Charge-Trapping Memory Cells with Additives for Better 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 maintaining data storage reliability in flash memory devices like NAND memory arrays.
Innovation Solution
Incorporating trap-enhancing-additives such as carbon, boron, phosphorus, or metal into the charge-trapping-material, specifically silicon nitride, to modify trap depths 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 framework of silicon nitride and the trap-depth modification from 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 shallow-dominated to deeper-trap-enriched, improving charge retention while maintaining manufacturing feasibility.
2Reliability
If trap-enhancing-additives are incorporated into charge-trapping-material, then charge retention is improved through deeper traps, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-mixing the trap-enhancing additives with the silicon nitride material before deposition. This preliminary preparation allows the additives to be uniformly distributed in the source material, simplifying the subsequent deposition process and making the enhanced manufacturing complexity manageable through advance preparation.
Solution Approach 2:
The trap-enhancing additives serve as intermediaries that mediate between the silicon nitride matrix and the charge storage function. These additive elements (carbon, boron, phosphorus, or metal) act as intermediate components that modify the electronic structure and trap depth without requiring complete restructuring of the material system, thus limiting the increase in manufacturing complexity.
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 incorporation of trap-enhancing-additives within the charge-trapping-material improves charge retention by creating deeper traps, addressing the issue of shallow traps and enhancing the overall performance of memory cells in NAND memory devices.
Implementation Method 1
charge-trapping-material includes silicon, nitrogen and trap-enhancing-additive... improves charge retention by creating deeper traps
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.