Charge-Trapping Material Additives for Flash Memory Retention
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Solution Overview
Problem
Charge-trapping-material in memory cells often has too many shallow traps, leading to poor charge retention, which is a challenge in improving the data storage capabilities of flash memory devices.
Innovation Solution
Incorporating trap-enhancing-additives such as carbon, boron, phosphorus, or metal into the charge-trapping-material, like silicon nitride, to modify the trap depth and increase trap density while maintaining desired retention properties, thereby enhancing charge retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charge-trapping-material is used in memory cells, then the device structure is simple and manufacturing is easier, but the charge retention is poor due to too many shallow traps
Solution Approach 1:
The patent applies composite materials by combining silicon nitride with trap-enhancing additives (carbon, boron, phosphorus, or metal) to create a composite charge-trapping-material. This composite structure provides both the structural foundation of silicon nitride and the trap-depth modification of the additives, resolving the contradiction between simple structure and improved charge retention.
Solution Approach 2:
The patent changes the chemical composition parameters of the charge-trapping-material by incorporating specific concentrations of trap-enhancing additives (e.g., carbon at 0.2-20 atomic percent, boron at 0.2-20 atomic percent). This parameter modification transforms the trap depth distribution from predominantly shallow to including deeper traps, thereby improving charge retention while maintaining manufacturing feasibility.
2Reliability
If trap-enhancing-additives are incorporated into charge-trapping-material, then deeper traps are created and charge retention improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the deposition of trap-enhancing-additives with the existing silicon nitride formation process. By combining these steps into a single integrated manufacturing process, the patent achieves improved charge retention through additive incorporation while minimizing the increase in manufacturing complexity.
Solution Approach 2:
The patent modifies existing manufacturing parameters (such as deposition conditions, temperature, or chemical ratios) to simultaneously achieve silicon nitride formation and trap-enhancing-additive incorporation. This parameter optimization allows the manufacturing process to produce the composite material in a streamlined manner, reducing the impact of added complexity.
3Reliability
If more trap-enhancing-additives are added to increase trap density, then charge retention improves, but the material composition becomes more complex and harder to control
Solution Approach 1:
The patent establishes specific parameter ranges for trap-enhancing-additive concentrations (e.g., carbon: 0.2-20 atomic percent, boron: 0.2-20 atomic percent, phosphorus: 0.2-20 atomic percent, metal: 0.2-20 atomic percent). These controlled parameter specifications enable precise composition control during manufacturing while ensuring sufficient trap density for improved charge retention.
Solution Approach 2:
The patent applies local quality by concentrating trap-enhancing-additives specifically within the charge-trapping-material layer rather than distributing them uniformly throughout the entire memory cell structure. This localized application improves composition control precision by limiting the complexity to a specific region where it is most needed for charge retention.
Data Source
AI summary
Some embodiments include a memory cell having charge-trapping-material between a semiconductor channel material and a gating region. The charge-trapping-material includes silicon, nitrogen and trap-enhancing-additive. The trap-enhancing-additive includes one or more of carbon, phosphorus, boron and metal. Some embodiments include an integrated assembly having a stack of alternating first and second levels. The first levels include conductive structures and the second levels are insulative. Channel-material-pillars extend through the stack. Charge-trapping-regions are along the channel-material-pillars and are between the channel-material-pillars and the conductive structures. The charge-trapping-regions include a charge-trapping-material which contains silicon, nitrogen and trap-enhancing-additive. The trap-enhancing-additive includes one or more of carbon, phosphorus, boron and metal.