly etched information storage pattern. This temporary addition does not become part of the final device structure, thus avoiding permanent complexity increase.
Data Source
AI summary
A memory device includes a substrate having a first source film thereon and an upper stacked structure on the first source film. An electrically conductive channel structure is provided, which extends through the upper stacked structure and the first source film. The channel structure includes a channel pattern, which extends vertically through the upper stacked structure and the first source film, and an information storage pattern on a sidewall of the channel pattern. A second source film is provided, which extends between the first source film and a surface of the substrate. The second source film, which contacts the channel pattern, includes an upward extending protrusion, which extends underneath the information storage pattern. A channel protective film is provided, which extends between at least a portion of the protrusion and at least a portion of the information storage pattern.