3D Memory Connection Strap for Vertical Channel Reliability
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently connecting vertical semiconductor channels to underlying semiconductor materials, leading to discontinuities and high resistance in the semiconductor channel layer, which affects the on-current and operability of NAND strings.
Innovation Solution
A three-dimensional semiconductor device is developed with connection straps made of single crystalline semiconductor material extending through memory films, contacting both the vertical semiconductor channels and the underlying semiconductor material, ensuring a robust physical and electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connection methods are used to connect vertical semiconductor channels to underlying semiconductor materials, then the device structure is simpler, but the resistance is high and the connection is discontinuous
Solution Approach 1:
A connection strap comprising single crystalline semiconductor material is introduced as an intermediary element between the vertical semiconductor channel and the underlying semiconductor material. This strap extends through an opening in the memory film to establish direct physical and electrical contact, ensuring continuous connection and reducing resistance at the interface.
Solution Approach 2:
The connection strap is formed using single crystalline semiconductor material with different crystallographic orientation than the vertical semiconductor channel. This parameter change in material structure enables improved electrical properties and continuous connection, transforming the discontinuous high-resistance interface into a low-resistance conductive path.
2Reliability
If single crystalline strap material is used for connection, then the electrical connection is continuous and resistance is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The opening through the memory film is formed in advance before depositing the connection strap material. This preliminary action creates a defined pathway that guides the subsequent deposition process, allowing the single crystalline material to be selectively grown or deposited only in the required location to form the connection strap.
Solution Approach 2:
The connection strap is formed using selective deposition processes (such as CVD or epitaxial growth) rather than mechanical assembly. This substitution enables precise control over the material's crystal structure and continuity, ensuring reliable electrical connection while maintaining manufacturing feasibility through standardized semiconductor fabrication techniques.
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
The solution enhances the on-current of NAND strings and improves operability by providing a continuous and reliable connection between the vertical semiconductor channels and the underlying material, reducing resistance and ensuring stable device performance.
Implementation Method 1
The connection strap comprises a single crystalline strap semiconductor material, and the vertical semiconductor channel comprises a polycrystalline semiconductor material
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 is formed in the memory opening. The memory film includes an opening at a bottom portion. A connection strap is formed by performing a selective semiconductor deposition process that grows a strap semiconductor material from a physically exposed surface of an underlying semiconductor material portion through the opening. A vertical semiconductor channel is formed on an inner sidewall of the memory film by non-selectively depositing a semiconductor channel material. The connection strap provides an electrical connection between the underlying semiconductor material portion and the vertical semiconductor channel through the opening in the memory film. The sacrificial material layers are then replaced with electrically conductive layers.